Identification, antimicrobial resistance and molecular characterization of the human emerging pathogen Streptococcus gallolyticus subsp. pasteurianus

•Phenotypic, MALDI, and 16S rRNA gene sequencing were used for S. bovis group members identification.•The combination of these methods identified strains as S. gallolyticus subsp. Pasteurianus (SGSP).•SGSP isolation was most frequently associated with diabetes, among women, and from urinary tract.•Approximately 30% of the SGSP were both erythromycin- and clindamycin-resistant, with erm(B).•PFGE analysis revealed a high genetic variability among SGSP isolates.

This study aimed to retrospectively identify 22 Streptococcus bovis clinical strains based on the new taxonomy, as well as to investigate their antibiotic-resistance and clonality. Strains were identified by Phoenix100 system, 16S rRNA sequencing, and two MALDI-TOF MS platforms (Bruker Biotyper, Vitek MS). Antibiotic resistance was determined both phenotypically and genotypically, and clonality was assessed by PFGE. Most of strains (63.6%) were isolated from urine, and diabetes was the most common underlying disease (31.8%). Phoenix100 system revealed all strains belonged to biotype II, and 16S rRNA sequencing identified all strains as S. gallolyticus subsp pasteurianus (SGSP). Although both MALDI-TOF MS systems correctly identified isolates to the species level, only Bruker Biotyper accurately identified to the subspecies level. Erythromycin-resistant strains (31.8%) were also clindamycin-resistant and positive for erm(B). Strains resistant to tetracycline (68.2%) were also resistant to erythromycin. PFGE showed high genetic variability identifying 17 different pulsotypes, most of which single.