Detection of extended-spectrum β-lactamases in Escherichia coli isolated from freshwater ecosystems in Havana

Abstract

Introduction: Extended-spectrum β-lactamase-producing Escherichia coli strains are multiresistant pathogens and one of the bacteria contributing most greatly to bacterial antibiotic resistance in clinical practice. However, they are increasingly isolated from natural environments, such as aquatic ecosystems, where they are used as fecal pollution indicators.

Objective: Evaluate antibiotic susceptibility and extended-spectrum β-lactamase enzyme production in Escherichia coli isolates from freshwater ecosystems in Havana.

Methods: An analysis was conducted of 43 E. coli isolates from the rivers Almendares, Quibú and Luyanó in Havana. Determination was made of susceptibility to 18 antibiotics and phenotypic production of extended-spectrum β-lactamases according to standards from the Clinical and Laboratory Standards Institute. Molecular detection of the enzymes was performed by polymerase chain reaction. Estimation was carried out of the antibiotic multiresistance index and the resistance patterns of each extended-spectrum E. coli β-lactamase isolate.

Results: Of the E. coli isolates studied, 65% were resistant to at least one antibiotic, whereas 35% were sensitive to all antibiotics. The extended-spectrum β-lactamase phenotype was detected in seven isolates, of which four were carriers of the gene bla_CTX-M-1 and three contained bla_TEM. 37% of the E. coli isolates displayed antibiotic multiresistance index values below 0.22, 16% of 0.22, 9.3% above 0.5 and 5% above 0.7. ESBL E. coli isolates displayed co-resistance to the families tetracyclines, quinolones, aminoglycosides and macrolides.

Conclusions: The presence of multiresistant extended-spectrum β-lactamase-producing environmental E. coli isolates in Havana freshwater ecosystems highlights the need to implement control strategies aimed at preventing the spread of these isolates in natural environments.