Genetic and phenotypic determinants of resistance to antibiotics in Aeromonas spp., strains isolated from pediatric patients

Abstract

Introduction: Intestinal and extraintestinal infections by Aeromonas spp., remain controversial, due to the existence of healthy carriers of Aeromonas spp. In children under five years old, the diarrhea of infectious origin constitutes the second cause of mortality and remains a major concern for public health. The aim of this work was to detect the pheno/genotype of β-lactamases and class 1 integrons in Aeromonas spp., strains isolated from pediatric patients in a tertiary referral hospital in Mexico. Methodology: Sixty-six strains of Aeromonas spp., were isolated from clinical samples of pediatric origin and were identified by RFLP-PCR 16S rRNA. Resistance phenotype according to CLSI, genetic and phenotypic detection of extended-spectrum β-lactamases (ESBL) and metallo-b-lactamases (MBL) was performed. Finally, characterization of class 1 integrons was performed. Results: Aeromonas spp., strains of diarrheic origin were more predominant. A wide heterogeneity was detected, where A. caviae was the predominant specie. Second-generation cephalosporins, fluoroquinolones, and nitrofurans had best antimicrobial activity; moreover, antibiotics of the β-lactamic and lincosamides families showed lower inhibitory activity. Phenotypically, prevalences of 4.55% and 3.03% were detected for MBL (intestinal origin) and ESBL (extraintestinal origin), respectively. blaIMIS-cphA and blaTEM-1 genes, and nineteen class 1 integrons carrying two variants of cassettes corresponding to adenylyl transferases (aadA), and dihydrofolate reductases (dfrA). Monogenic array with aadA1 cassette was predominantly. Conclusions: ESBL and class 1 integrons, in Aeromonas collected from pediatric patients, determines a major detection challenge for the clinical microbiology laboratory and represents a remarkable epidemiological risk of nosocomial spread of multidrug-resistant determinants.