- Email: [email protected]
Dissemination of methicillin-resistant Staphylococcus aureus sequence type 45 among nursing home residents and staff in Taiwan
Accepted Manuscript Dissemination of methicillin-resistant Staphylococcus aureus ST45 among nursing home residents and staff in taiwan Fang-Ying Tsao, Hao-Wei Kou, Yhu-Chering Huang, Dr. PII:
S1198-743X(14)00172-4
DOI:
10.1016/j.cmi.2014.12.019
Reference:
CMI 134
To appear in:
Clinical Microbiology and Infection
Received Date: 26 August 2014 Revised Date:
20 November 2014
Accepted Date: 19 December 2014
Please cite this article as: Tsao F-Y, Kou H-W, Huang Y-C, Dissemination of methicillin-resistant Staphylococcus aureus ST45 among nursing home residents and staff in taiwan, Clinical Microbiology and Infection (2015), doi: 10.1016/j.cmi.2014.12.019. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Dissemination of Methicillin-resistant Staphylococcus aureus ST45 among Nursing Home Residents and Staff in Taiwan
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Fang-Ying Tsao1, Hao-Wei Kou1, Yhu-Chering Huang1, 2 School of Medicine, Chang Gung University, Gueishan, Taoyuan, Taiwan,
2
Department of Pediatrics, Chang Gung Memorial Hospital at Linkou, Gueishan,
Taoyuan, Taiwan
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First two authors equally contributed to this work.
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Short title: MRSA in nursing homes in Taiwan
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Correspondence: Dr. Yhu-Chering Huang, Department of Pediatrics, Chang Gung Memorial Hospital, No. 5, Fu-Shin Street, Gueishan 333, Taoyuan, Taiwan. Fax: +886-3-3288957
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TEL: +886-3-3281200
E-mail: [email protected]
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The authors have indicated they have no financial relationships relevant to this article to disclose.
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ACCEPTED MANUSCRIPT Abstract Unlike hospital or community, nursing home provides a unique health-caring
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environment for patients. There have been no reports regarding methicillin-resistant Staphylococcus aureus (MRSA) carriage among nursing home residents and staff in
Taiwan. From May to November 2012, a total of 523 subjects, including 360 residents
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and 163 staff, in 14 nursing homes in Taiwan were surveyed for nasal MRSA carriage.
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Overall, nasal MRSA carriage rate was 20.1%, with 20.3% for residents and 19.6 % for staff. For residents, age order than 60 years old (adjust odds ratio (OR) 2.268; 95% confidence interval (CI) 1.185–4.342; p =0 .013) and the presence of chronic wound (adjust OR 2.449,;95% CI 1.082–5.544; p =0 .032) were the significant risk factors
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for MRSA carriage in multivariate models. Of the 105 MRSA isolates, 11 pulsed-field gel electrophoresis (PFGE) patterns were identified except five isolates untypeable by
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SmaI digestion, with one major pattern; 9 isolates (8.6%) possessed staphylococcal
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cassette chromosome (SCCmec) type II or III, 66 isolates type IV or V and 21 isolates unidentified types. The clone characterized as PFGE pattern BM-sequence type (ST) 45 was the most common clone, accounting for 50% of the isolates, and was multiresistant, including to ciprofloxacin. Intra- and inter- institutional transmission of MRSA was documented by molecular methods. Conclusively, one-fifth of residents and staff, respectively, in nursing homes in Taiwan harbored MRSA, mostly ST45
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ACCEPTED MANUSCRIPT strains, in their nares. Intra- and inter- institutional transmission of MRSA was
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documented.
Key words: methicillin-resistant Staphylococcus aureus; colonization; nursing home;
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sequence type 45; Taiwan
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ACCEPTED MANUSCRIPT Introduction Staphylococcus aureus is a common cause of clinically important infections,
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either in the community or in the hospitals. Nasal carriage of S. aureus is associated with subsequent infections [1-2]. Methicillin-resistant S. aureus (MRSA) were
classified as community-associated (CA)- and healthcare-associated (HA)-MRSA
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according to the epidemiologic or molecular characteristics [3].
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Unlike hospital or community, nursing home provides a unique health-caring environment for patients, characterized by long-term care of patients with advanced age, chronic illness, etc. The prevalence of MRSA carriage rates among nursing homes showed much variability, ranging from 1.1% to 58.6%, and it often exceeded
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that in acute medical care settings [4-12]. Though MRSA burden in nursing homes appears largely due to importation from hospitals, the genetic diversity was
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heterogeneous between nursing homes and even significantly higher than the diversity
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in hospitals [13,14]. Since nursing homes played a specific role in medical care, understanding the prevalence and molecular characteristics is critical for MRSA epidemiology in the society and patients’ health in nursing homes. [15,16]. On the other hand, there were rare studies regarding MRSA carriage among nursing home staff. It is very possible that transmission between residents and staff is the cause of spread of MRSA in the nursing homes [15]. However, there have been no reports
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ACCEPTED MANUSCRIPT regarding MRSA carriage in nursing homes in Taiwan. We hence conducted a study to evaluate nasal carriage rates, risk factors, molecular characterization, and antibiotics
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susceptibility of MRSA among nursing home residents and staff in Taiwan.
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ACCEPTED MANUSCRIPT Materials and Methods Confidentiality and ethical considerations
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This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital. A written informed consent was obtained from each resident or their family (when residents cannot sign the consent) and each staff enrolled in the
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study. All data were reported anonymously.
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Sample collection
This study was conducted in 14 nursing homes in Taiwan, located in southern (n = 8) and northern (n = 6) parts of Taiwan. From May to November 2012, a total of 523 nasal specimens were collected from 360 residents and 163 staff in 14 nursing
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homes. Only one specimen was collected from each subject at one time point. The participating rate was 48% for residents and 82% for staff. Swab samples were
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collected from the anterior nares with sterile cotton-top swabs for the residents and
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the staff after a written consent was obtained and a questionnaire was also completed. Each nasal swab was circled in the participant’s both nasal vestibules. The swabs was placed into the transport media (Venturi Transystem, Copan Innovation Ltd.) immediately and sent to the laboratory of Chang Gung Memorial Hospital (CGMH) within three days. Data collection
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ACCEPTED MANUSCRIPT To identify the potential risk factors for MRSA colonization, clinical information was collected from each participant. For the residents, with or without the assistance
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of their family, we collected the demographic data, personal history, duration of time living in nursing home, underlying diseases, mobility status, dialysis status, chronic
wounds, and insertion of medical devices. Antibiotic use, hospitalization, surgery, and
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infection events in recent three months were also collected. For the staff, personal
Microbiologic methods
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history, underlying diseases, and working information were collected.
Swab samples were inoculated onto Trypticase soy agar with 5% sheep blood plates by streak plate method. Those plates were incubated at 37 degree Celsius
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overnight. S. aureus was identified by morphology, gram stain, and coagulase tests. MRSA identification by cefoxitin susceptibility with the disc diffusion methods were
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Institute [17].
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confirmed according to the recommendations of Clinical and Laboratory Standards
Antimicrobial susceptibility testing The antimicrobial susceptibility of the isolates to 10 antibiotics including
oxacillin, trimethoprim/sulfamethoxazole, penicillin, teicoplanin, linezolid, clindamycin, doxycyclin, fusidic acid, vancomycin, and erythromycin was determined by using the disk-diffusion method, according to the guideline of Clinical and
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ACCEPTED MANUSCRIPT Laboratory Standard Institutes [17]. Molecular typing
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Chromosomal DNAs were extracted from all MRSA isolates for molecular characterization. All of them were characterized by pulsed-field gel electrophoresis
(PFGE), staphylococcal cassette chromosome (SCCmec) typing [18], and detected for
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the presence of Panton-Valentine leukocidin (PVL) genes [19]. Some selected isolates
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were further typed by multilocus sequence type (MLST) [20] and spa gene typing [21].
The procedures of PFGE with SmaI digestion were described in our previous studies [22]. The genotypes were designated in alphabetical order, and any identified
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new genotype was designated consecutively. The Staphylococcal cassette chromosome mec (SCCmec) typing was determined by a multiplex PCR strategy
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described previously [18]. Control strains for SCCmec types I, II, III and IVa were as
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follows: type I, NCTC10442; type II, N315; type III, 85/2082; and type IVa, JCSC4744. SCCmec typing for type VT was determined by a particular primer described elsewhere and the strain TSGH-17 was used as control. The presence of PVL genes was determined by a PCR strategy described previously [19]. MLST was examined for selective strains of representative PFGE patterns. Statistical analysis
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ACCEPTED MANUSCRIPT ANOVA method was conducted in analyzing variance of MRSA carriage prevalence in 14 nursing homes. To evaluate risk factors associated with MRSA
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colonization, we analyzed between people with MRSA colonization and that without MRSA colonization. For continuous variables Student t test was used. For categorical variables, chi-square test or Fisher’s exact test was conducted, as appropriate. We also
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calculated odd ratios (ORs) and 95% confidence intervals (CIs). The definition of
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statistical significance was p <0.05. Variables with a p value<0.05 in the univariate analysis were considered for inclusion in the multivariate model. SPSS software
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version 17.0 was used.
