Antibiotic resistance and the presence of blaCfxA and blaCSP genes in β-lactamase-producing clinical Capnocytophaga isolates from a university hospital in Japan

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 beta-lactamases (ESBLs). Gap statement. Information is lacking about the types of beta-lactamase genes possessed by Capnocytophaga spp. and the antimicrobial susceptibility of Capnocytophaga spp. possessing each beta-lactamase gene. Aim. The aim of this study was to investigate the presence of beta-lactamase genes in clinical strains of beta-lactamase-producing Capnocytophaga species isolated from clinical samples acquired at Shinshu University Hospital and examine the antimicrobial susceptibility of those strains. Methodology. The beta-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 beta-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 beta-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) beta-lactamase genes among Capnocytophaga species.