Phenotypic and Genotypic Characterization of Extended Spectrum Beta Lactamases Bacterial Producers Causing Urinary Tract Infection among Expectant Women Attending Antenatal Clinic at Ruiru Sub-County Hospital, Kenya

Abstract

Urinary tract infections (UTIs) are among the most common bacterial infections globally, with pregnant women being particularly vulnerable due to physiological and anatomical changes during pregnancy. The emergence of Extended Spectrum Beta-Lactamase (ESBL)-producing bacteria has further complicated UTI management by conferring resistance to commonly used antibiotics. There is limited data in Kenya on the prevalence, antimicrobial resistance profiles, and genetic characteristics of ESBL-producing uropathogens in pregnant women. This study was conducted to fill this knowledge gap and to support evidence-based treatment and infection control strategies in antenatal care. The main objective of the study was to determine the phenotypic and genotypic characteristics of ESBL-producing bacteria causing UTIs among expectant women attending the antenatal clinic at Ruiru Sub-County Hospital. A systematic random sampling cross-sectional study design was used; 300 pregnant women were selected. Data on socio-demographic factors were collected using structured questionnaires. Midstream urine samples were analyzed through urinalysis, culture, biochemical identification, and Gram staining. Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disc diffusion method. ESBL production was phenotypically confirmed using the double-disc synergy test. Genotypic detection of ESBL genes Bla CTX-M, Bla SHV, Bla TEM, and Bla OXA) was performed using polymerase chain reaction (PCR) and gel electrophoresis. Specific primers were used: Bla_CTX-M (593 bp, 60 °C), Bla_SHV (851 bp, 60 °C), Bla_TEM (999 bp, 52 °C), and Bla_OXA (920 bp, 52 °C). Statistical analysis was conducted using SPSS version 11.0, with chi-square and odds ratio tests applied at a significance level of p<0.05. The study results revealed, urinalysis markers positive 5.3% for protein, 4.7% for nitrites, 1.7% for ketones, and 1.0% for glucose, while all were negative for bilirubin. UTI prevalence was 32.7%, most cases occurring in women aged 28–37 years and in the second trimester. There were significant associations between UTIs and both previous UTI history (OR = 2.98, p = 0.02) and multigravidity (OR = 2.64, p = 0.01). The most common isolates were Escherichia coli (57.1%), Staphylococcus aureus (21.4%), Klebsiella pneumoniae (11.2%), and Proteus spp. (10.2%). High antibiotic resistance was observed among E. coli isolates, with 91.1% resistance to tetracycline and 55.4% to sulfamethoxazole. Phenotypic testing confirmed 37.6% of isolates as ESBL producers, and of these, 44.8% harbored ESBL genes, with Bla CTX-M being the most prevalent (53.8%), followed by Bla SHV (23.1%) and Bla TEM (23.1%). Bla OXA was not detected. The study demonstrates that multidrug-resistant ESBL producing uropathogens among pregnant women at Ruiru Sub-county Hospital and need for routine culture, antimicrobial susceptibility testing, and ESBL gene screening during antenatal care to guide effective treatment, prevent recurrence, and reduce the threat of antimicrobial resistance.