Bacterial colonization of chronic wounds. Studies on outpatients in a university dermatology clinic with special consideration of ORSA

In this retrospective investigation, we documented the bacterial colonization of 79 patients with chronic wounds,who had been treated between January 2002 and May 2003 in an outpatient wound healing clinic of a university dermatology program. We isolated 106 facultative pathogenic bacterial strains of which 56 were Staphylococcus aureus, 19 Pseudomonas aeruginosa, I I Escherichia coli,4 Proteus mirabilis,4 Enterobacter cloacae,2 Serratia marcescens, 2 Streptococcus group G und 8 further species. 68 of these bacterial strains were grampositive and 46 gram-negative. Moreover we identified one patient with Candida parapsilosis. Therefore, 70.8% of all patients showed Staphylococcus aureus in their chronic wounds. Determination of the specific resistances showed 17 patients to be colonized with oxacillin-resistant Staphylococcus aureus (ORSA) strain; this corresponds to 21.5% of all patients. Consequently, 30.4% of all Staphylococcus aureus isolates were ORSA strains. All of the ORSA isolates were sensitive to vancomycin. Sensitivity to tetracycline was documented in 15, to amikacin in 13, to clindamycin in 7, to gentamicin and erythromycin in 6 of the ORSA-positive patients. In the case of trimethoprim/sulfamethoxazole, 10 were sensitive and 3 were intermediate in sensitivity. Beside the obligate resistance to oxacillin, penicillin G, ampicillin, cefuroxime and imipenem, none of the ORSA was sensitive to ofloxacin. The results of our investigations demonstrate the actual spectrum of bacterial colonization in chronic wounds of patients in an university dermatologic wound clinic and underline the growing problem of ORSA.