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Impact of hypochlorite-based disinfection on bacterial contamination of cystic fibrosis patients' home-nebulisers
Journal of Hospital Infection (2009) 72, 351e357
Available online at www.sciencedirect.com
www.elsevierhealth.com/journals/jhin
Impact of hypochlorite-based disinfection on bacterial contamination of cystic fibrosis patients’ home-nebulisers G. Reychler a,b,*, A. Leonard b, C. Van Ossel c, V. Godding b, J. Gigi d, A. Simon c, P. Lebecque b a
Department of Physical Medicine and Rehabilitation, Cliniques universitaires Saint-Luc, Brussels, Belgium Paediatric Pulmonology and Cystic Fibrosis Unit, Cliniques universitaires Saint-Luc, Brussels, Belgium c Hygiene Unit, Cliniques universitaires Saint-Luc, Brussels, Belgium d Microbiology, Cliniques universitaires Saint-Luc, Brussels, Belgium b
Received 17 September 2008; accepted 21 May 2009 Available online 10 July 2009
KEYWORDS Aerosol; Bacterial contamination; Cystic fibrosis; Disinfection; Hygiene; Nebuliser
Summary Nebulisers are a potential source of bacterial contamination in cystic fibrosis (CF) patients. The aims of the study were to survey patient practice regarding maintenance of home nebulisers and to assess the impact of standardised guidelines derived from a previous in-vitro study. In total, 42 CF patients were studied. During two consecutive home visits, a questionnaire regarding routine patient practice was completed by a nurse while sputum and equipment samples were taken for bacteriological analyses. The first visit took place at baseline, and the second followed the implementation of detailed instructions for cleaning and disinfecting the nebulisers using a 0.5% hypochlorite solution. The first visit identified a great diversity in routine patient practices. Commensal bacteria, environmental bacteria and potential CF pathogens contaminated 78.5%, 57.1% and 14.3% of nebulisers respectively. After hypochlorite disinfection, rate and degree of global contamination decreased significantly, but the number of CF pathogens was not affected. There was no concordance between CF pathogens isolated from patients’ sputum and their
* Corresponding author. Address: Centre de re ´fe ´rence pour la mucoviscidose, Cliniques universitaires Saint-Luc, Avenue Hippocrate 10, B-1200 Brussels, Belgium. Tel.: þ32 2 764 19 39; fax: þ32 2 764 89 06. E-mail address: [email protected] 0195-6701/$ - see front matter ª 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2009.05.011
352
G. Reychler et al. equipment. We conclude that in this sample of patients, initial routine practices were varied. With regard to CF pathogens, the superiority of a hypochlorite solution over a mix of other disinfection methods was not demonstrated. ª 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Introduction
Methods
Previous outbreaks of nosocomial pneumonias and sepsis have been associated with contaminated nebulisers. Various pathogens have been involved in these outbreaks, including Klebsiella pneumoniae, Burkholderia cepacia, meticillin-resistant Staphylococcus aureus, Serratia marcescens, Legionella pneumophila and Pseudomonas aeruginosa.1e6 Moreover, bacterial contamination of nebulisers has long been reported.7e10 Contamination may be due to a previous user, the environment or to the use of opened multidose bottles of medications.11 Intrinsic contamination of nebulisation solution by B. cepacia complex has also been reported.12 Improved disinfection policies were effective and necessary in ending these outbreaks.3,13 This may be especially relevant for cystic fibrosis (CF) patients as most use nebulisers daily and are subject to airway infections. CF pathogens have been isolated from nebulisers when they were investigated in several studies.14e19 Furthermore, nebuliser use was demonstrated as a risk factor for acquisition of P. aeruginosa in CF patients.20 Nebulisation has also been associated with increased risk of nosocomial acquisition of Pseudomonas cepacia in CF patients.21 Conversely, an antimicrobial aerosol therapy and the cleaning and drying of nebulisers between uses have been shown to be associated with a decrease in B. cepacia complex acquisition.22 Hence, individual use of this equipment is recommended, as well as regular cleaning, disinfection and drying of nebulisers, which limits the risk of contamination.16 Although a recent consensus summarised recommendations regarding adequate maintenance of nebulisers in CF, the optimal disinfection method remains controversial.23 In this study, we first surveyed routine practices of CF patients regarding the care of their nebulisers. We then investigated bacterial contamination of their inhalation equipment before and after implementation of a standardised protocol that was based on the results of an in-vitro study.24 We also examined the concordance between microorganisms identified in sputum samples and those isolated from nebulisers in both phases of the study.
Subjects In total, 42 CF patients were enrolled. Twice-daily nebulisations were the only inclusion criterion. After approval by our local Ethics Committee, all patients or their guardians gave written informed consent.
Visits Each patient was visited twice, at an interval of at least six months. The first visit assessed routine procedures regarding care of the nebuliser (phase 1). The second visit quantified the impact of implementing a protocol for nebuliser maintenance including daily disinfection by a 0.5% hypochloritebased solution (Appendix) (phase 2).24 Patients were contacted by phone three days prior to these visits and were asked to maintain their routine procedures until the visit. At each visit, a questionnaire was completed. A sputum sample was taken from patients able to expectorate, and a throat swab was obtained from the others. We sampled each component of the nebulisers using a standardised method for bacteriological cultures.
