Antibiotic resistance and detection of the most common mechanism of resistance (MLSB) of opportunistic Corynebacterium.

BACKGROUND Determination of antibiotic resistance of opportunistic Corynebacterium colonizing the nose that cause infections and evaluation of the applicability of a simple method for detecting the most common constitutive-type resistance to macrolides, lincosamides and streptogramin B (MLSB). METHODS 70 isolates colonizing the nose and 70 clinical isolates of various infection sites were used and identified using APICoryne and 16S rRNA. Minimal inhibitory concentrations (MICs) were determined (Etest) for 12 antibiotics. MLSB was defined based on MIC, a simple method using two disks (erythromycin/clindamycin) and detection of the gene erm X (PCR). RESULTS There was a high percentage--in both groups at the same level--of strains with MLSB (88.5% colonizing the nose and 87.1% causing infections). Detection with the phenotypic method MLSB was confirmed genetically (erm X) in all cases. In both groups, a high percentage of resistance was found to trimethoprim/sulfamethoxazole (in both groups 71.4%), chloramphenicol (nose 44.2%/infections 37.1%), tetracycline (28 and 45.7%) and β-lactam antibiotics (18.5 and up to 32.8%). CONCLUSION Differences in antibiotic resistance were found between strains colonizing the respiratory tract and various infections. Isolates from infections more frequently exhibited multidrug resistance. The possibility of using a simple method was confirmed for MLSB detection, which can be applied to determine drug resistance in routine microbiological diagnostics of infections caused by opportunistic Corynebacterium.