Avian pathogenic Escherichia coli (APEC) causes extensive mortality in poultry flocks, leading to extensive economic losses. The aim of this study was to investigate the phenotypic and genotypic characteristics and antimicrobial resistance of recent APEC isolates. Of the 79 APEC isolates, the most predominant serogroup was O78 (16 isolates, 20.3%), followed by O2 (7 isolates, 8.9%) and O53 (7 isolates, 8.9%). Thirty-seven (46.8%) and six (7.6%) of the isolates belonged to phylogenetic groups D and B2, respectively, and presented as virulent extraintestinal E. coli. Among 5 analyzed virulence genes, the highest frequency was observed in hlyF (74 isolates, 93.7%), followed by iutA (72 isolates, 91.9%) gene. The distribution of the iss gene was significantly different between groups A/B1 and B2/D (P < 0.05). All group B2 isolates carried all 5 virulence genes. APEC isolates showed high resistance to ampicillin (83.5%), nalidixic acid (65.8%), tetracycline (64.6%), cephalothin (46.8%), and ciprofloxacin (46.8%). The β-lactamases-encoding genes blaTEM-1 (23 isolates, 29.1%), blaCTX-M-1 (4 isolates, 5.1%), and blaCTX-M-15 (3 isolates, 3.8%); the aminoglycoside-modifying enzyme gene aac(3)-II (4 isolates, 5.1%); and the plasmid-mediated quinolone genes qnrA (10 isolates, 12.7%) and qnrS (2 isolates, 2.5%) were identified in APEC isolates. The tetA (37 isolates, 46.8%) and sul2 (20 isolates, 25.3%) were the most prevalent among tetracycline and sulfonamide resistant isolates, respectively. This study indicates that APEC isolates harbor a variety of virulence and resistance genes; such genes are often associated with plasmids that facilitate their transmission between bacteria and should be continuously monitored to track APEC transmission in poultry farms.

Kim A, et al. J Vet Sci. 2007 Jun;8(2):155-161. http://dx.doi.org/10.4142/jvs.2007.8.2.155

Salmonellosis is one of the most prevalent foodborne illnesses. The outbreak of this disease is often associated with eggs. In this study, the preval

Ninety-nine Escherichia coli and 33 Salmonella isolates were assessed for antimicrobial susceptibility (disc diffusion test). Sulfonamide and tetracy

Genes encoding ciprofloxacin resistance in enterococci in animals may be transferred to bacteria in the animal gut and to zoonotic bacteria where they could pose a human health hazard. The objective of this study was to characterize antimicrobial resistance in high-level ciprofloxacin-resistant (HLCR) Enterococcus faecalis and Enterococcus faecium isolated from retail chicken meat. A total of 345 enterococci (335 E. faecalis and 10 E. faecium) were isolated from 200 chicken meat samples. Of these, 85 E. faecalis isolates and 1 E. faecium isolate were confirmed as HLCR enterococci. All 86 HLCR enterococci displayed gyrA-parC point mutations consisting of S83I-S80I (94.2%, 81 isolates), S83F-S80I (2.3%, 2 isolates), S83Y-S80I (2.3%, 2 isolates), and S83Y-S80F (1.2%, 1 isolate). Sixty-one (72.9%) of the 86 HLCR enterococci showed multidrug resistance to three to six classes of antimicrobial agents. Multilocus sequence typing revealed that E. faecalis had 17 different sequence types (ST) and E. faeci...

Salmonella enterica serovar Gallinarum (S. Gallinarum) is the causative agent of fowl typhoid, a severe systemic disease of chickens that results in high mortality. In this study we re-evaluated the ability of live S. Gallinarum 9R vaccine to protect from wild-type S. Gallinarum challenge. In laboratory trials, there was a significant difference between the vaccinated and unvaccinated control groups in mortality and the re-isolation rate of the challenge strain from the tissues (P<0.05). In field trials, efficacy of the 9R vaccine by one inoculation at the age of 18 weeks and two inoculations at the age of 6 weeks and 18 weeks was persistent throughout the duration of the study from 21 weeks old to 61 weeks old. The results from this study indicate that the protection against mortality and organ invasion in highly susceptible chickens exposed to virulent strains of S. Gallinarum may be severely limited by 9R vaccine.