نشریه تازه ها در میکروب شناسی دامپزشکی
سال پنجم شماره 2 (پاییز و زمستان 1401)

Brucellosis or Malta fever is a public health concern and an economically important disease with a worldwide distribution. After rabies, it is important zoonotic disease. The disease is endemic in some geographical areas, including Iran and it is one of the important problems in livestock and humans. The control of disease is highly dependent on the seroprevalence of this disease in livestock. Therefore, the aim of the present study is to evaluate the seroprevalence of brucellosis in sheep in Tabriz to better control this disease in this region. A total of 200 serum samples were obtained from sheep and brucellosis were detected using the Rose Bengal test. The overall prevalence of brucellosis was 18.5% in sheep. The prevalence of brucellosis was 2% in male and 16.5% in female. The odds of brucellosis exposure in > 1 Year sheep (adult) were about 2 times higher than that of <1 Year sheep. The results of the present study showed that the prevalence of ovine brucellosis in the Tabriz Zone was relatively high. Age groups and sex were associated risk factors with the seroprevalence of this disease. Thus, a control and prevention programs of this disease are very important in this region.

Avian pasteurellosis, a highly contagious and severe bacterial disease of wild and domestic birds, causing mortality and important devastating economic losses. This cross sectional study was performed to isolate and identify pasteurella multocida in backyard poultry. For the purpose of the study, a total of 350 pharyngeal swab specimens collected from backyard birds suspected of illness during two years in Golestan Province, Iran. Samples were packaged in modified stuart's transport medium, and transferred to the Razi vaccine and Serum Research Institute for bacteriological examination. Out of 350 samples, two isolates were identified as p. multocida on the basis of bacterial cultures, morphological and biochemical characteristics. The isolates were subjected to polymerase chain reaction (PCR) for the detection of KMT1 species specific gene fragment. According to the results of PCR assay none isolates have been confirmed as p. multocida. Since Backyard birds may serve as source of public health and economically important bacteria, implementation of a pasteurellosis surveillance program and biosecurity measures will be helpful to develop disease control measures in the future.

One of the current problems of treating bacterial infections is increasing their resistance to antibiotics. Antibiotic-resistant bacteria cause significant mortality compared to non-resistant bacteria. Therefore, the use of olive, luffa, and sage medicinal plants, due to their anti-inflammatory and antimicrobial properties against 10 human pathogens, was the target of this research. For this purpose, a completely random experiment was conducted in three replications. Traits such as phenol, flavonoid, antioxidant and the diameter of the growth zone were measured. Data analysis was done using Statistix10 software and charts using Excel software. The highest amount of flavonoids (398.02 micrograms per gram of dry matter) was found in olive fruit and the lowest amount (255.78 micrograms per gram of dry matter) was obtained in sage leaves. Methanolic extract of olive leaf with an average diameter of 8 mm of non-growth zone had the greatest effect on inhibiting the growth of Hafnia alvei.  Methanolic extract of sage leaves with an average diameter of 14 mm of non-growth zonehad the greatest effect on inhibiting the growth of Staphylococcus aureus. Methanolic extract of luffa seed with an average diameter of 12 mm of non-growth zone had the greatest effect on inhibiting the growth of Pseudomonas aeruginosa. Methanolic extract of olive fruit with an average diameter of 18 mm of non-growth zone had the greatest effect on inhibiting the growth of Bacillus cereus. The results of the present research showed that Luffa, olive and sage plants and even their different tissues were effective in treating some pathogenic bacteria such as Hafnia alevi, Staphylococcus aureus, Pseudomonas aeruginosa and the growth of Bacillus cereus. Also, it is recommended to conduct more research on various compounds of these plant extracts by extracting the effective ingredients of this plant extract and other plants.

Colicins are antibacterial compounds produced by Escherichia coli which give the producing strains the ability to compete ecologically against other bacteria. The aim of this study was to identify Escherichia coli strains producing colicin isolated from broiler carcasses by PCR and to investigate the inhibitory effect of colicinogenic strains on different Escherichia coli pathotypes. In this study, swab sample was obtained from 110 carcasses of broiler carcasses slaughtered in Kerman industrial slaughterhouse. one confirmed Escherichia coli isolate was selected from each carcass. Seven groups of colicin genes including Y.U, E1, V, 5.10.K, E2-9, Ia.Ib and A.N.S4 were screened using PCR and specific primers. Strains containing at least one colicin encoding gene were studied for their inhibitory effect on the growth of various Escherichia coli pathotypes. In this study, out of 110 isolates, 54 isolates (49.1%) were positive for at least one of the studied genes. Of the total samples, 33 isolates (30%) were positive for Ia.Ib gene. Also, V and E1 genes with frequencies of 20% (22 isolates) and 9% (10 isolates) were in the next ranks, respectively. The prevalence of A.N.S4 gene was 2.9% (3 isolates) and E2-9 and 5.10.K genes were only detected in 1 isolate (0.9%). The U.Y gene group was not detected in this study. Among 54 isolates with colicin genes, 18 isolates (33.3%) had an inhibitory effect on at least one of the ETEC, EIEC, EHEC, EAEC and EPEC patotypes. Phenotypically, the most inhibitory effect of colicinogenic strains was observed on ETEC and EAEC pathotypes.

