The gay community is disproportionately affected by a growing problem of antibiotic-resistant bacterial infections. Many of these bugs, such as staph, strep, and various forms of pneumonia, are spread through intimate contact where the hard-core elements of sex such as penetration are not required, and condoms offer little protection.
They can live on everything from doorknobs to wrestling mats and be picked up second hand.
Staphylococcus aureus, or staph, is a bacterium that can cause everything from a benign pimple, to serious wound and blood infections, to pneumonia. It is so common that more than a quarter of us carry it around on our skin or in our nose, but our immune system generally keeps it in check.
Penicillin-based drugs are used to treat staph infections. Bugs that have developed a resistance to those drugs are known by the acronym MRSA.
Drug-resistant staph largely has been a problem for hospitals and nursing homes, but over the last few years it has spread much more broadly. Outbreaks have been reported across the country, with the gay community in Los Angeles being particularly hard hit last year.
MRSA cases in San Francisco have increased more than three-fold, from fewer than 400 cases in 2000 to more than 1200 cases in 2004 in just the public health clinics operated by that city, Binh An Diep reported at a major scientific conference in Washington, DC in early November. Virtually all of the increase in infections has come from within the community, not in institutional settings.
He attributed the epidemic to 'the spread of a single clone, USA300' that researchers at the University of California San Francisco identified through genetic analysis of the staph DNA in September 2000. It appears to have evolved outside of the hospital setting and has spread rapidly across the country.
This is not some minor infection; '42 percent of these cases required hospitalization, they tend to be younger, and they are predominately male.' Diep said that includes men who have sex with men. The number of bacteria found at each site of infection is three times higher than seen with other strains.
In a paper published in the November 15 issue of the Journal of Infectious Disease, Diep and his colleagues said that MRSA has become so common that all suspected serious staph infections should be cultured for resistance to guide selection of the treatment regimen.
Recent reports have documented an outbreak of ten cases among a football team in Connecticut where body shaving and 'turf burns' from practicing on an artificial surface have contributed to the spread of MRSA.
Minor abrasions to the skin make it more vulnerable to infection and the bugs can survive on the carpet for an extended period of time. MRSA also can be transmitted by skin to skin contact and by sharing razors or towels.
Soap and hot water effectively kill the bug if you catch it early enough, before the infection sets in.
NEW APPROACHES
The ability of these bugs to develop resistance to antibiotics has led to new approaches to therapy. One interesting approach builds upon an old therapy, bacteriophages. Phages are the microscopic natural enemy of bacteria, evolving over the eons to feed upon them. They were used to treat patients prior to the discovery of penicillin.
Vincent Fischetti, a leading researcher in the field at Rockefeller University in New York City, has isolated enzymes that phages use to punch holes in the cell walls of bacterium. In the test tube and in animal models the enzymes have been able to kill the bacteria almost immediately.
'The pressure inside a bacterium is about half that inside a champagne bottle,' he explains. 'When the enzyme punctures its cell wall, the bacterium essentially explodes. As long as we can make contact with the organism we can kill it.'
Making that contact is easy if the bacterium is outside the body, it can become more difficult once it gets inside. Fiscetti says they can inject enzymes into the bloodstream and kill pathogens. But the half life of the enzymes is so short, only about 20 minutes, and an intravenous drip is required to keep infusing the enzymes. And even then, they often do not penetrate well into tissue compartments.
The enzymes are very specific to the particular bacteria and their effect 'is a very targeted killing with no effect on other organisms.' In contrast, most antibiotics are broad spectrum and kill off friendly bacteria including those in the gut that aid in digestion. This can result in side effects such as diarrhea or constipation.
One enzyme isolated from a bacteriophage lethal to anthrax was injected into mice that had been infected with the deadly killer. A single dose of the enzyme saved 90 percent of the animals.
Fischetti believes that one of the first uses of phage enzymes in humans will be to 'decontaminate' the mucus membranes of people working in settings such as hospitals, nursing homes, and day care centers so that they are no longer carriers of the infection.
A mist containing the enzyme and sprayed into the nose can kill off the bacteria almost immediately. The procedure likely will have to be repeated on a weekly or monthly basis depending on exposure and the likelihood of them becoming recolonized with the bacteria.
'We also see a synergy between enzymes and antibiotics,' Fischetti said. 'We believe the enzyme allows better access through the cell wall for the antibiotic…We might be able to control highly resistant organisms in this way.'
However it will require several more years of testing before the FDA considers approving these new approaches to treating infections.
