Introduction:
Methicillin resistance in staphylococci is primarily due to the acquisition of a mobile staphylococcal chromosomal cassette which carries the mecA-gene, known as SCCmec [1]. This mecA-gene encodes an altered PBP, PBP2a (or PBP2’) [2]. The affinity of beta-lactams towards PBP2a is much lower than towards native PBP2, thus allowing continuous cell wall assembly [3]. Many clinical MRSA isolates express resistance to methicillin heterogeneously. This means that the majority of cells are susceptible to low concentrations of methicillin, and only a minority of cells can grow at high concentrations [4]. Reliable microbiological diagnosis of MRSA is essential for treatment, surveillance and control. Clinical microbiology laboratories play a central role in the detection, identification, antibiotic susceptibility testing, and confirmation of MRSA. Conventional laboratory detection of MRSA includes culturing the specimen, confirmation of S. aureus with identification tests, antimicrobial susceptibility testing, and finally, verification of MRSA, usually with molecular methods. This may take several days. Rapid diagnostic testing for MRSA directly from specimens allows the infected patient to obtain a more rapid verification of antimicrobial therapy, leading to a decrease in mortality, a reduction in vancomycin usage, shorter stays in hospital, and lower hospital costs [5]. Rapid tests are still more expensive than conventional ones, and not all laboratories are able to use them for financial reasons. …show more content…
aureus infection. Although the phenotypic methods are dependent up on environmental conditions, they are costly. Therefore, the golden method for detection of MRSA was Polymerase Chain Reaction (PCR) through detection of the mecA gene or its product. However, the limitation of PCR to the reference labs leads the latex agglutination methods to be the best predictor to detect MRSA
Methicillin resistance in staphylococci is primarily due to the acquisition of a mobile staphylococcal chromosomal cassette which carries the mecA-gene, known as SCCmec [1]. This mecA-gene encodes an altered PBP, PBP2a (or PBP2’) [2]. The affinity of beta-lactams towards PBP2a is much lower than towards native PBP2, thus allowing continuous cell wall assembly [3]. Many clinical MRSA isolates express resistance to methicillin heterogeneously. This means that the majority of cells are susceptible to low concentrations of methicillin, and only a minority of cells can grow at high concentrations [4]. Reliable microbiological diagnosis of MRSA is essential for treatment, surveillance and control. Clinical microbiology laboratories play a central role in the detection, identification, antibiotic susceptibility testing, and confirmation of MRSA. Conventional laboratory detection of MRSA includes culturing the specimen, confirmation of S. aureus with identification tests, antimicrobial susceptibility testing, and finally, verification of MRSA, usually with molecular methods. This may take several days. Rapid diagnostic testing for MRSA directly from specimens allows the infected patient to obtain a more rapid verification of antimicrobial therapy, leading to a decrease in mortality, a reduction in vancomycin usage, shorter stays in hospital, and lower hospital costs [5]. Rapid tests are still more expensive than conventional ones, and not all laboratories are able to use them for financial reasons. …show more content…
aureus infection. Although the phenotypic methods are dependent up on environmental conditions, they are costly. Therefore, the golden method for detection of MRSA was Polymerase Chain Reaction (PCR) through detection of the mecA gene or its product. However, the limitation of PCR to the reference labs leads the latex agglutination methods to be the best predictor to detect MRSA