نشریه تازه ها در میکروب شناسی دامپزشکی
سال پنجم شماره 1 (بهار و تابستان 1401)

Staphylococcus aureus is one of the most important agents causing mastitis in dairy cattle. The emergence of methicillin resistance in S. aureus is a concern in veterinary medicine and public health. Due to the identification of new types of genes encoding methicillin resistance in recent years, the aim of this study was to investigate the presence of methicillin resistant (MRSA) and types of mec gene for the first time in the northeast of Iran. In the present study, the identity of 54 staphylococcus aureus isolates causing bovine subclinical mastitis were investigated using biochemical and molecular tests. Among them, the species-specific nuc gene was detected in 44 strains. Then, resistance of isolates to penicillin, cefoxitin, enrofloxacin, tylosin and trimethoprim-sulfamethoxazole were determined using the disk diffusion method. Finally, the molecular investigations for detection of the mecA, mecC, mecB genes were conducted. According to the results, the highest resistance were related to penicillin (54%) and trimethoprim-sulfamethoxazole (23%), and the lowest resistance was related to taylosin (7%). The mecA gene was observed in only one isolate (2.3%), while the isolate was not identified as MRSA in phenotypic test. The results of the present study show that the incidence of methicillin resistance in bovine mastitis strains of the area is not high. This study also showed that less known types of mec genes were not common in this region. However, further studies must be perform in this regard.

Mycoplasma haemofelis is the cause of infectious anemia among cats. Due to the asymptomatic nature of hemobartonella in the initial stage, the present study aimed to evaluate the incidence of hemobartonellosis and its related factors in domestic cats in Ahvaz, Iran. This cross-sectional study was performed to investigate the development of hemobartonella in 120 domestic cats referred to veterinary centers in Ahvaz city within 2021-2022. Factors, such as age, gender, race, castration, domesticity, and reasons for referring to the veterinary centers, as well as laboratory data of cats infected with hemobartonella infection, were compared with those of non-infected cats. The prevalence of hemobartonellosis in domestic cats in Ahvaz city was estimated at 13.3% (16 cases). The mean age of cats with hemobartonellosis was higher than those without hemobartonellosis (Z=-2.75, P=0.006). Lethargy and anorexia were the predominant reasons of referred to the veterinary centers among hemobartonellosis-infected cats (43.8%), followed by fever and neurological disorders (25%). No significant difference was found in terms of white blood cells (Z=-0.98, P=0.32), mean cell volume (Z=-1.17, P=0.24), mean corpuscular hemoglobin concentration (Z=-0.34, P=0.73), and mean corpuscular hemoglobin (Z=-2.17, P=0.29). However, the levels of red cell distribution width (Z=-2.21, P=0.02) and red blood cell (Z=-4.57, P<0.005) were lower in cats infected with hemobartonellosis than in healthy cats. According to the results of the present study, the incidence rate of hemobartonellosis was 13.3% among domestic cats in Ahvaz city. Age was found the most important factor in the development of hemobartonellosis in domestic cats. Therefore, it is recommended to perform periodic monitoring of red blood cell counts through regular blood tests in older cats.

Peste des petits ruminants (PPR) is one of the most important infectious diseases of livestock. This disease is endemic in Iran. The aim of this study was to use GIS to help control PPR over an eight-year period in Kermanshah province. Reports of PPR disease in Kermanshah province were collected over a period of 2011-2019. Using ArcGIS 10.6 software, the provincial segments were identified. The total number of livestock   infected, mortality and high risk centers were added to the descriptive table and It was connected to the province map using the Geographical Coordinate System. .Data analysis was performed based on the difference between disease incidence points, incidence rates and areas of Kermanshah province using SSPS 18 software and Fisher chi-square test.: There was a significant difference in disease incidence in different parts of the province (P <0.05). In conflict and infection centers, the highest and lowest statistics were related to the western region with 39.4%, the central region with35.9% and the eastern region with 24.6%, respectively. The highest and lowest casualties with 465 and 6 cases were related to 2012 and 2017. Due to the endemic nature of the disease in Iran, the results of this study in helping veterinary health policy makers in adopting control methods and better understanding of the epidemiology of the disease. Therefore, it is necessary to pay attention to the complete and comprehensive registration of the epidemiological codes of the GIS system and pay more attention to the monitoring system.

Avian influenza virus (AIV) subtype H9N2 is one of the most important AIV in poultry around the world. An experiment was carried out for studying the pathogenicity of three H9N2 isolates. Eighty four one-day-old SPF chickens were divided randomly into “four groups (21 chicks per group)” in separate isolators with positive Air pressure. At the age of 30 days-old chickens in group 1,2, and 3 were inoculated with 106EID50 of three H9N2 isolates by oculo-nasal route, 4th group was kept as control and inoculated with mock allantoic fluid. Samples including oropharyngeal and cloacal swabs and various tissues were collected at 2, 4, 6, 8, 10 and12 days post-inoculation (PI). The Real-time PCR assay was used for detection of the virus swab and tissue samples. In experiment groups, H9N2 AIV was detected from all examined tissues in 2, 4 and 6 dpi, exception was liver and thymus. Maximum histopathological lesions were seen from 2 till 8 dpi in trachea, lung, liver, kidney, spleen, cecal tonsil and thymus eventually. Lesions in other tissues including cecal tonsils, and cloaca was not significant. In immunohistochemical investigation, the presence of antigen in the epithelial cells of lung, kidney and intestinal tissues, was observed on 4 and 6 days post inoculation. Considering the fact that H9N2 viruses are of low pathogenicity but they show various clinical signs in commercial flocks. The results of this study showed that there was some pathogenic differences between three isolates but the differences were not significant.

