[Resistance of Staphylococcus aureus isolated from burn wounds to antibiotics].

OBJECTIVE

To determine the colonization rate of Staphylococcus aureus in burn wounds and to assess the variation in the resistance of Staphylococcus aureus strains to antibiotics.

MATERIAL AND

METHODS

A retrospective study of 72 patients with burn wounds was carried out during 1997 and 2003. Specimens taken from burn wounds at first, fifth, and later every seventh day of hospitalization were placed in transport medium. Isolates were grown on mannitol salt agar. Cultures of Staphylococcus aureus were determined using plasmacoagulase and DNA-ase tests. The resistance of Staphylococcus aureus strains to penicillin, oxacillin, ceftazidime, vancomycin, gentamicin, kanamycin, tobramycin, doxycycline, ciprofloxacin, cefepime, fusidic acid, and clindamycin was determined. The isolated strains of Staphylococcus aureus were tested for resistance to methicillin by performing a disc diffusion method using commercial discs (Oxoid) (5 microg methicillin per disk and 1 microg oxacillin per disk).

RESULTS

During 1997-2003, a total of 221 Staphylococcus aureus cultures were isolated from burn wounds. More than one-fourth of all isolated Staphylococcus aureus strains (25.3%) were resistant to methicillin; 64% of methicillin-sensitive Staphylococcus aureus strains were resistant to clindamycin and 28-30% - to gentamicin and kanamycin. The resistance rate of methicillin-resistant Staphylococcus aureus strains to doxycycline, clindamycin, oxacillin, tobramycin, gentamicin, and kanamycin was 78.5-98%. Majority of Staphylococcus aureus strains were non-susceptible to ceftazidime (91-100%); the rate of resistance to clindamycin decreased from 99% to 36%, (p<0.05) and to ciprofloxacin - increased from 55-65% to 81% (p<0.05).

CONCLUSIONS

Staphylococcus aureus was the most prevalent pathogen isolated from burn wounds. On the first day of hospitalization Staphylococcus aureus isolates were obtained from 25.3% of patients; 12.5% of patients with burn wounds had methicillin-resistant Staphylococcus aureus at the end of the first week of hospitalization and 66% of patients--after two weeks and later. The resistance of methicillin-susceptible Staphylococcus aureus to gentamicin, tobramycin, and clindamycin decreased. The resistance of methicillin-resistant Staphylococcus aureus to clindamycin decreased and to ciprofloxacin--increased.