Mayo Clinic Proceedings Home

Contamination of Stethoscopes and Physicians' Hands After a Physical Examination



      To compare the contamination level of physicians’ hands and stethoscopes and to explore the risk of cross-transmission of microorganisms through the use of stethoscopes.

      Patients and Methods

      We conducted a structured prospective study between January 1, 2009, and May 31, 2009, involving 83 inpatients at a Swiss university teaching hospital. After a standardized physical examination, 4 regions of the physician’s gloved or ungloved dominant hand and 2 sections of the stethoscopes were pressed onto selective and nonselective media; 489 surfaces were sampled. Total aerobic colony counts (ACCs) and total methicillin-resistant Staphylococcus aureus (MRSA) colony-forming unit (CFU) counts were assessed.


      Median total ACCs (interquartile range) for fingertips, thenar eminence, hypothenar eminence, hand dorsum, stethoscope diaphragm, and tube were 467, 37, 34, 8, 89, and 18, respectively. The contamination level of the diaphragm was lower than the contamination level of the fingertips ( P<.001) but higher than the contamination level of the thenar eminence ( P=.004). The MRSA contamination level of the diaphragm was higher than the MRSA contamination level of the thenar eminence (7 CFUs/25 cm 2 vs 4 CFUs/25 cm 2; P=.004). The correlation analysis for both total ACCs and MRSA CFU counts revealed that the contamination level of the diaphragm was associated with the contamination level of the fingertips (Spearman’s rank correlation coefficient, ρ=0.80; P<.001 and ρ=0.76; P<.001, respectively). Similarly, the contamination level of the stethoscope tube increased with the increase in the contamination level of the fingertips for both total ACCs and MRSA CFU counts (ρ=0.56; P<.001 and ρ=.59; P<.001, respectively).


      These results suggest that the contamination level of the stethoscope is substantial after a single physical examination and comparable to the contamination of parts of the physician’s dominant hand.

      Abbreviations and Acronyms:

      ACC ( aerobic colony count), CFU ( colony-forming unit), HUG ( University of Geneva Hospitals), IQR ( interquartile range), MRSA ( methicillin-resistant Staphylococcus aureus)


