Background: Multidrug-resistantSalmonellastrains are frequently encountered problems worldwide with considerable increased occurrences in recent years. The aim of this study was to investigate the occurrence and frequency of antimicrobial resistance and associated resistance genes inSalmonellaisolates from broiler farms in different regions of Iran covering a time period of four years.Results: From 2007 to 2011, 36Salmonellastrains were isolated from broiler farms located in three northern provinces of Iran. The isolates were serotyped, antimicrobial susceptibility tested, and characterized for antimicrobial resistance genes associated to the phenotype. Pulsed-field gel electrophoresis (PFGE) was applied for comparison of genetic relatedness.Two serovars were detected among the isolates;Salmonella entericaserovar Infantis (75%) andS.Enteritidis (25%). Thirty-four (94%) of the isolates exhibited resistance to nalidixic acid and ciprofloxacin caused by a single mutation in the quinolone resistance-determining region (QRDR) ofgyrA. For all strains this mutation occurred in the codon of Asp⁸⁷leading to a Asp^87-Tyr, Asp^87-Gly or Asp^87-Asn substitutions. AllS.Infantis (n = 27) were resistant to tetracycline, spectinomycin, streptomycin, and sulfamethoxazole and harbored the associated resistance genes;tetA,dfrA14,aadA1, andsulI together with class 1 integrons. The isolates revealed highly similar PFGE patterns indicating clonal relatedness across different geographical locations.Conclusion: The data provided fundamental information applicable when launching future control programs for broilers in Iran with the aim to conserve the effectiveness of important antimicrobials for treatment in humans.

Attenuated derivatives (delta cya delta crp mutants) of an O2 and an O78 avian septicemic Escherichia coli strain were used to immunize broiler chickens by spray to determine the safety, immunogenicity, and efficacy of the derivatives in single- and double-dose regimens. In the safety and immunogenicity studies, groups of 10 chickens were vaccinated by spray (droplet size approximately 20 microm) with the parent E. coli, the mutant organisms, or phosphate-buffered saline (PBS) at 14 days of age and euthanatised 21 days later. There was no deaths or gross pathologic finding in any of the chickens immunized with the vaccine strains. Compared with the levels in chickens exposed to PBS, there were significantly higher levels of immunoglobulin (Ig) G antibody in serum and air sac washings and of IgA antibody in air sac washings in response to the virulent parent strains than to the vaccine strains. In efficacy studies, chickens were immunized with the O2 or the O78 vaccine strain or PBS at day 14 and with the O2 vaccine strain or PBS at days 10 and 14 and challenged with the parent strain 10 days after the last vaccination. There was no significant difference in local IgA and IgG and serum IgG responses between vaccinated and control groups. Chickens vaccinated with the O2 strain, but not the O78 strain, had significantly lower air sac lesion scores compared with those of the unvaccinated groups in both single- and double-dose regimens. We conclude that the mutant O2 strain provided moderate protection against airsacculitis.

This study determined optimal conditions for experimental reproduction of colibacillosis by aerosol administration of avian pathogenic Escherichia coli to 2-to-4-wk-old broiler chickens. The basic model for reproducing disease was intranasal administration of approximately 10(4) mean embryo infectious dose of infectious bronchitis virus (IBV) followed by aerosol administration of an 02 or an 078 strain of E. coli in a Horsfall unit (100 ml of a suspension of 10(9) colony-forming units/ml over 40 min). Scores were assigned to groups of infected chickens on the basis of deaths; frequency and severity of lesions in the air sacs, liver and heart; and recovery of the challenge E. coli 6 days post-E. coli infection. An interval of 4 days between the IBV and E. coli challenges was best whether the chickens received the IBV at 8 or 20 days of age. Typically, 50%-80% of the chickens developed airsacculitis and 0 to 29% of the chickens developed pericarditis or perihepatitis, with little or no mortality. Escherichia coli alone resulted in no deaths and 0 to 20% airsacculitis, but these percentages increased to 0 to 5% and 52%-60% when the E. coli aerosol was administered through a cone-shaped chamber. Administration of IBV alone failed to induce lesions. Recovery of the challenge E. coli from chickens did not correlate well with lesions. On the basis of these data, administration of IBV to 20-day-old chickens followed 4 days later by exposure to an avian pathogenic E. coli reproduces avian colibacillosis with the low mortality, high percentage of airsacculitis, and low percentage of septicemic lesions characteristic of the conditions seen in the natural disease.

Chlamydiosis is one of the most important infectious diseases of birds. In this study, 253 clinical samples were taken from 27 bird species belonging to seven orders. Thirty-two (12.6%) samples were positive for Chlamydia psittaci major outer membrane gene (ompA) DNA by a nested polymerase chain reaction (PCR). Twelve nested PCR-positive specimens were typed by ompA gene-based PCR-restricted fragment length polymorphism, using CTU/CTL primers and AluI restriction enzyme. Four restriction patterns were identified, including genotype A (two specimens from an African grey parrot [Psittacus erithacus] and a lorikeet [Trichoglossus haematodus]), genotype B (two specimens from a rock dove [Columbia livia] and a canary [Serinus canaria]), a third new restriction pattern (six specimens from African grey parrots), and a fourth new restriction pattern (two specimens from a ring-necked parakeet [Psittacula krameri] and an Alexandrine parakeet [Psittacula eupatria]). The third and the fourth restriction patterns are suggested to be provisional genotypes I and J, respectively. Partial sequencing of the ompA gene of seven specimens completely correlated with the results of PCR-restricted fragment length polymorphism and confirmed the presence of genotypes A and B and the two new provisional genotypes I and J. The two new genotypes have the closest identity with C. psittaci genotype F and Chlamydia abortus, respectively. From an evolutionary perspective, both new genotypes, particularly genotype J, are intermediate between the two species, C. psittaci and C. abortus.

Background and Objectives: Escherichia coli and some Salmonella serovars cause various disease manifestations in poultry leading to significant economic losses. The widespread and imprudent use of antibacterial agents in poultry flocks have increased resistant to many antibacterial agents which has become a major public health concern. Some medicinal plants may be alternative to antibacterial agents. The purpose of this study was to investigate the antibacterial and anti-biofilm activity of summer savory essential oil against E. coli and Salmonella isolated from poultry. Materials and Methods: The essential oil was extracted using a Clevenger apparatus and subsequently its compounds were determined using GC-MS. Antibacterial properties of essential oil were determined by disc diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). To evaluate the anti-biofilm properties the Microtiter plate test was used. Herbal essential oil was extracted and its compounds were identified correctly. Results: The major components of Satureja hortensis essential oil were thymol (41.28%), γ-terpinene (37.63%), p-cymene (12.2%) and α-terpinene (3.52%). The inhibition zone diameter in the disc diffusion test for E. coli and Salmonella were 32 ± 3 and 38 ± 4 mm, respectively, which was confirmed by MIC and MBC values. Regarding anti-biofilm activity, the MIC/2 concentration of S. hortensis significantly inhibited biofilm formation of E. coli. However, inhibition of biofilm formation of Salmonella was shown at concentration of MIC/2 and MIC/4. Conclusion: Based on our results, S. hortensis essential oil showed the growth inhibition and bactericidal activity against E. coli and Salmonella. Moreover, this study demonstrated anti-biofilm activity of S. hortensis essential against both tested bacteria.

Prevalence of netB Gene among Clostridium perfringens Isolates Obtained from Healthy and Diseased Chickens