Skin and soft tissue infections: experience over a five-year period and clinical usefulness of ultrasonography-guided gun biopsy-based culture.

Background: Skin and soft tissue infections (SSTIs) are common clinical diseases, but only a few reports of microbiological data on SSTIs in Korea have been published. In practice, specimens are rarely obtained from infected lesions unless there is visible pus or an abscess pocket. However, identification of the causative pathogen is important, because of emerging drug resistance and the increase in immunocompromised hosts.

Methods: The medical records of 760 adult cases of community-acquired SSTIs (CA-SSTIs) from September 2003 to August 2008 were reviewed retrospectively. We analyzed epidemio-clinical features and microbiological distributions of CA-SSTIs and evaluated the positive culture rate of several diagnostic methods, including swab, tissue biopsy, blind needle aspiration, ultrasonography (US)-guided needle aspiration, and US-guided gun biopsy.

Results: Most CA-SSTIs (76.1%) occurred in previously healthy persons without underlying diseases. Re-infections were identified in 76 (10%) patients and cirrhosis was an independent risk factor for re-infection (odds ratio 3.64, 95% confidence interval 1.36-9.76). The most commonly identified pathogen was methicillin-susceptible Staphylococcus aureus, and 3(rd)-generation cephalosporins were the most commonly used empirical antibiotics (47.9%). US-guided needle aspiration had a high positive culture rate of 73.9% and the positive culture rate of US-guided gun biopsy was 17.5%.

Conclusions: Considering the microbiological distribution of CA-SSTIs in Korea, penicillinase-stable penicillin or a 1(st)-generation cephalosporin should be adequate for initial antibiotic treatment. US-guided needle aspiration was a good technique for the identification of causative pathogens, and additive productivity is expected with US-guided gun biopsy culture from lesions without fluid collection.