Prevalence of asymptomatic bacteriuria among pregnant women and changes in antibiotic resistance: a 6-year retrospective study

Objective: Asymptomatic bacteriuria (ASB) during pregnancy is a risk factor for development of urinary tract infections and pyelonephritis, which can lead to maternal and foetal consequences. This study aimed to determine the prevalence of ASB during pregnancy, the most common causative pathogens and their resistance patterns. Methods: A retrospective analysis was performed using microbiology laboratory data from urine sample cultures from pregnant women collected at our University hospital over a 6-year period (2014-2019). Identification and susceptibility testing were performed using standard microbiology procedures based on British Society of Antimicrobial Chemotherapy and European Committee on Antimicrobial Susceptibility Testing. Results: From a total of 18,938 urine samples, 1522 (8.04%) were positive for bacteriuria, the most common isolates were Escherichia coli and Coliform (lactose fermenters) (n = 1171, 76.9%), followed by Enterococcus faecalis and other enterococci (n = 191, 12.5%). In 2019, the resistance of E. coli was 56.8%, 25.3% and 4.7% to amoxicillin, trimethoprim and gentamicin, respectively, with an increasing pattern of resistance to trimethoprim and gentamicin from 2014 to 2019. The resistance rates to nitrofurantoin were 1% and 5.5% for E. coli and Group B Streptococcus, respectively. Conclusion: Our study shows the trends of antimicrobial resistance in this vulnerable group and will help confirm treatment effectiveness and direct guideline recommendations locally and internationally.