Babesia Starcovici 1893 and Theileria Theiler 1906 are the most important endemic blood parasites in domesticated animals. These parasites are transmitted by ticks and can causes clinical babesiosis and theileriosis both characterized by fever, hemolytic anemia which may lead to death. Therefore, the aim of our study is to determine the infection rates of Babesia spp. and Theileria spp. in Guilan province from Iran. A total number of 40 blood smears were collected from 40 different randomly selected cattle. The blood smears prepared and stained by Gimsa solution (10%) and light microscopic was used to examination of blood smears. The results showed that the number of 7 samples were infected by parasites. Among these, 3 samples (7.5%) were infected with Babesia spp. and 2 samples (5%) with Theileria spp. Along as 2 samples (5%) with bacterial parasites Anaplasma Theiler 1910. In the end, we recommend using both morphological and molecular methods together to get better results.

During the past two decades, the highly pathogenic avian influenza H5N1 virus has received considerable attention due to its zoonotic and mutative features. Purpose of the leading study is molecular and phylogenetic characteristics of hemagglutinin (HA) gene of H5N8 strain identified in Meighan wetland of Arak city, Markazi province were investigated. For this purpose, samples were inoculated with embryonic eggs of 14-10 days and after extraction of allantoic fluid and RNA extraction and PCR and sequencing of genes, phylogenetic trees were drawn by Mega7 program and molecular properties including Cleavage site, Glycosylation site, Antigenic site, Receptor Binding site and HA gene-related mutations were investigated. Based on the analysis of the amino acid sequence of the HA genes, the cleavage site of the gene includes the PLREKRRKR / GLF polybasic amino acid motif, which is a characteristic of highly pathogenic influenza viruses. The HA gene of two viruses had T156A, S123P, S133A mutations associated with the increased mammalian sialic acid binding. Phylogenetic analysis of the HA gene of the virus studied in this study indicated the classification of this virus in the 2.3.4.4 b Clade. It seems that the introduction of these H5N8 HPAI strains in Iran probably occurred through the West Asia-East African flyway by wild migratory aquatic birds.

Beta-lactamases and secretory pumps are the most important factors causing antibiotic resistance in Klebsiella pneumoniae bacteria due to the high prevalence of genes causing resistance and the spread of hospital infections, especially urinary tract infections caused by them, in In this study, Klebsiella pneumoniae isolates, isolated from urine samples were examined for the frequency of NDM-1, oqxA and oqxB genes using PCR technique.  DNA extraction was extracted by boiling method. PCR was done on 95 isolates of Klebsiella pneumoniae using the primers designed in this study. The showed that the prevalence of genes encoding antibiotic resistance including oqxA, oqxB and NDM-1 genes in 75 isolates (% 78.94), 75 isolates (78.94%) and 84 isolates (88.42%) respectively were evaluated. Prevalence of antibiotic resistance genes in this study is worrying and management of antibiotic prescription is necessary to control infection and prevent the spread of resistant bacteria and identify drug resistant isolates using molecular methods such as PCR.

Enterococcus as a part of the normal flora of human gastrointestinal tracts can cause infections in foods. Aim of this study was to determine tetracycline resistance in Enterococcus isolated from food. In this laboratory study, one hundred samples of food from different parts of Qom were collected. After determining the type, they were tested for their resistance against tetracycline genes by specific primer PCR. Out of 53 isolates, 45% isolates belonged to Enterococcus faecium 55% isolates were Enterococcus faecalis. Size band of this genes were tetS 647bp, tetO 442 bp, tetM 373 bp, tetL 306bp, ermb 311 bp. Among this samples tetO (12 %), tetS (6 %), tetM (17 %), tetL( 5%) and ermB (7%)isolate. Considering the results, increasing antibiotic resistant strains, especially tetracycline among Enterococcus, is a serious threat to the general public, Molecular method could help rapid diagnosis this resistance genes and help to treatment.

