Comparison of the PCR with the Cefoxitin Disc Diffusion Test for Detection of Methicillin Resistance in Oxacillin Resistant Coagulase-Negative Staphylococci (Cons)

ABSTRACT

Nosocomial infections are a prevalent problem all over the world. Bacteraemias are the commonest types of infections and have high mortality and morbidity rates. S. epidermidis and S. aureus are the most frequently associated infectious agents with bacteriemia-acquired in hospital. It is common that these pathogens are resistant to methicillin that limits treatment alternatives. Several methods are developed to detect methicillin resistance rapidly and accurately. This study was aimed to compare the oxacillin and cefoxitin disc diffusion test with PCR for detection of methicillin resistance. Thirty-two CNS strains isolated from blood culture samples that were collected from hospitalized patients in ICUs of our hospital between October-December 2007 and determined to be resistant by oxacillin disc diffusion test, were included. Three strains were sensitive to cefoxitin and the rest of them were resistant. A total of 59.3% of oxacillin resistant strains and 55.2% of cefoxitin resistant strains were mecA positive. The detection of methicillin resistance by disc diffusion test is often false in a high percentage and therefore, especially in ICUs where critical patients are hospitalized, the usage of molecular techniques is more suitable.

Keywords:

• coagulase-negative staphylococci
• methicillin resistance
• PCR
• cefoxitin disc diffusion test