Clonal dissemination of methicillin-resistant Staphylococcaceae between Algerian sheep farms.

OBJECTIVES

Sheep farming represents an important economic sector in Algeria, and the potential dissemination of methicillin-resistant Staphylococcaceae (MRS) is a critical veterinary and public health concern. This study aimed to determine the prevalence and types of MRS in ovine in Algeria and characterize them using whole-genome sequencing (WGS) analysis.

METHODS

Two hundred sheep from 20 different Algerian farms across 3 regions were screened for nasal colonization with MRS. The isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), their minimal inhibitory concentration (MIC) was determined by broth microdilution, and the presence of the mec gene was confirmed with polymerase chain reaction (PCR). The mec-positive isolates were sequenced using Illumina technology to build species specific core genome multilocus sequence typing (cgMLST)- and single nucleotide polymorphisms (SNPs)-based phylogenies and perform an in silico screening for antimicrobial resistance genes.

RESULTS

The prevalence of MRS-positive farms was 85% (95% confidence interval [CI] = 69.34%-100%) across the sampled farms. Ten distinct Staphylococcaceae species were identified, with Staphylococcus saprophyticus (S. saprophyticus; n = 29), Mammaliicoccus lentus (M. lentus; n = 24), and Staphylococcus haemolyticus (S. haemolyticus; n = 19) being the predominant species. WGS-based phylogeny and SNP analysis (0 to 126 SNPs) revealed that isolates of these three species were highly related, indicating clonal dissemination within and between farms. MRS exhibited a multi-drug resistance pattern, with detection of resistance genes for β-lactams, tetracyclines, fusidic acid, trimethoprim, aminoglycosides, tiamulin, and macrolides.

CONCLUSIONS

Specific clonal lineages of methicillin-resistant S. saprophyticus, S. haemolyticus, and M. lentus are widespread in Algerian sheep farms. Enhancing hygiene practices on farms is recommended to prevent further dissemination of these resistant strains to animals and humans. © 2025 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.