Babesiosis is caused by different species of babesiosis. It can infect a variety of vertebrate hosts, including domestic and wild animals and humans. The parasite is an intracellular monocyte found inside red blood cells. It is transmitted to sensitive hosts by ticks in the oxidized family. This disease is characterized by extensive lysis of red blood cells, which leads to anemia, jaundice, hemoglobinuria, and eventually death. In this work, 200 blood samples were examined taken from two populations of 100 urban and domestic dogs in Isfahan using common parasitological methods and molecular method (PCR) to amplify and confirm the presence of Babesia protozoa in the blood of these animals. The results were then statistically analyzed using SPSS software V.16 and the chi-square test (X2). In the samples obtained from pet dogs, a molecular prevalence of 21/10% was observed in urban dogs compared to 39/20%. It was reported by comparing the observational method of parasitology 13/6% and 17/9%, in domestic and urban dogs, respectively. This indicates the low prevalence of this parasite is in domestic dogs compared to the urban dogs in Isfahan. The results of the present study showed that Babesia canis has a higher prevalence in stray dogs in Isfahan. Owing to the potential of these dogs and the abundance of arthropod carriers in the spread of this disease, this issue should be further considered by officials to collect and organize. Urban animals are increasing than ever before.

59 horses with diarrhea and abdominal pain were monitored over a 9-year period (2011-2020). 54% of horses died and others survived. 30% of animals were salmonella positive in bacterial culture. Bacterial isolation was performed on naso-gastric reflux in 2 cases, fecal samples from 9 cases and intestinal contents at necropsy in 7 cases. Before any treatments or death, animals showed clinical signs such as depression, tachycardia and tachypnea. Other symptoms including congested mucous membranes, increased CRT, fever, hypothermia, diarrhea, bloody diarrhea, abdominal pain, nasogastric reflux, ileus, reduced abdominal sounds, and gas distended intestines upon rectal examination were also recorded. Necropsy findings of 20 horses, revealed severe dilation of stomach, gas distention of cecum and colons, petechial and ecchymotic hemorrhages in serosal and mucosal surfaces of small intestine and colons. Pale and enlarged kidneys along with hemorrhagic adrenals were observed. Microscopic examinations revealed severe lesions including: lamina propria and submucosal edema, vascular congestion, large intravascular thrombi, hemorrhages, superficial coagulative necrosis of villi epithelium and mixed inflammatory cell infiltration within lamina propria of cecum and colon. Clinical, macroscopic and histopathological signs of this study were similar to previous studies, and bacterial isolation was used as the most reliable method for diagnosis of involved horses.

Urinary tract infections (UTIs) are one of the most common infections in hospitalized patients and Escherichia coli is the most common pathogen and is also responsible for 50-85% of urinary tract infections in communities and hospitals. Recombinations in Escherichia coli bacterial populations lead to diversity among them and the formation of phylogenetic groups. By determining the ancestral identity of the strains and the group to which the bacterium belongs, the pathogenic nature or natural flora of the bacterium can be understood. In this study, in a period of 4 months, 50 samples of positive cultures with urinary tract infections were referred to the laboratory located in Samen Al-A'meh Hospital in Bojnourd. . Bacterial plates containing pink colonies in McConkey agar medium were selected as suspected Escherichia coli isolates and, after confirmation by biochemical tests (IMVIC) was performed to confirm the isolates. In this study, four genes yjaA, chuA, arpA and TspE4.C2 were used to determine phylogenetic groups C, F, E, B2, B1, A and D. In this study, the frequency of phylogenetic groups were B2 (24%), F (22%), B1 (18%), D (16%), A (8%), C (6%) and E (6%), respectively seen. All studied isolates could be classified using the new Clermont phylogenetic classification method. A variety of phylogenetic groups were observed among the studied isolate.

Mastitis is one of the most costly diseases in the veterinary industry, which in addition to financial losses, has many health consequences for human society. Staphylococcus aureus is one of the most important causes of this disease in livestock, which has a very high resistance to a wide range of industrial drugs due to the indiscriminate use of antibiotics and the presence of some microbiological properties. In this study, the Sahendica sage plant with the scientific name (Satureja Sahendica) was used for this purpose. For this study, after sampling the milk of mastitis animals, the samples were taken under sterile conditions and transferred to the laboratory beside the ice, and after culturing the sample in laboratory culture media and confirming the presence of Staphylococcus aureus. Minimum inhibitory concentration (MIC) and minimum lethal concentration (MBC) values ​​were determined for this species. The results showed that the essential oil of this plant in the average concentrations of 2.3±0.82 mg/ml for (MIC) and 10.14±3.66 mg / ml for (MBC) is effective on the bacterium. Finally, it was found that Sahandika safflower essential oil can be used to prevent the growth of Staphylococcus aureus to control the development of antibiotic resistance.

