Azithromycin_resistant_Salmonella_Typhi_in_Chandigarh__India

Routine blood culture surveillance for enteric fever was conducted at Civil Hospital Manimajra in Chandigarh, India from September 2016 to December 2017. DNA was extracted from patient patient (blood) samples that had positive blood culture results for Salmonella Typhi (S. Typhi). Whole Genome Sequencing was performed. The 66 isolates had broad genetic diversity, with eight co-circulating genotypes, and seven were azithromycin resistant, displaying the same R717Q mutation in the AcrB that has recently been described as conferring azithromycin resistance by colleagues in Bangladesh. Six of those seven isolates also displayed classic "triple mutations" in the quinolone resistance determining region. These isolates were put into phylogenetic context with a globally representative selection of S. Typhi sequences, including other azithromycin resistant organisms from India, Nepal, Bangladesh, and Pakistan, as well as extensively drug-resistant organisms from Pakistan. Based on our analysis, these mutations are occuring independently and are seen on at least six different occasions around the global tree.