Jundishapur Journal of Microbiology
Year:2011 | Volume:4 | Issue:2 (S.N. 11)|Papers Count:9

Introduction and objective: Hepatitis B virus (HBV) is a member of Hepadnaviridae and a major causative agent of chronic and acute hepatitis, liver cirrhosis and hepatocellular carcinoma. Genotype determination of HBV is based on PCR-RFLP and sequencing of genome of the virus. The genotype formation is mainly due to mutations of HBV precore, S, and YMDD (tyrosine-methionine-aspartate-aspartate motif in the C domain of the HBV DNA polymerase gene) genome area. Moreover, some of the mutant HBV remains undetectable by serological tests (occult hepatitis). Since the genotypes of HBV and occult hepatitis B has not been studied in our area, this study was conducted to determine both occult hepatitis B infection and genotypes among hemodialysis patients.Materials and methods: Two hundred and fifty hemodialysis patients were selected in this study. The sera of the patients were collected and the extracted DNA was used as template of PCR to amplify a 479bp fragment of the viral genome. The PCR products were digested by Ava2 and Mbo1 restriction enzymes. Based on RFLP patterns, the genotypes were determined. The HBV markers including; HBV surface antigen (HBsAg), hepatitis Bc antibody (HBcIgG), hepatitis B virus e antigen (HBeAg) and hepatitis B virus e antibody (HBeAb) were carried out for all the patients by ELISA test.Results: Fifty (20%) out of 250 sera showed positive HBV by PCR. Out of the 50 positive cases for HBV, 46 (92%) belonged to genotype D2 and 2 (4%) cases of them were B6 genotype. Ten cases were positive for HBV by PCR test but negative by ELISA test (4% occult hepatitis).Conclusion: Prevalence of HBV infection was high among the dialysis patients (20%), and occult hepatitis B was 4% in these patients. The dominant genotype of HBV was D2 (92%) followed by genotypes B6 (4%) in hemodialysis patients.

Introduction and objective: Cryptosporidium parvum is a protozoan parasite that is a common cause of diarrhea in both animals and humans worldwide. There is no effective specific chemotherapeutic treatment. The aim of this study was to survey and compare the anticryptosporidial effect of two anticoccidial drugs, Monensin, Toltrazuril and synergic effect on oocysts of C. parvum in vitro.Materials and methods: Cryptosporidium parvum oocysts were isolated from the fecal samples of calves after purification, stored in Hanks Balance Salt Solution at 4oC. They were exposed to different concentrations of the drugs, Monensin, Toltrazuril and the mixture of them (0, 0.1, 0.5, 1, 10, 20, 60 and 100μg/ml). The effects of the drugs were evaluated by counting the complete oocysts after 24h and 48h incubation at 37oC.Results: The results showed a significant decrease in the oocysts number related to the increase in the concentration and exposure time of the drugs. The mixture of two drugs had the highest efficacy on the C. parvum oocysts than each of drugs alone (P<0.001) and Monensin in contrast to Toltrazuril at the same concentration showed to be more effective (P<0.001). These drugs in all concentrations were effective on C. parvum oocysts, and at100mg/ml had the highest efficacy and at1mg/ml had the least.Conclusion: This study showed that two drugs were effective on C. parvum oocysts and Monensin was more effective than Toltrazuril and the mixture of them was more effective than each of them alone because of their synergism.

Introduction and objective: Hospital acquired infections are serious problems in patients care and adversely affect the mortality and morbidity despite antimicrobial therapy and advances in supportive care. The researchers aimed to determine the contamination of inanimate hospital environment to bacterial agents and their susceptibility to various antimicrobial agents. Seven different teaching hospitals were included in this study.Materials and methods: From April 2006 to January 2007, 1208 samples (1156 wet swabs, eight water dialysis and 44 hand washing samples) were taken from surface and medical instruments in different hospitals' wards. Susceptibility test for bacterial isolates was done by disk diffusion assay.Results: In the present study 57% of samples were positive and more than 10 species were isolated. Coagulase negative staphylococci (36.1%) and Klebsiella pneumoniae (8.9%) were the predominant isolates among Gram-positive and negative bacteria, respectively. Hands (79.5%), kitchen (71.4%), staffs' room (61.1%) and equipments (57.8%) were the most infected sites. Gram-negative enteric bacilli (50%) in food service personnel and Gram-positive cocci (46.6%) in medical personnel were predominant isolates from hand specimens.60% of Staphylococcs aureus yielded methicillin resistant (MRSA).Conclusion: Lack of a universal procedure for surveillance of nosocomial infection, presence of MRSA and some other pathogenic bacteria, poor hand hygiene and heavy contamination of some important surfaces are the most important problems in our hospitals.