      1. WHO Guidelines on Hand Hygiene in Health Care. World Health Organisation, Geneva2009
        • Pittet D.
        • Dharan S.
        • Touveneau S.
        • Sauvan V.
        • Perneger T.V.
        Bacterial contamination of the hands of hospital staff during routine patient care.
        Arch Intern Med. 1999; 159: 821-826
        • Pittet D.
        • Allegranzi B.
        • Sax H.
        • et al.
        Evidence-based model for hand transmission during patient care and the role of improved practices.
        Lancet Infect Dis. 2006; 6: 641-652
        • Pittet D.
        • Hugonnet S.
        • Harbarth S.
        • et al.
        Effectiveness of a hospital-wide programme to improve compliance with hand hygiene. Infection Control Programme.
        Lancet. 2000; 356: 1307-1312
        • Harbarth S.
        • Fankhauser C.
        • Schrenzel J.
        • et al.
        Universal screening for methicillin-resistant Staphylococcus aureus at hospital admission and nosocomial infection in surgical patients.
        JAMA. 2008; 299: 1149-1157
        • Raad I.
        • Hanna H.
        • Maki D.
        Intravascular catheter-related infections: advances in diagnosis, prevention, and management.
        Lancet Infect Dis. 2007; 7: 645-657
        • Cherkaoui A.
        • Renzi G.
        • Francois P.
        • Schrenzel J.
        Comparison of four chromogenic media for culture-based screening of methicillin-resistant Staphylococcus aureus.
        J Med Microbiol. 2007; 56: 500-503
        • Marinella M.A.
        • Pierson C.
        • Chenoweth C.
        The stethoscope. A potential source of nosocomial infection?.
        Arch Intern Med. 1997; 157: 786-790
        • Smith M.A.
        • Mathewson J.J.
        • Ulert I.A.
        • Scerpella E.G.
        • Ericsson C.D.
        Contaminated stethoscopes revisited.
        Arch Intern Med. 1996; 156: 82-84
        • Breathnach A.S.
        • Jenkins D.R.
        • Pedler S.J.
        Stethoscopes as possible vectors of infection by staphylococci.
        BMJ. 1992; 305: 1573-1574
        • Garner T.K.
        • Rimland D.
        Stethoscopes and infections.
        JAMA. 1982; 248: 310
        • Gerken A.
        • Cavanagh S.
        • Winner H.I.
        Infection hazard from stethoscopes in hospital.
        Lancet. 1972; 1: 1214-1215
        • Lecat P.
        • Cropp E.
        • McCord G.
        • Haller N.A.
        Ethanol-based cleanser versus isopropyl alcohol to decontaminate stethoscopes.
        Am J Infect Control. 2009; 37: 241-243
        • Tang P.H.
        • Worster A.
        • Srigley J.A.
        • Main C.L.
        Examination of staphylococcal stethoscope contamination in the emergency department (pilot) study (EXSSCITED pilot study).
        CJEM. 2011; 13: 239-244
        • Kerr J.R.
        • Martin H.
        • Chadwick M.V.
        • Edwards A.
        • Hodson M.E.
        • Geddes D.M.
        Evidence against transmission of Pseudomonas aeruginosa by hands and stethoscopes in a cystic fibrosis unit.
        J Hosp Infect. 2002; 50: 324-326
        • Youngster I.
        • Berkovitch M.
        • Heyman E.
        • Lazarovitch Z.
        • Goldman M.
        The stethoscope as a vector of infectious diseases in the paediatric division.
        Acta Paediatr. 2008; 97: 1253-1255
        • Cohen S.R.
        • McCormack D.J.
        • Youkhana A.
        • Wall R.
        Bacterial colonization of stethoscopes and the effect of cleaning.
        J Hosp Infect. 2003; 55: 236-237
        • Guinto C.H.
        • Bottone E.J.
        • Raffalli J.T.
        • Montecalvo M.A.
        • Wormser G.P.
        Evaluation of dedicated stethoscopes as a potential source of nosocomial pathogens.
        Am J Infect Control. 2002; 30: 499-502
        • Cohen H.A.
        • Amir J.
        • Matalon A.
        • Mayan R.
        • Beni S.
        • Barzilai A.
        Stethoscopes and otoscopes—a potential vector of infection?.
        Fam Pract. 1997; 14: 446-449
        • Sengupta S.
        • Sirkar A.
        • Shivananda P.G.
        Stethoscopes and nosocomial infection.
        Indian J Pediatr. 2000; 67: 197-199
        • Wood M.W.
        • Lund R.C.
        • Stevenson K.B.
        Bacterial contamination of stethoscopes with antimicrobial diaphragm covers.
        Am J Infect Control. 2007; 35: 263-266
        • Bernard L.
        • Kereveur A.
        • Durand D.
        • et al.
        Bacterial contamination of hospital physicians’ stethoscopes.
        Infect Control Hosp Epidemiol. 1999; 20: 626-628
        • Fenelon L.
        • Holcroft L.
        • Waters N.
        Contamination of stethoscopes with MRSA and current disinfection practices.
        J Hosp Infect. 2009; 71: 376-378
        • Muniz J.
        • Sethi R.K.
        • Zaghi J.
        • Ziniel S.I.
        • Sandora T.J.
        Predictors of stethoscope disinfection among pediatric health care providers.
        Am J Infect Control. 2012; 40: 922-925

      Linked Article

      • A “Solution” for Infectious Stethoscopes?
        Mayo Clinic ProceedingsVol. 89Issue 9
        • In Brief
          Although the article by Longtin et al1 published in the March 2014 issue of Mayo Clinic Proceedings is an important contribution, it does not offer a solution to the infectivity of stethoscopes. An article by my colleagues and me,2 which was cited by Longtin et al, documented that ethanol-based hand sanitizer effectively cleans stethoscope surfaces as well as the hands. The simple maneuver of concurrently wiping stethoscope surfaces and cleaning hands with sanitizer is proven to be effective in reducing colony counts of known pathogens and requires virtually no additional time.
        • Full-Text
        • PDF