Clostridium perfringens is an anaerobic bacterium that among its strains, only types B and C can produce beta-toxin. Beta-toxin plays an important role in many human and animal diseases and has detrimental effects on the intestine. The present study aimed to compare two purification methods for the extraction of beta-toxin from C. perfringens type B. As the first method, beta-toxin was purified using ammonium sulfate precipitation, column chromatography (Sephadex G-25), and ion-exchange chromatography (DEAE Sephadex), while the second method employed affinity chromatography. Hemolysis activity and protein content were measured in each step of purifications. The purity of beta-toxin was monitored in each step using SDS-PAGE. According to the results, a comparison of these two methods indicated that the yield of the first method was 82.8%, and the yield of the second method was 90.1%. The specific activity values for the first and second methods were calculated to be 2368.1 U/mg and 164.5 U/mg, respectively. Our results show that affinity chromatography could be used to purify beta-toxin from clostridium perfringens type B with high purity and specific activity (4370 HU/mg).

Pseudomonas aeruginosa is a Rod-shaped Gram-negative and strict aerobic bacterium that can causes infection in the urinary system, respiratory system, middle membrane of the skin, soft tissues, bacteremia, etc. Ceftolozan-tazobactam (C/T) is an effective antibiotic in controlling of this bacterium. But recently, reports of the emergence of resistant strains have created a serious challenge in the fight against infections caused by P. aeruginosa. ampC is one of the main genes for β-lactamase synthesis. Studies have shown that Ceftolozane-tazobactam has better outer membrane permeability and improved stability against chromosomal ampC β-lactamase than do other β-lactam antibiotics. Considering the importance of ampC in the process of P. aeruginosa resistance to the Ceftolozane-tazobactam antibiotic, the co-expression network of ampC was reconstructed and the resistance emerging process was analyzed. 31 genes in the beta-lactamase process in P. aeruginosa showed correlation with ampC. Network topology analyzes showed that five genes ampC, ampD, poxB, ampR and nagZ have the highest importance in the network. ampC gene had the highest number of direct connections with other genes in the network with 16 connections. Eight pathways had the highest number of representatives among genes. Based on the statistical analysis of the significant pathways among the studied genes, it seems there is a direct relationship between pyruvate metabolism and resistance to β-lactam antibiotics. Results showed ampC is the main gene for resistance to Ceftolozane-tazobactam. Although studies have shown that poxA and poxB genes do not have a significant effect on P. aeruginosa resistance to the antibiotics, the importance of these two genes in the reconstructed network emphasizes that more studies should be conducted on them.

Today, fungal toxins or mycotoxins are a major problem in the food industry and food chain safety, which can contaminate a wide range of agricultural products, and thus they have negatively affect on health and production of livestock and poultry, and consequently human health, the economies of countries and even international trade. Since mycotoxin contamination cannot be completely prevented before or after harvest, it is important to know exactly how to remove mycotoxins during technological processes and feed clearance strategies. Today, the biological control of mycotoxins by microorganisms and other biological factors is becoming a valid approach to protect food products from contamination by these toxins, which increases the safety and quality of crops and animal feed, and ultimately reduces toxin concentration in animal products (milk, meat and eggs), and increase food chain security.

Despite the widespread use of vaccination against Newcastle disease virus (NDV), the virus is still circulating in poultry farms. The present study was conducted to measure different histopathological effects and protective antibody levels in experimentally infected chickens with VII.2 and VII.1.1 NDV virulent strains. In this study, commercial layers and SPF(Specific Pathogen-Free) chickens were challenged with NDV genotypes VII.1.1 and VII.2 via oculo-nasal route.  Tracheal and cloacal swabs were collected from all chickens on the fourth day after challenge, then chicks were euthanized in order to collect tissue samples. Tissue specimens were chosen from trachea, proventriculus, heart, kidney, lung, spleen, brain, intestine and liver for evaluation and histopathological grading. All SPF chicks were died within the first 48h of experiment. The HI results of a day before challenge revealed the antibody titer of 6.46 in commercial layers and 0 in SPF chicks. The histopathological results did not show any severe damage in tissues of proventriculus and heart. Both SPF groups showed hemorrhages in tracheal tissues. The most lesions were observed in lung and kidney tissues with more severity in SPF chickens and also more severe in VII.2 infected groups rather than the two VII.1.1 infected groups. In conclusion, according to higher antibody titers and lower histopathological lesions in commercial layers, it can be concluded that antibodies in commercial flocks can prohibit viral replication to a great extent.