Clinical Capsules

Necrotizing Fasciitis

Cases of necrotizing fasciitis that are caused by community-acquired methicillin-resistant Staphylococcus aureus are on the rise, Loren G. Miller, M.D., of Harbor-UCLA Medical Center, Los Angeles, and colleagues reported.

Of 843 patients whose wound cultures grew MRSA over a 15-month period in 2003-2004, 14 had necrotizing fasciitis, necrotizing myositis, or both (N. Engl. J. Med. 2005;352:1445-53).

None of the 14 patients died, but all had one or more serious complications. Combined surgical and medical treatment was provided; all MRSA isolates showed in vitro susceptibility to clindamycin, trimethoprim-sulfamethoxazole, vancomycin, gentamicin, and rifampin.

S. aureus has been a rare cause of necrotizing fasciitis, but cases caused by community-acquired MRSA represent an emerging clinical syndrome.

Empirical treatment in suspected cases, particularly where MRSA is endemic, is necessary regardless of the presence of clinical risk factors, and should include antibiotics active against the locally circulating strains, they said.

This represents a major departure from currently recommended treatment for necrotizing fasciitis, the investigators added.

HSV-2 Shedding Risk

Hormonal contraception and two common genital tract conditions appear to be among the risk factors for genital tract shedding of herpes simplex virus type 2 in women.

In a 12-month study of 330 women who were evaluated every 4 months, independent predictors of genital tract shedding of HSV-2 were HSV-2 seroconversion during the previous 4 months (adjusted odds ratio [OR] 3.0), bacterial vaginosis (adjusted OR 2.3), heavy colonization with group B streptococcus (adjusted OR 2.2), and use of hormonal contraceptives (adjusted OR 1.8), reported Thomas L. Cherpes, M.D., and his colleagues at the University of Pittsburgh (Clin. Infect. Dis. 2005;40:1422-8).

Because use of hormonal contraception is widespread, and bacterial vaginosis and vaginal group B streptococcus colonization are two of the most common genital conditions in women of reproductive age, the associations between these variables and increased genital tract shedding of HSV-2 is of concern. The findings could have important implications for decreasing HSV-2 transmissions.

Multidrug-Resistant TB

Directly observed therapy, which has served as the primary strategy worldwide for preventing drug-susceptible tuberculosis transmissions, also is effective for reducing the transmission and incidence of drug-resistant tuberculosis, a study suggests.

In the population-based prospective study of 436 patients undergoing directly observed therapy, short course (DOTS), three indicators of ongoing TB transmissions showed that transmission declined between 1995 and 2000.

During those years, the pulmonary TB incidence rate decreased from 42 to 19 per 100,000 population, the percentage of clustered pulmonary TB cases decreased from 22% to 8%, and the rate of primary drug resistance decreased from 9 to 2 per 100,000 population, according to Kathryn DeRiemer, Ph.D., of Stanford (Calif.) University and her colleagues (Lancet 2005;365:1239-44).

Multidrug-resistant (MDR) TB also decreased significantly, as did the number of treatment failures, from 13 (11%) in 1995 to 1 (2%) in 2000. But the case-fatality rate over the study period was 12% for MDR TB, compared with 7% for strains resistant to one or more drugs (not including MDR cases), and 3% for strains susceptible to multiple drugs.

DOTS remains a valuable tool for preventing TB transmission even in this age of emerging drug resistance, but further interventions will be required to avoid treatment failure and reduce multidrug-resistant TB mortality rates, the investigators concluded.

Tomatoes and Salmonella

Roma tomatoes were implicated or suspected in three salmonella outbreaks involving more than 560 patients in 18 states and 1 Canadian province last year, according to the Centers for Disease Control and Prevention. No deaths were associated with the outbreaks, but 14%-30% of the patients were hospitalized.

In two of the outbreaks, case-control studies conducted by the CDC and state and local health departments showed associations between salmonella infection and Roma tomato consumption. For example, in the largest outbreak—involving 429 culture-confirmed cases in nine states— multivariate analysis showed that salmonella infection was strongly associated (adjusted odds ratio 7.1) with consumption of Roma tomatoes (MMWR 2005;54:325-8). In the third outbreak, no case-control study was conducted, but Roma tomatoes were the only common food exposure among patients.

Health officials investigating salmonella outbreaks should consider tomatoes as a potential vehicle, and future studies should focus on mechanisms of tomato contamination and methods of eradication of salmonella in fruit, according to the CDC.