A comparative study of antimicrobial resistance rates and phylogenetic groups of community-acquired versus hospital-acquired invasive Escherichia coli.

OBJECTIVES

Escherichia coli is the leading cause of various infections, both in community and nosocomial settings. Our objective was to determine the antibiotic resistance rates and the phylogenetic groups of invasive E. coli and to assess the relationship between these characteristics according to the community or nosocomial origin of the strains.

MATERIALS AND METHODS

One hundred non-redundant E. coli strains, causing invasive infections, were collected and investigated between 2010 and 2012. The phylogenetic groups were determined by triplex PCR. The statistical analysis was performed with Pearson χ(2) test and P-values below 0.05 were considered as statistically significant.

RESULTS

Sixty-three strains were community-acquired (CA) and 37 were hospital-acquired (HA). The resistance rates among CA and HA strains were respectively: cefotaxime (11.1/37.8%), ciprofloxacin (19/43.2%), amikacin (3.2/27.2%), and cotrimoxazole (42.8/64.8%). E. coli strains caused bacteremia (CA=34.9%; HA=83.7%), peritonitis (CA=58.7%; HA=13.5%), appendicitis (CA=3.2%; HA=2.7%), and cholecystitis (CA=3.2%; HA=0%). The distribution of phylogenetic groups among CA and HA strains was: A (25.4/18.9%), B1 (9.5/16.2%), B2 (23.8/37.8%), and D group (41.3/27%). High resistance rates to cefotaxime (P=0.02), ciprofloxacin (P=0.01), amikacin (P=0.001), and cotrimoxazole (P=0.05) were statistically significantly associated with a nosocomial origin.

CONCLUSION

Our results prove the diversity of phylogroups among E. coli invasive strains whatever their origin, and a higher antibiotic resistance rate in nosocomial strains. An adequate use of antibiotics and applying strict hygiene measures would limit the transmission and selection of these bacteria in hospital as well as in community settings.