نشریه میکروبیولوژی دامپزشکی
سال شانزدهم شماره 2 (پیاپی 41، پاییز و زمستان 1399)

Clostridium novyi type B is the causative agent of liver infectious diseases. Bacterial spores enter the body along with food and through the lymph system get into the liver. Due to the hypoxic condition of the liver, bacteria converts to the vegetative form and replicates and produces a large amount of toxin, which ultimately leads to death. Therefore, the detection of toxin and bacterial isolation from animal gastrointestinal contents especially the liver are used to diagnose of disease. In order to control the disease, the frequency of Clostridium novyi isolates from infected animals in Alborz province is essential to be known. The aim of this study was to determine the prevalence of Clostridium novyi in slaughterhouses in Alborz province. In this study, 386 liver samples were collected from the slaughterhouses, then the bacteriological (culture in selective horse blood medium and specific liquid medium, motility test and gram staining) and biochemical tests (fermentation of sugars, lecithinase, lipase, gelatinase, Indol, milk digestion and catalase) were done, and the samples were finally confirmed using PCR. For this purpose, the primers were designed using alpha toxin DNA sequence. Results showed that the infection rate in the slaughterhouses was 37 (9.5%) in which 33 cases (89.18%) had concurrent contamination with Clostridium novyi and only 4 cases without Fasciola infection were detected. Due to the highly economic losses, vaccination is very urgent

Polymeric substances, such as poly lactic acid are used for covering food stuffs. Zataria multiflora Boiss essential oil (ZMBEO) has antioxidant and antibacterial properties that can be used for preparation of films. The present study was conducted for first time to evaluate the effect of poly lactic acid films containing ZMBEO on some microbial and chemical properties of broiler chicks meat. Poly lactic acid films were contining 0.00, 0.20, 0.40, 0.60, 0.80 and 1.00% of the ZMBEO and placed on broiler chicks meat for 12 days. Microbial tests, antioxidant properties, pH, total volatile nitrogen and sensory scores were assessed in days 0 (12 h after packaging), 3, 6, 9 and 12 after packaging. The results showed that poly lactic acid films contining 1.00% of the ZMBEO showed better antibacterial, antioxidant and senosry properties (p<0.05)and lower pH, and total volatile nitrogen compared to other groups, especially control group (p<0.05). The results show that poly lactic acid films contining ZMBEO in higher levels showed antibacterial and antioxidant properties that are attributed to active compounds of the ZMBEO and the prepared films help to maintain it. Using poly lactic acid films contining ZMBEO is suggested for packaging of feedstuffs.

The present study investigated the effect of different levels of diatoms on the in vitro fermentation parameters, dry matter and organic matter digestibility of contaminated diet with aflatoxin B1. This experiment was conducted in a completely randomized design with 5 treatments and 4 replicate per treatment. The treatments were: 1.Control, 2.Control with methanol 3. Contaminated diet with methanol solution containing aflatoxin B1 at 800 ng/ml, 4, 5 and 6. Contaminated diet treated with diatoms at 7, 75 and 150 mg/200mg, respectively. Glass bottles with a volume of 100 ml was used in a constant culture to measure gas production and digestibility. All bottles were purged with anaerobic CO2, sealed with rubber stoppers and incubated in a water bath for 96 h at 39 °C. Culture parameters were measured at different time of incubation. The results showed that the lowest organic and dry matter digestibility value and highest ammonia concentration were related to treatment containing aflatoxin B1 (p<0.05). Aflatoxin caused reduction of gas production parameters, metabolisable energy and VFA compared to control groups. Addition of diatoms at medium and low level (7 and 75 mg/200mg) improved digestibility of dry matter and organic matter compared to aflatoxin group (p<0.05). Cultures containing low level of diatoms also was improved partitioning factor, microbial mass production and efficiency of microbial mass (p <0.05). In conclusion diatoms as feed additive showed promising potential in vitro to improve detrimental effect of aflatoxin on rumen function, therefore more research is guaranteed to investigate their mode of action in the ruminal microbial ecosystem.

Fungal toxins are responsible for many human and animal diseases and epidemics. This study was performed to identify and investigate the toxicogenic isolates of Aspergillus species in 30 poultry farms in Khorramabad. The 180 samples of poultry diets were collected and transferred to the laboratory. The samples were isolated and purified using different culture media such as Potato Dextrose Agar (PDA) and Yeast Extract Agar (YEA). Then the isolates were identified using valid mycological keys and articles. The toxinogenesis of this fungus was investigated using coconut agar medium, thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) on corn and peanut media. The results showed that 38 isolates were identified in the poultry diet. The corn with 20 isolates (66.6%) and finisher with three isolates (10%) had the highest and lowest frequencies, respectively. Also, by using coconut agar and TLC toxinogenesis, some of the isolates of this fungus have been proved and in HPLC experiments it was determined that this fungus has the ability to produce all four types of aflatoxins B1, B2, G1 and G2. So due to the presence of different toxinogenic isolates of this fungus on the diet and their pathogenicity, compliance with international standards of maintenance diets is recommended.

