coagulase-negative, Beta-lactam, antibiotic resistance, methicillin resistance

The incidence of resistance to groups of beta-lactam antibiotics has become one of the most common cases. This problem too many seen in hospital pathogens, that including coagulase-negative Staphylococcus. Therefore, distinguish of resistance factors can be helpful in treatment process. The aim of this study was to determine resistance in coagulase-negative Staphylococcus by phenotypic and genotypic ways.
Totally, 710 isolates from clinical samples reaped of health centers of Zahedan. After the determination genus and species of isolates obtained, their sensitivity specify to 10 beta-lactam antibiotics by disc diffusion method. For detection of blaZ and mecA gens used of specific primers and PCR method.
Of obtained isolates, 79 isolate was Staphylococcus saprophyticus and 198 isolate was Staphylococcus epidermidis. Of these, 74 isolates (98.1%) to penicillin, 69 isolates (34/87%) Oxacillin, 31 isolates (24/39%) to ceftriaxone, 71 isolates (87/89%) to Cefoxitin, 43 isolates (43/54%) to cefotaxime, 19 isolates (24.50%) to cefazolin and 27 isolates (17/34%) were resistant to cephalexin in Staphylococcus saprophyticus. PCR results in more isolates confirmed the presence of mecA and blaZ.
The Primary screening by phenotypic disk diffusion method showed high prevalence of resistance in the city of Zahedan and was determined that 20 to 95 percent of the isolates were resistant to all beta-lactam of different generations. PCR method approved presence of the mecA and blaZ genes. But those expression is different. This payoff achieving that singly disk diffusion phenotypic method lack of for determining strategy is not appropriate to treatment of infections caused by this organisms.