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ACCEPTED MANUSCRIPT Results Overall, nasal MSSA and MRSA carriage rates of these 523 subjects were 11.3%
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and 20.1%, respectively. The MSSA and MRSA carriage rates were 10.3% and 20.3%, respectively, for the residents and were 13.5% and 19.6%, respectively, for the staff. Details of MRSA carriage rates for both groups in each of the 14 nursing homes
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studied are shown in Table 1. MRSA carriage rates in each nursing home ranged from
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0% to 48.3% for the residents, and 0% to 33.3% for the staff. Only one nursing home was free from MRSA colonization. The prevalence of MRSA colonization in the residents was significantly different among the nursing homes (p=0.014), but the difference was not significant for the staff. These 14 nursing homes were then
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separated into the northern (n = 6) and southern group (n = 8) based on their geographic locations. However, there was no statistically significant difference
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between these two geographic groups.
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Detailed potential risk factors for MRSA colonization among residents are shown in Table 2. Age older than 60 years old, a history of skin infection within recent 3 months, the presence of chronic wound, and total stay time less than 3 months were the significant risk factors for MRSA carriage. In contrast, the presence of tracheotomy was a significant protective factor for MRSA colonization. In multivariate logistic regression analysis, the significant risk factors for MRSA
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ACCEPTED MANUSCRIPT colonization were age order than 60 years old and the presence of chronic wound. The presence of tracheotomy was still an independent protective factor.
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Detailed potential risk factors for MRSA colonization among staff working in nursing homes are shown in Table 3. Only foreign nursing workers and chronic wound were the significant risk factors for MRSA carriage. Moreover, alcohol
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drinking was found to be a significant protective factor. However, none of these risk
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factors reached statistic significance in the multivariate analysis.
Molecular characteristics of all 105 MRSA isolates are shown in Table 4. A total of 11 PFGE patterns were identified with three types accounting for > 10% (type BM, 50%; type D, 14%; type AG, 12%). Five isolates were non-typeable (NT)-PFGE by
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SmaI digestion and all belonged to ST398-spa t034. Seventy-five (71.4%) isolates carried SCCmec IV, V or VT, nine (8.6%) isolates carried SCCmec II or III, and
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twenty-one (20%) isolates carried unidentified type of SCCmec. In addition, only the
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isolates with PGFE type D-sequence type (ST) 59 carried PVL genes. The clone characterized as PFGE type BM-ST 45 was the most common clone and accounted for 50% of the isolates.
Pulsotypes analysis showed the significant variations (p=0.007) in genotypes of MRSA isolates from residents who stayed in nursing home less (n = 13) or more (n = 60) than 3 months. Three major PFGE patterns including types A (31%), BM (39%)
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ACCEPTED MANUSCRIPT and D (23%) were identified in residents with a stay duration of less than 3 months. Particularly, PFGE pattern A was not identified in residents with a stay duration of
(71.4%) was higher than that for domestic staff (36.4%).
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more than 3 months. The prevalence of ST45-PFGE BM for colonized foreign staff
Table 1 also shows the distribution and comparison of PFGE patterns of MRSA
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isolates from residents and staff in each nursing home. As shown, one nursing home
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was free from MRSA nasal colonization and two had only MRSA identified in residents. At least one identical PFGE pattern of MRSA for both residents and staff were found in nine of 11 remaining nursing homes (82%).
Table 5 shows the antimicrobial susceptibility of 105 MRSA isolates to different
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antibiotics stratified by SCCmec types. All these isolates were susceptible to vancomycin, teicoplanin, and linezoid, but were resistant to penicillin. The
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susceptibility rates for doxycyclin, and TMP-SMX were > 90%, while for
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ciprofloxacin, and erythormycin < 40%. MRSA isolates carrying the same SCCmec had similar antimicrobial susceptibility patterns. MRSA with SCCmec III were multi-resistant to erythormycin, ciprofloxacin, TMP-SMX and clindamycin.
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ACCEPTED MANUSCRIPT Discussion In this study, the prevalence of MRSA among nursing home residents in Taiwan
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was 20.3%, which was similar to that of UK (17-22%) [6,7] and Ireland (17%-23.3%) [8,15]. The carriage rate was lower than that in Hawaii (58.6%) [9] and California (31%) [10]. However, it was higher than that of Turkey (5%) [11] and European
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countries such as Germany (1.1-7.6%), Italy (7.8%-19%), and Spain (15.5%) [12,23].
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Contrary to the previous studies, in which most of the colonized S. aureus were MSSA, the current study showed that MRSA surpassed MSSA in prevalence, both for residents and staff. This discrepancy may be attributed to the different prevailing
in different countries.
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MRSA clones in the nursing homes and the different “culture” of anti-microbial usage
MRSA colonization among nursing home staff was less addressed before. MRSA
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carriage rate among nursing home staff was 5.8% in Italy [23], and 7.5% in Ireland
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[15]. Both rates were much lower than those for residents in the same nursing homes. Results from this study revealed that the MRSA prevalence among nursing home staff was 19.6%, which was similar to that for residents but was significantly higher than that for healthy adults (3.8% of 3098 adults) [25] and health care workers in Taiwan [25]. These suggest transmission of MRSA between the residents and the staff in nursing homes in Taiwan.
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ACCEPTED MANUSCRIPT It was reported that MRSA prevalence in nursing home was even higher in hospitals and in intensive care units [10]. In Taiwan, the MRSA nasal carriage rate for
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residents in nursing homes in the present study (20.3%) was higher than that for adult patients visiting emergency department (3.8%) [21], but comparable to that for adult patients hospitalized in intensive care units (15%-32%) [26,27]. Nursing homes
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provided special medical environment differing from hospitals and community. The
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residents were most aged, frequent antibiotics used, with chronic illness, invasive devices or catheterization. The patents usually had intensive contact with hospitals and people from community. However, compared with hospital setting, nursing homes usually had less staff with specific healthcare training, no formal cleaning or
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decolonization devises, and lack of isolation room for transmission control. Thus, it provides high risk circumstance for MRSA colonization, even in healthy staff.
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We demonstrated that age older than 60, and the presence of chronic wound were
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the risk factors for nursing home residents to carry MRSA in the multivariate model. The finding of chronic wound as a risk factor was consistent with a previous report [28]. Many of the new nursing home residents came from hospitals after an acute medical event and it may result in the increased colonization rate of new residents in nursing homes [29]. This finding was further confirmed by molecular evidences that MRSA isolates from these new residents were healthcare-associated, namely ST239.
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ACCEPTED MANUSCRIPT These suggest that transmission of MRSA between hospitals and nursing homes might be through the patients’ colonization, and thus screening for new nursing home
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residents may be reasonable for infection control. For nursing home staff, foreign nursing workers, and chronic wound were the significant risk factors for the MRSA carriage. However, none of these risk factors
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was significant in multivariate analysis. In the present study, nearly half of the health
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care workers were foreign workers, mostly from Southeastern Asian countries, and the investigation showed that foreign nursing workers were a potentially risk factor for MRSA carriage. The issue whether foreign health-care workers should be screened for MRSA colonization should be evaluated.
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Results from this study also revealed high variability of MRSA prevalence in each nursing home, with only one free from MRSA colonization. The results were
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similar to previous studies [9,10,12]. Molecular characterization in the present study
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revealed 11 PFGE patterns, and the clone characterized as PFGE type BM-ST45 was the most common clone, accounting for 50% of the isolates. However, this clone was neither among the prevalent HA-MRSA clones (mainly ST239 and ST5 in the past decade) nor CA-MRSA clones (mainly ST59) in Taiwan. In Taiwan, MRSA ST45 was first reported in 2011 in a respiratory care ward, colonizing a proportion of infected patients and health-care workers [30]. Clinical implication and impact of the
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ACCEPTED MANUSCRIPT emergency and spread of ST 45 among nursing homes in Taiwan needs further observations.
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MRSA ST45 strain was also called "Berlin epidemic MRSA" because it was first observed in Berlin in 1993 [31]. Later, it spread to many European countries [32].
