- Email: [email protected]
Carriage of meticillin-susceptible and -resistant Staphylococcus aureus by medical students in Hong Kong
184
Letters to the Editor / Journal of Hospital Infection 91 (2015) 183e186
Funding sources None.
References 1. Marinella MA, Pierson C, Chenoweth C. The stethoscope. A potential source of nosocomial infection? Archs Intern Med 1997;157: 786e790. 2. Schroeder A, Schroeder MA, D’Amico F. What’s growing on your stethoscope? (and what you can do about it). J Fam Pract 2009;58: 404e409. 3. Zuliani Maluf ME, Maldonado AF, Bercial ME, Pedroso SA. Stethoscope: a friend or an enemy? Sao Paulo Med J 2002;120: 13e15. 4. Lecat P, Cropp E, McCord Gary, Haller NA. Ethanol-based cleanser versus isopropyl alcohol to decontaminate stethoscopes. Am J Infect Control 2009;37:241e243. 5. Mehta AK, Halvosa JS, Gould CV, Steinberg JP. Efficacy of alcoholbased hand rubs in the disinfection of stethoscopes. Infect Control Hosp Epidemiol 2010;31:870e872.
L. Grandiere-Pereza,* J. Bovetb A. Beaudronb P. Saulnierc S. Blanchia M. Delemottea C. Ramanantsoab a Service de Maladies Infectieuses et Tropicales, Centre Hospitalier, Le Mans, France b
Laboratoire de Microbiologie, Centre Hospitalier, Le Mans, France
c
Cellule de Me´thodologie et Biostatistiques, DRCI, Centre Hospitalier Universitaire, Angers, France
* Corresponding author. Address: Laboratoire de Microbiologie, Centre Hospitalier, 194 Avenue Rubillard, 72000 Le Mans, France. Tel.: þ33 243432614. E-mail address: [email protected] (L. Grandiere-Perez). Available online 9 July 2015 http://dx.doi.org/10.1016/j.jhin.2015.05.018 ª 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
Carriage of meticillin-susceptible and -resistant Staphylococcus aureus by medical students in Hong Kong Sir, Meticillin-resistant Staphylococcus aureus (MRSA) is increasingly recognized in the community, especially among
children and young adults.1,2 Due to their younger age and exposure to the healthcare environment, medical students are a group that might be at risk of carriage of both community-associated (CA) and healthcare-associated (HA) MRSA. There are few published reports on this issue.3,4 We assessed the carriage of S. aureus, including MRSA, among year 1 medical students in the University of Hong Kong; during the first year of their studies they have only limited exposure to hospitals and patients. We investigated consecutive cohorts of year 1 students from 2006 to 2013, with the exception of 2008 when testing was not possible for administrative reasons. During clinical skill sessions, used to train students on collection of clinical specimens, students collected nasopharyngeal and throat swabs from each other under the supervision of tutors. Swabs were placed in Amies transport medium and sent to the microbiology laboratory for culture for S. aureus. Swabs underwent enrichment culture in mannitolesalt broth. After aerobic incubation at 35 C for 24 h, turbid broths were subcultured on to mannitolesalt agars (plain and supplemented with oxacillin 6 mg/L).2 Bacterial identification and antimicrobial susceptibility were carried out as previously described.2,5 No data about the students were collected. The MRSA isolates were further characterized by spa and SCCmec typing.1,2 Polymerase chain reaction was used to detect the presence of PantoneValentine Leucocidin (PVL) genes.1,2 Linear regression analyses were used to assess trend changes in the measurements (S. aureus carriage, MRSA carriage, antimicrobial resistance rates) over time. P 0.05 was considered statistically significant. The data were