Questionnaire The questionnaire assessed multiple issues, including all patient cleaning, disinfecting and drying practices (frequency, product and concentration used, and length of sessions) as well as the model of the device used and its storage conditions.
Samples First, 10 mL of Letheen broth capsules (lecithin and polysorbate) were prepared and sterilised in an autoclave for 15 min at 121 C. A cotton swab was dipped in the broth, and bacteriological samples were taken over the whole surface of each nebuliser component (mouthpiece, mask, tubing, water collector, reservoir), using the standardised method. Swab samples were then put into
Bacterial contamination of nebulisers
353
a buffered, non-nutritive transport medium and transferred within 8 h to the bacteriology laboratory. The transport medium was neutralised to ensure sample stability, to inhibit growth of commensal flora and to absorb toxins possibly liberated during material transportation.
Results
Microbiology
Questionnaire
Sputum samples were routinely cultured at the bacteriology department of our Institution, using the following media: TSA (tryptic soy agar) þ 5% sheep’s blood (Becton Dickinson, Erembodegem, Belgium), CNA (colimycin nalidixic acid) þ 5% sheep’s blood þ optochin disc, braineheart with bacitracin þ 5% horse’s blood þ disks of V factor and colimycin, MacConkey (Oxoid, Basingstoke, UK), Sabouraud dextrose gentamicin, and OFPBL (oxidative-fermentative baseepolymyxin Bebacitracinelactose). Swab samples were cultured on Columbia blood agar and bacteriological readings were taken after 48 h. Six days later, cultured results were double-checked. DNA fingerprinting by pulsedfield gel electrophoresis was carried out to confirm concordance between micro-organisms.
The median interval between the two visits was 9.6 months. The mean age of the nebulisers was 2 years. Almost all patients reported at least daily maintenance of the nebulisers, including disassembling, cleaning, disinfecting, rinsing and drying for 96%, 69%, 88%, 67% and 71% of patients, respectively. Overall, an incomplete sequence was reported by 33%. Cleaning and disinfection of the nebulisers in the previous 24 h were reported by 96% and 54% of patients, respectively. Patients reported using several different chemical substances to clean/disinfect the aerosol equipment: acetic acid (36%), hypochlorite (16%), Solution II (dimethyl benzyl ammonium chloride þ dimethyl ethylbenzyl ammonium chloride) (16%), Dettol (9%), Neosabenyl (9%), soap (5%), Virufen (5%), HAC (chlorhexidine þ cetrimide) (2%) and alcohol (2%). In phase 2, 94% of the patients reported disinfecting their nebuliser following the instructions provided within the 24 h preceding the visit.
Statistics The statistical analysis was performed using SPSS-v11.5 program. The results of the questionnaires were described using the frequency of positive answers for qualitative variables and means or medians for quantitative variables. A c2-test was used to assess the relationship between the prevalence of micro-organisms isolated during bacteriological analyses and during the test phase. Wilcoxon’s rank sum test was used to compare the number of non-CF pathogens identified per component of equipment between the two phases.
Table I Inhaled antibiotic treatment in the study group (N ¼ 42) Mean age SD (years) Pseudomonas aeruginosa colonisationa Ultrasonic nebuliser Inhaled antibiotics Colistin Tobramycin Amikacin a
Phase 1
Phase 2
16 10.1 36
16.8 10.1 36
86 78 29 12 38
67 81 40 7 31
According to the Lee criteria.33
Participants Table I summarises relevant data concerning the study group.
Bacteriological samples Bacteriological data from patients and their nebulisers at the two phases of the study are summarised in Tables II and III respectively. In phase 1, most nebulisers were contaminated by commensal (78.5%: coagulase-negative staphylococci, Corynebacterium spp., Enterococcus spp., Streptococcus viridans, etc.) and/or environmental bacteria (57%: Bacillus spp., Chryseomonas spp., Brevundimonas spp., Sphyngomonas spp.,
Table II
Respiratory cultures of the 42 patients
Pseudomonas aeruginosa Normal flora Staphylococcus aureus MRSA Aspergillus Haemophilus influenzae Stenotrophomonas maltophilia Achromobacter xylosoxidans Burkholderia cenocepacia
Phase 1
Phase 2
18 10 9 1 8 3 3 0 0
14 13 10 1 11 1 0 1 0
(43%) (23%) (21%) (2%) (19%) (7%) (7%)
MRSA, meticillin-resistant Staphylococcus aureus.
(33%) (31%) (23%) (2%) (26%) (2%) (2%)
354 Table III
G. Reychler et al. and 40) had nebulisers contaminated by such bacteria in both phases of the study. In half of the cases, the only growing micro-organism was S. maltophilia cultured from the reservoir of an ultrasonic device. Meticillin-susceptible S. aureus (MSSA) was identified simultaneously from sputum and from the patient’s nebuliser (patient no. 9, phase 1), but DNA fingerprinting demonstrated that the strains were different.
Bacterial contamination of nebulisers Phase 1 Phase 2
No cultured bacteria 5 (12%) Abundant culture 27 (64%) (>50 106 cfu) Mean no. of non-CF 4.6 pathogens/contaminated nebuliser Distribution of bacteria Commensal 92 Environmental 79 CF pathogens 7 Nebulisers contaminated by CF pathogens 6 (14%) CF pathogens, 3 (7%) excluding reservoirs
P
10 (24%) <0.001 6 (14%) <0.001 2.9
71 22 10
<0.001
<0.01 <0.001 NS
Discussion
7 (17%) NS 3 (7%) NS
CF, cystic fibrosis; NS, not significant.
