Stethoscope Contamination with MRSA

Date First Published:
October 22, 2007
Last Updated:
January 9, 2008
Report by:
Christine Young, MD, Resident (Grand Rapids Spectrum Health-Butterworth)
Search checked by:
Jeffrey S. Jones, MD, Grand Rapids Spectrum Health-Butterworth
Three-Part Question:
In [Emergency care providers] does [routine cleaning of stethoscopes] reduce [bacterial contamination with MRSA]?
Clinical Scenario:
You are evaluating an immunosuppressed patient in the emergency department. As you auscultate his chest, you wonder if your stethoscope could present a significant source of MRSA contamination
Search Strategy:
Medline 1950 to October week 3 2007 and Embase 1980 to 2007 week 43 using the OVID interface and Multifile Searching
The Cochrane Library, Issue 4, 2007.
Search Details:
Medline/Embase: (exp stethoscopes/or stethoscop$.mp) AND (exp Staphylococcus aureus/or staphylococcus aureus.mp or MRSA.mp.). LIMIT to English.

Cochrane: stethoscopes.ti.ab.kw.
Outcome:
A total of 30 papers were found, of which five were relevant
Relevant Paper(s):
Study Title Patient Group Study type (level of evidence) Outcomes Key results Study Weaknesses
Stethoscopes and otoscopes - a potential vector of infection? Cohen HA, Amir J, Matalon A, et al. 1997 USA Stethoscopes (55) and otoscopes of pediatric physicians in community clinics. Survey Bacterial contamination Staphylococcus species isolated from 85.4%; 54% was Staph aureus, 7.3% MRSA Study group was pediatricians in an outpatient clinic setting. The study initially had 42 stethoscopes, then added an additional 8, not sure how they chose these and why they added them.
Bacterial contamination after cleaning with alcohol wipe Colony count reduced by 96.3%
Stethoscopes: A potential vector of infection? Jones JS, Hoerle D, Riekse R. 1995 USA Emergency care providers' stethoscopes (physicians, nurses, and prehospital). 150 total. Survey Staphylococcus carriage 89% grew Staphylococcus species, 19% Staph aureus. Did not address MRSA (possibly because it was published in 1995). The interviewer was a physician, which may have influenced answer of nurses and prehospital personnel.
CFU reduction after various cleaning methods 94% reduction with alcohol swab, 88% with nonionic detergent, 75% with antiseptic soap.
Cleansing routine and CFU count CFUs markedly increased when cleaned less frequently.
The stethoscope. A potential source of nosocomial infection? Marinella MA, Pierson C, Chenoweth C. 1997 USA Stethoscopes (47) of medical ICU and general medical ward including physicians, nurses, medical students and house staff. Survey Staphylococcal contamination of diaphram 87.5% Staphylococcus coag neg, 27.5% Staph aureus. Nurse's stethoscopes significantly less contaminated. The study did not address MRSA. Small study size (47 stethoscopes). Study participants not from emergency department and their conclusion must be extrapolated.
Cleansing agents Isopropyl alcohol most effective.
Transmission of Micrococcus luteus to human skin Human skin was inoculated after contact with a contaminated stethoscope, clinical relevance uncertain.
The stethoscope in the emergency department: a vector of infection. Nunez S, Moreno A, Green K, et al. 2000, Spain Stethoscopes (122) from ED clinicians Survey Bacterial contamination S epidermides 97%,
Bacterial contamination after cleaning Number of contaminated stethoscopes reduced by 70%
El estetoscopio: un potencial vector de infeccion. Barrio Torres J, Pinto Fuentes I, Paez Pena M, et al. 2003, Spain Stethescopes (73) from ED, paediatric and ICU clinicians Survey Bacterial contamination 62.23 cfu general, 9.19 cfu S aureus Results given as average colony forming units
Bacterial contamination after cleaning 7.45 cfu general, 0.6 cfu S aureus
Author Commentary:
A number of surveys have shown general contamination of stethoscopes and have demonstrated that cleaning with isopropyl alcohol reduces this contamination. No direct evidence is presented that links contamination to cross-infection.
Bottom Line:
Routine cleansing of stethoscopes significantly decreases bacterial contamination.
References:
  1. Cohen HA, Amir J, Matalon A, et al.. Stethoscopes and otoscopes - a potential vector of infection?
  2. Jones JS, Hoerle D, Riekse R.. Stethoscopes: A potential vector of infection?
  3. Marinella MA, Pierson C, Chenoweth C.. The stethoscope. A potential source of nosocomial infection?
  4. Nunez S, Moreno A, Green K, et al.. The stethoscope in the emergency department: a vector of infection.
  5. Barrio Torres J, Pinto Fuentes I, Paez Pena M, et al.. El estetoscopio: un potencial vector de infeccion.