Bacterial contamination of stethoscopes with antimicrobial diaphragm covers

Respiratory Therapy Department, Saint Alphonsus Regional Medical Center, Boise, ID 83706, USA.
American Journal of Infection Control (Impact Factor: 2.21). 06/2007; 35(4):263-6. DOI: 10.1016/j.ajic.2006.09.004
Source: PubMed


Antimicrobial stethoscope covers impregnated with silver ions have been developed to prevent surface contamination and potential transmission of bacterial pathogens to patients. To test their practical utility, covers were distributed with the manufacturers' recommendations to a mixed group of health care professionals in a medical/surgical intensive care unit and an emergency department. Seventy-four clinicians were selected from a convenience sample for surface cultures and standard questioning regarding cleaning and cover use. Surface colony counts were significantly lower for uncovered stethoscope diaphragms (mean, 71.4 colonies) compared with covers used <or=1 week (mean, 246.5 colonies) and those >1 week old (mean, 335.6 colonies). After controlling for type of clinician, frequency of stethoscope cleaning, and method of stethoscope cleaning, only the presence of a stethoscope cover was associated with higher colony counts (P<.0001). We question the practical utility of the antimicrobial diaphragm covers evaluated in this study for reducing the surface colonization of potentially harmful microorganisms.

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    • "Even though the antibacterial mechanism of silver is still unclear, it has been proposed that it is a combination of the action of silver ions and particles where the smaller the nanoparticle, the biggest the importance of the activity of silver ions [26]. Humidity is a key factor for ion transportation [27] and the drop of efficacy in antibacterial activity is expected in dry environments according to previous reports [11] [28]. Nevertheless, humidity is not only a pathway for ion transportation, it is also a trigger for silver ions generation [29] "
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    ABSTRACT: Hospital acquired infections are recognized as critical public health problems. Infections are frequently caused by organisms residing in healthcare environment, including contaminated medical equipment like Stethoscopes. To determine bacterial contamination, bacterial profile and anti-microbial susceptibility pattern of the isolates from stethoscopes at Jimma University Specialized Hospital.Methodology: Cross-sectional study conducted from May to September 2011 at Jimma University Specialized Hospital. One hundred seventy-six stethoscopes owned by Health Care Workers (HCWs) and Medical students were randomly selected and studied. Self-administered structured questionnaire was used to collect socio-demographic data. Specimen was collected using moisten sterile cotton swab and 1 ml normal saline was used to transport the specimen, all laboratory investigations were done following standard microbiological techniques, at Microbiology Laboratory, Jimma University. SPSS windows version 16 used for data analysis and P <0.05 was considered statistically significant. Result: A total, of 151 (85.8%) stethoscopes were contaminated. A total of 256 bacterial strains and a mean of 1.44x104 CFUs/diaphragm of stethoscopes was isolated. Of the 256 isolates, 133 (52%) were potential pathogens like S. aureus, Klebsiella spp., Citrobacter spp., Salmonella spp., Proteus spp., Enterobacter spp., P. aeruginosa and E. coli. All strains were resistant to multiple classes of antibiotics (two to eight classes of antibiotics). Disinfection practice was poor. Disinfection practice was found to be associated with bacterial contamination of stethoscopes (P < 0.05). High contamination rate 100 (90.9%) was observed among stethoscopes that had never been disinfected; while the least contamination 29 (72.2%) was found on those disinfected a week or less before the survey. Bacterial contamination of the stethoscope was significant. The isolates were potential pathogens and resistant to multiple classes of antibiotics. Stethoscope is potential vehicle in the transmission of infections between patients and Healthcare Workers. Stethoscope diaphragm should be disinfected before and after each patient contact.
    Full-text · Article · Dec 2013 · Annals of Clinical Microbiology and Antimicrobials
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    • "The lack of efficacy of silver ion-containing materials was recently verified by Wood et al. (2007) in a hospital setting, which approximates the 24% RH and 20°C test conditions. It was determined that stethoscope protective diaphragm covers, made from silver ion-containing material Ag-A, had a mean colony count of 246AE5 per sample, while the uncovered stethoscopes diaphragms had 71AE4 colonies per sample (Wood et al. 2007). Thus the silver ion-containing protective covers, which were reported to be antimicrobial, were more heavily contaminated than the unprotected stethoscope diaphragms. "
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