Acinetobacter spp., etc.). The total number of micro-organisms cultured from the 42 nebulisers decreased from 178 in phase 1 to 103 in phase 2, a reduction of 42%. This change was significant for environmental and commensal bacteria, but CF pathogens were not affected. Other significant changes included an increased proportion of micro-organism-free nebulisers, a decreased percentage of heavily contaminated devices and a lower mean number of non-CF pathogens per contaminated nebuliser. Data concerning CF pathogens isolated from the nebulisers are summarised in Table IV. These bacteria contaminated a similar proportion of nebulisers in both phases of the study. S. aureus and Stenotrophomonas maltophilia were the only pathogens isolated. Three patients (nos. 6, 9 Table IV
Cystic fibrosis pathogens isolated from nebulisers Patient no. (ID no.)
Contaminated piece(s) Mouthpiece
Phase 1
Phase 2
We have shown that, when compared to a variety of other cleaning methods, the use of a 0.5% hypochlorite solution reduced the global rate of contamination without affecting the isolation rate of CF pathogens. A comparison between our findings and those of previous studies investigating the bacterial contamination of nebulisers in CF patients is difficult for several reasons (Table V).14e17,19,25 First, some authors have only looked for specific bacteria such as Gram-negative bacilli, Pseudomonas spp., B. cepacia or S. maltophilia.14,15,19 Additionally, the proportion of patients on inhaled antibiotics is not always specified, although this may be considered a disinfection method. In accordance with previous studies, nebulisers were often heavily contaminated by commensal or environmental bacteria but less often by CF pathogens (15%).7,10,14,15,19 With respect to CF pathogens, the most frequently contaminated part of the nebulisers was the cooling chamber of ultrasonic devices. In agreement with Denton’s study, S. maltophilia was commonly isolated from this chamber. This bacterium presents in-vitro resistance to many
1 2 3 4 5 6 1 2 3 4 5 6 7
(6) (9) (20) (24) (40) (41) (4) (6) (9) (12) (13) (31) (40)
Mask
Collector
Sputum
Reservoir
Tubing
MSSA MSSA MSSA
MSSA MSSA MSSA
PA, MSSA, Asp Asp PA, Asp, SM MSSA PA PA
SM SM SM SM SM SM SM MSSA MSSA
MSSA
PA, MSSA, Asp PA PA
SM
MSSA, meticillin-susceptible Staphylococcus aureus; PA, Pseudomonas aeruginosa; Asp, Aspergillus; SM, Stenotrophomonas maltophilia.
Comparison of nebuliser contamination rates according to the literature Present study
Patients
Nebulisers Disinfection
Results
No. Mean age (years) Inhaled antibiotics (%) Pseudomonas aeruginosa colonisation (%) Ultrasonic (%) Samples/nebuliser Method Frequency Estimated compliance (%) CF pathogens (%)a Pseudomonas aeruginosa (%) Staphylococcus aureus (%) Stenotrophomonas maltophilia (%) Achromobacter xylosoxidans Burkholderia cepacia complex (%) Klebsiella (%) Aspergillus (%) Simultaneity of sputum and nebuliser sampling Concordance between sputum and nebuliser
Phase 1
Phase 2
42 16 78 36 86 3e4 Various
42 16.8 81 36 67 3e4 NaClO (0.5%)
54 14.3 [7] 0 7.1 9.5 0 0 0 0 Yes
Daily 94 16.6 [7] 0 7.1 9.5 0 0 0 0 Yes
0
0
Pitchford et al.14
Hutchinson et al.15
36 17
36.1 22.2 22.2
35 Adults 80 97 0 5 NaClO (0.35%) Weekly 51.4 20 0
11.9
11.4 2.9 8.6
86
Various
Jakobsson et al.16
Rosenfeld et al.17
49 31 20 18.7 0 8 42 74.7 0 9 1 1 Acetic acid or Various boiling water Daily 79 6 >55 6 35 0 55
Denton et al.19 89 >16
0 3 NA
59 0 3 Various
10 35 0 9
Yes 1 (BCC)
29 0.75e44
Every use 38
0 24 0 Yes
19
1 (?)
Blau et al.25
Bacterial contamination of nebulisers
Table V
No 0
Poorb
NA
?
NA, not applicable; BCC, Burkholderia cepacia complex. a Excluding reservoirs of the ultrasonic nebulisers. b DNA fingerprinting not performed.
