BACKGROUND: AmpC and ESBLs as mediated-plasmid extended spectrum β-lactabases are the main factors of resistance to extended-spectrum cephalosporins in enterobacteriacea especially E. coli and will follow treatment failure, high costs of treatment in human and economic losses in the poultry industry. OBJECTIVES: The purpose of this study was to screen and study the faecal E. coli isolates producing extended spectrum β-lactamases (ESBLs) and AmpC enzymes and related workers. METHODS: A total of 500 cloacal swab samples from broiler chickens and 25 rectal swab samples from workers were collected from five poultry houses around Tehran. All samples were seeded on MacConkey agar and identification of E. coli isolates were performed via biochemical tests. Antibiotic susceptibility was determined against 12 antibiotics using the disk diffusion method as recommended by the clinical and laboratory standard institute (CLSI2012). Ceftazidim / ceftazidim-clavolanic acid and cefoxitin / cefoxitin-EDTA disks were used for the detection of ESBL and AmpC phenotypes, respectively. phonetic analysis of the drug resistances was performed via SPSS software and Chi-square test. ESBL- producing E. coli screened by PCR for the presence of genes encoding beta-lactamases of TEM, CTX-M and SHV.       RESULTS: A total 467 E. coli isolates were isolated from 88.9% of the samples as 92% and 72.7% of isolates presenting MDR phenotype among chickens and workers respectively. ESBL phenotype detected in 5.5% (26) of poultry isolates while, none of the workers isolates have this phenotype. Six isolates carried both of TEM and CTX-M whereas, five and one isolates were detected only for TEM and CTX-M, respectively. Eighty-eight and nine-tenths percent of ESBL E. coli displayed AmpC phenotype. CONCLUSIONS: Since cephalosporins are not used in broilers in Iran, isolation of faecal E. coli isolates producing extended spectrum β-lactamases in broilerchickens can indicate transfer of the resistance genes via plasmids and other mobile genetic elements among Enterobacteriaceae.

Escherichia (E.) coli is commensal bacteria found in the intestine; however, some pathogenic strains cause diseases in animals and humans. Although E. coli does not typically produce hydrogen sulfide (H2S), H2S-producing strains of E. coli have been identified worldwide. The relationship between virulence and H2S production has not yet been determined. Therefore, characteristics of H2S-producing isolates obtained from swine feces were evaluated including antibiotic resistance patterns, virulence gene expression, and genetic relatedness. Rates of antibiotic resistance of the H2Sproducing E. coli varied according to antibiotic. Only the EAST1 gene was detected as a virulence gene in five H2S-producing E. coli strains. Genes conferring H2S production were not transmissible although the sseA gene encoding 3-mercaptopyruvate sulfurtransferase was detected in all H2S-producing E. coli strains. Sequences of the sseA gene motif CGSVTA around Cys238 were also identical in all H2S- producing E. coli strains. Diverse genetic relatedness among the isolates was observed by pulsed-field gel electrophoresis analysis. These results suggested that H2S-producing E. coli strains were not derived from a specific clone and H2S production in E. coli is not associated with virulence genes.

The aim of this study was to evaluate the antimicrobial activity and determine the minimum bactericidal concentration (MBC) of the essential oils derived from Origanum vulgare (oregano), Melaleuca alternifolia (tea tree), Cinnamomum cassia (cassia), and Thymus vulgaris (white thyme) against Salmonella Typhimurium, Salmonella Enteritidis, Escherichia coli, Staphylococcus aureus and Enterococcus faecalis. The study also investigated the ability of these different bacterial strains to develop adaptation after repetitive exposure to sub-lethal concentrations of these essential oils. The MBC of the essential oils studied was determined by disc diffusion and broth dilution methods. All essential oils showed antimicrobial effect against all bacterial strains. In general, the development of adaptation varied according to the bacterial strain and the essential oil (tea tree > white thyme > oregano). Therefore, it is important to use essential oils at efficient bactericidal doses in animal feed, food, and sanitizers, since bacteria can rapidly develop adaptation when exposed to sub-lethal concentrations of these oils.

In this study, the immune responses to and protective efficacy of a live attenuated Salmonella-delivered vaccine candidate secreting the papA, papG, iutA, and clpG antigens of Escherichia coli were evaluated against infection with avian pathogenic E. coli (APEC) in layer chickens. Primary vaccination was done at age 7 d and booster vaccination at age 5 wk. The levels of intestinal secretory immunoglobulin A specific to the 4 antigens were significantly higher in the vaccinated group than in the control group. A potent lymphocyte-proliferation response and increased levels of interferon-γ, interleukin-2, and interleukin-6 in the plasma and in culture supernatants of antigen-stimulated lymphocytes from the vaccinated group suggested significant induction of the cell-mediated immune response in this group compared with the control group. Upon challenge with a virulent APEC strain at 8 wk of age, the vaccinated group had no deaths, whereas the control group had a 15% mortality rate. In addition, the morbidity rate was significantly higher in the control group (55%) than in the vaccinated group (15%). Thus, giving primary and booster vaccination with the Salmonella-delivered APEC vaccine candidate significantly elevated both mucosal and cellular immune responses, which protected the chickens against colibacillosis.

