Clinical observation and microbiological analysis of outpatients with incision and drainage of skin and soft tissue infection

Department of Infectious Disease，Gulou Medical College，Nanjing Medical University，Nanjing 210008，China

Abstract:Objective　 Skin and soft-tissue infection (SSTI) with community-associated methicillin resistant staphylococcus aureus (CA-MRSA) is common in American and European countries，but the prevalence in China is less evaluated and hence a unified therapeutic guideline is unavailable.Methods Total 146 of outpatients with incision and drainage SSTIs were enrolled.The pathogens were cultured after separation and preliminary evaluation.The susceptibility to antimicrobial agents was tested by disk diffusion，while presence of mecA gene，a marker for MRSA of Staphylococcus aureus and coagulase-negative staphylococci (CNS) was examined by PCR analysis.The patient′s prognostic situation including antibiotic use before and after incision and drainage were carried out by statistical analysis；the preoperative course of disease and the kind of identified isolates in followed-up patients was also analyzed.Results　Among 100 isolates,33 isolates were identified as Staphylococcus aureus (33%)，of which 97.0%(32/33) were penicillin resistant and 54.5% (18/33) were erythromycin resistant，but we found no methicillin resistant staphylococcus aureus (MRSA) by mecA gene test of PCR.We also found coagulase-negative staphylococci accounted for 44% (44/100)，of which methicillin resistant coagulase-negative staphylococci (MRCNS) accounted for 15.9% (7/44) as determined by PCR analysis.Ninety five cases successful followed-up after incision and drainage,56 preoperative use antibiotics and 39 not use，the average healing time were 22.88±7.99 and 20.49±8.35 days (P＝0.801)，respectively，postoperative use and no use antibiotics were 71 and 24，the average healing time were 21.61±8.04 and 22.75±8.71 days(P＝0.706)，respectively.Statistical analysis showed no statistic difference was observed in average healing time，no matter the species of the isolates or duration of time before incision and drainage.Conclusions　The main pathogens that skin and soft tissue infection of community of Nanjing area are gram positive coccus，but not CA-MRSA strains.The bacteriological test is necessary for surveillance of antibiotics resistance.For simple SSTI，an incision and drainage is the first choice.There is no need to use antibiotics since the outcome was independent of the use of antibiotics.

Key words:Skin；　Soft tissue infections；　Microbial sensitivity tests；　Methicillin resistance；Drainage；　Prognosis