Golden rules
Authors: Geoff Watts
Journal: BMJ (2004)

Few events in biology offer a more powerful demonstration of the wonders of natural selection than the spread of antibiotic resistance. Hospital staff struggling to contain the golden staph may, of course, take a more jaundiced view of its triumph.

Fortunately the microbe is not invincible. This week's review by Cooper and colleagues is a reminder that strict isolation measures can limit the spread of methicillin resistant Staphylococcus aureus (MRSA).1 In a similar vein we have the recent report of a successful attempt at eradicating the organism by “ring fencing” elective orthopaedic beds.2 The consequent drop in the incidence of postoperative infection allowed surgeons to do more joint replacements. Better research is urgently needed.

The literature on infection control began with Ignaz Semmelweis, a Hungarian physician, in the mid 19th century, and is now extensive. A review by Muto et al on behalf of the Society for Healthcare Epidemiology of America provides a useful insight into our current understanding of the spread of MRSA, and so what needs to be done to combat it.3 The key to interrupting transmission is, of course, a firm understanding of what makes it possible. Do dirty rooms, dirty equipment, or dirty habits make the greatest contribution?

As many studies of MRSA have testified, hands (gloved or otherwise) are still the leading culprit. And transmission does not have to be direct. One investigation showed that almost half of the gloves worn by a group of nurses became contaminated with MRSA when they touched not the patients themselves, but various surfaces in the rooms where those patients were being nursed. Another study found the microbe on the keyboards of computers used only by clinicians.

There's evidence too of MRSA from gowns, white coats, all manner of portable equipment from stethoscopes to pagers, domestic items such as mops and furniture, and many types of environmental surface. In one hospital more than a quarter of 350 surfaces tested in the rooms of 38 patients colonised by MRSA were positive for the organism.

All this one might have suspected; more worrisome is the period for which the microbe can continue to pose a threat. One study of the outer surfaces of packages of sterile goods revealed the presence of MRSA that had survived for more than 38 weeks.

Given the part that antibiotics have played in fostering the emergence of resistant strains, it comes as something of a disappointment to learn that strict policies to limit their use are not enough to reverse the trend. Once MRSA has gained a foothold, there is, it seems, little correlation between its prevalence and the parsimonious use of antibiotics. Finland, the United Kingdom, and Italy all consume roughly the same amounts of these drugs, but they have big differences in the proportion of methicillin resistant isolates.

In short, while antibiotics do give the golden genie a selective advantage over its susceptible brethren once it has escaped its bottle, squeezing it back from whence it came depends principally on sustained efforts at preventing transmission. When it comes to regular hand washing, at least one survey has suggested that doctors are more blameworthy than nurses.

So, once more unto the sink, dear friends, once more...