The aim of this study was to investigate the antibacterial effects of Ganoderma+silver extract complex nanocomplex on bacteria causing nosocomial infections including Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii. In the present study, silver nanoparticles were first loaded on Ganoderma extract. Then, tests such as FTIR and scanning electron microscopy were performed to confirm the loading of silver nanoparticles on Ganoderma extract. Then, the effects of nanocomplexes on Vero cell line were investigated to determine the toxicity of this compound on the cell. Also, the antibacterial properties of nanocomplexes of Ganoderma+silver extract on the studied bacteria were investigated. The MIC results of the fungus+silver nanocomplex were observed on Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes and Acinetobacter baumannii at 875, 218.75, 109.375 and 54.68, respectively. The results of this study showed that this complex has no toxic effect on eukaryotic cell line. Therefore, the synthesis of Ganoderma+silver nanocomplex can be used in medicine and food industry as an innovative, economical and environmental antimicrobial agent.

Malassezia pachydermatis, as an opportunistic yeast, exists on the skin of humans and animals and takes effect if the immune system is weak. Salix egyptica flower has antioxidant and cholesterol-lowering properties, and it is also used to relieve pain and inflammation. In the study, the inhibitory effects of aqueous, ethanolic, and methanolic extracts of this plant on this yeast were investigated. Aqueous, ethanolic, and methanolic extracts were prepared with a Soxhlet extractor. The disk and well diffusion, the determination of minimum inhibitory concentration (MIC), and the determination of minimum fungal concentration (MFC) were studied in the laboratory to evaluate the antifungal effects of these extracts on Malassezia pachydermatis. This yeast prepared of the collection microbial center shahriar with code ATCC 10231. The mean minimum inhibitory concentrations (MIC) on Malassezia packydermatis were 8.3 ×103 μg/ml for ethanolic extract, 1.2×104 μg/ml for methanolic, and 1.4 ×104 μg/ml for aqueous. MFC 20.8 ×104 μg/ml was in ethanolic extract, 1.6 ×104 μg/ml in methanolic extract, 5×104 μg/ml in aqueous extract. Findings indicate that alcoholic and aqueous extracts of Pussy willow have anti- Malassezia Pachydermatis effects, however, lower than Clotrimazole.

There are different methods to identify bacteria. One of the ways of identification is the use of nano bio sensors. Recently, these nano bio sensors have been widely used due to their non-invasive and rapid detection. The silicon nitride-based bio sensor, which is designed based on dielectric materials, has a very high sensitivity in detecting bacteria. In this paper, we have used nano bio sensor based on silicon nitride grating to detect Escherichia coli serotype O157:H7. The simulations show that the electromagnetic wave reflection spectrum in the proposed structure has a very narrow width of 6nm, and the measured FOM (Figure of Merit) and sensitivity of this bio sensor when exposed to this bacterium are 17.5RIU-1 and 105nm/RIU has been obtained, respectively, which shows the high accuracy and sensitivity of this bio sensor. This sensor can be used to detect bacteria whose refractive index is within the range of this bacteria.

Theileriosis and Anaplasmosis are very prevalent in native ruminants of Sistan region of Iran. Bovine babesiosis could be found with fewer prevalence. Also, Trypanosoma evansi induce the Surra disease in the camels of the region. The objective of present study is study and comparison of common available methods in identification of such infective organisms including clinical appearance, giemsa staining and molecular techniques (2013-2018). The blood specimens of 636 cattle, 80 sheep and 213 camels have been investigated with giemsa staining and molecular methods. Also, the clinical features were evaluated. The current results indicated that molecular PCR amplification is a more sensitive tool as compared to smear scanning for the detection of blood protozoa. However, it doesn’t mean that molecular techniques could be considered more preferable. The advantages and disadvantages of each identification method is discussed comprehensively based on the type of the parasites, hosts and economical condition in the area.

Staphylococcus aureus is a food pathogen and is a serious threat to humans. This study was conducted in order to evaluate the antibacterial effects of Hibiscus sabdariffa in inhibiting Staphylococcus aureus bacteria alone and together with nisin in Vanami shrimp minced meat. The plant was extracted using a vacuum evaporation method with the help of a rotary machine. The effect of different concentrations of alcoholic extract of Hibiscus sabdariffa (0, 1, 2.5, 3.5, 5%) and nisin (0, 0.5, 2.5 micrograms/gram) and the combination of different amounts of nisin (micrograms per gram) and extract (%) (0.25+3.5), (0.25+5), (0.5+1), (2.5+1), (2.5+2.5) were investigated on the growth behavior of the bacteria at a 4°C during 21 days. The results showed that bacterial growth in low concentrations of Hibiscus sabdariffa extract (2.5.1%) had no significant difference in inhibiting bacterial growth. Combined treatments of the extract with nisin could stop the growth of bacteria from the 6th day onwards. According to the findings of this research, it can be suggested that Hibiscus sabdariffa extract and nisin have inhibitory effects and are introduced as a natural food preservative instead of its chemical and industrial types. The combined use of these compounds proved their synergistic effects.