Detection ofmecA, femA, andfemBgenes in clinical strains of staphylococci using polymerase chain reaction

Abstract

SUMMARYMecA, a structural gene located on the chromosome of Staphylococcus aureus, characterizes methicillin-resistant S. aureus (MRSA), and femA and femB(fem) genes encode proteins which influence the level of methicillin resistance of S. aureus. In order to examine effectiveness of detecting mecA and fem genes in identification of MRSA, the presence of these genes in 237 clinically isolated strains of staphylococci was investigated by polymerase chain reaction (PCR). An amplified mecA DNA fragment of 533 base pairs (bp) was detected in 100 % of oxacillin-resistant S. aureus, in 16'7 % of oxacillin-sensitive S. aureus, in 81-5 % of S. epidermidis, and in 58'3 % of other coagulase-negative staphylococci (CNS). While the PCR product of femA (509 bp) or femB (651 bp) was obtained from almost all the S. aureus strains except for five oxacillin-resistant strains (2'5%), neither of these genes were detected in CNS. Therefore, the detection offemA and femB together with mecA by PCR was considered to be a more reliable indicator to identify MRSA by differentiating it from mecA-positive CNS than single detection of mecA.

Phenotypic and Genotypic Characterization of Nosocomial Isolates of <i>Staphylococcus aureus</i> with Reference to Methicillin Resistance

“…Positive correlation of phenotype with genotype tests were reported for MRSA isolates, which harboured mecA and femB genes [27]. Kobayashi et al reported that mecA was detected in 100 % of MRSA, 16.7 % of MSSA isolates [28]. In Egypt, only few studies have reported the use of femA along with mecA as molecular targets for identification of S. aureus and characterisation of MRSA [12,22] and there were no reports which specifically investigated the prognostic value of femB gene for the detection of S. aureus.…”

Antibiotic Resistance and Detection of femA Gene in Staphylococcus Aureus Isolates from Raw Milk

“…Li et al found a similar finding in a study on MRSA isolates and reported increased expression of this gene in MRSA strains compared to methicillin-susceptible S. aureus (MSSA) strains (9). Kobayash et al detected femA and femB gene in 237 S. aureus isolates and claimed that these two genes could be used for identification of MRSA strains (23). These In this study, microbiological and biochemical methods showed that 43 (39.09%) of 110 milk samples collected were contaminated with S. aureus.…”

Development and evaluation of a PCR-based immunoassay for the rapid detection of methicillin-resistant Staphylococcus aureus

“…A number of previous studies have assessed the use of PCR-based strategies, with a range of DNA targets, for identification of MRSA [5,10,12,14,151. Most of these studies have been concerned with the specific identification of bacterial strains already isolated in pure culture, although Vannuffel et al [14] were able to detect small numbers of MRSA successfully in freshly collected spiked blood samples.…”

“…The mecA gene is the primary structural requirement for methicillin resistance in staphylococci [8] and has been used as a PCR target in other studies [5,10,12,14,151. It is important to note that DNAbased methods differ from phenotypic techniques in that they examine the genetic potential of an organism to exhibit resistance [20].…”