دو ماهنامه میکروب شناسی پزشکی ایران
سال سوم شماره 1 (بهار 1388)

Due to importance and prevalence of ESBL producing isolates in nosocomial infections, this study was undertaken with the aims to determine antibiotic susceptibility patterns,identification of ESBL producing isolates and detection of blaCTX, blaTEM of Acinetobacter spp in clinical isolates from selected Tehran hospitals. Ninety five isolates of Acinetobacter were collected from Tehran’s hospitals.Susceptibility patterns of various antibiotics and MIC for ceftazidime were determined by disk diffusion and microbroth dilution methods respectively based on CLSI protocols. The ESBL producers were screened by phenotypic confirmatory test. PCR was used for detection of blaCTX and blaTEM genes. The lowest and highest resistance rates to investigated antibiotics were seen against colistin (4.2%) and cefexime (100%) respectively. By using PCT, 18.9% of the isolates were ESBL positive. About 83.1 % of Acinetobacter isolates showed MIC ≥ 64 μg/ml to ceftazidime, however only 18.9% of isolates were ESBL producer. Based on the results from PCR technique,1.2% and 12.8% of the isolates were TEM and CTX positive respectively. The rate of MIC to ceftazidime and presence of blaTEM and blaCTX among ceftazidime resistant isolates was very noteworthy in present study. Since less than one fifth of the isolates in present study were ESBL producer, it seems that apart from beta-lactamases, other resistance mechanisms such as efflux pumps and impermeability of the cell membrane may be responsible for this situation.As resistance factors are located on mobile elements, identification and detection of strains producing these enzymes is important in preventing of the expansion of these isolates

Bacillus anthracis as a spore-forming, aerobic, gram-positive bacterium is the causative agent of the anthrax disease. In recent years, it has been used in the bioterrorism attacks. Its spore is highly resistant to physical and chemical agents. For rapid detection of B.anthracis spore by molecular methods, it is necessary to extract genomic DNA by disrupting the spores. The aim of this study was rapid molecular detection of B.anthracis DNA by Multiplex PCR using rapid physical disruption of spore in a short time without extraction of the genome. Genome of non-virulent strain of B.anthracis spores (Stern Vaccine strain) was extracted by Mini Bead Beater-8 system by using 0.1 mm glass beads in 5000 RPM. The sample was directly used for PCR. Multiplex PCR technique was used for detection of bacterial DNA using 3 pairs of primers.Amplified PCR products generated 3 fragments of DNA that were analyzed by agarose gel electrophoresis.Detection limit and specificity of the test were determined at different spore dilutions by using other bacterial strains belonging to the same genus. By this method, B.anthracis spores could be disrupted within 3 minutes, and detected with specific primers by Multiplex PCR method. PCR products of 1083bp, 385bp, 164bp were analyzed in %2 agarose gel. By Hind III restriction enzyme, larger PCR product (1083bp) was confirmed. Detection limit by CFU/ml method was determined by 1/512 dilution of suspension with 7680/ml spore or 7 spore/μl. The results of optimization showed that the physical disruption method by glass bead and Bead Meal Homogenization has the proper speed of 3 minutes and there is no need for DNA extraction. By this method, we were able to rapidly disrupt, detect the spore of B.anthracis in samples specifically and with high sensitivity.

The Number of drug-resistant Mycobacterium tuberculosis strains have increased significantly since the chemotherapy started against TB. The incidence rates of MDR-TB in adjacent countries of Iran such as Azerbaijan has been reported in extremely high level. The referring patients from these countries to Tabriz research center for TB and pulmonary diseases have been raised the anxiety of contagion risk of drug-resistant TB. The aim of this study was to investigate the in vitrosusceptibility of isolated M. tuberculosis strains to the first and some second line anti-tuberculosis drugs. Initially, 103 M. tuberculosis strains were identified by conventional culture and biochemical tests. Then drug susceptibility of the strains were investigated by proportional method on Lowenstein – Jensen medium. H37Rv M. tuberculosis (susceptible to all drugs) was used as a control strain.The tested drugs were isoniazid, rifampin, ethambutol and streptomycin as first line anti-tuberculosis drugs,and amikacin, kanamycin, ofloxacin and ciprofloxacin as second line drugs. Thirteen out of 103 tested strains (12.6%), were resistant to kanamycin, two strains (1.9%) were resistant to ofloxacin, one strain (1%) was resistant to amikacin and one strain (1%) was resistant to ciprofloxacin. Among the first line drugs, the highest resistance was observed against streptomycin (7.8 %).Besides, the strains showed the highest level of resistance against kanamycin (12.6%). The rate of multidrugresistant (MDR) strains was 2.9 % in present study. The majority of strains were resistant to all first line drugs and the rate of MDR was low in this study. Among the first and second line drugs, the highest rates of resistance were observed against streptomycin and kanamycin respectively.

Metronidazole is a key component for treatment of peptic ulcer caused by Helicobacter pylori infection. The aim of this study was to determine the role of rdxA gene in metronidazole resistance in H.pylori strains isolated from Hajar hospital of Shahrekord, Iran. This cross-sectional study was done on 263 patient who referred to endoscopy department of Hajar hospital of Shahrekord on summer 2007. H.pylori was identified using gram stain,urease, catalase, oxidase tests and PCR method. Metronidazole Resistance was evaluated according to Standard Clinical and Laboratory Standards Institute (CLSI). Specific primers were used for detection of 200bp deletion in sensitive, semi-sensitive and resistance strains. Out of 84 isolated strains, 49 (58.33%) and 7 (%8.33) were resistant and semi-sensitive to metronidazole respectively. However 200bp deletion in rdxA gene was observed in only 2 strains. Statistical analysis indicated that there was no relation between metronidazole resistance, clinical criteria and rdxA gene deletion. Regarding to low frequency of rdxA gene mutation observed in our survey, the study of other possible molecular mechanisms involved in resistance to metronidazole is recommended.