analysed using SPSS version 17.0 (SPSS, Hong Kong). The study was approved by the Institutional Review Board at the Hong Kong West Cluster/University of Hong Kong. A total of 1149 students were tested. The annual number of subjects varied from 126 to 213 due to variations in the student intake. Overall, S. aureus was identified in 532 students, comprising meticillin-susceptible S. aureus (MSSA) in 526 students and MRSA in six students (one in 2009, two in 2011, two in 2012, and one in 2013). The annual ( standard deviation) rates of MSSA and MRSA carriage were 45.8 12.3% and 0.5 0.6%, respectively. Resistance rates were low for most antibiotics (<1% to 3% for chloramphenicol, cotrimoxazole, fusidic acid, gentamicin, and rifampicin) except for erythromycin and tetracycline. Overall, 135 (25.4%) isolates including 131 MSSA and four MRSA were erythromycin resistant. Tetracycline resistance rates in MSSA and MRSA were 12.7% (67/526) and 50% (3/6), respectively. There were no significant trend changes in the carriage rates of S. aureus (R2 ¼ 0.139, P ¼ 0.4) and MRSA (R2 ¼ 0.328, P ¼ 0.2) over time. Temporal rates of erythromycin (R2 ¼ 0.05, P ¼ 609) and tetracycline (R2 ¼ 0.02, P ¼ 0.773) resistance also remained stable. The spa/SCCmec types of the six MRSA were as follows: t437/SCCmec IV or V (N ¼ 3, one each in 2009, 2011 and 2012), t11642/SCCmec IV (N ¼ 1, in 2011), t1081/SCCmec IV (N ¼ 1, in 2013), and t267/SCCmec IV (N ¼ 1, in 2012). One of the t437 strains was PVL positive whereas the other five strains were PVL negative. In Hong Kong, MRSA spa t437 and the related spa t11642 types represent CA-MRSA of the ST59 clone whereas MRSA spa t1081 and t267 are HA-MRSA of the ST45 and ST97 clones, respectively.1,2
Letters to the Editor / Journal of Hospital Infection 91 (2015) 183e186 This study showed that whereas carriage of MSSA by medical students was widespread, the prevalence of either CA-MRSA or HA-MRSA is low. To our knowledge this is the first study to report on trends in carriage over a period of several years. MRSA carriage among healthcare personnel has been implicated in outbreaks, but whether they should be screened routinely remains debatable.4 Our data indicated that there is no need to screen medical students routinely for MRSA in our region. Conflict of interest statement None.
185
Investigation for Ebola virus environmental contamination in an Ebola virus disease convalescent ward
Sir,
Funding sources This work was supported by grants from the Health and Medical Research Fund of the Health and Food Bureau of the Government of the HKSAR.
References 1. Ho PL, Chuang SK, Choi YF, et al. Community-associated methicillin-resistant and methicillin-sensitive Staphylococcus aureus: skin and soft tissue infections in Hong Kong. Diagn Microbiol Infect Dis 2008;61:245e250. 2. Ho PL, Chiu SS, Chan MY, et al. Molecular epidemiology and nasal carriage of Staphylococcus aureus and methicillin-resistant S. aureus among young children attending day care centers and kindergartens in Hong Kong. J Infect 2012;64:500e506. 3. Chen CS, Chen CY, Huang YC. Nasal carriage rate and molecular epidemiology of methicillin-resistant Staphylococcus aureus among medical students at a Taiwanese university. Int J Infect Dis 2012;16:e799ee803. 4. Hawkins G, Stewart S, Blatchford O, et al. Should healthcare workers be screened routinely for meticillin-resistant Staphylococcus aureus? A review of the evidence. J Hosp Infect 2011;77:285e289. 5. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing: twentyfourth informational supplement M100-S25. Wayne, PA: CLSI; 2015.
