Objective:To investigate the phenotypes, molecular types and drug-resistance genes of erythromycin (ERY)-resistant group B Streptococcus (GBS) in pregnant women in late pregnancy in Zhengzhou and provide basic data for the prevention, control and treatment of GBS infection. Methods:This study retrospectively collected 86 GBS strains isolated from the vaginal secretions of pregnant women in late pregnancy at Maternal and Child Health Hospital of Henan Province from 2021 to 2022. ERY-resistant GBS strains were selected using the ERY disk diffusion method, and their susceptibility to 10 different antibiotics was tested. Whole-genome sequencing was performed to analyze their molecular features including molecular types, clonal complex groups and drug-resistance genes. Drug-resistance genes carried by GBS strains belonging to different clonal complex groups were compared.Results:There were 70 ERY-resistant GBS strains. Among them, 7.14%(5/70) exhibited an inducible resistance phenotype to macrolide-lincosamide-streptogramin B (MLSB) antibiotics; 84.29%(59/70) showed constitutive resistance to MLSB antibiotics; 8.57%(6/70) were resistant to macrolides but susceptible to lincosamides. The resistance rates of these strains to clindamycin (CLI), tetracycline (TE) and levofloxacin (LEV) were 91.43%(64/70), 54.29%(38/70) and 60.00%(42/70), respectively. These ERY-resistant strains exhibited multidrug resistance patterns with 40.00%(28/70) showing ERY-CLI-LEV resistance phenotype and 30.00%(21/70) showing ERY-CLI-TE resistance phenotype. The major drug-resistance genes carried by the 70 GBS strains were macrolide/lincosamide resistance genes mreA (100.00%) and ermB (53/70, 75.71%), aminoglycoside resistance genes ant (6)-Ⅰ a (22/70, 31.43%) and aph(3′)-Ⅲ (18/70, 25.71%), and tetracycline resistance genes tetM (22/70, 31.43%) and tetO (13/70, 18.57%). These strains belonged to 12 sequence types derived from seven clonal complexes (CCs) and 48.57%(34/70) of them were clustered into CC12. All CC12 strains harbored ermB, but none carried ermA. The positive rates of lsaE, lunB, and aac (6′)- aph(2" ) in CC19 and CC651 strains, ant (6)-Ⅰ a in CC651 and CC452 strains, and mefA and msrD in CC19 and CC23 strains were significantly higher than those in CC12 strains ( P<0.001). Conclusions:ERY-resistant GBS in Zhengzhou exhibited diverse drug resistance phenotypes and molecular types. CC12 was the most prevalent clonal complex in this region. The constitutive MLSB resistance phenotype and ermB gene were the most common ERY resistance phenotype and genotype, respectively, and tetM gene was related to tetracycline resistance. Furthermore, the drug-resistance genes varied in GBS strains of different clonal complexes. This study suggested that close attention should be paid to the epidemiological situation of GBS in this region and the effectiveness of antibiotics used for clinical prevention and treatment of GBS infection should be carefully evaluated.

To test the therapeutic effect of recombinant fusion polypeptide hEGF-AWRK6 (EK) on burn infection of model mice. EK6 was expressed and purified with Escherichia coli expression system, and the Ⅱ degree burns and Pseudomonas aeruginosa infection model mouse were established. Experiment group was treated with EK (30 mg/L), and the control group was treated with PBS, gentamicin (30 mg/L), burn ointment (10 mg/L). The wound healing rate and colony count were calculated. Wound and surrounding skin were taken for HE staining and collagen western-blot analysis, and the wound pathological changes were observed after 10 days of drug delivery. The results showed that fusion peptide EK was successfully expressed and purified with significant antibacterial activities against Pseudomonas aeruginosa. Compared to the control group, the colony count (CFU) of the wound surface in EK mouse had a remarkable decrease (P<0.01) and healing rate had a significant increase in group EK6 (P<0.01). Pathological analysis result showed that compared to the control group, wound dermal cells in group EK arranged regularly, had more hair growth and a faster epithelization. These results indicated that the fusion peptide EK would be a good candidate for the drug development for the treatment of burning wounds.