Guest Author - Anita Grace Simpson

Have you heard of MRSA, a new and dangerous infection, and wondered what it is? In the past it was usually confined to hospital and similar health care settings, where it often caused surgical incisions to become infected. Now it has moved out into the community. Because it is resistant to most antibiotics, it can be deadly.

MRSA is a mutated version of Staphylococcus aureus, a bacterium which has been around for a long time. Before the advent of antibiotics, staph infections (like other bacterial diseases) were often fatal. But penicillin and similar medicines put staph and other bacteria in their place, for a time at least.

Like viruses, bacteria are able to mutate. This means they genetically adapt to changing conditions so that they can survive. The onslaught of antibiotic therapy sent the bacteria reeling, but they didn’t die out completely. Staphylococcus aureus bacteria are found everywhere; therefore, it was impossible to get rid of them entirely. They were able to continue their involvement with human beings by developing resistance to the current antibiotics.

Did you know that in the 1940’s and early 1950’s penicillin was available over the counter? The public viewed the drug as a cure for everything including cancer, and it sold like wildfire until it was designated “by prescription only” in the mid-1950’s. Alexander Fleming, who discovered penicillin, warned that antibiotic resistance would develop. He stated that the danger in self-medication lay in the use of doses that were too small. Taking too little antibiotic teaches the bacteria to resist penicillin because it isn’t enough to wipe it out. This is the same problem that occurs when individuals fail to take a full 10-day course of prescribed antibiotics for a bacterial infection. If they stop too soon, some bacteria are left and these become resistant.

Even when antibiotics became limited by prescription, overprescribing of antibiotics by doctors (often in response to patient insistence) just furthered the problem of resistant bacteria. Diseases that we thought we’d seen the last of, such as tuberculosis, have begun making a comeback. We can barely stay ahead of them by developing new, more potent medicines.

Similarly, Staph aureus has learned to be resistant to a whole class of antibiotics. MRSA stands for Methicillin Resistant Staphylococcus Aureus. Methicillin is a penicillin derivative; thus MRSA is resistant to all drugs related to penicillin. Most strains of S. aureus are also unaffected by sulfonamides (“sulfa drugs”). Chloramphenicol, a broad-spectrum antibiotic isolated from soil samples in Venezuela, does work against some strains of S. aureus, but it can have serious side effects such as bone marrow suppression and leukemia.

As MRSA infections increased in hospitals, doctors became desperate for a solution. Another drug developed from soil (in this case, soil from Borneo), vancomycin, seemed promising. It was effective against MRSA, but it did have problems. Because it is poorly absorbed when taken orally, it must be administered intravenously. It was used only as a last resort, and this slowed the development of vancomycin resistant S. aureus. However, inevitably vancomycin resistant strains have appeared. The drug, Linezolid, approved in 2000, is the first example in over 30 years of an antibiotic from a new class. It is effective against S. aureus in almost all cases.

But the fight is not over. Antibiotic resistance will continue to increase as bacteria mutate. Prevention is very important – for instance, antibiotics should not be prescribed for viral infections (they are useless against viruses) unless the patient has a medical condition that predisposes them to secondary bacterial infections (a person with chronic lung disease probably needs a course of antibiotics when s/he catches a cold). When a bacterial infection is present and antibiotics are appropriately prescribed, the patient must complete the entire course. Doctors, nurses, and pharmacists should explain how important this is; hearing it from three different sources will emphasize that it is truly necessary. Agricultural use of antibiotics should be better regulated to reduce the development of resistance through animals. Finally, broad-spectrum antibiotics such as azithromycin (Zithromax) and amoxicillin-clavulanate (Augmentin) should not be prescribed for mild bacterial infections and certainly not for viral infections. Older antibiotics, which will usually do the job just as well, should be tried first.