Disease relevance of mecA

• We report on the structural diversity of mecA gene complexes carried by 38 methicillin-resistant Staphylococcus aureus and 91 methicillin-resistant coagulase-negative Staphylococcus strains of seven different species with a special reference to its correlation with phenotypic expression of methicillin resistance [1].
• Homology of mecA gene in methicillin-resistant Staphylococcus haemolyticus and Staphylococcus simulans to that of Staphylococcus aureus [2].

High impact information on mecA

• Mutants with the class C mecA gene complex were obtained in vitro by selecting strain SH621, containing the IS431L-class A mecA gene complex with low concentrations of methicillin (1 and 3 mg/liter) [1].
• Genetic organization of the chromosome region surrounding mecA in clinical staphylococcal strains: role of IS431-mediated mecI deletion in expression of resistance in mecA-carrying, low-level methicillin-resistant Staphylococcus haemolyticus [1].
• Our study indicated that the mecI-encoded repressor function is responsible for the low-level methicillin resistance of some S. haemolyticus clinical strains and that the IS431-mediated mecI gene deletion causes the expression of methicillin resistance through the derepression of mecA gene transcription [1].
• Expression of methicillin resistance could be explained for all mecA-positive staphylococci with mutations within mecI or in the mec promoter region or in which mecI was deleted [3].
• Screening of 300 staphylococci (100 S. aureus, 100 S. intermedius and 100 coagulase-negative staphylococci (CNS)) randomly chosen from the strain collection of the Veterinary Microbiological Diagnostic Center yielded five oxacillin-resistant coagulase-negative staphylococci, four of which were mecA-positive [4].

Analytical, diagnostic and therapeutic context of mecA

• PCR was used to detect mecA and the regulatory genes mecR1 and mecI [3].
• The distribution of mecA, mecR1 and mecI and sequence analysis of mecI and the mec promoter region in staphylococci expressing resistance to methicillin [3].

References