The growth of antibiotic resistance continues to complicate the treatment of common community-acquired infections, including urinary tract infections (UTIs) and skin and soft tissue infections (SSTIs), according to presenters at a symposium during the 47th Annual Meeting of IDSA.
While several regimens are currently available for the empiric treatment of acute uncomplicated cystitis (AUC), many clinicians are likely to use a fluoroquinolone, such as ciprofloxacin, because it is well tolerated and highly effective, said Thomas M. Hooton, MD, FIDSA, professor of clinical medicine at the University of Miami. But increasing rates of fluorquinolone resistance, reported in several U.S. and European studies, have highlighted the need for antimicrobial stewardship to preserve these drugs while they are still effective in treating UTIs, which affect at least 60 percent of adult women at some point in their lifetime.
Updated IDSA guidelines for the diagnosis and management of uncomplicated UTIs, currently in draft form, will likely stress that there is no single best agent to treat acute cystitis but will emphasize the need to limit the use of fluorquinolones, Dr. Hooton said. The guidelines will also likely suggest that clinicians consider effectiveness, antimicrobial resistance, potential for “collateral damage,” adverse effects, and specific patient factors, such as allergy history, in empiric treatment decisions.
Another presenter, Donald E. Low, MD, microbiologist-in-chief at Mount Sinai Hospital in Toronto, addressed resistance levels for SSTI methicillin-resistant Staphylococcus aureus (MRSA) infections, and at what point these levels in a community should change therapy recommendations. Although surgical drainage may be sufficient for patients with uncomplicated SSTIs, appropriate therapy is associated with better outcomes in those with complicated infections.
While acknowledging the lack of guidance on the subject, Dr. Low suggested that rates of MRSA as a cause of complicated SSTIs in a community greater than 10 percent warrant a change in empirical therapy.
Even with appropriate treatment recommendations in place, however, educating physicians and other health care workers on the front lines remains a challenge. A recently published retrospective analysis of community-acquired and health care-associated USA300 MRSA infections in a Detroit hospital found that approximately 36 percent of patients with these infections were empirically treated with a drug inactive against USA300. “The message is obviously not getting out there to front-line physicians in centers where this is a major problem,” Dr. Low said.
The USA300 strain is also posing clinical challenges in other situations, as shown in a poster presentation at the meeting. The research found that patients admitted to the hospital with community-acquired invasive pneumonia caused by USA300 were at higher risk of early complications —but not of death—than patients with invasive pneumonia due to the USA100 strain. Fernanda Lessa, a medical epidemiologist with the Centers for Disease Control and Prevention (CDC), said the increased virulence caused by USA300 in otherwise healthy patients was a concern, along with the strain’s increasing movement from the community to the health care setting.Audio and synchronized speaker slides from sessions at the 2009 IDSA Annual Meeting are available for purchase online.
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