Phylogenetic background of E. coli isolated from asymptomatic pregnant women from Kolkata, India.

Introduction: Asymptomatic bacteriuria (ABU) in pregnancy generates medical complications. E. coli is the common etiologic agent responsible for ABU-associated infections. This study aimed to identify the phylogenetic background and drug resistance in asymptomatic E. coli from a pregnant population.

Methodology: E. coli was confirmed biochemically from culture-positive urine samples collected from asymptomatic pregnant women. Phylogenetic typing was done by polymerase chain reaction (PCR). The isolates were subjected to antibiotic susceptibility testing and extended-spectrum beta-lactamase (ESBL) production. Statistical significance was determined using SPSS 17.0 software.

Results: Bacteriuria was observed in 113 (22.6%) of 500 asymptomatic pregnant females. E. coli was reported in 44 (38.9%) of 113 isolates. The mean age-wise distribution was 25.14 ± 4.63. Although pathogenic phylogroup B2 was predominant (54.5%), incidence of non-pathogenic phylogroup B1 (27.3%) was found to be statistically significant (p ≤ 0.001), and B1 and B2 were correlated with respect to total ABU population. Antibiotic sensitivity against ampicillin (34.1%), ceftazidime (50%), cefotaxime (47.7%), ciprofloxacin (47.7%), amikacin (86.4%), nitrofurantion (79.5%), and co-trimoxazole (36.4%) was observed. Multidrug resistance (MDR) and ESBL production was reported in 26 (59.1%) of 44 and 18 (69.2%) of the 26 MDR isolates, respectively. A significant distribution of phylogroup B1 (p = 0.03) with drug resistance was also observed.

Conclusions: This is the first study that reported significant incidence of non-pathogenic phylogroup B1 in asymptomatic E. coli with high incidence of MDR isolated from pregnant women in Kolkata, India.  These varied resistance patterns present major therapeutic and infection control challenges during pregnancy.