Introduction
. Capnocytophaga species are common inhabitants of the oral cavity and can be responsible for systemic diseases in immunocompromised patients with granulocytopenia. Furthermore, it has been reported that some clinical isolates of
Capnocytophaga
species produce extended-spectrum β-lactamases (ESBLs).
Gap statement. Information is lacking about the types of β-lactamase genes possessed by
Capnocytophaga
spp. and the antimicrobial susceptibility of
Capnocytophaga
spp. possessing each β-lactamase gene.
Aim. The aim of this study was to investigate the presence of β-lactamase genes in clinical strains of β-lactamase-producing
Capnocytophaga
species isolated from clinical samples acquired at Shinshu University Hospital and examine the antimicrobial susceptibility of those strains.
Methodology. The β-lactamase-producing
Capnocytophaga
species (n=49) were obtained from clinical specimens. PCR assays were used to detect bla
CfxA, bla
CSP, bla
TEM, bla
CepA/CblA and transposon Tn4555 genes. Southern hybridization assays were used to detect bla
CfxA and bla
CSP. The minimum inhibitory concentration of some β-lactams was determined using the E-test method.
Results. PCR analysis indicated that the bla
CfxA gene was present in 15 (30.6 %) and the bla
CSP gene in 35 (69.3 %) of the 49
Capnocytophaga
strains investigated, . Both bla
CfxA and bla
CSP genes were detected in a
Capnocytophaga gingivalis
strain. The PCR results were confirmed by Southern hybridization assays. Transposon Tn4555 was only detected in
Capnocytophaga
spp. harbouring the bla
CfxA gene. All the β-lactamase-producing
Capnocytophaga
isolates were susceptible to ceftazidime–clavulanic acid, cefoxitin and imipenem. In contrast, most of the isolates were resistant to amoxicillin.
Conclusions. The clinical isolates of
Capnocytophaga
spp. showed a high prevalence of the bla
CSP gene in Japan. The presence of the bla
CSP gene was distributed in
Capnocytophaga sputigena
as well as other
Capnocytophaga
spp. These results seem to suggest the dissemination of bla
CfxA and bla
CSP β-lactamase genes among
Capnocytophaga
species.