Azithromycin susceptibility testing of Salmonella enterica serovar Typhi: Impact on management of enteric fever

Drug-resistant enteric fever is increasingly common in the Indian subcontinent. Correctly determining azithromycin resistance matters where drug-resistant and oral therapy necessary. In two patients returning from Pakistan to UK with cephalosporin-resistant Salmonella enterica serovar Typhi, gradient strip testing erroneously indicated resistance; errors were detected by repeat confirmed whole genome sequencing. Both treated meropenem and, when revised susceptibility results known, azithromycin, allowing a switch therapy. As cephalosporin becomes more common, will be key for treating optimizing practice crucial. Practitioners should aware of steps minimize error testing, alert possible reported discordant known prevalence resistance.