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Bacterial Contamination of Spacer Devices Used by Children With Asthma
To the Editor: The currently available methods to deliver aerosolized medication are nebulization, pressurized metered dose inhalers, and breath-actuated nebulizer.1-3 In children, the effectiveness of nebulizers and metered-dose inhalers are enhanced with the use of spacers.1
Bacterial contamination of nebulizers is well documented. Takigawa et al4 reported that nebulization equipment, even after cleaning and disinfection, might be responsible for nosocomial infection. Hutchinson et al5 reported that even after cleaning, 69% of nebulizers were contaminated by various types of gram-negative bacteria and that drying after cleaning was helpful because gram-negative bacteria survive better in a moist environment. Furthermore, incorrect cleaning, maintenance and disinfection procedures may adversely affect the performance of these devices.6 We examined the degree of bacterial contamination in a spacer device used by children with asthma.
Methods.
Participants were 30 consecutive children aged 2 years to 5 years with known asthma who presented at the Community Pediatric Clinic, Petah Tiqva, Israel, with an acute asthma attack. Approval for the study was obtained from the local ethics committee.
In all cases, the acute asthma attacks were treated by delivery of bronchodilator drugs 3 to 4 times a day using a spacer device with a face mask. The parents were asked to bring the spacer to the follow-up visit, which was conducted 4 to 7 days after the initial visit, if the asthma symptoms were still present and, therefore, the spacer device was still being used.
Culture samples were obtained from the devices at the follow-up visit. Sterile cotton-tipped swabs moistened in sterile transport medium (COPAN, Bovezzo, Italy) were rotated 10 times in a concentric pattern around the inner surface of the masks and spacer and smeared, within 2 hours, onto a blood agar plate (TSA + 5% sheep blood, HY-LAB, Rehovot, Israel). The plates were incubated at 37°C for 48 hours and examined for colony growth at 24 and 48 hours. Gram-negative organisms were identified with a test strip inoculated with the organism and suspended in physiological saline (API, VITEK, Hazelwood, Mo). Gram-positive bacteria were identified by standard laboratory methods. The culture results were recorded as mean number of colony-forming units (CFUs). Sites with less than 10 CFUs were defined as clean, sites with 10 to 100 CFUs as mildly contaminated, and sites with more than 100 CFUs as contaminated.
Parents were interviewed to determine cleaning and disinfection routines (ie, frequency of cleaning, cleaning agents, drying methods, duration of use), last inhalation episode, and drugs inhaled.
Results.
All 30 children returned for the follow-up visit. Twelve (40%) of the 30 spacer reservoirs were found to be contaminated. In 8 cases (26.7%), the face mask also was contaminated. Rates of isolation of bacterial species from reservoirs and face masks are shown in the Table 1. In 5 spacers (41.7%), the same bacteria were isolated from the reservoirs and masks: Pseudomonas species in 3 (25%), Klebsiella in 2 (16.7%), Staphylococcus aureus in 1, and Staphylococcus gram-negative in 1.
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Table. Organisms Isolated From Spacer Reservoir and Face Masks (N = 30)*
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Only 11 parents (36.7%) reported that they had obtained cleaning and maintenance instructions from the medical staff. Seventeen parents (56.7%) cleaned the spacer device after each use. Sixteen cleaned the device with tap water, and 14 cleaned with soap and water. To dry the devices 21 parents used a towel, 4 left to air dry, and 5 used a blow drier. The latter 5 spacers were found to be free of bacteria.
Four (13.3%) of the 30 children had pneumonia during the acute asthma exacerbation. All 4 were found to have contaminated spacer devices.
Comment.
Pseudomonas species and Klebsiella are relatively common human pathogens, but other bacteria found in our study are also capable of causing pneumonia, especially in immune-compromised patients and patients with asthma, cystic fibrosis, and chronic lung disease. Although the small number of devices in our study may limit its generalizability, our results reinforce the importance of regular washing and drying of spacer devices after each use.
AUTHOR INFORMATION
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Acknowledgment: We thank Dorit Karsh from the Department of Epidemiology, Section of Information and Statistics, Clalit Heath Services for the statistical analysis, and Drs Sara Beni, Brigita Czitron, and H. Ocladec for helping with the research.
Herman A. Cohen, MD
Pediatric Ambulatory Center
Clalit Health Services
Petah Tiqva, Israel
Zeev Cohen;
Ernesto Kahan, MD, MPH
Israeli Pediatric Research in Office Clinic (IPROS)
Sackler Faculty of Medicine
Tel Aviv University
Tel Aviv, Israel
1. Bisgaard H. A metal aerosol holding chamber devised for young children with asthma. Eur Respir J. 1995;8:856-860.
ABSTRACT
2. Bisgaard H. Delivery of inhaled medication to children. J Asthma. 1997;34:443-467.
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3. Everard ML. Guidelines for devices and choices. J Aerosol Med. 2001;14 Suppl 1:S59-S64.
4. 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;67:1115-1125.
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5. Hutchinson GR, Parker S, Pryor JA, 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;34:584-587.
ABSTRACT
6. Struycken VH, Tiddens HA, van der Broek ET, Dzoljic-Danilovic G, van der Velden AJ, de Jongste JC. Problems in the use, cleaning and maintenance of nebulization equipment in the home situation [in Dutch]. Ned Tijdschr Geneeskd. 1996;140:654-658.
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Letters Section Editor: Stephen J. Lurie, MD, PhD, Senior Editor.
JAMA. 2003;290:195-196.
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