Infertility is one of the most important problems for every couple.Micoorganisms, in particular Ureaplasma urealyticum, are among the causative agents of infertility,although the correlation of this organism and infertility is not quite clear.The aim of this study was to determine the prevalence of Ureaplasma urealyticum in semen of infertile men. In this case- control study, presence of Ureaplasma urealyticum was investigated in 40 infertile patients referred to infertility clinic of Rooyan institute. The study group was compared to 40 normal men as a control case group. The prepared questionnaires were filled by both groups. Semen samples were taken and added to PPLO broth containing urea, antibiotics and necessary additives with pH 5.5 astransport medium, and sent to microbiology laboratory. The samples were cultured on PPLO agar then the grown colonies were studied by Dienes staining followed by standard identification tests. The information were analyzed with SPSS software by frequency, chi-square and T-test Method. The mean age of patient and control groups were 31.87 ± 5.22 and 31.45 ± 5.81 respectively. The rates of isolation of Ureaplasma urealyticum were 11(27.5%) in patients and 4 (10%) in normal controls,which the difference was statistically significant (P < 0.045). We have shown a significant increase in Ureaplasma urealyticum infection in infertile men.The finding of this study reveals the significant correlation between infertility and Ureaplasma urealyticum infection in patient's group compared to healthy controls.

Microbial contamination of butter out of the range of standard as other food products is a hazard for human health. In this research the microbial level contamination of butter marketed in north, centre and south of Tehran were studied. In this study, the existence of Coliforms, Escherichia coli, Staphylococus aureus,Psychrotrophic bacteria and moulds in 48 samples of packed butter, collected from markets in three area of north, centre and south of Tehran were tested and measured according to the examination of Standard Institute of Iran. Of 41 butter samples, 31 (64.58%) were out of the acceptable level of the microbial contamination.The number of contaminated samples in north, centre and south of Tehran were as 9 (29%), 11 (35.5%) and 11(35.5%) respectively. The results of confirmation and IMViC tests of fecal Coliforms showed contamination of eight samples (16.66%) to E. coli, five samples (16.12%) to Citrobacter spp. and 18 samples (58.06%) to Enterobacter spp. Staphylococus aureus contamination was not observed in any samples. Besides, statistical analysis indicated that psychrotrophic bacteria were not out of the range of standard in any of samples. Three samples (6.25%) were contaminated to moulds that one and two samples were from centre and south of Tehran respectively. The significant number of butter samples contained coliforms, which definitely are not suitable for consumption. More attention is needed to hygienic control of factories related to dairy products for food safety in the community.

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies in a few region of northern Iran (Mazandaran and Golestan). Epstein Bar Virus (EBV) infection is an important cause of many human malignancies including Burkett's lymphoma and Hodgkin's disease. EBV has also been associated with nasopharyngeal and gastric cancers. The aim of this study was todetermine the prevalence of EBV in biopsy sections obtained from patients with ESCC in Mazandaran and Golestan provinces in 2008. This was a cross-section descriptive study on 40 surgical specimens of clinically and pathologically confirmed esophageal cancer. DNA was extracted from paraffin-embedded blocks using a commercial DNA extraction kit. EBV-DNA was amplified by using EBV-sequence specific primers using polymerase chain reaction. DNA amplification product was revealed by electrophoresis on 1% agarose gel. The biopsy sections were belonged to 22 (55%) male and 18 (45%) female patients. We found EBV in 4 (10%) of 40 specimens. Three (13.2%) of 4 EBV-positive biopsies denoted to males and the only one (5.5%) was female. Identification of EBV in 10% of esophageal cancer biopsies, might suggests a role of EBV in ESCC in Northern Iran.

Hepatitis B virus is one of the most common and important agent of acute,chronic hepatitis, liver cirhhosis and hepato cellular carcinoma in the world. In Iran the rate of infection varies in different provinces.The aim of this research was to study the prevalence of hepatitis B and its comparison with the results obtained from opium and syphilis tests in young men who want to get married in Tehran. The blood samples belonging to males (20-45 years old) referred to Hasheminejad Laboratory were collected and examined for HBs Ag levels by ELISA. Syphilis and opium were investigated by RPR and TLC tests respectively. The data were analyzed by chi-square and descriptive statistical tests. Among 1000 persons tested, 8(0.8%) cases were HBs Ag positive, 2(0.2%) cases were TLC positive and there was any positive result for RPR. There was any HBs Ag and opium positive in the same case. According to the results obtained from our study, the rates of HBs Ag positive was less than expected rate. It is maybe due to prevention plans in our country.

Mycobacterium tuberculosis is usually associated with pulmonary infections.However, it may affect any organ other than lungs in one third of patients. This study was conducted to assess the epidemiology of extra-pulmonary tuberculosis in patients referred to Shahriar Tuberculosis Center. In this cross-sectional study, new cases of extra-pulmonary tuberculosis were evaluated using statistical analysis. All patients were registered from April 2008 to March 2009. Out of 127 patients with tuberculosis, extra-pulmonary tuberculosis was diagnosed in 41(32.3%) cases with the mean age of 35.9±16.4(SD).There were 16(39%) males and 25(61%) females. Of these patients, 73.2% were Iranian and the others were Afghani. The sites commonly involved were lymph nodes (29.3%), bones and joints (17.1%), pleura (9.8%) and gastrointestinal tract (9.8%) respectively. Moreover,one patient (2.4%) was co-infected with HIV. Correct diagnosis of extra-pulmonary tuberculosis is a major obstacle for medicine because it resembles many other infections. Hence, proper screening tests should be carried out.