P.-L. Ho* E.L. Lai K.-H. Chow Department of Microbiology and Carol Yu Centre for Infection, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China * Corresponding author. Address: Department of Microbiology, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong, China. Tel.: þ852 2855 4897; fax: þ852 2855 1241. E-mail address: [email protected] (P.-L. Ho). Available online 9 July 2015 http://dx.doi.org/10.1016/j.jhin.2015.06.012 ª 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
According to the daily report of the Ministry of Health and Sanitation in Sierra Leone, the number of newly confirmed Ebola virus disease (EVD) cases is gradually decreasing. However, a number of EVD patients remain recovering in hospitals after medical treatment. Ebola virus often transmits via fomites contaminated with infected body fluids.1 The virus may persist in body fluids such as semen and ocular fluid of convalescent patients without viraemia.2,3 To elucidate whether the virus can be found in the environment of an EVD convalescent ward, we evaluated Ebola virus contamination at different places on the ward. In the Jui SLeChina Friendship Hospital, Freetown, we assessed Ebola virus contamination in the ward of one EVD convalescent patient and that of another suspected patient as a control, whose laboratory virus result was negative. The EVD patient was admitted to the hospital on April 11th, 2015, with a positive result for Ebola virus infection. The patient’s EVD symptoms included nausea, vomiting, diarrhoea, and fatigue; these had diminished by April 26th, after treatment; after April 30th, viraemia was not detected. On May 1st, we collected samples using cotton swabs in the sterile saline sampling tubes from the surface of mattress, bed railing, bedside cupboard, sink, dustbin, floor, and the outer gloves of the nurses, who had just infused the patients from the two wards respectively. The samples were sent to the SLeChina Friendship Biological Safety Laboratory for Ebola virus test with quantitative reverse transcriptionepolymerase chain reaction immediately. The results of the samples from EVD convalescent ward were all negative as well as those from the control ward. Our result showed that the ward of the EVD convalescent patient was negative for Ebola virus contamination. Although this is only a single case report, the study suggests that EVD convalescent patients are less likely to contaminate hospital environments. The risk of nosocomial infection or of occupational exposure of medical staff will be low in such circumstances.
Acknowledgements Dr R. Zu and The China Lab Team of Assistance to Sierra Leone. Conflict of interest statement None declared. Funding sources None.
Letters to the Editor / Journal of Hospital Infection 91 (2015) 183e186
Funding sources None.
References 1. Marinella MA, Pierson C, Chenoweth C. The stethoscope. A potential source of nosocomial infection? Archs Intern Med 1997;157: 786e790. 2. Schroeder A, Schroeder MA, D’Amico F. What’s growing on your stethoscope? (and what you can do about it). J Fam Pract 2009;58: 404e409. 3. Zuliani Maluf ME, Maldonado AF, Bercial ME, Pedroso SA. Stethoscope: a friend or an enemy? Sao Paulo Med J 2002;120: 13e15. 4. Lecat P, Cropp E, McCord Gary, Haller NA. Ethanol-based cleanser versus isopropyl alcohol to decontaminate stethoscopes. Am J Infect Control 2009;37:241e243. 5. Mehta AK, Halvosa JS, Gould CV, Steinberg JP. Efficacy of alcoholbased hand rubs in the disinfection of stethoscopes. Infect Control Hosp Epidemiol 2010;31:870e872.
