Faster Than a Speeding Antibiotic…

By Jim McVeagh 24/10/2009 3


I see once again the “superbug” is in the news, with poor old North Shore Hospital attempting to control an outbreak by splitting up their wards. Having worked in such an environment, I know exactly how frustrating that can be for nursing staff. Reverse barrier nursing (gloves, gowns, caps and overshoes to protect the nurse rather than the patient) makes everything take twice as long. Doctors and hospital administrators also become frustrated because they often can’t admit patients to empty beds because the patient is “clean” and the room is “contaminated”. Or vice versa.

Extended Spectrum Beta Lactamase (ESBL) resistant bugs (superbugs) have really only been in the country for less than a decade but are already a real nuisance in hospitals. A contaminated patient is not normally at risk unless they are very sick or to be operated on. The ESBL bug is only a problem if it enters your bloodstream. Septicaemia (blood-borne infection) is fatal unless treated with an antibiotic, but ESBL is resistant to most, making it very hard to treat. Most people with ESBL, however, are merely carriers and are in no danger.

Microbiologists tend to blame the development of superbugs on the over-use of antibiotics. While this is true, I am not convinced that it is the overuse of antibiotics by GPs in the community that produces this sort of resistance, but rather the blind use of very broad spectrum antibiotics in hospital situations. Community organisms seem to maintain a certain level of resistance to an antibiotic and that level does not seem to rise or fall much. Despite the increase in MRSA and ESBL superbugs, most Staphylococcal infections of the skin seem to clear up with Augmentin, despite it’s being in use for 40 years, to use but one example. The levels of resistance and antibiotic recommendations for community diseases have barely changed over the last 20 years. In addition, people rarely seem to become ESBL positive in the community, even when they live with an ESBL family member. It seems to be a bug you almost entirely acquire in hospital

These two things suggest to me that it is not GPs handing out antibiotics for viral infections that causes the development of these resistant bacteria. Use of very-broad-spectum antibiotics in hospital increases every year. This is because one cannot wait for a microbiologist to tell you which type of bug and which type of antibiotic to use, if the patient is seriously ill. Bacterial cultures take days to get a result. Therefore one tends to simply hit the infection with everything you’ve got. The common practice is then to switch to the more specific antibiotic when the culture results return. I suspect that some bacteria manage to survive this massive onslaught for a couple of days and go on to be the ESBL of the future when the powerful antibiotics are stopped. I suspect that, if one carried the very-broad-spectrum regime on for a week to 10 days, this kind of resistance bug would not survive to form resistant colonies.

I firmly expect stroppy comments from microbiologists and pharmacists. Don’t disappoint me.


3 Responses to “Faster Than a Speeding Antibiotic…”

  • From a hospital patient’s perspective, what can the patient do to proactively decrease the chances of avoiding a superbug (or other) infection while in hospital?

  • I don’t think hospital prescribing to be substantially different to that of GP’s. If and when an infection occurs, the most appropriate antibiotic is prescribed and it’s only where there is severe illness and/or no clear source of infection would a patient be started on a broad spectrum antibiotic which may or may not be changed as further information emerges. Realistically, all doctors can be affected by lack of information when faced with a patient and have to make decisions based on what they see at the time. The same standard antibiotics are used for specific indications i,e, Fluclox for cellulitis and it’s not infrequently seen that the same antibiotic the GP prescribed will be given except IV. This would tend to counteract many of the problems seen with prescription of antibiotics in the community such as prescribing antibiotics when there is no bacterial infection, forgotten doses, irregular timing of dosages, stopping an antibiotic when feeling better rather than completing the course etc which create less than optimal concentrations of the antibiotic and contribute to resistance. It just seems more complicated than just a difference between hospital and general practice, including the use of antibiotics in farming feed and what happens out in the community. The main cause of the development of antibiotic resistance seems to be more linked to the total use of antibiotics rather than one specific prescribing practice. Hand washing and other basic hygiene measures is as mentioned the best preventative, but it’s hard not to use common areas as it’s not possible to have dedicated facilities for every patient in a hospital.

    In an evolutionary sense I suppose bacteria evolve constantly to get around our defences so what is happening is that we are selecting for the bugs that can circumvent the treatments thrown at them via Mutation and using horizontal gene transfer. They then can thrive in places like hospitals where they can flourish by not being responsive to standard treatment, and because hospital patients are more debilitated they can become invasive in when normally they wouldn’t in a healthy person. With a broad spectrum antibiotic this can also disrupt the normal balance of flora on the skin and this can give a super bug the opportunity to colonise without anything to keep the bug in check.

    In The New Scientist recently there was an report about this issue states: “The perception that antibiotic resistance is primarily the undesirable consequence of antibiotic abuse or misuse is a view that is simplistic and inaccurate, according to a recent report by the American Academy of Microbiology. The reasons behind the spread of resistance are much more complex, including appropriate antibiotic use, lack of proper sanitation and hygiene, and even the environment.

    The report, “Antibiotic Resistance: An Ecological Perspective on an Old Problem,” is based on a colloquium convened by the Academy in October 2008. It states that resistance development is founded in the inevitability of microbial evolution. There are no scapegoats, and responsibility is partly due to medical practice, including patient demand, industrial practices, politics, and antibiotics themselves. http://www.sciencedaily.com/releases/2009/10/091015163557.htm