MRSA ST45 strain was also implicated in outbreaks in Asia, including China, Hong
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Kong, and Singapore in recent years [33,34]. Not only in the hospital settings, MRSA
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ST45 strain also emerged and prevailed in nursing homes or long term care facilities in many countries, including Germany, Hong Kong, and China [34-36]. There are several limitations for the present study. First, less than 50%, lower than expected, of the residents in the nursing homes participated in this study, which
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reduced the size of case number for evaluation and indirectly affected the analysis of statistic significance. Second, from each study subject, samplings for MRSA detection
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were obtained only from one site (nares) and once, so some MRSA colonizing
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patients might be undetected [37] and the longitudinal trends could not traced. Conclusions
One-fifth of residents and staff, respectively, in nursing homes in Taiwan
harbored MRSA, mostly ST45 strains, in their nares. Age older than 60 years, and the presence of chronic wound were the risk factors for nursing home residents to carry MRSA. MRSA ST45 accounted for half of the colonizing isolates and the intra- and
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ACCEPTED MANUSCRIPT inter- institutional transmission of MRSA was documented by molecular methods. In Taiwan, effective infection control measures should be implemented to interrupt intra-
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and inter- institutional transmission of MRSA as soon as possible.
Acknowledgements
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The authors thanked the residents and staff of all the participating nursing homes,
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and the research assistants Ya-Lin Huang and Yu-Chiao Huang. This work was supported by a grant from Ministry of Science and Technology, Executive Yuan of Taiwan (NSC 102-2628-B-182A-010-MY3) and partly by a grant from Medical
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Foundation in Memory of Dr. Deh-Lin Cheng.
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ACCEPTED MANUSCRIPT Table 1. Prevalence of nasal MSSA and MRSA carriage among residents and staff, and comparison of pulsed-field gel electrophoresis (PFGE) patterns between MRSA isolates from residents and staff in 14 nursing homes (NH) in Taiwan NHa
Category Subject No.
MSSA No.(%)
MRSA PFGE patterns b No.(%) A AG AK B BA BM BR C
D
F U UT*
1
Resident Staff
24 23
0(0.0) 1(4.3)
4(16.7) 7(30.4)
1 1
-
-
-
1
2
Resident Staff
49 14
2(4.1) 0(0.0)
10(20.4) 4(28.6)
-
-
-
2 1
-
3
Resident Staff
13 6
2(15.4) 1(16.7)
2(15.4) 1(16.7)
-
-
-
-
-
4
Resident Staff
18 11
1(5.6) 3(27.3)
0(0.0) 0(0.0)
-
-
-
-
-
5
Resident Staff
21 10
5(23.8) 3(30.0)
7(33.3) 2(20.0)
2 -
1 -
-
-
6
Resident Staff
19 9
0(0.0) 1(11.1)
5(26.3) 1(11.1)
-
2 -
-
7
Resident Staff
33 8
9(27.3) 2(25.0)
5(15.2) 0(0.0)
1 -
-
8
Resident Staff
14 7
1(7.1) 3(42.9)
4(28.6) 0(0.0)
-
9
Resident Staff
26 19
4(15.4) 0(0.0)
5(19.2) 6(31.6)
10
Resident Staff
28 10
0(0.0) 2(20.0)
11
Resident Staff
20 8
12
Resident Staff
38 18
13
Resident Staff
14
-
-
1
-
1
-
7 2
-
-
1
-
1 -
-
2 -
-
-
-
-
1
-
-
-
-
-
-
-
-
-
1 1
1 -
1
1 -
1 -
-
-
-
-
-
-
-
3 1
-
-
-
-
-
-
3 -
-
-
1 -
-
-
-
1 -
-
-
-
0 -
-
-
-
-
-
3 -
-
3 -
-
-
-
2 6
-
-
-
-
-
-
6(21.4) 2(20.0)
-
-
-
-
-
1 -
-
1 1
2 1
-
2 -
-
7(35.0) 2(25.0)
4(20.0) 1(12.5)
-
2 -
1
-
-
-
-
-
-
-
-
2 -
2(5.3) 1(5.6)
4(10.5) 4(22.2)
-
-
-
-
-
3 4
-
-
1 -
-
-
-
29 9
3(10.3) 1(11.1)
14(48.3) 3(33.3)
-
3 1
-
-
-
10 2
-
-
1 -
-
-
-
Resident Staff
28 11
1(3.6) 2(18.2)
3(10.7) 1(9.1)
-
-
-
-
-
1 1
-
-
2 -
-
-
-
Total Resident Staff
360 163
37(10.3) 73(20.1) 22(13.5) 32(19.6)
4 1
12 1
0 1
2 1
0 1
33 19
1 0
1 11 1 2 4 0
3 2
5 0
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a
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3 3
Nursing homes are listed according to time of sampling.
b
Prevalence of MRSA carriage rate was significant different among residents (p value = 0.014),but not among staff (p value= 0.439). *UT, untypeable by SmaI digestion
1
ACCEPTED MANUSCRIPT Table 2. Potential risk factors for MRSA colonization among residents in nursing homes in Taiwan Demographic and clinical data
Odds ratio 95% confidence interval p valuea
No. (%) of subjects Total(n=360) MRSA(n=73) Non-MRSA(n=287)
Ageb
30(41.4)
145(50.5)
66.81±18.769 69.11±17.792 >60 years old
0.683
0.406-1.150
66.22±18.994
242(67.2)
58(79.5)
18(64.1)
DM
101(28.1)
26(35.6)
75(26.1)
Hypertension
188(52.2)
42(57.5)
146(50.9)
Arrhythmia
34(9.4)
8(11.0)
Heart failure
14(3.9)
History of pneumonia
0.150 0.241
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175(48.6)
Male
2.164
1.168-4.011
0.013*
1.564
0.905-2.701
0.107
1.308
0.779-2.198
0.309
26(9.1)
1.236
0.535-2.855
0.620
3(4.1)
1(3.8)
1.075
0.292-3.959
1.000
29(8.1)
5(6.8)
24(8.4)
0.806
0.297-2.190
0.671
History of TB infection
9(2.5)
2(2.7)
7(2.4)
1.127
0.229-5.541
1.000
History of asthma
9(2.5)
3(4.1)
6(2.1)
2.007
0.490-8.225
0.394
COPD
12(3.3)
1(1.4)
11(3.8)
0.348
0.044-2.744
0.472
Chronic kidney disease
23(6.4)
6(8.2)
17(5.9)
1.422
0.540-3.746
0.432
HBV carrier
8(2.2)
0(0.0)
8(2.8)
1.262
1.196-1.331
0.367
HCV carrier
6(1.7)
2(2.7)
4(1.4)
1.993
0.358-1.099
0.352
Liver cirrhosis
12(3.3)
3(4.1)
9(3.1)
1.324
0.349-5.019
0.715
Cancer
22(6.1)
6(8.2)
16(5.6)
1.517
0.572-4.024
0.413
Allergic rhinitis
11(3.1)
2(2.7)
9(3.1)
0.870
0.184-4.117
1.000
History of coronary artery disease
12(3.3)
2(2.7)
10(3.5)
0.780
0.167-3.641
1.000
26(7.2)
8(11.0)
18(6.3)
1.839
0.766-4.416
0.167
26(7.2)
4(5.5)
22(7.7)
0.698
0.233-2.093
0.519
Antibiotics using
67(18.7)
14(19.2)
53(18.5)
1.043
0.542-2.007
0.899
Skin or soft tissue infection
51(14.2)
17(23.3)
34(11.8)
2.259
1.179-4.328
0.012*
Chronic wound d
43(11.9)
15(20.5)
28(9.8)
2.392
1.201-4.763
0.011*
UTI
40(11.1)
10(13.7)
30(10.5)
1.360
0.632-2.928
0.431
Hospitalization
58(16.1)
16(21.9)
42(14.6)
1.637
0.860-3.118
0.131
Hemodialysis status
11(3.1)
4(5.5)
7(2.4)
2.319
0.660-8.146
0.244
Immunosupressant
9(2.5)
4(5.5)
5(1.7)
3.270
0.855-12.498
0.087
160(44.4)
28(38.4)
132(46.0)
0.731
0.432-1.236
0.241
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Pneumonia URTI
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Current diseasesc
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Underlying diseases
Other risk factors
Nasogastric tube
2
ACCEPTED MANUSCRIPT Foley tube
100(27.8)
19(26.0)
81(28.2)
0.895
0.500-1.602
0.708
Tracheostomy
44(12.2)
3(4.1)
41(14.3)
0.257
0.077-0.855
0.018*
Smoking
124(34.4)
23(31.5)
101(35.2)
0.847
0.489-1.468
0.554
Alcohol drinking
113(31.4)
22(30.1)
91(31.7)
0.929
0.532-1.624
0.796
40(11.1)
13(17.8)
27(9.4)
2.086
1.017-4.281
0.041*
Duration < 3 months
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Total living time in NH
-
Ambulation No limitation
50(13.9)
9(12.3)
41(14.3)
Move with help
107(29.7)
21(28.8)
86(30.0)
bedridden
203(56.4)
43(58.9)
160(55.7)
-
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DM: diabetes mellitus, HBV: hepatitis B virus , HCV: hepatitis C virus , TB: tuberculosis, COPD: chronic obstructive pulmonary disease, URTI: upper respiratory
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tract infection, a For categorical variables, Fisher’s exact test was used for extreme proportions (expected count <5) instead of Pearson’s chi-square test. b
