Biocide tolerance and antibiotic resistance of Enterobacter spp. isolated from an Algerian hospital environment

Abstract

Objectives: In this study, 77 Enterobacter spp. isolates from a collection of 175 Gram-negative bacilli isolated from Tlemcen University Hospital Center (North-West of Algeria) were tested for antibiotic resistance, biocide tolerance and genetic determinants of antimicrobial resistance.

Methods: The isolates were identified by 16S rDNA gene sequencing. Biocide tolerance was determined by broth microdilution, and antibiotic resistance was determined by disk diffusion. Genetic determinants of resistance were studied by PCR amplification using suitable primers.

Results: The most common Enterobacter species was Enterobacter cloacae (58.4%), followed by Enterobacter hormaechei (24.7%). The most common antibiotic resistance was to ticarcillin either alone or in combination with clavulanic acid (70.1%), followed by cefepime (68.8%), cefotaxime (63.6%), ceftazidime (54.5%) and gentamicin (54.5%). Tobramycin was active against 87.0% of the isolates. Levels of biocide tolerance were high for hexachlorophene and to a lesser extent for benzalkonium chloride. The extended-spectrum β-lactamase genes bla_TEM and bla_CTX-M were detected in 44.2% and 36.4% of isolates, respectively. Other antimicrobial resistance genes (ARGs) frequently detected were aac(6')-Ib (57.1%) and sul2 (50.6%). Multidrug-resistant isolates carrying several ARGs were common. Significant positive correlations were detected for efflux pump genes with ARGs and also between ARGs.

Conclusion: The results of this study reveal thatEnterobacter spp. isolates from hospital settings are both resistant to clinically-used antibiotics and tolerant to biocides. Biocide tolerance could be an advantage for antibiotic-resistant strains in hospitals.

Keywords: Antibiotics; Biocides; Enterobacter; Resistance.