*3.4. Antibiotic Resistant Genes in E. coli*

In human stool, plasmid-mediated cephalosporin-coding genes of the *blaCTX-M-1* group was predominant, especially the gene *blaCTX-M-1*. In environmental samples *blaCTX-M-1* and *blaCTX-M-9* genes were also common (Table 4). Plasmid-mediated quinolone resistance genes (i.e., *qnrA, qnrS*, *qnrS*) were detected in 34% human and in 9% environmental quinolone resistant isolates. The *qnrS* gene was most common in human (23/72), and only three household drinking waters were carrying quinolone-resistant genes from environmental isolates (*n* = 33) (Table 4). The coexistence of *blaCTX-M-1* and *qnrS* genes were also common (*n* = 12). Carbapenemases encoding genes *NDM-1*, *VIM*, and *IMP* were not detected in any of the carbapenem resistant isolates (*n* = 35) and colistin-resistant gene *mcr-1* was also not detected in any of the isolates (*n* = 292).

The majority (56%–100%) of cephalosporin, quinolone, and carbapenem resistant *E. coli* isolates belonged to phylogenetic group A and B1 (considered as commensal) and 0%–40% belonged to D (considered as extra-intestinal virulent). Human samples carried significantly higher numbers (30%–52%) of group D isolates than environmental samples (0%–40%) (Table 5). Isolates, which showed susceptibility to all drugs, belonged equally to groups A, B1, B2, and D in human samples, but in environmental samples these isolates mainly belonged to the A or B1 groups. The majority (82%) of isolates carrying resistant genes belonged to phylogenetic group A and B1 and the rest (18%) were categorized into group D. Human stool and wastewater were the source of most of the group D *E. coli* isolates.


**Table 3.** Distribution of various antibiotic resistant *E. coli* isolates in human and drinking water collected from households in a village in Central India.

HDW: household drinking-water; \*: *p* = 0.001


**Table 4.** Antibiotic resistant genes in commensal *E. coli* isolated from samples from humans and their shared environment from a village in Central India.

HS: human stool; AS: animal stool; SW: source-water; WW: wastewater.

**Table 5.** Phylogenetic grouping of resistant commensal *E. coli* isolates collected from various samples from a village in Central India.

