Background: Antibiotics have long been the first line of defense to prevent Escherichia coli infections, but they have lost their potency since bacteria have grown increasingly resistant to treatment. The present research aimed to study the drug resistance and the prevalence of tetracycline resistance genes in E. coli isolated from broilers with colibacillosis. Results: The results showed that the most prevalent type of drug resistance was to tetracycline at 95.0%, and the least was to gentamicin at 21.7%. The prevalences of antimicrobial resistance among the tested antibiotics were significantly different (p < 0.001). A statistically significant difference was observed between the prevalence of the tet genes (p < 0.001). The tetD positive isolates and antibiotic sensitivity to tetracycline showed statistical significant differences (p = 0.017). Conclusions: Considering the results, tetA is the most common tetracycline resistance gene, and the presence of tetD and antibiotic sensitivity to tetracycline had a significant relationship in E. coli isolated from colibacillosis infections.

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Infectious bronchitis (IB) is a highly contagious disease of the respiratory and urogenital tract of chickens, caused by infectious bronchitis virus (IBV), a member of the family Coronaviridae. The disease is common throughout the world where chickens are produced commercially. PCR on reverse transcribed RNA is a potent technique for the detection of IBV. In comparison with classical detection methods, PCR-based techniques are both sensitive and fast. Dozens of serotypes and genotypes of IBV have been detected, and many more will surely be reported in future. This research was conducted to identify the infectious bronchitis virus with group specific primers of avian Coronaviruses in Zabol, southeast of Iran. Tracheal swabs were collected from eleven commercial broiler flocks and these swabs were used for RNA extraction. General primers included XCE2+ and XCE2- that amplify all IBV serotypes were used. Primers MCE1+, BCE1+ and DCE1+ was used to amplifying the specific nucleotide sequence of Massachusetts, 4/91 and D274 serotypes, respectively. The results of this study showed that 36.36% of the sampled flocks were positive to IBV by RT-PCR. Moreover, the Massachusetts was the identified serotype of infectious bronchitis virus. The results provide the first molecular evidence for the presence of infectious bronchitis virus and Massachusetts serotype in Zabol.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-36) contains supplementary material, which is available to authorized users.

Colibacillosis refers to any localized or systemic infection caused entirely or partly by avian pathogenic Escherichia coli (APEC). Colibacillosis in mammals is most often a primary enteric or urinary tract disease, whereas colibacillosis in poultry is typically a localized or systemic disease occurring secondarily when host defenses have been impaired or overwhelmed by virulent E. coli strains. The purpose of this study was to investigate the antimicrobial drug resistance pattern of Escherichia coli isolated from broiler chickens farms with colibacillosis infection. Dead birds from commercial broiler chicken farms showing signs of colibacillosis were necropsied and swab samples were collected from internal organs and blood aseptically for the isolation of Escherichia coli. Pure colonies of the bacteria were isolated on solid media and the isolates were identified as E. coli based on morphological and biochemical characteristics. For determination of susceptibility to antibacterial agents, the disc diffusion method on Muller-Hinton agar was used. The following antimicrobial agents were tested: gentamycin, oxytetracyline, colistin, ciprofloxacin, doxycycline, nalidixic acid, co-trimoxazole (trimethoprim-sulfamethoxazole), norefloxacin, lincospectin and cefuroxime. The drug resistance patterns of the organisms were determined as a percentage and reported at three levels: susceptible, intermediate and resistant. All the isolates of Escherichia coli showed resistance to several antibiotics and a pattern of multiple drug resistance was observed. The highest rate of resistance was observed against nalidixic acid (100%) and the least rate of resistance was observed against gentamycin (17%). According to the results of this research care must be taken to avoid secondary infection (colibacillosis) in chicken farms and also avoid in careless antimicrobial consumption in food animals including chickens.

External parasites or ectoparasites, are arthropods that live on or in the skin or feathers, using the host as both shelter and food source. Ectoparasites can have significant impacts on animal health and productivity. The aim of this research was to estimate the prevalence and ectoparasites diversity in pigeons of Zabol, southeast of Iran. A total of 264 pigeons were selected randomly (175 males and 89 females) to evaluate the presence of different ectoparasites. Ectoparasites were collected from different parts of the body and from walls and seams of cubbyholes, using hand lens, forceps, and flashlights to increasing the see sight. The samples were preserved in 70 % alcohol and cleared in lactophenol. The overall prevalence of external parasites in pigeon was 78.40 % [female (33.3 %) and male (66.7 %)]. There was no significant difference of infestation of ectoparasites between male and female (P [ 0.05). Prevalence was higher in adult pigeons (84.11 %) than pipers (54.0 %). Two species of ectoparasites were identified: Argas reflexus and Columbicola columbae.

The skin is the largest organ of the body and is composed of epidermis (the outermost layer of cells consisting mainly of keratinized, stratified, squamous epithelium) and dermis (a layer of connective tissue composed of cells and fibrils such as collagen bundles). The aim of this study was to assess the effect of excess methionine on the histomorphology and histomorphometry of collagen bundles in these layers. Eighty, 9-10-week old, male rats were randomly allocated into eight equal groups. Each group received one of the following treatments: L-methionine (50, 100 or 200 mg/kg B.W.), vitamin C (50 mg/kg B.W), combination of L-methionine (all 3 concentrations) and vitamin C (Met + Vit C), or normal saline as control (CT) for 20 consecutive days. After terminating the animals on day 21, skin samples were taken, and the epidermis, papillary, and reticular layers were evaluated histologically. The data obtained revealed that methionine does not increase collagen bundle thickness unless combined with vitamin C. We suggest that lack of crosslinking occurs when using methionine alone. The greatest increase in both epidermis and dermis occurred in the Met 100 + Vit C group. There was no significant difference between Vit C and control groups. Histopathology did not show any congestion or inflammatory cell infiltration in any treatment groups compared to the controls.

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