Molecular Features and Antimicrobial Susceptibilities of ssp. Isolates from Strangles Cases in Indonesia.

Strangles, caused by ssp. (), is a highly infectious and frequent disease of equines worldwide. No data are available regarding the molecular epidemiology of strangles in Indonesia. This study aimed to characterize isolates obtained from suspected strangles cases in Indonesia in 2018. Isolates originated from seven diseased horses on four different farms located in three provinces of Indonesia. Whole genome sequences of these isolates were determined and used for typing, multilocus sequence typing (MLST), and core genome MLS typing (cgMLST). Genomes were also screened for known antimicrobial resistance genes and genes encoding for the recombinant antigens used in the commercial Strangvac subunit vaccine. All seven isolates from Indonesia belonged to ST179 and carried allele 166. Isolates differed from each other by only 2 to 14 cgSNPs and built an exclusive sub-cluster within the Bayesian Analysis of Population Structure (BAPS) cluster 2 (BAPS-2) of the cgMLST scheme. All isolates revealed predicted amino acid sequence identity to seven and high similarity to one of the eight antigen fragments contained in Strangvac. Furthermore, all isolates were susceptible to beta-lactam antibiotics penicillin G, ampicillin, and ceftiofur. Our data suggest that the horses from this study were affected by strains of the same novel sublineage within globally distributed BAPS-2 of . Nevertheless, penicillin G can be used as a first-choice antibiotic against these strains and Strangvac may also be protective against Indonesian strains.