Antimicrobial Susceptibility Pattern of and Isolates.

A combined agar and broth dilution method followed by qPCR was used to determine the antimicrobial susceptibility of feline and isolates. All isolates showed a monomodal distribution of MICs for all the antimicrobial agents tested. For , a bimodal distribution was observed for azithromycin, enrofloxacin, spectinomycin, and lincomycin. Single nucleotide polymorphisms (SNPs) were found in 50S ribosomal proteins L2 and L3 of the isolate not belonging to the WT population for azithromycin, and in 30S ribosomal proteins S1, S7, and S12 of the isolate not belonging to the WT population for spectinomycin. The antimicrobial resistance mechanism to enrofloxacin and lincomycin remains unknown (2 and 1 isolate(s), resp.). Furthermore, isolates showed higher MICs for neomycin compared to isolates which may be related to the presence of SNPs in several 30S and 50S ribosomal protein encoding genes and ribosomal RNA methyltransferase genes. This study shows that acquired resistance to azithromycin, spectinomycin, enrofloxacin, and lincomycin occasionally occurs in feline isolates. As pets may constitute a source of infection for humans, this should be kept in mind when dealing with a human patient infected with .