355
356 disinfecting agents, adheres and forms a biofilm on plastic and contaminates tap water, which is regularly used to fill these chambers.19,26e28 To our knowledge, airway infections have never been attributed to a contaminated piece of equipment, specifically in CF. However, transmission of micro-organisms to the oropharyngeal cavity of users and relationships between nebulisations and outbreak of pneumonias or sepsis have been demonstrated previously.1e6,29,30 The absence of concordance between sputum and equipment in our study is supported by previous data.14e18 Moreover, it seems that the nebulisers do not support bacterial growth in a 24 h period, implying that the contamination risk associated with a single session of aerosol therapy is low.31 Although this risk is repetitive due to daily nebulisation, it is not evident that the nebulisers are a source of infections in CF patients. Several limitations should be addressed. First, we lacked data on the bacterial contamination of undisinfected nebulisers. Although it may be difficult not to recommend cleaning and drying of the nebuliser for ethical reasons, a group of patients without disinfection could be considered for comparison in future studies. Second, the results likely reflect the particularly low prevalence of P. aeruginosa in our centre.32 Indeed, in two studies, P. aeruginosa was only isolated from devices of colonised patients.14,25 Third, the proportion of patients on inhaled antibiotics may have influenced the results of such studies. Furthermore, new generations of nebulisers may require different recommendations. The disinfection procedure is time-consuming and sometimes expensive. Use of the hypochlorite solution in this study was based on the results of a previous in-vitro study. Rigorous laboratory conditions could not realistically mimic in-vivo conditions. For instance, the concentration chosen based on this study might be too low for home practice due to the rough surface of some elements and their degree of contamination. Although the 0.5% hypochlorite solution was not more effective against CF pathogens than a mix of other methods, we believe that it remains a reasonable choice. Further studies are needed to identify the optimal method for disinfecting the home nebulisers of CF patients, information which would be of great practical value for patients and/ or their parents.
Acknowledgements The authors are indebted to the nurses, A. Beaudelot and Ch. Dutranoix, for their contribution to the home survey.
G. Reychler et al. Conflict of interest statement None declared. Funding source This study was supported by a grant from the Belgian Cystic Fibrosis Association.
Appendix. Practical recommendations for the upkeep of the nebuliser After each use, clean the equipment a. Take apart. b. Clean with water and washing detergent. c. Rinse abundantly under running tap water. d. Dry. e. Wrap in a clean cloth and store in a clean and dry place. Disinfect the equipment once daily aþbþcþRþcþdþe R: soak the equipment for 20 min in a chlorine rinse: 5e10 mL (1 teaspoon) of hypochlorite solution at 12 C in 1 L of water. This solution should be made freshly every day. Every day replace the water in the reservoir of the ultrasonic device. Clean this reservoir once a week with hot water and washing detergent, then rinse under running water and dry with a clean cloth or paper towel.
References 1. Mertz J, Scharer L, McClement JH. A hospital outbreak of Klebsiella pneumonia from inhalation therapy with contaminated aerosol solutions. Am Rev Respir Dis 1967;95: 454e460. 2. Takigawa K, Fujita J, Negayama K, et al. Nosocomial outbreak of Pseudomonas cepacia respiratory infection in immunocompromised patients associated with contaminated nebulizer devices. Kansenshogaku Zasshi 1993;67: 1115e1125 (Abstract). 3. Schultsz C, Meester H, Kranenburg A, et al. Ultra-sonic nebulizers as a potential source of methicillin-resistant Staphylococcus aureus causing an outbreak in a university tertiary care hospital. J Hosp Infect 2003;55:269e275. 4. Ringrose R, McKown B, Felton F, Barclay B, Muchmore H, Rhoades E. A hospital outbreak of Serratia marcescens associated with ultrasonic nebulizers. Ann Intern Med 1968;69: 719e729. 5. Mastro T, Fields B, Breiman R, Campbell J, Plikaytis B, Spika J. Nosocomial Legionnaires’ disease and use of medication nebulizers. J Infect Dis 1991;163:667e671. 6. Cobben N, Drent M, Jonkers M, Wouters E, Vaneechoutte M, Stobberingh E. Outbreak of severe Pseudomonas aeruginosa respiratory infections due to contaminated nebulizers. J Hosp Infect 1996;33:63e70.
Bacterial contamination of nebulisers 7. Barnes K, Clifford R, Holgate S, Murphy D, Comber P, Bell E. Bacterial contamination of home nebuliser. Br Med J 1987; 295:812. 8. Jones P, Moritz V, Pierce R. Microbial contamination of domiciliary nebuliser therapy equipment. Aust N Z J Med 1985;15:585e589. 9. Monforte V, Roman A, Gavalda J, et al. Contamination of the nebulization systems used in the prophylaxis with amphotericin B nebulized in lung transplantation. Transplant Proc 2005;37:4056e4058. 10. Cohen H, Kahan E, Cohen Z, et al. Microbial colonization of nebulizers used by asthmatic children. Pediatr Int 2006;48: 454e458. 11. Estivariz C, Bhatti L, Pati R, et al. An outbreak of Burkholderia cepacia associated with contamination of albuterol and nasal spray. Chest 2006;130:1346e1353. 12. Balkhy H, Cunningham G, Francis C, et al. A National Guard outbreak of Burkholderia cepacia infection and colonization secondary to intrinsic contamination of albuterol nebulization solution. Am J Infect Control 2005;33:182e188. 13. Pierce A, Sanford J, Thomas G, Leonard J. Long-term evaluation of decontamination of inhalation-therapy equipment and the occurrence of necrotizing pneumonia. N Engl J Med 1970;282:528e531. 14. Pitchford K, Corey M, Highsmith A, et al. Pseudomonas species contamination of cystic fibrosis patients’ home inhalation equipment. J Pediatr 1987;111:212e216. 15. Hutchinson G, Parker S, Pryor J, et al. Home-use nebulizers: a potential primary source of Burkholderia cepacia and other colistin-resistant, gram-negative bacteria in patients with cystic fibrosis. J Clin Microbiol 1996;34:584e587. 16. Jakobsson B, Onnered A, Hjelte L, Nystrom B. Low bacterial contamination of nebulizers in home treatment of cystic fibrosis patients. J Hosp Infect 1997;36:201e207. 17. Rosenfeld M, Emerson J, Astley S, et al. Home nebulizer use among patients with cystic fibrosis. J Pediatr 1998;132:125e131. 18. Vassal S, Taamma R, Marty N, et al. Microbiologic contamination study of nebulizers after aerosol therapy in patients with cystic fibrosis. Am J Infect Control 2000;28:347e351. 19. Denton M, Rajgopal A, Mooney L, et al. Stenotrophomonas maltophilia contamination of nebulizers used to deliver aerosolized therapy to inpatients with cystic fibrosis. J Hosp Infect 2003;55:180e183. 20. Kosorok M, Jalaluddin M, Farrell P, et al. Comprehensive analysis of risk factors for acquisition of Pseudomonas aeruginosa in young children with cystic fibrosis. Pediatr Pulmonol 1998;26:81e88. 21. Burdge D, Nakielna E, Noble M. Caseecontrol and vector studies of nosocomial acquisition of Pseudomonas cepacia
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33.
