Distribution of Integrons and Phylogenetic Groups among Enteropathogenic Escherichia coli Isolates from Children <5 Years of Age in Delhi, India

Abstract

Integrons by means of horizontal gene transfer carry multidrug resistance genes (MDR) among bacteria, including E. coli. The aim of this study was to determine the antibiotic resistance profiles and the genes associated with them, to gain insights in the distribution of phylogroups, prevalence, and characterization of class 1, 2 and 3 integrons among Enteropathogenic E. coli (EPEC) isolates, from children upto 5 years of age from Delhi and National Capital Region (NCR), India. A total of 120 E. coli isolates, including 80 from diarrheagenic E. coli (cases) and 40 from healthy isolates (controls) were recruited in this study. After isolation of E. coli, screening for EPEC was done by conventional multiplex PCR. Antibiotic suseptibility test was performed using disk diffusion method and further confirmed by minimum inhibitory concentration (MICs) by E-test. The presence and characterization of integrons and antimicrobial resistance genes were performed by PCR and DNA sequencing. Phylogeny determination was carried out by quadruplex PCR. EPEC strains were found in 64 of the 80 diarrheagenic cases, out of which 38 were MDR. In the 40 healthy controls, 23 were found to be EPEC strain, out of which only 2 were MDR. Amongst 80 diarrheagenic cases, class 1 integron were observed in 43 isolates, class 2 integron in 12 isolates and 9 isolates were found with co-existence of both. Similarly, in healthy controls; class 1 integron in 9 and class 2 integron in 7 isolates were observed with co-existence in 3 isolates. None of the isolates included class 3 integron. The dfr was the most commonly identified gene cassette within the integron-positive isolates. Phylogenetic studies showed considerable representation of phylogroup B2 in both diarrheagenic cases and healthy controls. This study reiterates the importance of class 1 integron predominantly for acquisition of antibiotic resistance genes among EPEC isolates. Furthermore, it also ascertains the possible association between multidrug resistance and presence of integrons. Approximately 91% of isolates were easily assigned to their respective phylogroups. Assessment of the relationship between antibiotic resistance and dominant phylogroups detected was also attempted. This study also highlights the increased burden of antimicrobial resistance in healthy controls.

Interrelationship between tetracycline resistance determinants, phylogenetic group affiliation and carriage of class 1 integrons in commensal Escherichia coli isolates from cattle farms

“…In the present study, significant differences in the numbers of isolates with and without integrons were observed ( P < 0.01) between phylogroups D and B1. These agree with those of a previous study that demonstrated that strains associated with phylogroups A and B1 tend to carry integrons more often than those associated with B2 and D [ 10 , 38 ]. In contrast, affiliation with a specific phylogenetic group was not linked to the presence of integrons in E. coli strains recovered from river water [ 39 ].…”

“…The coding regions of the gene cassettes have no promoters; however, most cassettes encode various antimicrobial resistance genes, with more than 130 distinguishable resistance genes having been found to date [ 6 ]. The majority of class 1 integrons harbors an aminoglycoside adenyltransferase gene ( aadA ) and a dihydrofolate reductase gene ( dfr ), which confer resistance to streptomycin and spectinomycin, and trimethoprim, respectively [ 10 , 11 ].…”

Determination of Antibiotic Resistance Profile and Virulence Genes in Escherichia coli Isolates from Palestinian Patients

“…In this study, the prevalence of integron genes among E. coli isolates was 57%. This result is in contrast to other study previously published [31], which showed that 80% diarrheagenic E. col isolates carried integron genes. However, other studies showed lower prevalence (22%-43.56%) [8][9][10][11].…”

“…In current study, all E. coli isolates that had integron genes were carried only class 1 integron and none other tested classes. This result is in contrast to other reports previously published, which showed that the class 1 and 2 integrons were detected in E. coli isolates [9,[29][30][31]. However, this result is in agreement with other report previously published, which showed that the class 1 integron was the only type detected among clinical E. coli isolates [8].…”

A study of virulence and antimicrobial resistance pattern in diarrhoeagenic Escherichia coli isolated from diarrhoeal stool specimens from children and adults in a tertiary hospital, Puducherry, India

“…A similar study from Iran reported only int1 and int2 genes while none of the DEC strains harbored int3 gene [ 61 ]. Studies from India also reported the presence of int1 and int2 genes in various DEC pathotypes [ 52 , 62 ]. Low prevalence of class 2 integron ( int2 gene) and very rarely class 3 integron ( int 3 genes) have been reported so far among these strains.…”