Introduction and objective: Several Gram-positive and Gram-negative bacteria isolated from methyl tertiary butyl ether (MTBE) reached soil. Among them one Gram-positive, oxidize positive, partial acid fast, which had strong nitrate reductase activities was identified as Gordonia. The effects of methanol, nitrate and nanosilver on MTBE removal were studied.Materials and methods: Gordonia was isolated from MTBE enriched soil and identified by sequencing and biochemical test. The removal of MTBE was studied by Gordonia with COD Hach reagent. The production of formaldehyde and formate were determined by Hantzsch reagent and potassium permanganate, respectively. Also MTBE oxidation by nanosilver, nitrate and bacteria were compared.Results: The results showed that the addition of 5 or 10ppm nanosilver inhibits the reaction, however 0.2ppm nanosilver increased MTBE oxidation by 15% and gives maximum 70% removal in 6h. The biodegradation of MTBE by this isolated strain only occurred when nitrate was added in media with or without Nanosilver. Also Methanol for induction or co-oxidation is necessary for MTBE oxidation by Gordonia.Conclusion: Gordonia has a good capacity to remove MTBE only with nitrate respiration. Therefore nitrate as electron acceptor for respiration, methanol as co-oxidation and nanosilver as catalyses in special concentration help Gordonia for MTBE removal.

Introduction and objective: Salmonellosis is responsible for large numbers of infections in both humans and animals. Conventional methods of isolation of Salmonella strains take 4-7 days to complete and are therefore laborious and require substantial manpower. Our main objective was to develop a rapid detection method using shortened PCR cycles in a conventional thermal cyclers and fast electrophoresis for Salmonella. Materials and methods: The PCR primers for tyv (rfbE), prt (rfbS) and invA, genes were used for the rapid identification of S. enterica serovars typhi and paratyphi A, with rapid and short cycles of multiplex PCR. By using very fast and simple DNA extraction method in 10mins, rapid PCR cycles with total times of 35mins and rapid electrophoresis procedure with simple and very cheap buffer in 15mins we were able to separate the PCR products. Results: All references and clinical isolates of Salmonella serovars typhi and paratyphi were accurately identified. Specificity analysis revealed no cross reaction with other enterobacterial strains. The sensitivity of the assay was 1-10 cells. The total time of multiplex PCR from sample preparation to final result is 45 to 50mins. Conclusion: These data indicate that the specificity and sensitivity of optimized rapid cycle multiplex PCR is a potentially valuable tool for rapid diagnosis of S. typhi using a conventional thermal cycler. This method cut the time of a PCR reaction from 3.5h to less than 60mins. These findings could also be applied to other PCR programs detecting various genes allowing researchers to significantly shorten their PCR reaction times.

Introduction and objective: Metronidazole (Mtz) resistance in Helicobacter pylori has been found to be associated with mutations in rdxA, a gene encoding an oxygen insensitive NADPH nitroreductase, and enhanced by mutations in frxA a gene encoding a NAD (P) H-flavin oxidoreductase. In this study, we examined the prevalence of rdxA deletion among local isolates of H. pylori. Materials and methods: We tested 63 H. pylori isolates obtained from 191 patients referred to endoscopy unit of Afzalipour hospital in Kerman, Iran, during 2009 for their susceptibility to common anti-H. pylori antibiotics using a modified disk diffusion test. Then the metronidazole resistant and sensitive isolates were evaluated for deletion in rdxA gene by PCR methods and compared with each other. Results: From 35 resistant H. pylori isolates in this study only 22.9% (8 isolates) detected with deletion rdxA gene. No rdxA deletion was detected in sensitive isolates. Conclusion: According to rdxA deletion rates in this study, it seems that some other nitroreductases are involved in metronidazole activation or there are other metronidazole resistance mechanisms involved.

