Introduction: This study aimed to characterize antimicrobial resistance (AMR), molecular determinants of AMR and virulence, as well as clonal relationship of Streptococcus agalactiae isolates from women at 35-37 weeks of gestation in the Chaoshan metropolitan area of southern China. Methodology: Bacterial strains isolated from vaginal swabs were identified and antimicrobial susceptibility tests were performed by using a Vitek 2 Compact system (BioMérieux, France). Resistance and virulence genes were detected by polymerase chain reaction (PCR) and the clonal relationship was analysed by multiple locus variable number tandem repeat analysis (MLVA). Statistical analysis was carried out by using SPSS software, version 19.0. Results: All GBS were susceptible to benzylpenicillin, ampicillin, quinupristin/dalfopristin, tigecycline, linezolid and vancomycin, but a considerable proportion was resistant to clindamycin (29.67%), erythromycin (46.15%)， azithromycin (63.74%), tetracycline (84.62%) and quinolones (25.27%). The carrier rates of ermB (69.04%) and mefA/E (64.28%) were detected in these GBS strains resistant to erythromycin. In terms of MLVA detection, 91 GBS strains were categorized into 43 genotypes and 6 clusters. All GBS harboured hylB and cylE genes, most of which carried a combination of PI-1 and PI-2a genes as a common virulence gene profile. Conclusions: The high level of resistance conferred by some corresponding resistance genes to macrolides, lincosamides and quinolones of GBS isolates from pregnant women in southern China, has reinforced the necessity for monitoring GBS strain resistance to the above agents. Comparative genetic studies of GBS isolates, especially efforts to understand the relationship between pilus islands and genotype, were essential for conducting infection control and epidemiological comparisons between countries.

This study aims to characterize antimicrobial resistance (AMR), with particular reference to carbapenems and aminoglycosides, in MDR A. baumannii isolates recovered from an intensive care unit in a tertiary hospital. Methods:A. baumannii (n = 95 strains) isolated from patients were subjected to antimicrobial susceptibility test (AST) by Vitek 2 Compact system to determine minimum inhibitory concentrations, followed by genotyping by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). Resistance genes of interest were PCR-ampli ed and sequenced. Results:All isolates were quali ed as MDR, with a resistance rate of >80% to 8 antimicrobials tested. In terms of beta-lactamase detection, the bla OXA23 and bla TEM-1 genes were detected frequently at 92.63% and 91.58%, respectively. The metallo-β-lactamase genes bla IMP , bla VIM , and bla NDM were undetected. Aph (3')-I was detected in 82 isolates (86.32%), making it the most prevalent aminoglycoside-modifying enzyme (AMEs) encoding gene. In addition, ant (3")-I was detected at 30.53%, while 26.32% of the strains harboured an aac (6')-Ib gene. ERIC-PCR typing suggested moderate genetic diversity among the isolates, which might be organized into 10 distinct clusters, with Cluster A (n = 86 isolates or 90.53%) being a dominant cluster of epidemic clones. Conclusions:Substantial fractions of the A. baumannii strains prevailing in the ICU were MDR clones exhibiting extremely high resistance to carbapenems and aminoglycosides as monitored throughout the study period. They principally belonged to a single cluster of isolates carrying bla OXA23 and armA co-producing different AMEs genes. Declarations

Purpose: This study aims to characterize antimicrobial resistance (AMR), with particular reference to carbapenems and aminoglycosides, in MDR A. baumannii isolates recovered from an intensive care unit in a tertiary hospital. Methods: A. baumannii (n = 95 strains) isolated from patients were subjected to antimicrobial susceptibility test (AST) by Vitek 2 Compact system to determine minimum inhibitory concentrations, followed by genotyping by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). Resistance genes of interest were PCR-amplified and sequenced. Results: All isolates were qualified as MDR, with a resistance rate of >80% to 8 antimicrobials tested. In terms of beta-lactamase detection, the blaOXA23 and blaTEM-1 genes were detected frequently at 92.63% and 91.58%, respectively. The metallo-β-lactamase genes blaIMP, blaVIM, and blaNDM were undetected. Aph (3’)-I was detected in 82 isolates (86.32%), making it the most prevalent aminoglycoside-modifying enzyme (AMEs) encoding gene. In addition, ant (3”)-I was detected at 30.53%, while 26.32% of the strains harboured an aac (6')-Ib gene. ERIC-PCR typing suggested moderate genetic diversity among the isolates, which might be organized into 10 distinct clusters, with Cluster A (n = 86 isolates or 90.53%) being a dominant cluster of epidemic clones.Conclusions: Substantial fractions of the A. baumannii strains prevailing in the ICU were MDR clones exhibiting extremely high resistance to carbapenems and aminoglycosides as monitored throughout the study period. They principally belonged to a single cluster of isolates carrying blaOXA23 and armA co-producing different AMEs genes.