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Stethoscope Contamination with MRSA

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.
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.

Search Outcome

A total of 30 papers were found, of which five were relevant

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Cohen H
1997
USA
Stethoscopes (55) and otoscopes of pediatric physicians in community clinics.SurveyBacterial contaminationStaphylococcus species isolated from 85.4%; 54% was Staph aureus, 7.3% MRSAStudy 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 wipeColony count reduced by 96.3%
Jones JS
1995
USA
Emergency care providers' stethoscopes (physicians, nurses, and prehospital). 150 total.SurveyStaphylococcus carriage89% 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 methods94% reduction with alcohol swab, 88% with nonionic detergent, 75% with antiseptic soap.
Cleansing routine and CFU countCFUs markedly increased when cleaned less frequently.
Marinella MA
1997
USA
Stethoscopes (47) of medical ICU and general medical ward including physicians, nurses, medical students and house staff.SurveyStaphylococcal contamination of diaphram87.5% 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 agentsIsopropyl alcohol most effective.
Transmission of Micrococcus luteus to human skinHuman skin was inoculated after contact with a contaminated stethoscope, clinical relevance uncertain.
Nunez et al,
2000,
Spain
Stethoscopes (122) from ED cliniciansSurveyBacterial contaminationS epidermides 97%,
Bacterial contamination after cleaningNumber of contaminated stethoscopes reduced by 70%
Barrio Torres et al,
2003,
Spain
Stethescopes (73) from ED, paediatric and ICU cliniciansSurveyBacterial contamination62.23 cfu general, 9.19 cfu S aureusResults given as average colony forming units
Bacterial contamination after cleaning7.45 cfu general, 0.6 cfu S aureus

Comment(s)

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.

Editor Comment

cfu, colony-forming units; MRSA, methicillin-resistant Staphylococcus aureus.

Clinical 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? Family Practice 1997; 14 (6):446-449.
  2. Jones JS, Hoerle D, Riekse R. Stethoscopes: A potential vector of infection? Ann Emerg Med 1995; 26 (3):296-299.
  3. Marinella MA, Pierson C, Chenoweth C. The stethoscope. A potential source of nosocomial infection? Arch Intern Med 1997;157 (7): 786-790.
  4. Nunez S, Moreno A, Green K, et al. The stethoscope in the emergency department: a vector of infection. Epidemiol Infect 2000; 124: 2337.
  5. Barrio Torres J, Pinto Fuentes I, Paez Pena M, et al. El estetoscopio: un potencial vector de infeccion. Pediatrika 2003; 23: 33540.