Hygiene, the second [referring to "Hygiene" 10.01.2011]

Question

Many thanks for your detailed answer. But to be honest. I do not understand how it can come to such differing statements concerning the occurence of MRSA:
You say: the frequency of MRSA in the standard population is however much smaller as in hospitals and lies clearly under 1%.
And the Paul Ehrlich Institute (Germany) talks about the by me mentioned numbers over 20%: http://www.p-e-g.org/aktuelles/141.
Or does it mean if both numbers are true that in hospitals and old peopel's homes etc the frequency is so high that the mean of the population is 22%, even if the "standard population" (who however that is, then) is colonized only in 1% of cases?
Probably the right question would be: how many MRSA-carrier do I meet in the bus or the fitness center?
Again many thanks, also for your patience.

Answer

Dear questioner,
between both statements, there is no contradiction. The statements made on the Paul Ehrlich Institute website refer obviously also on the MRSA frequency in hospitals. The phrasing "Germany" is in that context simply not very exact, as the emphasis has been mainly on the international comparison. In the article an early-warning system for hospitals has been presented (see below).

MRSA-frequencies in Germany about 20% are for example taken from the data of the EARSS (The European Antimicrobial Resistance Surveillance System) - NET (ecdc.europa.eu). These data has mainly been generated from microbiological laboratories, which are responsible for the supply of hospitals. According to the antibiotc resistance surveillance (ARS) database of the Robert-Koch Institute (Germany) for 2008 an MRSA-frequency of 22.6% in the hospital section and of 12.7% in the ambulant section has been documented (www.rki.de/). Hereby it deals with persons with contact to the health care system.

The MRSA-frequency found in studies depends on the population in which the investigation has been performed. The frequency in the general population can of course not exactly be determined resp. at the moment no profound data exists about that. I say therefore for orientation "clearly under 1%" (the real value lies probably nearer to 0 than to 1).

Much more important than the question if one can meet an MRSA-carrier in daily life are the following thoughts. MRSA can not easily be transmitted in case of every possible contact. To transmit an MRSA-germ, several requirements have to be fullfilled: a sufficient number of germs on the skin of the MRSA-carrier, direct and repeated contact (exposition) with colonized body surfaces of the MRSA-carrier, the colonization of the skin/mucosa of the contact person, the transition of the MRSA from transient to permanent flora via multiplication and implementation of the skin of the contact person, which is mainly the case if risk factors occur in the contact person (anitbiotics, wounds, etc.). The transmission of MRSA in case of a single contact e.g. in the bus is hardly possible. The probability raises in case of frequent and intensive contact or in case high amounts of MRSA are deliberated due to medical procedures (endotracheal succtioning in case of colonization of the lungs). Therefore, special protection measures are necessary in the hospital.
Regards,
M. Hogardt

07.02.2011