MRSA: Increasingly a Community-Based Pathogen?
Source: Charlebois ED, et al. Clin Infect Dis. 2002:34:425-433.
Methicillin-resistant Staphylococcus aureus (MRSA) is increasingly found in persons in the community, although whether it is truly a community-based pathogen or "health care acquired" is a matter of debate. Charlebois and colleagues assessed the nasal colonization of 833 homeless and marginally housed individuals in San Francisco for S aureus and MRSA. A total of 190 persons (22.8%) were culture-positive for S aureus, 23 of which (2.8%) were resistant to methicillin. Risk factors for staph colonization included older age, hospitalization in the previous 12 months, and a history of or recent injection drug use. Patients with a history of abscess and endocarditis were also at significant risk for staph colonization, although only endocarditis remained significant in multi-variate analysis. HIV infection was also significantly associated with nasal staph colonization, but not specifically MRSA. Interestingly, contact with the outpatient clinics or the emergency room was not associated with colonization. While many of the MRSA isolates were resistant to erythromycin, many remained susceptible to other agents, and only 1 was resistant to ciprofloxacin.
Among the 23 MRSA isolates, a total of 6 different genotypes were identified, including 2 with a unique genotypic fingerprint. Twenty-two of the 23 isolates matched clinical isolates of MRSA, and 15 were identical to clones isolated from hospital patients. In other words, most of the MRSA isolates from the community were derived from clones endemic in the community hospital. Only 2 individuals (0.24%) with MRSA had no known risk factors for staph colonization. Thus, colonization with MRSA in the absence of recent hospitalization or injection drug use was rare, and most "community-acquired" isolates were, in fact, probably hospital-acquired.
Is Safe Sex a Matter of Freedom of Choice?
Study: New HIV infections on the rise in S.F. The Sacramento Bee, April 4, 2002; www.sacbee.com/content.
A recent survey of 554 gay men in San Francisco conducted between July 2000 and February 2001 found that 22% of HIV-positive men and 10% of HIV-negative men had engaged in barebacking within the past 14 months. Barebacking, where an individual foregoes the use of a condom, is gaining popularity with gay and bisexual men, who are apparently tired of hearing the same safe sex messages and who want to be able to "choose" their own lifestyle—condom free. Barebacking "parties," organized for this purpose, are catered to positives, negatives, and, sometimes, undisclosed persons. Some men actually seek out partners who are willing to have unsafe sex with them. Other data that we’ve collected at several centers on the West Coast suggest that up to 42% of HIV-positive gay or bisexual men have engaged in unprotected sex within the past 3 months, and ~25% fail to disclose their HIV status to their partners. The net result: HIV infection is once again on the increase, with 700-800 new infections anticipated this year in San Francisco alone.
Mathematical modeling shows that given current rates of drug resistance, 42% of all HIV patients in SF will not respond to drugs currently used to treat the illness by the year 2005.
Experts and behaviorists remain baffled. Once again, gay men in SF demonstrate that education has little to do with behavior. As a good friend of mine likes to say: everything you ever need to know about safe sex you could write on the back of a 3" × 5" recipe card in crayon.
After recently participating in a behavioral intervention directed at patients in my own practice, I was stunned to learn that there was no apparent effect on behavior. The frequency of unprotected sex and the number of partners within the previous 3 months was virtually unchanged. I had assumed that my relationship with my patients, coupled with a direct and open conversation about sexual behavior and HIV disclosure, would translate into some beneficial effect. Not so. So, how can we reach our patients and change their behavior? It would be easy for clinicians to ignore this problem. But, just like anti-tobacco messages, it is our job to find effective ways to promote safe sex with our own patients.
Dr. Kemper, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases; Santa Clara Valley Medical Center, is Associate Editor of Infectious Disease Alert.
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