in adult patients with cystic fibrosis. Infect Control Hosp Epidemiol 1993;14:127e130. Walsh N, Casano A, Manangan L, Sinkowitz-Cochran R, Jarvis WR. Risk factors for Burkholderia cepacia complex colonization and infection among patients with cystic fibrosis. J Pediatr 2002;141:512e517. Saiman L, Siegel J. Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission. Am J Infect Control 2003;31:S1e62. Reychler G, Aarab K, Van Ossel C, et al. In vitro evaluation of efficacy of 5 methods of disinfection on mouthpieces and facemasks contaminated by strains of cystic fibrosis patients. J Cyst Fibros 2005;4:183e187. Blau H, Mussaffi H, Mei Zahav M, et al. Microbial contamination of nebulizers in the home treatment of cystic fibrosis. Child Care Health Dev 2007;33:491e495. Spencer R. The emergence of epidemic, multiple-antibiotic-resistant Stenotrophomonas (Xanthomonas) maltophilia and Burkholderia (Pseudomonas) cepacia. J Hosp Infect 1995;30(Suppl.):453e464. Denton M, Kerr K. Microbiological and clinical aspects of infection associated with Stenotrophomonas maltophilia. Clin Microbiol Rev 1998;11:57e80. Denton M, Todd N, Kerr K, Hawkey P, Littlewood J. Molecular epidemiology of Stenotrophomonas maltophilia isolated from clinical specimens from patients with cystic fibrosis and associated environmental samples. J Clin Microbiol 1998;36:1953e1958. Botman M, de Krieger R. Contamination of small-volume medication nebulizers and its association with oropharyngeal colonization. J Hosp Infect 1987;10:204e208. Wexler M, Rhame F, Blumenthal M, Cameron S, Juni B, Fish L. Transmission of gram-negative bacilli to asthmatic children via home nebulizers. Ann Allergy 1991;66:267e271. O’Malley CA, VandenBranden SL, Zheng XT, Polito AM, McColley SA. A day in the life of a nebulizer: surveillance for bacterial growth in nebulizer equipment of children with cystic fibrosis in the hospital setting. Respir Care 2007;52:258e262. Lebecque P, Leal T, Zylberberg K, Reychler G, Bossuyt X, Godding V. Towards zero prevalence of chronic Pseudomonas aeruginosa infection in children with cystic fibrosis. J Cyst Fibros 2006;5:237e244. Lee TW, Brownlee KG, Conway SP, Denton M, Littlewood JM. Evaluation of a new definition for chronic Pseudomonas aeruginosa infection in cystic fibrosis patients. J Cyst Fibros 2003;2:29e34.
Available online at www.sciencedirect.com
www.elsevierhealth.com/journals/jhin
Impact of hypochlorite-based disinfection on bacterial contamination of cystic fibrosis patients’ home-nebulisers G. Reychler a,b,*, A. Leonard b, C. Van Ossel c, V. Godding b, J. Gigi d, A. Simon c, P. Lebecque b a
Department of Physical Medicine and Rehabilitation, Cliniques universitaires Saint-Luc, Brussels, Belgium Paediatric Pulmonology and Cystic Fibrosis Unit, Cliniques universitaires Saint-Luc, Brussels, Belgium c Hygiene Unit, Cliniques universitaires Saint-Luc, Brussels, Belgium d Microbiology, Cliniques universitaires Saint-Luc, Brussels, Belgium b
Received 17 September 2008; accepted 21 May 2009 Available online 10 July 2009
KEYWORDS Aerosol; Bacterial contamination; Cystic fibrosis; Disinfection; Hygiene; Nebuliser
Summary Nebulisers are a potential source of bacterial contamination in cystic fibrosis (CF) patients. The aims of the study were to survey patient practice regarding maintenance of home nebulisers and to assess the impact of standardised guidelines derived from a previous in-vitro study. In total, 42 CF patients were studied. During two consecutive home visits, a questionnaire regarding routine patient practice was completed by a nurse while sputum and equipment samples were taken for bacteriological analyses. The first visit took place at baseline, and the second followed the implementation of detailed instructions for cleaning and disinfecting the nebulisers using a 0.5% hypochlorite solution. The first visit identified a great diversity in routine patient practices. Commensal bacteria, environmental bacteria and potential CF pathogens contaminated 78.5%, 57.1% and 14.3% of nebulisers respectively. After hypochlorite disinfection, rate and degree of global contamination decreased significantly, but the number of CF pathogens was not affected. There was no concordance between CF pathogens isolated from patients’ sputum and their
* Corresponding author. Address: Centre de re ´fe ´rence pour la mucoviscidose, Cliniques universitaires Saint-Luc, Avenue Hippocrate 10, B-1200 Brussels, Belgium. Tel.: þ32 2 764 19 39; fax: þ32 2 764 89 06. E-mail address: [email protected] 0195-6701/$ - see front matter ª 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2009.05.011
352
G. Reychler et al. equipment. We conclude that in this sample of patients, initial routine practices were varied. With regard to CF pathogens, the superiority of a hypochlorite solution over a mix of other disinfection methods was not demonstrated. ª 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Introduction