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data was presented as the mean value ± standard error of the mean for continuous variables. Performed by Student t test. c any event happened in 3 months before sampling. d wound presented more than 3 moths
3
0.864
ACCEPTED MANUSCRIPT Table 3. Potential risk factors for MRSA colonization among staff working in nursing homes in Taiwan Demographic and clinical data
Odds ratio 95% confidence interval p valuea
No. (%) of subjects Total(n=163) MRSA(n=32) Non-MRSA(n=131)
Ageb
31(96.9)
122(93.1)
37.20±11.061 34.91±10.798
2.287
0.279-18.730
37.76±11.092
75(46.0)
21(65.6)
54(41.2)
DM
3(1.8)
0(0.0)
3(2.3)
Hypertension
9(5.5)
0(0.0)
9(6.9)
Allergic rhinitis
22(13.5)
3(9.4)
19(14.5)
Alcohol drinking
18(11.0)
0(0.0)
18(13.7)
Smoking
14(8.6)
1(3.1)
13(9.9)
URTI
35(21.5)
10(31.3)
Antibiotics using
17(10.4)
Skin infection
0.688 0.191
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153(93.9)
Female
2.722
1.213-6.108
0.013*
0.5648
0.029-11.21
1.000
0.1984
0.011-3.499
0.207
0.610
0.169-2.203
0.572
0.095
0.000-1.623
0.025*
0.293
0.037-2.325
0.307
25(19.1)
1.927
0.811-4.578
0.133
5(15.6)
12(9.2)
1.836
0.597-5.650
0.332
5(3.1)
1(3.1)
4(3.1)
1.024
0.111-9.489
1.000
Chronic wound d
3(1.8)
3(9.4)
0(0.0)
31.20
1.569 - 620.5
0.007*
UTI
4(2.5)
1(3.1)
3(2.3)
1.376
0.138-13.686
1.000
Hospitalization
1(0.6)
0(0.0)
1(0.8)
1.339
0.053-33.62
1.000
15(9.2)
4(12.5)
11(8.4)
1.558
0.462~5.258
0.497
-
-
0.153
Foreign nursing workers
Total working times in NH Duration < 3 months
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Job types Nurses
37(22.7)
5(15.6)
32(24.4)
98(60.1)
24(75.0)
74(56.5)
3(9.4)
25(19.1)
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Health care workers Others
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Current diseasesc
28(17.2)
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Underlying diseases
Working hours (hours/week) b
45.68±11.995 37.60±15.126
46.94±11.199
0.106
71.48±18.619 70.58±12.573
71.77±20.261
0.788
Nurse
45.19±24.433
39.00±8.031
46.16±26.035
0.234
Caretaker
12.49±12.278
10.92±6.406
13.00±13.649
0.473
Nurse Caretaker
Number of Caring residents
b
DM: diabetes mellitus, TB: tuberculosis, COPD: chronic obstructive pulmonary disease, URTI: upper respiratory tract infection, a For categorical variables, Fisher’s exact test was used for extreme proportions 4
ACCEPTED MANUSCRIPT (expected count <5) instead of Pearson’s chi-square test. data was presented as the mean value ± standard error of the mean for continuous
b
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variables. Performed by Student t test. c any event happened in 3 months before sampling. d wound presented more than 3 moths
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ACCEPTED MANUSCRIPT Table 4. Molecular characteristics of 105 MRSA isolates, categorized by pulsed-field gel electrophoresis (PFGE) patterns. SCCmec
PVL-positive
MLST type
pattern
(%)
type
A
5(5)
AG
III
0
239
t037,t138
13(12)
IV
0
30
t019,t1836
AK
1(1)
IV
0
508
t015
B
3(3)
III
0
BA
1(1)
IV
0
BM
29(28)
V
21(20)
UT
2(2)
IV
BR
1(1)
IV
C
2(2)
F
UT
t286
0
45
t1081,t1861,t9377
0
45
t1081
0
45
t1081
0
8
t008
IV
0
59
t437
VT
0
59
t437
VT
13
59
t4135,t437a,t441,t13876
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1
1(1)
II
0
5
t002
5(5)
IV
0
573, 2963#
t3525,t345
VT
0
398
t034
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U
15(14)
t037
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D
900*
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1(1)
Spa typing
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No. isolate
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PFGE
5(5)
SCCmec: staphylococcal cassette chromosome; MLST: multilocus sequence type; PVL:Panton-Valentine leukocidin; UT: untypeable a
One isolate of spa typing t437 didn’t carry PVL genes *single locus variant of ST239 # single locus variant of ST573
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ACCEPTED MANUSCRIPT Table 5. Distribution of antimicrobial susceptibility rates of 105 MRSA isolates stratified by staphylococcal cassette chromosomes (SCCmec) No. (%)
Total
105(100) 104(99)
II
F
III
Total
IV
Dox
5
Cip
EM
42(40)
40(38)
82(78)
77(73)
97(92)
1(100)
0(0)
1(100)
6(75)
1(13)
0(0)
3(60)
1(20)
0(0)
1(1)
1(100)
0(0)
0(0)
8(8)
8(100)
0(0)
0(0) 0(0)
A
239
5(5)
5(100)
0(0)
B
900*
3(3)
3(100)
0(0)
25(24)
25(100)
23(92)
Total
FA
CL
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MLST
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PFGE
SXT
0(0)
3(100)
0(0)
0(0)
12(48)
25(100
23(92)
25(100)
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SCCmec
13(100)
13(100)
1(100)
1(100)
30
13(12)
13(100)
13(100)
4(31)
AK
508
1(1)
1(100)
1(100)
1(100)
) 13(100 ) 1(100)
BA
1
1(1)
1(100)
1(100)
1(100)
1(100)
1(100)
1(100)
BM
45
2(2)
2(100)
2(100)
2(100)
2(100)
2(100)
2(100)
BR
8
1(1)
1(100)
1(100)
0(0)
1(100)
1(100)
1(100)
C
59
2(2)
2(100)
2(100)
0(0)
2(100)
0(0)
2(100)
U
2963#,
5(5)
5(100)
3(60)
4(80)
5(100)
5(100)
5(100)
V
BM
573 45
29(28)
28(97)
0(0)
12(41)
27(93)
29(100)
VT
Total
21(20)
21(100)
19(90)
10(48)
29(100 ) 21(100
10(48)
21(100)
1(1)
1(100)
1(100)
1(100)
) 1(100)
1(100)
1(100)
15(14)
15(100)
13(87)
4(27)
EP
C
59
D
59
X
398
5(5)
5(100)
5(100)
BM
45
21(20)
21(100)
0(0)
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UT
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AG
4(27)
15(100)
5(100)
15(100 ) 5(100)
5(100)
5(100)
6(29)
0(0)
16(76)
21(100)
UT, untypeable; PFGE, pulsed-field electrophoresis; MLST, multilocus sequence type; Dox, doxycycline; Cip, ciprofloxacin; EM, erythromycin; FA, fusidic acid; CL, clindamycin; SXT, trimethoprim/sulfamethoxazole All 105 MRSA isolates were susceptible to Vancomycin, Teicoplanin, and Linezoid and all resistant to Penicillin *single locus variant of ST239 # single locus variant of ST573 7
S1198-743X(14)00172-4
DOI:
10.1016/j.cmi.2014.12.019
Reference:
CMI 134
To appear in:
Clinical Microbiology and Infection
Received Date: 26 August 2014 Revised Date:
20 November 2014
Accepted Date: 19 December 2014
Please cite this article as: Tsao F-Y, Kou H-W, Huang Y-C, Dissemination of methicillin-resistant Staphylococcus aureus ST45 among nursing home residents and staff in taiwan, Clinical Microbiology and Infection (2015), doi: 10.1016/j.cmi.2014.12.019. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Dissemination of Methicillin-resistant Staphylococcus aureus ST45 among Nursing Home Residents and Staff in Taiwan
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Fang-Ying Tsao1, Hao-Wei Kou1, Yhu-Chering Huang1, 2 School of Medicine, Chang Gung University, Gueishan, Taoyuan, Taiwan,
2
Department of Pediatrics, Chang Gung Memorial Hospital at Linkou, Gueishan,
Taoyuan, Taiwan
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First two authors equally contributed to this work.
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Short title: MRSA in nursing homes in Taiwan
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Correspondence: Dr. Yhu-Chering Huang, Department of Pediatrics, Chang Gung Memorial Hospital, No. 5, Fu-Shin Street, Gueishan 333, Taoyuan, Taiwan. Fax: +886-3-3288957
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TEL: +886-3-3281200
E-mail: [email protected]
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The authors have indicated they have no financial relationships relevant to this article to disclose.