Introduction and objective: The amount of nitrogen fixed by Azotobacter varied from 0.02-0.25 KgN/ha/d and has been reported to be variable with various physiological and environmental factors. The nitrogen fixation by mesophilic soil isolates and their analogue resistant mutants of Azotobacter chroococcum was compared with their thermotolerant mutants at three different temperatures (30oC, 37oC, 42oC). Material and methods: Mutants spontaneously resistant to methylammonium chloride were derived originally from a soil isolate of A. chroococcum. Ammonia excretion ability of different strains of A. chroococcum was determined by the method of Chaney and Marbach (1962). Nitrogenase activity of different strains of A. chroococcum was assayed by growing the cultures in the Burk medium. Effect of Azotobacter inoculation on cotton biomass was followed. Results: Growth and ammonia excretion were related in both mesophilic as well as thermotolerant mutants at 30oC but not at elevated temperature (42oC). A thermotolerant strain (HTR71) has excreted as much as 24.1mg ammonia/ml of culture broth in a sucrose supplemented synthetic Jensen’s medium at elevated temperature of 37oC under stationary conditions of growth while a thermotolerant mutant (HTR54) showed nitrogenase activity of 46.13 nmoles C2H4 /h/mg protein at 37oC while Mac68, a mesophilic strain from which HTR54 is derived by mutation has nitrogenase activity of 35.07 nmoles C2H4 /h/mg protein. Thermotolerant mutants showed better performance over mesophilic strains on the cotton biomass under pot house conditions. Conclusion: The present study suggest that these thermotolerant mutants would be the ideal diazotroph to be used as biofertilizers for crops in semiarid regions having high temperature (40oC or above).

Introduction and objective: Previous studies have shown the potential antibacterial activity of black tea, Camellia sinensis, extract against many pathogenic bacteria including Gram-positives (Listeria monocytogenes and Staphylococcus aureus) and Gram-negatives (Vibrio cholerae and Salmonella enterica serovar Typhi). The aim of the current study was to assess the in vitro antibacterial activity of C. sinensis ethanolic extract (CAS) against multidrug-resistant (MDR) clinical isolates of S. Typhi and V. cholerae O1 biotype El Tor serotype Ogawa (V. cholerae Ogawa). Materials and methods: The zone diameter of inhibition (ZDI) and minimum inhibitory concentration (MIC) values of CAS for S. Typhi and V. cholerae Ogawa isolates were determined by agar diffusion and agar dilution techniques. Bacterial killing studies were carried out in order to assess the bactericidal activity of CAS against S. Typhi and V. cholerae Ogawa, from Kolkata, India. Results: For the S. Typhi and V. cholerae Ogawa isolates, the ZDIs of CAS ranged 12-17mm and 13-21mm, respectively, and the MICs of the extract were 400-600mg/ml and 200-600mg/ml, respectively. The CAS had bactericidal action at concentrations 512mg/ml and 256mg/ml, respectively for S. Typhi and V. cholerae Ogawa. Conclusion: The black tea (C. sinensis) extract could be useful in combating emerging drug-resistance among enteropathogens including S. Typhi and V. cholerae Ogawa.

Introduction and objective: Hydatidosis is one of the most important common zoonosis diseases in most parts of the world. This parasite causes many damages to animal husbandry. Several strains of this parasite have been identified based on the biologic and epidemiologic characteristics of strains and this is important for the improvement of the control and prevention of this disease. As the aim of the present study, identification of these strains and their incidence can help recognition of the biologic cycle of the parasite in Lorestan province.Materials and methods: One hundred and forty livestock isolates from sheep, goat and cow were collected from the abattoir of the Lorestan province. To investigate the genetic variation of the isolates, after the extraction of DNA, PCR-RLFP analysis of a fragment of ribosomal DNA was performed using four different restriction enzymes of TaqI, HpaII, RsaI and AluI.Results: The amplified PCR product for all isolates was a 1000bp band which is the same as the expected band in sheep strain. The results of RFLP analysis also were the same for all isolates.Conclusion: The results of PCR and the RFLP analysis showed that only the sheep strain of this parasite is present in Lorestan province and based on RFLP pattern all the sheep, cow and goat isolates are infected with sheep strain.