Methods
Previous outbreaks of nosocomial pneumonias and sepsis have been associated with contaminated nebulisers. Various pathogens have been involved in these outbreaks, including Klebsiella pneumoniae, Burkholderia cepacia, meticillin-resistant Staphylococcus aureus, Serratia marcescens, Legionella pneumophila and Pseudomonas aeruginosa.1e6 Moreover, bacterial contamination of nebulisers has long been reported.7e10 Contamination may be due to a previous user, the environment or to the use of opened multidose bottles of medications.11 Intrinsic contamination of nebulisation solution by B. cepacia complex has also been reported.12 Improved disinfection policies were effective and necessary in ending these outbreaks.3,13 This may be especially relevant for cystic fibrosis (CF) patients as most use nebulisers daily and are subject to airway infections. CF pathogens have been isolated from nebulisers when they were investigated in several studies.14e19 Furthermore, nebuliser use was demonstrated as a risk factor for acquisition of P. aeruginosa in CF patients.20 Nebulisation has also been associated with increased risk of nosocomial acquisition of Pseudomonas cepacia in CF patients.21 Conversely, an antimicrobial aerosol therapy and the cleaning and drying of nebulisers between uses have been shown to be associated with a decrease in B. cepacia complex acquisition.22 Hence, individual use of this equipment is recommended, as well as regular cleaning, disinfection and drying of nebulisers, which limits the risk of contamination.16 Although a recent consensus summarised recommendations regarding adequate maintenance of nebulisers in CF, the optimal disinfection method remains controversial.23 In this study, we first surveyed routine practices of CF patients regarding the care of their nebulisers. We then investigated bacterial contamination of their inhalation equipment before and after implementation of a standardised protocol that was based on the results of an in-vitro study.24 We also examined the concordance between microorganisms identified in sputum samples and those isolated from nebulisers in both phases of the study.
Subjects In total, 42 CF patients were enrolled. Twice-daily nebulisations were the only inclusion criterion. After approval by our local Ethics Committee, all patients or their guardians gave written informed consent.
Visits Each patient was visited twice, at an interval of at least six months. The first visit assessed routine procedures regarding care of the nebuliser (phase 1). The second visit quantified the impact of implementing a protocol for nebuliser maintenance including daily disinfection by a 0.5% hypochloritebased solution (Appendix) (phase 2).24 Patients were contacted by phone three days prior to these visits and were asked to maintain their routine procedures until the visit. At each visit, a questionnaire was completed. A sputum sample was taken from patients able to expectorate, and a throat swab was obtained from the others. We sampled each component of the nebulisers using a standardised method for bacteriological cultures.
Questionnaire The questionnaire assessed multiple issues, including all patient cleaning, disinfecting and drying practices (frequency, product and concentration used, and length of sessions) as well as the model of the device used and its storage conditions.
Samples First, 10 mL of Letheen broth capsules (lecithin and polysorbate) were prepared and sterilised in an autoclave for 15 min at 121 C. A cotton swab was dipped in the broth, and bacteriological samples were taken over the whole surface of each nebuliser component (mouthpiece, mask, tubing, water collector, reservoir), using the standardised method. Swab samples were then put into
Bacterial contamination of nebulisers
353
a buffered, non-nutritive transport medium and transferred within 8 h to the bacteriology laboratory. The transport medium was neutralised to ensure sample stability, to inhibit growth of commensal flora and to absorb toxins possibly liberated during material transportation.
Results
Microbiology
Questionnaire
Sputum samples were routinely cultured at the bacteriology department of our Institution, using the following media: TSA (tryptic soy agar) þ 5% sheep’s blood (Becton Dickinson, Erembodegem, Belgium), CNA (colimycin nalidixic acid) þ 5% sheep’s blood þ optochin disc, braineheart with bacitracin þ 5% horse’s blood þ disks of V factor and colimycin, MacConkey (Oxoid, Basingstoke, UK), Sabouraud dextrose gentamicin, and OFPBL (oxidative-fermentative baseepolymyxin Bebacitracinelactose). Swab samples were cultured on Columbia blood agar and bacteriological readings were taken after 48 h. Six days later, cultured results were double-checked. DNA fingerprinting by pulsedfield gel electrophoresis was carried out to confirm concordance between micro-organisms.
