OBJECTIVES: An increase in non-toxigenic Corynebacterium diphtheriae infections--mainly invasive infections--has been observed in countries with high vaccination coverage. However, reasons for this situation are unknown. In this study we characterized and compared human clinical isolates of non-toxigenic C. diphtheriae strains isolated from infections that have occurred over recent years and C. diphtheriae strains isolated from diphtheria cases from past outbreaks in Poland. METHODS: We determined biotypes, genotypes, the occurrence of plasmids, and antimicrobial susceptibilities of 19 clinical C. diphtheriae strains. Genotypes were determined using pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) techniques. RESULTS: The non-toxigenic C. diphtheriae strains isolated over the last few years were found to belong to biotype gravis and were genetically indistinguishable using PFGE and ERIC-PCR techniques. No plasmids were detected in the strains. All tested strains were susceptible to penicillin and erythromycin, as well as to imipenem, vancomycin, daptomycin, gentamicin, tetracycline, clindamycin, trimethoprim/sulfamethoxazole, rifampin, quinupristin/dalfopristin, and linezolid. Of the strains tested, 47% were intermediate for cefotaxime. CONCLUSIONS: The genetic similarity of non-toxigenic C. diphtheriae strains causing infection suggests that the strains represent a single clone. They may possess additional virulence genes in a chromosome, related with higher pathogenicity and invasiveness. The genetic changes have not been followed by resistance to antibiotics.
OBJECTIVES: An increase in non-toxigenic Corynebacterium diphtheriae infections--mainly invasive infections--has been observed in countries with high vaccination coverage. However, reasons for this situation are unknown. In this study we characterized and compared human clinical isolates of non-toxigenic C. diphtheriae strains isolated from infections that have occurred over recent years and C. diphtheriae strains isolated from diphtheria cases from past outbreaks in Poland. METHODS: We determined biotypes, genotypes, the occurrence of plasmids, and antimicrobial susceptibilities of 19 clinical C. diphtheriae strains. Genotypes were determined using pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) techniques. RESULTS: The non-toxigenic C. diphtheriae strains isolated over the last few years were found to belong to biotype gravis and were genetically indistinguishable using PFGE and ERIC-PCR techniques. No plasmids were detected in the strains. All tested strains were susceptible to penicillin and erythromycin, as well as to imipenem, vancomycin, daptomycin, gentamicin, tetracycline, clindamycin, trimethoprim/sulfamethoxazole, rifampin, quinupristin/dalfopristin, and linezolid. Of the strains tested, 47% were intermediate for cefotaxime. CONCLUSIONS: The genetic similarity of non-toxigenic C. diphtheriae strains causing infection suggests that the strains represent a single clone. They may possess additional virulence genes in a chromosome, related with higher pathogenicity and invasiveness. The genetic changes have not been followed by resistance to antibiotics.
Authors: Fernando Encinas; Michel A Marin; Juliana N Ramos; Verônica V Vieira; Ana Luiza Mattos-Guaraldi; Ana Carolina P Vicente Journal: Mem Inst Oswaldo Cruz Date: 2015-09 Impact factor: 2.743
Authors: Klaudia Brodzik; Katarzyna Krysztopa-Grzybowska; Maciej Polak; Jakub Lach; Dominik Strapagiel; Aleksandra Anna Zasada Journal: Pol J Microbiol Date: 2019
Authors: Revati K Phalkey; Rajesh V Bhosale; Abhijeet P Joshi; Sushil S Wakchoure; Muralidhar P Tambe; Pradip Awate; Michael Marx Journal: BMC Public Health Date: 2013-04-08 Impact factor: 3.295