Bin Liang,1,* Huiyu Chen,2,* Donghong Yu,3,4 Wantong Zhao,1,3 Xiaoling Cai,1,3 Huahong Qiu,2 Liangpu Xu1 1Medical Genetic Diagnosis and Therapy Center, Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fuzhou, People’s Republic of China; 2Laboratory Department, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fuzhou, People’s Republic of China; 3Fujian Obstetrics and Gynecology Hospital, Fuzhou, Fujian, People’s Republic of China; 4Medical Research Center, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fuzhou, Fujian, People’s Republic of China*These authors contributed equally to this workCorrespondence: Liangpu Xu; Huahong Qiu, Fujian Maternity and Child Health Hospital, Fuzhou, 350001, People’s Republic of China, Tel +86-0591-87554929 ; +86-0591-87604121, Email xiliangpu@fjmu.edu.cn; 722hhq@sina.comObjective: This study investigated the molecular epidemiology of Group B Streptococcus (GBS) in pregnant women with premature rupture of membranes (PROM) in Fuzhou region of China as a source of clinical reference.Methods: GBS isolates were obtained from pregnant women with PROM. All isolates were genotyped, serotyped, and tested for drug-resistance and virulence genes using PCR and DNA sequencing. Antibiotic susceptibility testing was performed using the Vitek® 2 automated system.Results: Among the 140 GBS isolates, seventeen sequence types (STs) were identified, of which ST19 (20.0%) was the most prevalent, followed by ST862, ST10, and ST12. Three clonal complexes (CC19, CC10 and CC1) were identified. The predominant serotype was III (45.7%), followed by V (23.6%), Ib (18.6%), Ia (7.1%), and II (3.6%). The prevalence of multidrug resistance was 72.8% (102/140). All isolates were susceptible to penicillin G, ampicillin, quinupristin, linezolid, vancomycin, and tigecycline. The majority of isolates were resistant to erythromycin (70.0%), clindamycin (72.1%), and tetracycline (81.4%), and 28.6% of isolates were resistant to levofloxacin and moxifloxacin. Of the 98 erythromycin-resistant strains, mreA, ermB, mefA, mefE, ermA, and ermTR were detected in 100%, 70.4%, 49.0%, 22.4%, 13.3%, and 9.2%, respectively. No linB was detected among 101 clindamycin-resistant strains. Of the 114 tetracycline-resistant strains, tetM, tetK, tetL and tetO were detected in 52.6%, 61.4%, 7.9%, and 23.7%, respectively. Regarding virulence genes, all strains carried rib and hylB, followed by scpB (98.6%), and bca (80.7%), whereas only one strain carried bac.Conclusion: ST19/III and ST862/III were the most prevalent GBS subtypes. Penicillin G remains a first-line antibiotic for intrapartum antibiotic prophylaxis and treatment of GBS infections. The prevalence of resistance to clindamycin, erythromycin, and tetracycline is high among GBS isolates in the Fuzhou region. ST862 and ST651 are emerging animal origin STs in human infections, and may become potential zoonotic threats.Keywords: Group B Streptococcus, molecular epidemiology, premature rupture of the membranes, antibiotic resistance, China