The draft genomes and investigation of serotype distribution, antimicrobial resistance of group B Streptococcus strains isolated from urine in Suzhou, China

Background: The group B Streptococcus (GBS) is a human commensal bacterium, which is capable of causing several infectious diseases in infants, and people with chronic diseases. GBS has been the most common cause of infections in urinary tract of the elders, but relatively few studies reported the urine-isolated GBS and their antimicrobial susceptibilities. Hence, we decided to investigate GBS specially isolated from urine in Suzhou, China. Methods: 27 GBS samples were isolated from urine in Suzhou, China. The PCR and agarose gel electrophoresis were used to identify the serotype distribution. Susceptibility tests were based on MIC test and Kirby-Bauer test. Genome were sequenced via Illumina Hiseq platform and assembled by SPAdes. Genomes of five isolates were sequenced and submitted to NCBI genome database. The sequencing files in fastq format were submitted to NCBI SRA database. Results: Five serotypes were identified. The resistant rates measured for tetracycline, erythromycin, clindamycin and fluoroquinolones were 74.1, 63.0, 44.4 and 48.1%, respectively. 18.5% of the isolates were nonsusceptible to nitrofurantoin. The resistance to tetracycline was mainly associated with the gene tetM. The erythromycin resistance was mainly associated with the genes ermB and mefE. The genes ermB and lnuB were the prevalent genes in cMLSB type. No known nitrofurantoin resistance gene was found in nitrofurantoin-nonsusceptible GBS. Conclusions: Five serotypes were identified in our study. High rates of GBS isolates were resistant to tetracycline, erythromycin, clindamycin and fluoroquinolones. The genes ermB and lnuB occupied high rates in cMLS(B) phenotype.