Phenotypic and genetic differences among group B Streptococcus recovered from neonates and pregnant women in Shenzhen, China: 8-year study.

BACKGROUND: Group B Streptococcus (GBS) is a leading cause of early-onset disease (EOD) and late-onset disease (LOD) in infants. We sought to investigate the antibiotic susceptibility profiles, resistance genes, virulence-related genes, serotype distribution and genotypic characteristics of GBS recovered from infected or colonized neonates and pregnant women in a tertiary teaching hospital in Shenzhen, China, from 2008 to 2015. RESULTS: High resistance rates of erythromycin (66.7-100%) were detected among early-onset GBS (EOGBS), late-onset GBS (LOGBS), neonatal colonizing GBS (NCGBS) and maternal colonizing GBS (MCGBS). 89.5-100% of four groups of GBS isolates showed resistance to tetracycline. More than 90 % of erythromycin resistant isolates of EOGBS (8/8, 100%), LOGBS (16/17, 94.1%) and NCGBS (10/11, 90.9%) harbored ermB, while only 9.1-17.6% harbored mefA/E. By contrast, 55.8% (24/43) and 62.8% (27/43) of erythromycin resistant MCGBS isolates carried ermB and mefA/E genes, respectively. The tetO gene was more common in tetracycline resistant EOGBS (10/11, 90.9%), LOGBS (17/17, 100%) and NCGBS (10/11, 90.9%), compared to tetracycline resistant MCGBS (12/51, 23.5%). Additionally, the tetM gene accounted for 90.9% (10/11), 76.5% (13/17), 45.5% (5/11) and 80.4% (41/51) of four groups of isolates, respectively. Serotype III was the most predominant in EOGBS (8/12, 66.7%) and LOGBS (15/17, 88.2%), while serotype Ib accounted for 50.0% (6/12) of NCGBS, and serotype Ia and III accounted for 45.6% (26/57) and 33.3% (19/57) of MCGBS, respectively. Sequence type 17 (ST17) was the most common in EOGBS (6/12, 50%) and LOGBS (12/17, 70.6%), while ST12 was predominant in NCGBS (5/12, 41.7%), and five STs (ST19, ST23, ST12, ST103 and ST485) accounted for 66.7% (38/57) of the MCGBS. All serotype III-ST17 isolates recovered from neonates were associated with invasive infections. CONCLUSIONS: This study shows the meaningful differences in molecular mechanisms of resistance to erythromycin and tetracycline, and the prevalence of serotypes and STs among GBS recovered from neonates and pregnant women. ST17 is predominant in neonatal invasive GBS, but rare in NCGBS and MCGBS.

[Quality characteristics of human spermatozoa with hyaluronic acid receptors].

OBJECTIVE: To analyze the quality characteristics of human spermatozoa with hyaluronic acid (HA) receptors and search for a new indicator for the assessment of sperm quality. METHODS: Using sperm-HA binding assay with HA-coated slides, we determined the binding rate of motile sperm with HA receptors and analyzed its correlation with routine semen parameters, sperm membrane function, sperm fertilizing function and diminished/arrested sperm maturation. RESULTS: The motile sperm with HA binding sites in the acrosomal region showed significantly higher acrosomal integrity ([95.4 +/- 3.9]%) and mitochondrial membrane potential (MMP) ([97.8 +/- 2.1]%) than those in the initial semen ([68.8 +/- 6.2]% and [72.8 +/- 7.4]%) (P < 0.01). The sperm-HA binding scores were correlated mildly with many routine semen parameters (r = 0.195-0.268, P < 0.05), positively with the acrosome reaction level after ionophore challenge (r = 0.666, P < 0.01) and normal sperm morphology (r = 0.417, P < 0.01), and negatively with sperm nucleoprotein immaturation (r = -0.266, P < 0.01), DNA fragmentation (r = -0. 308, P < 0.01) and excessive residual cytoplasm (r = -0.218, P < 0.05). CONCLUSION: Sperm with HA receptors in the acrosomal region exhibit significant advantages in plasma membrane structure, fertilizing potential and maturation. The sperm-HA binding assay, which is based on a relationship between sperm receptors for zona pellucida and HA, is likely to become a new independent indicator for assessing the multiple qualities of spermatozoa.