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ACCEPTED MANUSCRIPT Abstract Unlike hospital or community, nursing home provides a unique health-caring
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environment for patients. There have been no reports regarding methicillin-resistant Staphylococcus aureus (MRSA) carriage among nursing home residents and staff in
Taiwan. From May to November 2012, a total of 523 subjects, including 360 residents
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and 163 staff, in 14 nursing homes in Taiwan were surveyed for nasal MRSA carriage.
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Overall, nasal MRSA carriage rate was 20.1%, with 20.3% for residents and 19.6 % for staff. For residents, age order than 60 years old (adjust odds ratio (OR) 2.268; 95% confidence interval (CI) 1.185–4.342; p =0 .013) and the presence of chronic wound (adjust OR 2.449,;95% CI 1.082–5.544; p =0 .032) were the significant risk factors
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for MRSA carriage in multivariate models. Of the 105 MRSA isolates, 11 pulsed-field gel electrophoresis (PFGE) patterns were identified except five isolates untypeable by
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SmaI digestion, with one major pattern; 9 isolates (8.6%) possessed staphylococcal
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cassette chromosome (SCCmec) type II or III, 66 isolates type IV or V and 21 isolates unidentified types. The clone characterized as PFGE pattern BM-sequence type (ST) 45 was the most common clone, accounting for 50% of the isolates, and was multiresistant, including to ciprofloxacin. Intra- and inter- institutional transmission of MRSA was documented by molecular methods. Conclusively, one-fifth of residents and staff, respectively, in nursing homes in Taiwan harbored MRSA, mostly ST45
2
ACCEPTED MANUSCRIPT strains, in their nares. Intra- and inter- institutional transmission of MRSA was
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documented.
Key words: methicillin-resistant Staphylococcus aureus; colonization; nursing home;
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sequence type 45; Taiwan
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ACCEPTED MANUSCRIPT Introduction Staphylococcus aureus is a common cause of clinically important infections,
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either in the community or in the hospitals. Nasal carriage of S. aureus is associated with subsequent infections [1-2]. Methicillin-resistant S. aureus (MRSA) were
classified as community-associated (CA)- and healthcare-associated (HA)-MRSA
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according to the epidemiologic or molecular characteristics [3].
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Unlike hospital or community, nursing home provides a unique health-caring environment for patients, characterized by long-term care of patients with advanced age, chronic illness, etc. The prevalence of MRSA carriage rates among nursing homes showed much variability, ranging from 1.1% to 58.6%, and it often exceeded
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that in acute medical care settings [4-12]. Though MRSA burden in nursing homes appears largely due to importation from hospitals, the genetic diversity was
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heterogeneous between nursing homes and even significantly higher than the diversity
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in hospitals [13,14]. Since nursing homes played a specific role in medical care, understanding the prevalence and molecular characteristics is critical for MRSA epidemiology in the society and patients’ health in nursing homes. [15,16]. On the other hand, there were rare studies regarding MRSA carriage among nursing home staff. It is very possible that transmission between residents and staff is the cause of spread of MRSA in the nursing homes [15]. However, there have been no reports
4
ACCEPTED MANUSCRIPT regarding MRSA carriage in nursing homes in Taiwan. We hence conducted a study to evaluate nasal carriage rates, risk factors, molecular characterization, and antibiotics
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susceptibility of MRSA among nursing home residents and staff in Taiwan.
5
ACCEPTED MANUSCRIPT Materials and Methods Confidentiality and ethical considerations
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This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital. A written informed consent was obtained from each resident or their family (when residents cannot sign the consent) and each staff enrolled in the
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study. All data were reported anonymously.
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Sample collection
This study was conducted in 14 nursing homes in Taiwan, located in southern (n = 8) and northern (n = 6) parts of Taiwan. From May to November 2012, a total of 523 nasal specimens were collected from 360 residents and 163 staff in 14 nursing
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homes. Only one specimen was collected from each subject at one time point. The participating rate was 48% for residents and 82% for staff. Swab samples were
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collected from the anterior nares with sterile cotton-top swabs for the residents and
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the staff after a written consent was obtained and a questionnaire was also completed. Each nasal swab was circled in the participant’s both nasal vestibules. The swabs was placed into the transport media (Venturi Transystem, Copan Innovation Ltd.) immediately and sent to the laboratory of Chang Gung Memorial Hospital (CGMH) within three days. Data collection
6
ACCEPTED MANUSCRIPT To identify the potential risk factors for MRSA colonization, clinical information was collected from each participant. For the residents, with or without the assistance
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of their family, we collected the demographic data, personal history, duration of time living in nursing home, underlying diseases, mobility status, dialysis status, chronic
wounds, and insertion of medical devices. Antibiotic use, hospitalization, surgery, and
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infection events in recent three months were also collected. For the staff, personal
Microbiologic methods
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history, underlying diseases, and working information were collected.
Swab samples were inoculated onto Trypticase soy agar with 5% sheep blood plates by streak plate method. Those plates were incubated at 37 degree Celsius
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overnight. S. aureus was identified by morphology, gram stain, and coagulase tests. MRSA identification by cefoxitin susceptibility with the disc diffusion methods were
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Institute [17].
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confirmed according to the recommendations of Clinical and Laboratory Standards
Antimicrobial susceptibility testing The antimicrobial susceptibility of the isolates to 10 antibiotics including
oxacillin, trimethoprim/sulfamethoxazole, penicillin, teicoplanin, linezolid, clindamycin, doxycyclin, fusidic acid, vancomycin, and erythromycin was determined by using the disk-diffusion method, according to the guideline of Clinical and
7
ACCEPTED MANUSCRIPT Laboratory Standard Institutes [17]. Molecular typing
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Chromosomal DNAs were extracted from all MRSA isolates for molecular characterization. All of them were characterized by pulsed-field gel electrophoresis
(PFGE), staphylococcal cassette chromosome (SCCmec) typing [18], and detected for
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the presence of Panton-Valentine leukocidin (PVL) genes [19]. Some selected isolates
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were further typed by multilocus sequence type (MLST) [20] and spa gene typing [21].
The procedures of PFGE with SmaI digestion were described in our previous studies [22]. The genotypes were designated in alphabetical order, and any identified
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new genotype was designated consecutively. The Staphylococcal cassette chromosome mec (SCCmec) typing was determined by a multiplex PCR strategy
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described previously [18]. Control strains for SCCmec types I, II, III and IVa were as
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follows: type I, NCTC10442; type II, N315; type III, 85/2082; and type IVa, JCSC4744. SCCmec typing for type VT was determined by a particular primer described elsewhere and the strain TSGH-17 was used as control. The presence of PVL genes was determined by a PCR strategy described previously [19]. MLST was examined for selective strains of representative PFGE patterns. Statistical analysis
8
ACCEPTED MANUSCRIPT ANOVA method was conducted in analyzing variance of MRSA carriage prevalence in 14 nursing homes. To evaluate risk factors associated with MRSA
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colonization, we analyzed between people with MRSA colonization and that without MRSA colonization. For continuous variables Student t test was used. For categorical variables, chi-square test or Fisher’s exact test was conducted, as appropriate. We also
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calculated odd ratios (ORs) and 95% confidence intervals (CIs). The definition of
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statistical significance was p <0.05. Variables with a p value<0.05 in the univariate analysis were considered for inclusion in the multivariate model. SPSS software
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version 17.0 was used.
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ACCEPTED MANUSCRIPT Results Overall, nasal MSSA and MRSA carriage rates of these 523 subjects were 11.3%
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and 20.1%, respectively. The MSSA and MRSA carriage rates were 10.3% and 20.3%, respectively, for the residents and were 13.5% and 19.6%, respectively, for the staff. Details of MRSA carriage rates for both groups in each of the 14 nursing homes
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studied are shown in Table 1. MRSA carriage rates in each nursing home ranged from
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0% to 48.3% for the residents, and 0% to 33.3% for the staff. Only one nursing home was free from MRSA colonization. The prevalence of MRSA colonization in the residents was significantly different among the nursing homes (p=0.014), but the difference was not significant for the staff. These 14 nursing homes were then
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separated into the northern (n = 6) and southern group (n = 8) based on their geographic locations. However, there was no statistically significant difference
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between these two geographic groups.
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Detailed potential risk factors for MRSA colonization among residents are shown in Table 2. Age older than 60 years old, a history of skin infection within recent 3 months, the presence of chronic wound, and total stay time less than 3 months were the significant risk factors for MRSA carriage. In contrast, the presence of tracheotomy was a significant protective factor for MRSA colonization. In multivariate logistic regression analysis, the significant risk factors for MRSA
10
ACCEPTED MANUSCRIPT colonization were age order than 60 years old and the presence of chronic wound. The presence of tracheotomy was still an independent protective factor.
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Detailed potential risk factors for MRSA colonization among staff working in nursing homes are shown in Table 3. Only foreign nursing workers and chronic wound were the significant risk factors for MRSA carriage. Moreover, alcohol
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drinking was found to be a significant protective factor. However, none of these risk
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factors reached statistic significance in the multivariate analysis.