Newcastle disease virus has been investigated in several studies as an oncolytic virus to treat human tumors. However, precise mechanism of tumor cell killing by this virus is unknown. The aim of this study was isolation of Newcastle disease virus from industrial poultry and examination of its ability to induce expression of the extrinsic and the intrinsic pathways of apoptosis-related genes in human breast carcinoma cells. Newcastle disease virus was isolated from industrial poultry by culture in embryonated chicken eggs and then identified by haemagglutination test and RT-PCR technique. MCF-7 breast carcinoma cells were infected with the isolated virus in vitro. After RNA extraction and cDNA synthesis, gene expression levels of BAX, BAK, caspases-3, -8, and -9 were assessed in the virus-infected tumor cells using real-time RT-PCR technique. PCR data analysis showed that gene expression levels of BAX and caspase-9 were significantly higher in virus-infected tumor cells than that in control tumor cells. Gene expression levels of BAK and caspases-3 and -8 were not significantly altered in virus-infected tumor cells in comparison with control tumor cells. These results suggest that Newcastle disease virus isolated from industrial poultry can trigger the intrinsic pathway of apoptosis in MCF-7 tumor cells.

Helicobacter pullorum is a gram-negative and zoonotic pathogen which can cause gastroenteritis in human and poultry. The purposes of this study were to evaluate the prevalence of H. pullorum in chicken liver samples using culture methods and polymerase chain reaction (PCR) as well as to assess the antibiotic resistance of the isolates using the disk diffusion method in various regions of Semnan. A total of 50 packed liver samples were collected from various regions of Semnan city. By use of culture method and biochemical tests, 17 samples (34%) were found to be positive for H. pullorum. By use of PCR test which was performed in parallel with culture method and biochemical tests, 11 (22%) samples were confirmed H. pullorum. With regard to the results of antibiogram test, all of the samples were resistant to ciprofloxacin and gentamicin, and the lowest resistance rate was observed against ampicillin, colistin and erythromycin with 14%. This study is the first report on prevalence and antibiotic resistance of H. pullorum in chicken liver samples in Semnan and more studies are needed in this regard. Furthermore, due to low sensitivity of biochemical tests in recognition of H. pullorum, the present study suggests that the PCR test, as a sensitive and reliable method, can be used to detect H.pullorum from chicken liver samples.

The aim of this study is determination the prevalence and geographical distribution of viral haemorrhagic septicemia (VHS) and infectious hematopoietic necrosis (IHN) in rainbow trout (Oncorhynchus mykiss) by national annual surveillance program. In this study, data was conducted in two phases of winter and spring, sampling was carried out from all centers of breeding, hatching and rearing of trout in Iran. The data were entered into Excel software and analyzed by SPSS software. The results showed that the prevalence of VHS in the autumn and winter of 2017 and 2018 was 96% in Khorasan Razavi (4.54%), Kohgiluyeh and Boyer Ahmad provinces (3.5%) and Chaharmahal Bakhtiari (2.04%). In the spring of 2018, the prevalence of VHS were about 16.66 % in the Ardebil , 15.38% in the Zanjan and 2.56% in the Mazandaran . In the whole country the prevalence of disease in the autumn and winter of 2017 and 2018 was 0.86% and in the the spring of 2018 was 97.1%. About IHN , the prevalence of disease in the autumn and winter of 2017 and 2018 was 96% in the centers of reproduction and hatching in the provinces of Chaharmahal Bakhtiari (4.081%) and Mazandaran (2.56%). Also, the prevalence of IHN in the the spring of 2018 were about (7. 4%) in the Qazvin and (2.56%) in the Mazandaran . In the whole country the prevalence of disease in the autumn and winter of 2017 and 2018, was 0.86% and in the the spring of 2018, was 0.95%. Considering the prevalence of diseases and the economic importance of these diseases, it is important to consider the methods of prevention and promotion of the biological safety conditions of the centers in order to provide healthy fish for the reduction of damage.

Escherichia coli O157:H7 is one of the potential causes of foodborne diseases. The role of cattle meat is known as the source of Escherichia coli strains O157:H7. The present study was performed to evaluate the prevalence and antibiotic resistance of Escherichia coli O157:H7 strains isolated from hamburger samples collected from Mazandaran province. Two-hundred samples of hamburgers were randomly collected from the shopping centers of Mazandaran province. Confirmation of Escherichia coli O157:H7 isolates grown in microbial culture medium was performed using biochemical tests and PCR reaction. The pattern of antibiotic resistance of the isolates was evaluated using the antibiotic disk diffusion method. According to the results, 19 out of 200 samples (9.50%) of hamburger collected from Mazandaran province were contaminated with Escherichia coli O157:H7. Escherichia coli O157:H7 strains had the highest resistance to tetracycline (100%), ampicillin (100%), gentamicin (89.47%), sulfamethoxazole (73.68%) and ciprofloxacin (73.68%) antibiotics. The lowest resistance was obtained against chloramphenicol (15.78%) and cefotaxime (42.10%) antibiotics. Hamburger was considered as a source of transmission of antibiotic- resistant Escherichia coli O157:H7 strains.

