Dataset Information

Determination of the chromosomal relationship between mecA and gyrA in methicillin-resistant coagulase-negative staphylococci.

ABSTRACT: mecA, the gene that mediates methicillin resistance, and its accompanying mec locus DNA, insert near the gyrA gene in Staphylococcus aureus. To investigate whether there is a similar relationship between mecA and gyrA in coagulase-negative staphylococci (CNS), mecA- and gyrA-specific DNA fragments were used to probe methicillin-resistant isolates of Staphylococcus epidermidis (MRSE) (n = 11) and Staphylococcus haemolyticus (MRSH) (n = 11). The gyrA probe hybridized to the same SmaI DNA fragment as the mecA probe in all strains tested. However, since the size of the SmaI fragments containing mecA and gyrA varied from 73 to 600 kb, the distance between the two genes was determined more precisely. Cloned mecA or gyrA fragments plus vector sequences each containing a SmaI site were introduced into the chromosome of three isolates each of MRSE and methicillin-resistant S. aureus (MRSA), and the sizes of the generated SmaI fragments were determined by pulsed-field gel electrophoresis. The distance between gyrA and mecA was found to be between 38 and 42 kb in both MRSE and MRSA, and the two genes were in the same relative orientation in all strains. Restriction fragment length polymorphism (RFLP) patterns around the gyrA gene in CNS were identical, but species specific, for all 10 MRSE and 10 MRSH isolates examined. In contrast, 8 of 11 methicillin-susceptible S. epidermidis isolates and 7 of 7 methicillin-susceptible S. haemolyticus isolates had different gyrA RFLP patterns. These data show that mecA is site and orientation specific, relative to gyrA, in both MRSE and MRSA. In addition, the local environment around gyrA in methicillin-resistant CNS, in contrast to methicillin-susceptible isolates, is similar, suggesting clonality or the requirement for specific DNA sequences with which the mec complex must interact for chromosomal integration to occur.

SUBMITTER: Fey PD

PROVIDER: S-EPMC105405 | biostudies-literature | 1998 Feb

REPOSITORIES: biostudies-literature

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Determination of the chromosomal relationship between mecA and gyrA in methicillin-resistant coagulase-negative staphylococci.

Fey P D PD Climo M W MW Archer G L GL

Antimicrobial agents and chemotherapy 19980201 2

mecA, the gene that mediates methicillin resistance, and its accompanying mec locus DNA, insert near the gyrA gene in Staphylococcus aureus. To investigate whether there is a similar relationship between mecA and gyrA in coagulase-negative staphylococci (CNS), mecA- and gyrA-specific DNA fragments were used to probe methicillin-resistant isolates of Staphylococcus epidermidis (MRSE) (n = 11) and Staphylococcus haemolyticus (MRSH) (n = 11). The gyrA probe hybridized to the same SmaI DNA fragment ...[more]

PMID: 9527777

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Project description:Methicillin-resistant coagulase negative staphylococci (MR-CoNS) are the major cause of infectious diseases because of their potential ability to form biofilm and colonize the community or hospital environments. This study was designed to investigate the biofilm producing ability, and the presence of mecA, icaAD, bap and fnbA genes in MR-CoNS isolates. The MR-CoNS used in this study were isolated from various samples of community environment and five wards of hospital environments, using mannitol salt agar (MSA) supplemented with 4 μg/ml of oxacillin. The specie level of Staphylococcus haemolyticus, Staphylococcus epidermidis, Staphylococcus hominis and Staphylococcus warneri was identified by specific primers of groESL (S. haemolyticus), rdr (S. epidermidis) and nuc (S. hominis and S. warneri). The remainder isolates were identified by tuf gene sequencing. Biofilm production was determined using Congo red agar (CRA) and Microtiter plate (MTP) assay. The mecA and biofilm associated genes (icaAD, fnbA and bap) were detected using PCR method. From the 558 samples from community and hospital environments, 292 MR-CoNS were isolated (41 from community environments, and 251 from hospital environments). S. haemolyticus (41.1%) and S. epidermidis (30.1%) were the predominant species in this study. Biofilm production was detected in 265 (90.7%) isolates by CRA, and 260 (88.6%) isolates were detected by MTP assay. The staphylococci isolates derived from hospital environments were more associated with biofilm production than the community-derived isolates. Overall, the icaAD and bap genes were detected in 74 (29.5%) and 14 (5.6%) of all isolates from hospital environments. When tested by MTP, the icaAD gene from hospital environment isolates was associated with biofilm biomass. No association was found between bap gene and biofilm formation. The MR-CoNS isolates obtained from community environments did not harbor the icaAD and bap genes. Conversely, fnbA gene presented in MR-CoNS isolated from both community and hospital environments. The high prevalence of biofilm producing MR-CoNS strains demonstrated in this study indicates the persisting ability in environments, and is useful in developing prevention strategies countering the spread of MR-CoNS.

Dataset Information

Determination of the chromosomal relationship between mecA and gyrA in methicillin-resistant coagulase-negative staphylococci.

Publications

Determination of the chromosomal relationship between mecA and gyrA in methicillin-resistant coagulase-negative staphylococci.

Similar Datasets

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