The median interval between the two visits was 9.6 months. The mean age of the nebulisers was 2 years. Almost all patients reported at least daily maintenance of the nebulisers, including disassembling, cleaning, disinfecting, rinsing and drying for 96%, 69%, 88%, 67% and 71% of patients, respectively. Overall, an incomplete sequence was reported by 33%. Cleaning and disinfection of the nebulisers in the previous 24 h were reported by 96% and 54% of patients, respectively. Patients reported using several different chemical substances to clean/disinfect the aerosol equipment: acetic acid (36%), hypochlorite (16%), Solution II (dimethyl benzyl ammonium chloride þ dimethyl ethylbenzyl ammonium chloride) (16%), Dettol (9%), Neosabenyl (9%), soap (5%), Virufen (5%), HAC (chlorhexidine þ cetrimide) (2%) and alcohol (2%). In phase 2, 94% of the patients reported disinfecting their nebuliser following the instructions provided within the 24 h preceding the visit.
Statistics The statistical analysis was performed using SPSS-v11.5 program. The results of the questionnaires were described using the frequency of positive answers for qualitative variables and means or medians for quantitative variables. A c2-test was used to assess the relationship between the prevalence of micro-organisms isolated during bacteriological analyses and during the test phase. Wilcoxon’s rank sum test was used to compare the number of non-CF pathogens identified per component of equipment between the two phases.
Table I Inhaled antibiotic treatment in the study group (N ¼ 42) Mean age SD (years) Pseudomonas aeruginosa colonisationa Ultrasonic nebuliser Inhaled antibiotics Colistin Tobramycin Amikacin a
Phase 1
Phase 2
16 10.1 36
16.8 10.1 36
86 78 29 12 38
67 81 40 7 31
According to the Lee criteria.33
Participants Table I summarises relevant data concerning the study group.
Bacteriological samples Bacteriological data from patients and their nebulisers at the two phases of the study are summarised in Tables II and III respectively. In phase 1, most nebulisers were contaminated by commensal (78.5%: coagulase-negative staphylococci, Corynebacterium spp., Enterococcus spp., Streptococcus viridans, etc.) and/or environmental bacteria (57%: Bacillus spp., Chryseomonas spp., Brevundimonas spp., Sphyngomonas spp.,
Table II
Respiratory cultures of the 42 patients
Pseudomonas aeruginosa Normal flora Staphylococcus aureus MRSA Aspergillus Haemophilus influenzae Stenotrophomonas maltophilia Achromobacter xylosoxidans Burkholderia cenocepacia
Phase 1
Phase 2
18 10 9 1 8 3 3 0 0
14 13 10 1 11 1 0 1 0
(43%) (23%) (21%) (2%) (19%) (7%) (7%)
MRSA, meticillin-resistant Staphylococcus aureus.
(33%) (31%) (23%) (2%) (26%) (2%) (2%)
354 Table III
G. Reychler et al. and 40) had nebulisers contaminated by such bacteria in both phases of the study. In half of the cases, the only growing micro-organism was S. maltophilia cultured from the reservoir of an ultrasonic device. Meticillin-susceptible S. aureus (MSSA) was identified simultaneously from sputum and from the patient’s nebuliser (patient no. 9, phase 1), but DNA fingerprinting demonstrated that the strains were different.
Bacterial contamination of nebulisers Phase 1 Phase 2
No cultured bacteria 5 (12%) Abundant culture 27 (64%) (>50 106 cfu) Mean no. of non-CF 4.6 pathogens/contaminated nebuliser Distribution of bacteria Commensal 92 Environmental 79 CF pathogens 7 Nebulisers contaminated by CF pathogens 6 (14%) CF pathogens, 3 (7%) excluding reservoirs
P
10 (24%) <0.001 6 (14%) <0.001 2.9
71 22 10
<0.001
<0.01 <0.001 NS
Discussion
7 (17%) NS 3 (7%) NS
CF, cystic fibrosis; NS, not significant.
Acinetobacter spp., etc.). The total number of micro-organisms cultured from the 42 nebulisers decreased from 178 in phase 1 to 103 in phase 2, a reduction of 42%. This change was significant for environmental and commensal bacteria, but CF pathogens were not affected. Other significant changes included an increased proportion of micro-organism-free nebulisers, a decreased percentage of heavily contaminated devices and a lower mean number of non-CF pathogens per contaminated nebuliser. Data concerning CF pathogens isolated from the nebulisers are summarised in Table IV. These bacteria contaminated a similar proportion of nebulisers in both phases of the study. S. aureus and Stenotrophomonas maltophilia were the only pathogens isolated. Three patients (nos. 6, 9 Table IV
Cystic fibrosis pathogens isolated from nebulisers Patient no. (ID no.)
Contaminated piece(s) Mouthpiece
Phase 1
Phase 2
We have shown that, when compared to a variety of other cleaning methods, the use of a 0.5% hypochlorite solution reduced the global rate of contamination without affecting the isolation rate of CF pathogens. A comparison between our findings and those of previous studies investigating the bacterial contamination of nebulisers in CF patients is difficult for several reasons (Table V).14e17,19,25 First, some authors have only looked for specific bacteria such as Gram-negative bacilli, Pseudomonas spp., B. cepacia or S. maltophilia.14,15,19 Additionally, the proportion of patients on inhaled antibiotics is not always specified, although this may be considered a disinfection method. In accordance with previous studies, nebulisers were often heavily contaminated by commensal or environmental bacteria but less often by CF pathogens (15%).7,10,14,15,19 With respect to CF pathogens, the most frequently contaminated part of the nebulisers was the cooling chamber of ultrasonic devices. In agreement with Denton’s study, S. maltophilia was commonly isolated from this chamber. This bacterium presents in-vitro resistance to many
1 2 3 4 5 6 1 2 3 4 5 6 7
(6) (9) (20) (24) (40) (41) (4) (6) (9) (12) (13) (31) (40)
Mask
Collector
Sputum
Reservoir
Tubing
MSSA MSSA MSSA
MSSA MSSA MSSA
PA, MSSA, Asp Asp PA, Asp, SM MSSA PA PA
SM SM SM SM SM SM SM MSSA MSSA
MSSA
PA, MSSA, Asp PA PA
SM
MSSA, meticillin-susceptible Staphylococcus aureus; PA, Pseudomonas aeruginosa; Asp, Aspergillus; SM, Stenotrophomonas maltophilia.