In this article in order to determine the sonographic indexes in bovine clinical mastitis, 30 involved cows with a watery discharge or some flocks in milk, pain, swelling and redness in the udder, and high temperature were selected. Streak canal diameter of the teats, udder cistern epithelium and alveolar parenshyma of milk glands on top of the udder were examined with a 7 MHZ SONO probe in involved quarter as a test, and in the contralateral and normal quarter as a control case. Milk samples obtained from involved quarters for following microbiological evaluations. Finally, the findings with non-normal distributions were compared between control and test groups with the Mann-Withny and Wilcocson-Rank, and data with normal distribution were compared with the Student T test. The diameter of streak canal was (0.82±0.67, (MED=0.8); (0.99±0.13, (MED=. 97) cm, P<0.05), the diameter of udder cistern epithelium was (0.68±0.17, (MED=0.65); (0.68±0.18, (MED=. 65) cm, P>0.05), the diameter of milk gland alveolar parenchyma on top of the udder was (0.98±0.31, (MED=0.9); (0.88±0.3, (MED=. 8) cm, P>0.05) in normal and involved quarters, respectively. Staphylococcus aureus (n= 12), Streptococcus uberis (n=2) and Corinebacterium bovis (n=2) were isolated from the mastitis involved quarters, but their distributions were not statistically different among the various degrees of mastitis. It was concluded that only the diameter of the streak canal increased in mastitis cases. There was no correlation between the kind of isolated bacteria and the site of inflammation in the mastitis cases.

Olive is an evergreen tree with antibacterial properties and showed beneficial effects on the microbial flora of the digestive tract. Also, oregano plant with antioxidant properties can improve the feed conversion ratio. This experiment was conducted to investigate the effects of olive leaf and oregano powder on performance, blood parameters and ileal bacteria population of broiler chickens. A total number of 400 male and female Cobb 500 broiler chicks in a completely randomized design with 5 treatments, 4 replicates and 20 chicks per each were used. Birds were kept under same condition during the first week of rearing period. From 8 days of age until the end of rearing period, each of experimental groups was fed with one of the following diets: 1- basal diet without additive (control) 2- diet containing 50 g/ton erythromycin 3- diet containing 0. 5% olive leaf 4- diet containing 0. 5% oregano 5- diet containing 0. 5% mixture of olive leaf and oregano. The management conditions of all groups were the same throughout the breeding period. At the end of the experiment (42 days), two chicks of each replicates were selected and slaughtered. Statistical evaluation was performed using SAS program. The results indicated that although supplementation with olive leaf, mixture of olive leaf and oregano as well as antibiotic significantly improved feed conversion ratio during 8-21 days of age compared to control group, but performance parameters (feed intake, body weight gain and feed conversion ratio) of broilers during 8 to 42 days of age were significantly not influenced by experimental treatments. The highest and the lowest levels of blood HDL were observed in olive leaf and mixture of olive leaf and oregano and oregano groups, respectively (p<0. 05). All additives significantly increased ileum lactobacillus and decreased E. coli count compared to the control group (p<0. 05). In conclusion, the results showed that dietary addition of oregano and olive leaf can beneficially influence some blood parameters and also ileal bacteria of broilers.

Vibrio cholerae is one of the most studied bacterial toxins in the AB5 family and is widely used as a potent mucosal adjuvant because of its ability to enhance the immune response to the antigen injected with it. This toxin consists of two subunits, a pentameric subunit called subunit B, and a subunit A. This toxin enters the target cell by binding to the GM1 ganglionic receptor . In this study Vibrio cholerae were cultured in 100 ml of AKI and Craig's medium in two groups. One group was then incubated at 37 ° C and the other group was incubated at 30 ° C for 72 h. All media were sampled on a regular basis from the beginning of the incubation period to evaluate the toxin production. Finally, the amount of toxin production was evaluated by ELISA GM1 test. The results showed that the bacteria in both culture medium were capable of producing relatively high levels of toxin. The highest toxin production was observed in Craig's medium at 30 ° C after 50 h. The results of ELISA GM1 test showed that the bacterium had the highest production in Craig's medium after 50 hours at 30 ° C, while the highest toxin production in AKI medium after 24 hours at 37° C.

Foot and mouth disease virus is found in the Picornaviridae family and a genus of aphthovirus, which causes highly contagious disease among cattle.Prevention of FMD has always been a major challenge in dairy herds.Therefore, vaccination has been a first step in preventive measures of the disease.Sixty heifers (30 BLV-infected and 30 BLV-free) that were negative for BVDV were considered for this project.In both groups, 5 ml of FMD vaccine was injected twice.10 ml Blood samples were taken at 0, 7, 14 and 21 days after the first vaccination and 10, 7, 14 and 21 days after the second vaccination.The serum neutralization test (SNT) was used to determine the presence of antibody against FMD virus. In both groups, vaccination induced increase of antibody against vaccinal virus and there was no statistically difference between two groups.