# Antibiotic resistance profiles and genetic characterization of Salmonella enterica from water supplies in Kaduna State, Northwest Nigeria

## TL;DR

This study found antibiotic-resistant Salmonella in drinking water in Kaduna State, Nigeria, highlighting a public health risk linked to antibiotic misuse and poor water quality.

## Contribution

The study provides new insights into the genetic basis of antibiotic resistance in Salmonella from drinking water in Kaduna State.

## Key findings

- Six Salmonella enterica isolates were identified, with 66.7% showing resistance to multiple antibiotics.
- Resistance genes tetA and sul1 were detected in isolates from treated pipe-borne and well water.
- The findings suggest antibiotic misuse and the potential for horizontal gene transfer in the region.

## Abstract

Communities across Kaduna State, Nigeria, depend on diverse water sources, and the presence of Salmonella enterica is particularly concerning when the bacteria are resistant to antibiotics and possess resistance genes. The One Health approach recognizes that water quality, antimicrobial resistance patterns, and human health are closely linked, yet significant knowledge gaps exist regarding both the resistance patterns and the underlying genetic mechanisms of Salmonella in local drinking water sources of Kaduna state. This study aimed to determine the phenotypic antibiotic susceptibility patterns and detect some resistance genes in Salmonella enterica isolated from various drinking water sources in Kaduna State.

Five hundred sources of water used for drinking in six selected Local Government Areas of Kaduna state were sampled from 2014 to 2015. The samples were processed using standard bacteriological methods to isolate and identify Salmonella species, followed by molecular confirmation through 16 S rRNA gene sequencing. The consensus sequences of the isolates were subjected to BLAST in the GenBank of the National Center for Biotechnology Information (NCBI). The isolates were subjected to antibiotic susceptibility tests and investigation of some resistance genes were assessed.

Six isolates (1.2% isolation rate) were obtained from various sources and were identified as Salmonella enterica. The sequences were submitted to the NCBI GenBank and have been assigned accession numbers. Four (66.7%) of the isolates were resistant to tetracycline, nalidixic acid and sulfamethoxazole-trimethoprim, while 2 (33.3%) were pan-susceptible. One isolate was resistant to three (3) different classes of antibiotics. Antibiotic resistance genes –tetA and sul1 were both detected in two isolates, obtained from treated pipe borne and well water respectively. The genes detected correlate with the phenotypic resistance observed.

Antibiotic-resistant Salmonella enterica in drinking water poses a critical One Health threat, linking human, animal, and environmental health risks. The correlation between resistance genes and phenotypic patterns indicates antibiotic misuse in the study area at the time, creating reservoirs for multidrug-resistant pathogens and horizontal gene transfer. Urgent implementation of multi-sectoral One Health surveillance, strict antibiotic regulation, improved water treatment, antimicrobial stewardship programs, and rapid response protocols is essential across Kaduna state and Nigeria.