The stethoscope and cross-infection revisited

Jevons first reported methicillin resistant Staphylococcus aureus (MRSA) in 1961¹ and it has now become a serious cause for concern in UK hospitals. Indeed, it has even entered the political arena.² In 2003, a search for MRSA using www.yahoo.com yielded 153 000 results; this has now risen to 329 000 references.

Last year, a letter of mine was published here; it detailed a bacteriological examination of my practice stethoscope, which showed that it did not carry MRSA bacteria over a 2-week period.³ I have since examined 50 stethoscopes chosen at random. They were in daily use by doctors in general practice in the London area drawn from the membership of the Independent Doctors Forum. Their stethoscope bells and diaphragms were imprinted on blood agar medium plates, which were then incubated for 24 hours at 37°C. The Doctors Laboratory examined those culture plates that grew bacteria and identified these bacteria, further testing staphylococci to establish if they were MRSA species.

Of the 50 stethoscopes examined, 13 carried no bacteria at all, 15 carried mixed skin flora, and coagulase negative staphylococci were isolated in 22. Not one of these 50 stethoscopes carried MRSA. This can be contrasted with previous studies, and particularly with a paper by Smith et al,⁴ which showed that in 1996 in the hospital environment, MRSA frequently colonised stethoscopes used on medical and surgical wards. They found 68 out of 200 stethoscopes (34%) to be positive for MRSA; comparing this with my results, a χ² test gives P<0.001, which is highly significant.

My study, therefore, clearly demonstrates that the stethoscope is not a vector for MRSA in the community. This observation strongly suggests, but does not prove, that MRSA presents a problem in the UK that is confined to the hospital environment.