A rise in azithromycin resistance among Salmonella isolates in India: a comprehensive review

Abstract

Salmonella Typhi and Salmonella Paratyphi A susceptibility profiles across Asia underwent changes through horizontal gene transfer and point mutations during the past thirty years. The remaining oral antibiotic Azithromycin faces a critical challenge because of developing resistance among Salmonella strains. This review evaluates azithromycin resistance patterns across India from 2015 through 2025. The emergence of azithromycin-resistant strains threatens the current oral treatment options for typhoid which may cause treatment failures and enhance antimicrobial resistance transmission between Gram-negative bacteria. Multiple socioeconomic factors in the region intensify antimicrobial resistance (AMR) which creates a high-risk environment for resistant Salmonella spread. The mph(A) and erm genes together with AcrB efflux pump protein mutations and ribosomal protein mutations function as essential factors that contribute to azithromycin resistance in Salmonella. The extensive documentation of resistance does not explain the independent emergence of resistant strains in Northern India which shows how local elements influence resistance patterns. Antimicrobial Susceptibility Testing (AST) results of azithromycin require standardized breakpoints for interpretation because AST functions as a critical method to determine antimicrobial treatment for S. Paratyphi A and nontyphoidal Salmonella (NTS) in low-resource settings. Laboratories need to perform detailed assessments of uncertain azithromycin susceptibility test results while they must provide full transparency about their resistance test outcomes. Standardized testing protocols combined with molecular confirmation methods demonstrate potential to solve diagnostic ambiguities. The implementation of these measures together with enhanced surveillance systems will generate essential information for clinical choices and resistance control of Salmonella strains.