Comparison of nebuliser contamination rates according to the literature Present study
Patients
Nebulisers Disinfection
Results
No. Mean age (years) Inhaled antibiotics (%) Pseudomonas aeruginosa colonisation (%) Ultrasonic (%) Samples/nebuliser Method Frequency Estimated compliance (%) CF pathogens (%)a Pseudomonas aeruginosa (%) Staphylococcus aureus (%) Stenotrophomonas maltophilia (%) Achromobacter xylosoxidans Burkholderia cepacia complex (%) Klebsiella (%) Aspergillus (%) Simultaneity of sputum and nebuliser sampling Concordance between sputum and nebuliser
Phase 1
Phase 2
42 16 78 36 86 3e4 Various
42 16.8 81 36 67 3e4 NaClO (0.5%)
54 14.3 [7] 0 7.1 9.5 0 0 0 0 Yes
Daily 94 16.6 [7] 0 7.1 9.5 0 0 0 0 Yes
0
0
Pitchford et al.14
Hutchinson et al.15
36 17
36.1 22.2 22.2
35 Adults 80 97 0 5 NaClO (0.35%) Weekly 51.4 20 0
11.9
11.4 2.9 8.6
86
Various
Jakobsson et al.16
Rosenfeld et al.17
49 31 20 18.7 0 8 42 74.7 0 9 1 1 Acetic acid or Various boiling water Daily 79 6 >55 6 35 0 55
Denton et al.19 89 >16
0 3 NA
59 0 3 Various
10 35 0 9
Yes 1 (BCC)
29 0.75e44
Every use 38
0 24 0 Yes
19
1 (?)
Blau et al.25
Bacterial contamination of nebulisers
Table V
No 0
Poorb
NA
?
NA, not applicable; BCC, Burkholderia cepacia complex. a Excluding reservoirs of the ultrasonic nebulisers. b DNA fingerprinting not performed.
355
356 disinfecting agents, adheres and forms a biofilm on plastic and contaminates tap water, which is regularly used to fill these chambers.19,26e28 To our knowledge, airway infections have never been attributed to a contaminated piece of equipment, specifically in CF. However, transmission of micro-organisms to the oropharyngeal cavity of users and relationships between nebulisations and outbreak of pneumonias or sepsis have been demonstrated previously.1e6,29,30 The absence of concordance between sputum and equipment in our study is supported by previous data.14e18 Moreover, it seems that the nebulisers do not support bacterial growth in a 24 h period, implying that the contamination risk associated with a single session of aerosol therapy is low.31 Although this risk is repetitive due to daily nebulisation, it is not evident that the nebulisers are a source of infections in CF patients. Several limitations should be addressed. First, we lacked data on the bacterial contamination of undisinfected nebulisers. Although it may be difficult not to recommend cleaning and drying of the nebuliser for ethical reasons, a group of patients without disinfection could be considered for comparison in future studies. Second, the results likely reflect the particularly low prevalence of P. aeruginosa in our centre.32 Indeed, in two studies, P. aeruginosa was only isolated from devices of colonised patients.14,25 Third, the proportion of patients on inhaled antibiotics may have influenced the results of such studies. Furthermore, new generations of nebulisers may require different recommendations. The disinfection procedure is time-consuming and sometimes expensive. Use of the hypochlorite solution in this study was based on the results of a previous in-vitro study. Rigorous laboratory conditions could not realistically mimic in-vivo conditions. For instance, the concentration chosen based on this study might be too low for home practice due to the rough surface of some elements and their degree of contamination. Although the 0.5% hypochlorite solution was not more effective against CF pathogens than a mix of other methods, we believe that it remains a reasonable choice. Further studies are needed to identify the optimal method for disinfecting the home nebulisers of CF patients, information which would be of great practical value for patients and/ or their parents.
Acknowledgements The authors are indebted to the nurses, A. Beaudelot and Ch. Dutranoix, for their contribution to the home survey.
G. Reychler et al. Conflict of interest statement None declared. Funding source This study was supported by a grant from the Belgian Cystic Fibrosis Association.
Appendix. Practical recommendations for the upkeep of the nebuliser After each use, clean the equipment a. Take apart. b. Clean with water and washing detergent. c. Rinse abundantly under running tap water. d. Dry. e. Wrap in a clean cloth and store in a clean and dry place. Disinfect the equipment once daily aþbþcþRþcþdþe R: soak the equipment for 20 min in a chlorine rinse: 5e10 mL (1 teaspoon) of hypochlorite solution at 12 C in 1 L of water. This solution should be made freshly every day. Every day replace the water in the reservoir of the ultrasonic device. Clean this reservoir once a week with hot water and washing detergent, then rinse under running water and dry with a clean cloth or paper towel.
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