Investigation of erythromycin and tetracycline resistance genes in methicillin-resistant staphylococci

In this study, erythromycin [erm(A) and erm(C)] and tetracycline [tet(K) and tet(M)] resistance genes were investigated by multiplex polymerase chain reaction (PCR) in a total of 56 methicillin-resistant (mecA+) staphylococcal hospital isolates, 28 of which were determined to be Staphylococcus aureus (MRSA) and the other 28 were coagulase-negative staphylococci (MRCNS). Internal control primers amplifying a specific fragment of 16S rDNA of staphylococci were included in the multiplex PCR protocol to ensure the efficacy of amplification and to determine any PCR inhibition. No resistance genes were detected in 5 of 56 (8.9%) isolates in the study. In the study, tet(K) genes were detected widely (42.9%) in MRCNS, whilst tet(M) genes were detected in MRSA (50.0%). Regarding the erythromycin resistance genes, whilst erm(A) genes were detected in most (71.4%) MRSA isolates, detection rates of erm(C) genes were the same (64.3%) both in MRCNS and MRSA. The resistance rates for tetracycline and erythromycin were 57.1% and 78.6%, respectively, in MRSA isolates. In conclusion, in this study, the multiplex PCR technique including an internal control is shown to be a fast, sensitive, reliable, practical, reproducible and economic technique for the detection of erythromycin and tetracycline resistance in staphylococcal isolates.