Dissertation (MMED Obstetrics and Gynecology)Background: Incidence of premature rupture of membranes ranges from 3% to 10% worldwide but higher in Sub-Saharan Africa up to 18%. It is reported to be highly associated with bacterial infections as a consequence causing ascending infections or as a cause of premature rupture of membranes. Different bacterial isolates have been known to colonize the vagina and are associated with adverse fetal and maternal outcomes as well as the increasing rate of antimicrobial resistance. Objectives: this study aimed to establish vaginal bacterial colonization, antimicrobial susceptibility patterns and associated obstetric outcomes in women with premature rupture of membranes. Methods: It was a hospital based prospective cross-sectional study among pregnant women with term and preterm premature rupture of membranes. Purposive sampling technique was used with a sample size of 250 participants. Structured questionnaires were used to collect demographic information. Sterile speculum examination on the other hand was done to confirm diagnosis of premature rupture of membranes while high vaginal swab was taken for culture and sensitivity. SPSS version 25 was used for data analysis. Logistic regression was used to analyze association of obstetric outcomes and premature rupture of membranes. Results: Mean age of all women was 25.38±6.286. The microbes commonly isolated were Enterobacter spp 62 (24.80%), Staphylococcus spp. 60 (24.00%). Coagulase negative staphylococcus. 42 (16.80%), E. coli 42 (16.80%). Sensitivity were more on gentamicin 207(82.80%), amikacin 136(54.40%), ceftriaxone 123(49.20%), meropenum 152(60.80%), ciprofloxacin 157(62.80%) and tobramycin 165(66.0%). Mothers who had PPROM were eight times more to give birth to babies with low birth weight compared to those with PROM, (AOR=8.598, 95% CI=3.396-21.772, p=0.000). Women who had PPROM were three times more to have babies with low Apgar score compared to those with PROM, (AOR=3.851, 95% CI=1.502-9.879, p=0.005). Mothers who had PPROM were two times more at risk to have their babies admitted to NICU compared to their counterparts who had PROM, (AOR=2.884, 95% CI=1.187-7.007, p=0.019). Conclusion: On culture results the common microbes isolated were; Enterobacter spp 62 (24.80%), Staphylococcus spp. 60(24.00%). Coagulase negative staphylococcus. 42 (16.80%), E. coli 42 (16.80%), Klebsiella spp. 19 (7.60%). Most bacteria were sensitive to gentamicin 207(82.80%), tobramycin 165(66.0%), ciprofloxacin 157(62.80%), meropenum 152(60.80%), amikacin 136(54.40%), ceftriaxone 123(49.20%).