Molecular epidemiology and antimicrobial susceptibilities of 273 exfoliative toxin-encoding-gene-positive Staphylococcus aureus isolates from patients with impetigo in Japan

Abstract

The molecular epidemiology and antimicrobial susceptibilities of 273 Staphylococcus aureus isolates positive for the exfoliative toxin-encoding gene obtained from patients with impetigo in Japan in 2006 were studied. The mecA gene was detected in 74 meticillin-resistant S. aureus (MRSA) and 23 meticillin-susceptible S. aureus (MSSA) isolates. All isolates with the staphylococcal cassette chromosome (SCC) mec were classified into type IV (92.8 %, 90/97) or V (7.2 %, 7/97). The ET-encoding gene etb was found primarily in strains with mecA (87.7 %, 71/ 81), whilst eta (86.6 %, 161/186) was detected mainly in strains without mecA. The chromosomal enterotoxin-encoding gene cluster egc was found in 83.0 % of strains with eta, whilst no enterotoxin-encoding gene was detected in strains with only etb. PFGE showed that each strain carrying eta, etb and etd could be classified into distinct groups. The susceptibility profiles of MRSA to antimicrobial agents excluding b-lactams were similar to those of MSSA. Gentamicinand clarithromycin-resistant strains were frequently found for both MRSA and MSSA. The aminoglycoside-resistance gene aacA-aphD was detected in 97.3 % of MRSA and 85.4 % of MSSA. Additionally, the macrolide-resistance gene ermA or ermC was detected in 67.6 % of MRSA and 71.4 % of MSSA. Therefore, these results suggest that SCCmec types IV or V have spread, particularly in MSSA carrying etb in the community.

Increase in SCCmec type IV strains affects trends in antibiograms of meticillin-resistant Staphylococcus aureus at a tertiary-care hospital

“…All strains were cultured on tryptone soy agar (Oxoid) under aerobic conditions at 35 uC for 24 h. All collected isolates were confirmed as S. aureus by growth on mannitol salt agar (Oxoid), Gram staining and coagulase production (PS Latex; Eiken Chemical) (Nakaminami et al, 2008). Furthermore, MRSA strains were identified by coagulase testing, growth on Mueller-Hinton agar (Oxoid) containing 6 mg oxacillin ml 21 (Sigma-Aldrich) and 4% NaCl, and PCR-based detection of the mecA gene (Noguchi et al, 2006).…”

“…PCR assays for the detection of mecA, the toxic shock syndrome toxin-1 gene tst and the PVL gene pvl were performed as described previously (Nakaminami et al, 2008). PCR was performed in the following cycles: for mecA, 25 cycles (30 s denaturation at 95 uC, 30 s annealing at 58 uC and 30 s extension at 72 uC) and for tst and pvl, 25 cycles (30 s denaturation at 95 uC, 30 s annealing at 55 uC and 60 s extension at 72 uC).…”

“…We investigated the annual transitions of the SCCmec types, rates of possession of virulence factors and antimicrobial susceptibilities for MRSA strains isolated from a tertiary-care hospital in Tokyo, Japan, between 2005 and 2012. (Nakaminami et al, 2008).…”

Methicillin-Resistant <i>Staphylococcus epidermidis</i> Is Part of the Skin Flora on the Hands of Both Healthy Individuals and Hospital Workers

“…7) The mecA gene, which is located on the mobile genetic element, staphylococcal cassette chromosome mec (SCCmec), plays a key role in β-lactam resistance in staphylococci. 8) Currently, SCCmec in MRSA is divided into 11 types (I-XI) by mec gene complex and ccr gene complex. 9,10) S. epidermidis, especially MRSE, acquired various antimicrobial resistance determinants including SCCmec.…”

“…8,19) Antimicrobial Susceptibility Testing Minimum inhibitory concentrations (MICs) were determined by an agar doubling-dilution method, according to the Clinical and Laboratory Standards Institute guidelines. 20) The following antimicrobial agents were used: ampicillin (Wako), oxacillin (Sigma-Aldrich), cefotaxime (Wako), cefdinir (Sigma-Aldrich), levofloxacin (Wako), clarithromycin (Wako), spiramycin (Sigma-Aldrich), gentamicin (Wako), minocycline (SigmaAldrich), vancomycin (Wako), fusidic acid (Sigma-Aldrich), benzalkonium chloride (Wako), and chlorhexidine digluconate (Wako).…”