The Public Health Burden of Virulent Extended-Spectrum β-Lactamase-Producing Strains Isolated from Diseased Horses.

has been associated with both nosocomial and community-acquired infections with mounting public health concern throughout the world. The purpose of this study was to investigate the burden of virulent extended-spectrum β-lactamase (ESBL)-producing among diarrheic horses or those with respiratory illness to underscore the public health implication of such strains. Rectal and nasal swabs were gathered from 100 diseased horses (50 diarrheic and 50 with respiratory illness). The collected swabs were processed for isolation of ESBL-producing using a selective medium followed by phenotypic and molecular identification of the isolates. All ESBL-producing strains were investigated for six virulence genes (type 3 fimbrial adhesin [D], enterobactin [B], regulator of mucoid phenotype A [A], ferric iron uptake [], mucoviscosity-associated gene A [A], and type 2 capsular polysaccharide []). Of the 100 examined animals, ESBL-producing was recovered from 13 (13%), with isolation rates in horses suffering from diarrhea and respiratory illness being 20% and 6%, respectively. Among the obtained isolates, TEM and SHV were found in all strains (100%) followed by CTX-M in 92.3%, while none of the isolates had OXA. In addition, 13 ESBL-producing strains exhibited a multidrug resistance (MDR) pattern. Regarding the occurrence of virulence genes among the isolates, D (100%) and B (100%) were the most predominant virulence genes followed by A (76.9%) and (46.2%). On the contrary, A and were negative in all ESBL-producing strains. Furthermore, this work provides four D partial sequences that displayed high genetic relatedness with those obtained from human to clarify the public health burden of such isolates. The occurrence of virulent ESBL-producing among diseased horses highlights the potential role of this animal in the epidemiology of such virulent and antimicrobial-resistant strains, which may have great public health threat.