Molecular characteristics of all 105 MRSA isolates are shown in Table 4. A total of 11 PFGE patterns were identified with three types accounting for > 10% (type BM, 50%; type D, 14%; type AG, 12%). Five isolates were non-typeable (NT)-PFGE by
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SmaI digestion and all belonged to ST398-spa t034. Seventy-five (71.4%) isolates carried SCCmec IV, V or VT, nine (8.6%) isolates carried SCCmec II or III, and
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twenty-one (20%) isolates carried unidentified type of SCCmec. In addition, only the
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isolates with PGFE type D-sequence type (ST) 59 carried PVL genes. The clone characterized as PFGE type BM-ST 45 was the most common clone and accounted for 50% of the isolates.
Pulsotypes analysis showed the significant variations (p=0.007) in genotypes of MRSA isolates from residents who stayed in nursing home less (n = 13) or more (n = 60) than 3 months. Three major PFGE patterns including types A (31%), BM (39%)
11
ACCEPTED MANUSCRIPT and D (23%) were identified in residents with a stay duration of less than 3 months. Particularly, PFGE pattern A was not identified in residents with a stay duration of
(71.4%) was higher than that for domestic staff (36.4%).
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more than 3 months. The prevalence of ST45-PFGE BM for colonized foreign staff
Table 1 also shows the distribution and comparison of PFGE patterns of MRSA
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isolates from residents and staff in each nursing home. As shown, one nursing home
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was free from MRSA nasal colonization and two had only MRSA identified in residents. At least one identical PFGE pattern of MRSA for both residents and staff were found in nine of 11 remaining nursing homes (82%).
Table 5 shows the antimicrobial susceptibility of 105 MRSA isolates to different
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antibiotics stratified by SCCmec types. All these isolates were susceptible to vancomycin, teicoplanin, and linezoid, but were resistant to penicillin. The
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susceptibility rates for doxycyclin, and TMP-SMX were > 90%, while for
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ciprofloxacin, and erythormycin < 40%. MRSA isolates carrying the same SCCmec had similar antimicrobial susceptibility patterns. MRSA with SCCmec III were multi-resistant to erythormycin, ciprofloxacin, TMP-SMX and clindamycin.
12
ACCEPTED MANUSCRIPT Discussion In this study, the prevalence of MRSA among nursing home residents in Taiwan
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was 20.3%, which was similar to that of UK (17-22%) [6,7] and Ireland (17%-23.3%) [8,15]. The carriage rate was lower than that in Hawaii (58.6%) [9] and California (31%) [10]. However, it was higher than that of Turkey (5%) [11] and European
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countries such as Germany (1.1-7.6%), Italy (7.8%-19%), and Spain (15.5%) [12,23].
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Contrary to the previous studies, in which most of the colonized S. aureus were MSSA, the current study showed that MRSA surpassed MSSA in prevalence, both for residents and staff. This discrepancy may be attributed to the different prevailing
in different countries.
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MRSA clones in the nursing homes and the different “culture” of anti-microbial usage
MRSA colonization among nursing home staff was less addressed before. MRSA
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carriage rate among nursing home staff was 5.8% in Italy [23], and 7.5% in Ireland
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[15]. Both rates were much lower than those for residents in the same nursing homes. Results from this study revealed that the MRSA prevalence among nursing home staff was 19.6%, which was similar to that for residents but was significantly higher than that for healthy adults (3.8% of 3098 adults) [25] and health care workers in Taiwan [25]. These suggest transmission of MRSA between the residents and the staff in nursing homes in Taiwan.
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ACCEPTED MANUSCRIPT It was reported that MRSA prevalence in nursing home was even higher in hospitals and in intensive care units [10]. In Taiwan, the MRSA nasal carriage rate for
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residents in nursing homes in the present study (20.3%) was higher than that for adult patients visiting emergency department (3.8%) [21], but comparable to that for adult patients hospitalized in intensive care units (15%-32%) [26,27]. Nursing homes
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provided special medical environment differing from hospitals and community. The
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residents were most aged, frequent antibiotics used, with chronic illness, invasive devices or catheterization. The patents usually had intensive contact with hospitals and people from community. However, compared with hospital setting, nursing homes usually had less staff with specific healthcare training, no formal cleaning or
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decolonization devises, and lack of isolation room for transmission control. Thus, it provides high risk circumstance for MRSA colonization, even in healthy staff.
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We demonstrated that age older than 60, and the presence of chronic wound were
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the risk factors for nursing home residents to carry MRSA in the multivariate model. The finding of chronic wound as a risk factor was consistent with a previous report [28]. Many of the new nursing home residents came from hospitals after an acute medical event and it may result in the increased colonization rate of new residents in nursing homes [29]. This finding was further confirmed by molecular evidences that MRSA isolates from these new residents were healthcare-associated, namely ST239.
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ACCEPTED MANUSCRIPT These suggest that transmission of MRSA between hospitals and nursing homes might be through the patients’ colonization, and thus screening for new nursing home
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residents may be reasonable for infection control. For nursing home staff, foreign nursing workers, and chronic wound were the significant risk factors for the MRSA carriage. However, none of these risk factors
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was significant in multivariate analysis. In the present study, nearly half of the health
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care workers were foreign workers, mostly from Southeastern Asian countries, and the investigation showed that foreign nursing workers were a potentially risk factor for MRSA carriage. The issue whether foreign health-care workers should be screened for MRSA colonization should be evaluated.
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Results from this study also revealed high variability of MRSA prevalence in each nursing home, with only one free from MRSA colonization. The results were
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similar to previous studies [9,10,12]. Molecular characterization in the present study
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revealed 11 PFGE patterns, and the clone characterized as PFGE type BM-ST45 was the most common clone, accounting for 50% of the isolates. However, this clone was neither among the prevalent HA-MRSA clones (mainly ST239 and ST5 in the past decade) nor CA-MRSA clones (mainly ST59) in Taiwan. In Taiwan, MRSA ST45 was first reported in 2011 in a respiratory care ward, colonizing a proportion of infected patients and health-care workers [30]. Clinical implication and impact of the
15
ACCEPTED MANUSCRIPT emergency and spread of ST 45 among nursing homes in Taiwan needs further observations.
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MRSA ST45 strain was also called "Berlin epidemic MRSA" because it was first observed in Berlin in 1993 [31]. Later, it spread to many European countries [32].
MRSA ST45 strain was also implicated in outbreaks in Asia, including China, Hong
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Kong, and Singapore in recent years [33,34]. Not only in the hospital settings, MRSA
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ST45 strain also emerged and prevailed in nursing homes or long term care facilities in many countries, including Germany, Hong Kong, and China [34-36]. There are several limitations for the present study. First, less than 50%, lower than expected, of the residents in the nursing homes participated in this study, which
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reduced the size of case number for evaluation and indirectly affected the analysis of statistic significance. Second, from each study subject, samplings for MRSA detection
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were obtained only from one site (nares) and once, so some MRSA colonizing
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patients might be undetected [37] and the longitudinal trends could not traced. Conclusions
One-fifth of residents and staff, respectively, in nursing homes in Taiwan
harbored MRSA, mostly ST45 strains, in their nares. Age older than 60 years, and the presence of chronic wound were the risk factors for nursing home residents to carry MRSA. MRSA ST45 accounted for half of the colonizing isolates and the intra- and
16
ACCEPTED MANUSCRIPT inter- institutional transmission of MRSA was documented by molecular methods. In Taiwan, effective infection control measures should be implemented to interrupt intra-
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and inter- institutional transmission of MRSA as soon as possible.
Acknowledgements
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The authors thanked the residents and staff of all the participating nursing homes,
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and the research assistants Ya-Lin Huang and Yu-Chiao Huang. This work was supported by a grant from Ministry of Science and Technology, Executive Yuan of Taiwan (NSC 102-2628-B-182A-010-MY3) and partly by a grant from Medical
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Foundation in Memory of Dr. Deh-Lin Cheng.
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molecular epidemiology of meticillin-resistant Staphylococcus aureus in nursing home residents in northern Germany. J Hosp Infect 2011; 78: 108-112. 13.
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15. Baldwin NS, Gilpin DF, Hughes CM, et al. Prevalence of methicillin-resistant Staphylococcus aureus colonization in residents and staff in nursing homes in Northern Ireland. J Am Geriatr Soc 2009; 57: 620-626.
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ACCEPTED MANUSCRIPT of Staphylococcus aureus. J Clin Microbiol 2000; 38: 1008-1015. 21. Harmsen D, Claus H, Witte W, et al. Typing of methicillin-resistant
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Staphylococcus aureus in a university hospital setting by using novel software for spa repeat determination and database management. J Clin Microbiol 2003;41: 5442-5448.