This study compared a new live attenuated Salmonella Enteritidis vaccine candidate secreting Escherichia coli heat-labile enterotoxin B subunit (SE-LTB) with a commercial Salmonella Enteritidis (SE) vaccine for efficacy of protection against SE infection in laying hens. Chickens were divided into 3 groups of 20 each. Group A chickens were inoculated orally with phosphate-buffered saline and served as controls, group B chickens were inoculated orally with the vaccine candidate, and group C chickens were inoculated intramuscularly with a commercial vaccine, the primary inoculation in groups B and C being at 10 wk of age and the booster at 16 wk. Groups B and C showed significantly higher titers of plasma immunoglobulin G, intestinal secretory immunoglobulin A, and egg yolk immunoglobulin Y antibodies compared with the control group, and both vaccinated groups showed a significantly elevated cellular immune response. After virulent challenge, group B had significantly lower production of thin-shelled and/or malformed eggs and a significantly lower rate of SE contamination of eggs compared with the control group. Furthermore, the challenge strain was detected significantly less in all of the examined organs of group B compared with the control group. Group C had lower gross lesion scores only in the spleen and had lower bacterial counts only in the spleen, ceca, and ovary. These findings indicate that vaccination with the SE-LTB vaccine candidate can efficiently reduce internal egg and internal organ contamination by Salmonella and has advantages over the commercial vaccine.

Oregano (Origanum vulgare) is an aromatic herb belonging to the Lamiaceae family. This study evaluated the therapeutic effect of oregano essential oil (OEO) on clinical bovine mastitis caused by Staphylococcus (S.) aureus and / or Escherichia (E.) coli. Thirty - two quarters from 18 lactating cows with subclinical mastitis were selected from a dairy farm and were divided into 4 groups (8 quarters / group): negative control (CON), positive control (GEN) and two OEO-treated groups (OEO-1 and OEO-2). Each group was intramammarily treated with saline, 10 g/tube of gentamicin ointment, and single and double doses of 0.9 mL OEO ointment twice a day for three days, respectively. After the treatments, physical udder conditions were greatly improved in GEN and OEO groups. In CON group, somatic cell counts (SCCs), number of white blood cells (WBC) and bacteria were increased. However, in OEO groups, SCCs and number of WBC were significantly decreased and S. aureus and E. coli were not detected in milk as compared with those before the treatments as well as GEN group. These results suggest that OEO may be a useful alternative to antibiotics for the control of subclinical bovine mastitis caused by S. aureus and/or E. coli.

OBJECTIVE To determine pet-related management factors associated with the carriage of antimicrobial-resistant Salmonella spp and Escherichia coli in a population of pet dogs. SAMPLE 138 dogs from 84 households in Ontario, Canada. PROCEDURES From October 2005 through May 2006, dogs and households in Ontario, Canada, were recruited to participate in a cross-sectional study. Fecal samples were submitted for culture of Salmonella spp and E coli, which provided 515 bacterial isolates for antimicrobial susceptibility testing. Multilevel logistic regression models with random effects for household and dog were created to identify pet-related management factors associated with antimicrobial resistance. RESULTS Bacterial species, feeding a homemade diet or adding homemade food to the diet, feeding a raw diet or adding anything raw to the diet, feeding a homemade raw food diet, and feeding raw chicken in the past week were significant risk factors for antimicrobial resistance in this population of dogs. CONCLUSIONS AND CLINICAL RELEVANCE In this study, several potentially important pet-related risk factors for the carriage of antimicrobial-resistant Salmonella spp and E coli in pet dogs were identified. Further evaluation of risk factors for antimicrobial resistance in dogs may lead to development of evidence-based guidelines for safe and responsible dog ownership and management to protect the public, especially pet owners who are immunocompromised.

The aim of this study was to investigate the bacteria found in different parts of the genital system in cows and the susceptibility to different types of antibiotics. The genital systems of sixteen cows were collected from Al-Hilla, Iraq slaughterhouse. Isolation and identification of bacteria were made for each part of the genital system and antibiotic susceptibility tests was conducted to the isolated bacteria. The results of this study indicated that there were several types of bacteria present in the genital systems of cows. Different species of bacteria were isolated from the samples including, Escherichia coli (28.97)%, Klebsiella spp. (16.82)%, Salmonella spp. (14.95)%, Proteus spp. (13.08)%, Staphylococcus aureus (11.21)%, Staphylococcus epidermidis (8.41)% and Streptococcus spp. (6.54)%. In vitro susceptibility towards different types of antibiotic indicated high susceptibility of Escherichia coli to antibiotic group impenem and ciprofloxacin, while Klebsiella spp. was found to be most susceptible to ciprofloxacin and amikacin. Both Escherichia coli and Klebsiella spp. showed resistance to piperacillin and tetracycline. It was concluded that Escherichia coli was the most predominant bacteria in genital system of cows and were most susceptible to antibiotic impenem and ciprofloxacin.