L. Grandiere-Pereza,* J. Bovetb A. Beaudronb P. Saulnierc S. Blanchia M. Delemottea C. Ramanantsoab a Service de Maladies Infectieuses et Tropicales, Centre Hospitalier, Le Mans, France b
Laboratoire de Microbiologie, Centre Hospitalier, Le Mans, France
c
Cellule de Me´thodologie et Biostatistiques, DRCI, Centre Hospitalier Universitaire, Angers, France
* Corresponding author. Address: Laboratoire de Microbiologie, Centre Hospitalier, 194 Avenue Rubillard, 72000 Le Mans, France. Tel.: þ33 243432614. E-mail address: [email protected] (L. Grandiere-Perez). Available online 9 July 2015 http://dx.doi.org/10.1016/j.jhin.2015.05.018 ª 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
Carriage of meticillin-susceptible and -resistant Staphylococcus aureus by medical students in Hong Kong Sir, Meticillin-resistant Staphylococcus aureus (MRSA) is increasingly recognized in the community, especially among
children and young adults.1,2 Due to their younger age and exposure to the healthcare environment, medical students are a group that might be at risk of carriage of both community-associated (CA) and healthcare-associated (HA) MRSA. There are few published reports on this issue.3,4 We assessed the carriage of S. aureus, including MRSA, among year 1 medical students in the University of Hong Kong; during the first year of their studies they have only limited exposure to hospitals and patients. We investigated consecutive cohorts of year 1 students from 2006 to 2013, with the exception of 2008 when testing was not possible for administrative reasons. During clinical skill sessions, used to train students on collection of clinical specimens, students collected nasopharyngeal and throat swabs from each other under the supervision of tutors. Swabs were placed in Amies transport medium and sent to the microbiology laboratory for culture for S. aureus. Swabs underwent enrichment culture in mannitolesalt broth. After aerobic incubation at 35 C for 24 h, turbid broths were subcultured on to mannitolesalt agars (plain and supplemented with oxacillin 6 mg/L).2 Bacterial identification and antimicrobial susceptibility were carried out as previously described.2,5 No data about the students were collected. The MRSA isolates were further characterized by spa and SCCmec typing.1,2 Polymerase chain reaction was used to detect the presence of PantoneValentine Leucocidin (PVL) genes.1,2 Linear regression analyses were used to assess trend changes in the measurements (S. aureus carriage, MRSA carriage, antimicrobial resistance rates) over time. P 0.05 was considered statistically significant. The data were analysed using SPSS version 17.0 (SPSS, Hong Kong). The study was approved by the Institutional Review Board at the Hong Kong West Cluster/University of Hong Kong. A total of 1149 students were tested. The annual number of subjects varied from 126 to 213 due to variations in the student intake. Overall, S. aureus was identified in 532 students, comprising meticillin-susceptible S. aureus (MSSA) in 526 students and MRSA in six students (one in 2009, two in 2011, two in 2012, and one in 2013). The annual ( standard deviation) rates of MSSA and MRSA carriage were 45.8 12.3% and 0.5 0.6%, respectively. Resistance rates were low for most antibiotics (<1% to 3% for chloramphenicol, cotrimoxazole, fusidic acid, gentamicin, and rifampicin) except for erythromycin and tetracycline. Overall, 135 (25.4%) isolates including 131 MSSA and four MRSA were erythromycin resistant. Tetracycline resistance rates in MSSA and MRSA were 12.7% (67/526) and 50% (3/6), respectively. There were no significant trend changes in the carriage rates of S. aureus (R2 ¼ 0.139, P ¼ 0.4) and MRSA (R2 ¼ 0.328, P ¼ 0.2) over time. Temporal rates of erythromycin (R2 ¼ 0.05, P ¼ 609) and tetracycline (R2 ¼ 0.02, P ¼ 0.773) resistance also remained stable. The spa/SCCmec types of the six MRSA were as follows: t437/SCCmec IV or V (N ¼ 3, one each in 2009, 2011 and 2012), t11642/SCCmec IV (N ¼ 1, in 2011), t1081/SCCmec IV (N ¼ 1, in 2013), and t267/SCCmec IV (N ¼ 1, in 2012). One of the t437 strains was PVL positive whereas the other five strains were PVL negative. In Hong Kong, MRSA spa t437 and the related spa t11642 types represent CA-MRSA of the ST59 clone whereas MRSA spa t1081 and t267 are HA-MRSA of the ST45 and ST97 clones, respectively.1,2
Letters to the Editor / Journal of Hospital Infection 91 (2015) 183e186 This study showed that whereas carriage of MSSA by medical students was widespread, the prevalence of either CA-MRSA or HA-MRSA is low. To our knowledge this is the first study to report on trends in carriage over a period of several years. MRSA carriage among healthcare personnel has been implicated in outbreaks, but whether they should be screened routinely remains debatable.4 Our data indicated that there is no need to screen medical students routinely for MRSA in our region. Conflict of interest statement None.