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22. Lu SY, Chang FY, Cheng CC, Lee KD, Huang YC. Methicillin-resistant
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24. Monaco M, Bombana E, Trezzi L, et al. Meticillin-resistant Staphylococcus
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25. Huang YC, Chen CJ. Community-associated methicillin-resistant Staphylococcus aureus in children in Taiwan, 2000s. Int J Antimicrob Agent 2011;38:2-8. 26. Chen CB, Chang HC, Huang YC. Nasal meticillin-resistant Staphylococcus aureus carriage among intensive care unit hospitalised adult patients in a Taiwanese medical centre: one time-point prevalence, molecular characteristics and risk factors
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community-associated methicillin-resistant Staphylococcus aureus acquired infection or colonization in intensive-care-unit patients. J Clin Microbiol 2010; 48: 4439-4444. 28. Beaujean DJ, Weersink AJ, Blok HE, Frenay HM, Verhoef J. Determining risk
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factors for methicillin-resistant Staphylococcus aureus carriage after discharge from
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29. Verrall A, Merchant R, Dillon J, Ying D, Fisher D. Impact of nursing home residence on hospital epidemiology of meticillin-resistant Staphylococcus aureus: a perspective from Asia. J Hosp Infect 2013; 83: 250-252.
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30. Lee YT, Lin DB, Wang WY, et al. First identification of methicillin-resistant Staphylococcus aureus MLST types ST5 and ST45 and SCCmec types IV and Vt by
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Microbiol Infect Dis 2011; 70: 175-182. 31.
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J Antimicrob Chemother 1999; 44 Suppl A: 1-9. 32.
Enright MC, Robinson DA, Randle G, et al. The evolutionary history of
methicillin-resistant Staphylococcus aureus (MRSA). Proc Natl Acad Sci U S A 2002; 99: 7687-7692.
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34. Luk S, Ho AY, Ng TK, et al. Prevalence, prediction, and clonality of methicillin-resistant Staphylococcus aureus carriage at admission to medical units in Hong Kong, China. Infect Control Hosp Epidemiol 2014; 35: 42-48.
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35. Ghebremedhin B, Konig W, Konig B. Heterogeneity of methicillin-resistant
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Staphylococcus aureus strains at a German university hospital during a 1-year period. Eur J Clin Microbiol Infect Dis 2005; 24: 388-398.
36. Ho PL, Chow KH, Lo PY, et al. Changes in the epidemiology of methicillin-resistant Staphylococcus aureus associated with spread of the ST45
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ACCEPTED MANUSCRIPT Table 1. Prevalence of nasal MSSA and MRSA carriage among residents and staff, and comparison of pulsed-field gel electrophoresis (PFGE) patterns between MRSA isolates from residents and staff in 14 nursing homes (NH) in Taiwan NHa
Category Subject No.
MSSA No.(%)
MRSA PFGE patterns b No.(%) A AG AK B BA BM BR C
D
F U UT*
1
Resident Staff
24 23
0(0.0) 1(4.3)
4(16.7) 7(30.4)
1 1
-
-
-
1
2
Resident Staff
49 14
2(4.1) 0(0.0)
10(20.4) 4(28.6)
-
-
-
2 1
-
3
Resident Staff
13 6
2(15.4) 1(16.7)
2(15.4) 1(16.7)
-
-
-
-
-
4
Resident Staff
18 11
1(5.6) 3(27.3)
0(0.0) 0(0.0)
-
-
-
-
-
5
Resident Staff
21 10
5(23.8) 3(30.0)
7(33.3) 2(20.0)
2 -
1 -
-
-
6
Resident Staff
19 9
0(0.0) 1(11.1)
5(26.3) 1(11.1)
-
2 -
-
7
Resident Staff
33 8
9(27.3) 2(25.0)
5(15.2) 0(0.0)
1 -
-
8
Resident Staff
14 7
1(7.1) 3(42.9)
4(28.6) 0(0.0)
-
9
Resident Staff
26 19
4(15.4) 0(0.0)
5(19.2) 6(31.6)
10
Resident Staff
28 10
0(0.0) 2(20.0)
11
Resident Staff
20 8
12
Resident Staff
38 18
13
Resident Staff
14
-
-
1
-
1
-
7 2
-
-
1
-
1 -
-
2 -
-
-
-
-
1
-
-
-
-
-
-
-
-
-
1 1
1 -
1
1 -
1 -
-
-
-
-
-
-
-
3 1
-
-
-
-
-
-
3 -
-
-
1 -
-
-
-
1 -
-
-
-
0 -
-
-
-
-
-
3 -
-
3 -
-
-
-
2 6
-
-
-
-
-
-
6(21.4) 2(20.0)
-
-
-
-
-
1 -
-
1 1
2 1
-
2 -
-
7(35.0) 2(25.0)
4(20.0) 1(12.5)
-
2 -
1
-
-
-
-
-
-
-
-
2 -
2(5.3) 1(5.6)
4(10.5) 4(22.2)
-
-
-
-
-
3 4
-
-
1 -
-
-
-
29 9
3(10.3) 1(11.1)
14(48.3) 3(33.3)
-
3 1
-
-
-
10 2
-
-
1 -
-
-
-
Resident Staff
28 11
1(3.6) 2(18.2)
3(10.7) 1(9.1)
-
-
-
-
-
1 1
-
-
2 -
-
-
-
Total Resident Staff
360 163
37(10.3) 73(20.1) 22(13.5) 32(19.6)
4 1
12 1
0 1
2 1
0 1
33 19
1 0
1 11 1 2 4 0
3 2
5 0
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a
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3 3
Nursing homes are listed according to time of sampling.
b
Prevalence of MRSA carriage rate was significant different among residents (p value = 0.014),but not among staff (p value= 0.439). *UT, untypeable by SmaI digestion
1
ACCEPTED MANUSCRIPT Table 2. Potential risk factors for MRSA colonization among residents in nursing homes in Taiwan Demographic and clinical data
Odds ratio 95% confidence interval p valuea
No. (%) of subjects Total(n=360) MRSA(n=73) Non-MRSA(n=287)
Ageb
30(41.4)
145(50.5)
66.81±18.769 69.11±17.792 >60 years old
0.683
0.406-1.150
66.22±18.994
242(67.2)
58(79.5)
18(64.1)
DM
101(28.1)
26(35.6)
75(26.1)
Hypertension
188(52.2)
42(57.5)
146(50.9)
Arrhythmia
34(9.4)
8(11.0)
Heart failure
14(3.9)
History of pneumonia
0.150 0.241
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175(48.6)
Male
2.164
1.168-4.011
0.013*
1.564
0.905-2.701
0.107
1.308
0.779-2.198
0.309
26(9.1)
1.236
0.535-2.855
0.620
3(4.1)
1(3.8)
1.075
0.292-3.959
1.000
29(8.1)
5(6.8)
24(8.4)
0.806
0.297-2.190
0.671
History of TB infection
9(2.5)
2(2.7)
7(2.4)
1.127
0.229-5.541
1.000
History of asthma
9(2.5)
3(4.1)
6(2.1)
2.007
0.490-8.225
0.394
COPD
12(3.3)
1(1.4)
11(3.8)
0.348
0.044-2.744
0.472
Chronic kidney disease
23(6.4)
6(8.2)
17(5.9)
1.422
0.540-3.746
0.432
HBV carrier
8(2.2)
0(0.0)
8(2.8)
1.262
1.196-1.331
0.367
HCV carrier
6(1.7)
2(2.7)
4(1.4)
1.993
0.358-1.099
0.352
Liver cirrhosis
12(3.3)
3(4.1)
9(3.1)
1.324
0.349-5.019
0.715
Cancer
22(6.1)
6(8.2)
16(5.6)
1.517
0.572-4.024
0.413
Allergic rhinitis
11(3.1)
2(2.7)
9(3.1)
0.870
0.184-4.117
1.000
History of coronary artery disease
12(3.3)
2(2.7)
10(3.5)
0.780
0.167-3.641
1.000
26(7.2)
8(11.0)
18(6.3)
1.839
0.766-4.416
0.167
26(7.2)
4(5.5)
22(7.7)
0.698
0.233-2.093
0.519
Antibiotics using
67(18.7)
14(19.2)
53(18.5)
1.043
0.542-2.007
0.899
Skin or soft tissue infection
51(14.2)
17(23.3)
34(11.8)
2.259
1.179-4.328
0.012*
Chronic wound d
43(11.9)
15(20.5)
28(9.8)
2.392
1.201-4.763
0.011*
UTI
40(11.1)
10(13.7)
30(10.5)
1.360
