Antibiotic Susceptibility Patterns and Biofilm Production by Uropathogenic Escherichia coli from Reproductive Age Women in a Region of NSW

Background: Urinary tract infections (UTIs), mostly caused by uropathogenic E. coli (UPEC), are important human infections. Understanding UTI pathogenesis is important for combating the rise in treatment failure and recurrent infections. We studied the distribution of biofilm production by host and non-host factors, among UPEC antibiotic resistant and sensitive cystitis isolates, from reproductive age women. Methods: Cystitis isolates (n = 534) from women were tested for (i) Biofilm production using a microtitre plate method, (ii) Susceptibility to 14 antibiotics using the CLSI disk method, and finally, (iii) Phylogenetic group status using the improved Clermont method. Results: A total of 534 UPEC isolates from women were studied. Biofilm production was highest in the 26-30 years age group (73%), and lowest in the 16-20 years age group (35%). A greater proportion of isolates from inpatients (72%) produced biofilms vs. 45% for outpatients. Most of recurrent UTI isolates (92%) were biofilm producers vs. 48% for first time UTI. The majority of the isolates (61%) were resistant to one or more antibiotics. In the overwhelming majority of cases, biofilm production was highest among the resistant isolates vs. susceptible ones, on average by twice as much. A higher proportion of B2 isolates (77%) were biofilm producers compared to any another group. Conclusion: Our findings suggest a strong association between biofilm production and several host and non-host factors, including age, UTI recurrence, hospitalisation, and phylogenetic groups B2 and D. These factors are associated with multidrug resistance, suggesting a strong link between biofilm production and multidrug resistance, as previously suggested.