185
Investigation for Ebola virus environmental contamination in an Ebola virus disease convalescent ward
Sir,
Funding sources This work was supported by grants from the Health and Medical Research Fund of the Health and Food Bureau of the Government of the HKSAR.
References 1. Ho PL, Chuang SK, Choi YF, et al. Community-associated methicillin-resistant and methicillin-sensitive Staphylococcus aureus: skin and soft tissue infections in Hong Kong. Diagn Microbiol Infect Dis 2008;61:245e250. 2. Ho PL, Chiu SS, Chan MY, et al. Molecular epidemiology and nasal carriage of Staphylococcus aureus and methicillin-resistant S. aureus among young children attending day care centers and kindergartens in Hong Kong. J Infect 2012;64:500e506. 3. Chen CS, Chen CY, Huang YC. Nasal carriage rate and molecular epidemiology of methicillin-resistant Staphylococcus aureus among medical students at a Taiwanese university. Int J Infect Dis 2012;16:e799ee803. 4. Hawkins G, Stewart S, Blatchford O, et al. Should healthcare workers be screened routinely for meticillin-resistant Staphylococcus aureus? A review of the evidence. J Hosp Infect 2011;77:285e289. 5. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing: twentyfourth informational supplement M100-S25. Wayne, PA: CLSI; 2015.
P.-L. Ho* E.L. Lai K.-H. Chow Department of Microbiology and Carol Yu Centre for Infection, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China * Corresponding author. Address: Department of Microbiology, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong, China. Tel.: þ852 2855 4897; fax: þ852 2855 1241. E-mail address: [email protected] (P.-L. Ho). Available online 9 July 2015 http://dx.doi.org/10.1016/j.jhin.2015.06.012 ª 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
According to the daily report of the Ministry of Health and Sanitation in Sierra Leone, the number of newly confirmed Ebola virus disease (EVD) cases is gradually decreasing. However, a number of EVD patients remain recovering in hospitals after medical treatment. Ebola virus often transmits via fomites contaminated with infected body fluids.1 The virus may persist in body fluids such as semen and ocular fluid of convalescent patients without viraemia.2,3 To elucidate whether the virus can be found in the environment of an EVD convalescent ward, we evaluated Ebola virus contamination at different places on the ward. In the Jui SLeChina Friendship Hospital, Freetown, we assessed Ebola virus contamination in the ward of one EVD convalescent patient and that of another suspected patient as a control, whose laboratory virus result was negative. The EVD patient was admitted to the hospital on April 11th, 2015, with a positive result for Ebola virus infection. The patient’s EVD symptoms included nausea, vomiting, diarrhoea, and fatigue; these had diminished by April 26th, after treatment; after April 30th, viraemia was not detected. On May 1st, we collected samples using cotton swabs in the sterile saline sampling tubes from the surface of mattress, bed railing, bedside cupboard, sink, dustbin, floor, and the outer gloves of the nurses, who had just infused the patients from the two wards respectively. The samples were sent to the SLeChina Friendship Biological Safety Laboratory for Ebola virus test with quantitative reverse transcriptionepolymerase chain reaction immediately. The results of the samples from EVD convalescent ward were all negative as well as those from the control ward. Our result showed that the ward of the EVD convalescent patient was negative for Ebola virus contamination. Although this is only a single case report, the study suggests that EVD convalescent patients are less likely to contaminate hospital environments. The risk of nosocomial infection or of occupational exposure of medical staff will be low in such circumstances.
Acknowledgements Dr R. Zu and The China Lab Team of Assistance to Sierra Leone. Conflict of interest statement None declared. Funding sources None.