0.632-2.928
0.431
Hospitalization
58(16.1)
16(21.9)
42(14.6)
1.637
0.860-3.118
0.131
Hemodialysis status
11(3.1)
4(5.5)
7(2.4)
2.319
0.660-8.146
0.244
Immunosupressant
9(2.5)
4(5.5)
5(1.7)
3.270
0.855-12.498
0.087
160(44.4)
28(38.4)
132(46.0)
0.731
0.432-1.236
0.241
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Pneumonia URTI
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Current diseasesc
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Underlying diseases
Other risk factors
Nasogastric tube
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ACCEPTED MANUSCRIPT Foley tube
100(27.8)
19(26.0)
81(28.2)
0.895
0.500-1.602
0.708
Tracheostomy
44(12.2)
3(4.1)
41(14.3)
0.257
0.077-0.855
0.018*
Smoking
124(34.4)
23(31.5)
101(35.2)
0.847
0.489-1.468
0.554
Alcohol drinking
113(31.4)
22(30.1)
91(31.7)
0.929
0.532-1.624
0.796
40(11.1)
13(17.8)
27(9.4)
2.086
1.017-4.281
0.041*
Duration < 3 months
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Total living time in NH
-
Ambulation No limitation
50(13.9)
9(12.3)
41(14.3)
Move with help
107(29.7)
21(28.8)
86(30.0)
bedridden
203(56.4)
43(58.9)
160(55.7)
-
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DM: diabetes mellitus, HBV: hepatitis B virus , HCV: hepatitis C virus , TB: tuberculosis, COPD: chronic obstructive pulmonary disease, URTI: upper respiratory
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tract infection, a For categorical variables, Fisher’s exact test was used for extreme proportions (expected count <5) instead of Pearson’s chi-square test. b
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data was presented as the mean value ± standard error of the mean for continuous variables. Performed by Student t test. c any event happened in 3 months before sampling. d wound presented more than 3 moths
3
0.864
ACCEPTED MANUSCRIPT Table 3. Potential risk factors for MRSA colonization among staff working in nursing homes in Taiwan Demographic and clinical data
Odds ratio 95% confidence interval p valuea
No. (%) of subjects Total(n=163) MRSA(n=32) Non-MRSA(n=131)
Ageb
31(96.9)
122(93.1)
37.20±11.061 34.91±10.798
2.287
0.279-18.730
37.76±11.092
75(46.0)
21(65.6)
54(41.2)
DM
3(1.8)
0(0.0)
3(2.3)
Hypertension
9(5.5)
0(0.0)
9(6.9)
Allergic rhinitis
22(13.5)
3(9.4)
19(14.5)
Alcohol drinking
18(11.0)
0(0.0)
18(13.7)
Smoking
14(8.6)
1(3.1)
13(9.9)
URTI
35(21.5)
10(31.3)
Antibiotics using
17(10.4)
Skin infection
0.688 0.191
RI PT
153(93.9)
Female
2.722
1.213-6.108
0.013*
0.5648
0.029-11.21
1.000
0.1984
0.011-3.499
0.207
0.610
0.169-2.203
0.572
0.095
0.000-1.623
0.025*
0.293
0.037-2.325
0.307
25(19.1)
1.927
0.811-4.578
0.133
5(15.6)
12(9.2)
1.836
0.597-5.650
0.332
5(3.1)
1(3.1)
4(3.1)
1.024
0.111-9.489
1.000
Chronic wound d
3(1.8)
3(9.4)
0(0.0)
31.20
1.569 - 620.5
0.007*
UTI
4(2.5)
1(3.1)
3(2.3)
1.376
0.138-13.686
1.000
Hospitalization
1(0.6)
0(0.0)
1(0.8)
1.339
0.053-33.62
1.000
15(9.2)
4(12.5)
11(8.4)
1.558
0.462~5.258
0.497
-
-
0.153
Foreign nursing workers
Total working times in NH Duration < 3 months
EP
Job types Nurses
37(22.7)
5(15.6)
32(24.4)
98(60.1)
24(75.0)
74(56.5)
3(9.4)
25(19.1)
AC C
Health care workers Others
M AN U
TE D
Current diseasesc
28(17.2)
SC
Underlying diseases
Working hours (hours/week) b
45.68±11.995 37.60±15.126
46.94±11.199
0.106
71.48±18.619 70.58±12.573
71.77±20.261
0.788
Nurse
45.19±24.433
39.00±8.031
46.16±26.035
0.234
Caretaker
12.49±12.278
10.92±6.406
13.00±13.649
0.473
Nurse Caretaker
Number of Caring residents
b
DM: diabetes mellitus, TB: tuberculosis, COPD: chronic obstructive pulmonary disease, URTI: upper respiratory tract infection, a For categorical variables, Fisher’s exact test was used for extreme proportions 4
ACCEPTED MANUSCRIPT (expected count <5) instead of Pearson’s chi-square test. data was presented as the mean value ± standard error of the mean for continuous
b
AC C
EP
TE D
M AN U
SC
RI PT
variables. Performed by Student t test. c any event happened in 3 months before sampling. d wound presented more than 3 moths
5
ACCEPTED MANUSCRIPT Table 4. Molecular characteristics of 105 MRSA isolates, categorized by pulsed-field gel electrophoresis (PFGE) patterns. SCCmec
PVL-positive
MLST type
pattern
(%)
type
A
5(5)
AG
III
0
239
t037,t138
13(12)
IV
0
30
t019,t1836
AK
1(1)
IV
0
508
t015
B
3(3)
III
0
BA
1(1)
IV
0
BM
29(28)
V
21(20)
UT
2(2)
IV
BR
1(1)
IV
C
2(2)
F
UT
t286
0
45
t1081,t1861,t9377
0
45
t1081
0
45
t1081
0
8
t008
IV
0
59
t437
VT
0
59
t437
VT
13
59
t4135,t437a,t441,t13876
M AN U
1
1(1)
II
0
5
t002
5(5)
IV
0
573, 2963#
t3525,t345
VT
0
398
t034
AC C
U
15(14)
t037
EP
D
900*
TE D
1(1)
Spa typing
RI PT
No. isolate
SC
PFGE
5(5)
SCCmec: staphylococcal cassette chromosome; MLST: multilocus sequence type; PVL:Panton-Valentine leukocidin; UT: untypeable a
One isolate of spa typing t437 didn’t carry PVL genes *single locus variant of ST239 # single locus variant of ST573
6
ACCEPTED MANUSCRIPT Table 5. Distribution of antimicrobial susceptibility rates of 105 MRSA isolates stratified by staphylococcal cassette chromosomes (SCCmec) No. (%)
Total
105(100) 104(99)
II
F
III
Total
IV
Dox
5
Cip
EM
42(40)
40(38)
82(78)
77(73)
97(92)
1(100)
0(0)
1(100)
6(75)
1(13)
0(0)
3(60)
1(20)
0(0)
1(1)
1(100)
0(0)
0(0)
8(8)
8(100)
0(0)
0(0) 0(0)
A
239
5(5)
5(100)
0(0)
B
900*
3(3)
3(100)
0(0)
25(24)
25(100)
23(92)
Total
FA
CL
RI PT
MLST
SC
PFGE
SXT
0(0)
3(100)
0(0)
0(0)
12(48)
25(100
23(92)
25(100)
M AN U
SCCmec
13(100)
13(100)
1(100)
1(100)
30
13(12)
13(100)
13(100)
4(31)
AK
508
1(1)
1(100)
1(100)
1(100)
) 13(100 ) 1(100)
BA
1
1(1)
1(100)
1(100)
1(100)
1(100)
1(100)
1(100)
BM
45
2(2)
2(100)
2(100)
2(100)
2(100)
2(100)
2(100)
BR
8
1(1)
1(100)
1(100)
0(0)
1(100)
1(100)
1(100)
C
59
2(2)
2(100)
2(100)
0(0)
2(100)
0(0)
2(100)
U
2963#,
5(5)
5(100)
3(60)
4(80)
5(100)
5(100)
5(100)
V
BM
573 45
29(28)
28(97)
0(0)
12(41)
27(93)
29(100)
VT
Total
21(20)
21(100)
19(90)
10(48)
29(100 ) 21(100
10(48)
21(100)
1(1)
1(100)
1(100)
1(100)
) 1(100)
1(100)
1(100)
15(14)
15(100)
13(87)
4(27)
EP
C
59
D
59
X
398
5(5)
5(100)
5(100)
BM
45
21(20)
21(100)
0(0)
AC C
UT
TE D
AG
4(27)
15(100)
5(100)
15(100 ) 5(100)
5(100)
5(100)
6(29)
0(0)
16(76)
21(100)
UT, untypeable; PFGE, pulsed-field electrophoresis; MLST, multilocus sequence type; Dox, doxycycline; Cip, ciprofloxacin; EM, erythromycin; FA, fusidic acid; CL, clindamycin; SXT, trimethoprim/sulfamethoxazole All 105 MRSA isolates were susceptible to Vancomycin, Teicoplanin, and Linezoid and all resistant to Penicillin *single locus variant of ST239 # single locus variant of ST573 7