Antibiotic-Resistant Strains of Staph Infections Increase Outside of Hospital Settings, Study Finds

Drug-resistant strains of staph bacteria -- which typically are spread in hospitals and health care settings and can cause "hard-to-treat" infections -- are emerging at an "alarming rate" in other populations in many communities, according to a study published on Thursday in the New England Journal of Medicine, the AP/Boston Globe reports. CDC researchers over two years reviewed lab reports of 12,553 instances of drug-resistant staph infections -- also known as methicillin-resistant Staphylococcus aureus -- in Baltimore, Atlanta and Minnesota.

They found that about 17% of all MRSA cases were contracted outside health care settings. The rate was 20% in Atlanta, 12% in Minnesota and 8% in Baltimore. According to the study, 75% of the cases acquired outside hospital settings were skin infections and 23% were "serious enough to require hospitalization," the AP/Globe reports.

Staph bacteria are a common cause of skin infections, and many people carry the bacteria on their skin or nasal passages. In most cases, infections cause pimples and boils on the skin. If the germ penetrates an opening in the skin it can cause surgical wound infections, bloodstream infections and pneumonia (Nano, AP/Boston Globe, 4/6).

Staph infections are treated with antibiotics in the penicillin family, such as methicillin and amoxicillin. Some strains of staph became resistant to many antibiotics, but until recently those strains had been limited almost exclusively to hospitals. Researchers have observed small outbreaks of antibiotic-resistant staph infections among athletes, prison inmates, children and other groups (Stein, Washington Post, 4/7).

According to the Atlanta Journal-Constitution, doctors may have "unwittingly" aided the spread of MRSA by treating it with ineffective antibiotics because it was rarely accurately diagnosed (Toner, Atlanta Journal-Constitution, 4/7). Staph infections are spread more easily in crowded or unhygienic conditions.

Studies have shown that resistant strains among people who acquired the infection outside of a health care setting appear to be different from the MRSA strain found in hospitals, which "suggests the bug hasn't just seeped from hospitals into local communities, but came from somewhere else," the St. Petersburg Times reports (Greene, St. Petersburg Times, 4/7).

A second study published in the journal found that drug-resistant staph also has acquired "flesh-eating" capabilities and caused 14 cases of necrotizing fasciitis in the Los Angeles area. In the study, all patients with necrotizing fasciitis required surgery and 10 were in intensive care.

The condition usually is caused by strep bacteria. Only one other previous case was confirmed to have been caused by staph (AP/Boston Globe, 4/7).

According to the Post, the study indicates that doctors should routinely test all skin infections to identify those patients who require treatment with the small number of drugs to which the bacteria has not developed a resistance (Washington Post, 4/7).

Study leader Scott Fridkin, a CDC researcher, said, "Close to one-fifth of what used to be a hospital-specific problem is now a community problem. And that's a large number. We didn't think it would be anywhere near that high when we started the study" (AP/Boston Globe, 4/7). He added, "This should serve as a red flag to doctors whenever they are treating skin infections. It's a cause for concern."

Walter Stamm, president of the Infectious Disease Society of America, said, "What people are concerned about is that we'll be losing these drugs one by one until we don't have any effective ones left" (Washington Post, 4/7).

Loren Miller of Harbor-UCLA Medical Center said, "The bugs are winning, unfortunately, and we need to catch up. We really need to rapidly develop antibiotics to catch up with the bugs and start using antibiotics more appropriately" (AP/Boston Globe, 4/7). CDC has begun a nine-state study to test MRSA's prevalence (St. Petersburg Times, 4/7).

An abstract of the study is available online.

NPR's "Morning Edition" on Thursday reported on the research (Knox, "Morning Edition," NPR, 4/7). The complete segment is available online in RealPlayer.