JOURNAL OF MICROBIAL WORLD
Year:2014 | Volume:7 | Issue:2 (19)|Papers Count:10

Background & Objectives: Tuberculosis is the second reason of deaths caused by known infectious agents. Although molecular approaches, such as PCR, are suitable techniques for detection of Mycobacterium tuberculosis (MTB), these techniques suffer of variable results in different laboratory conditions. This study aimed to design, manufacture and apply an internal PCR control used for detection of MTB.Materials & Methods: To produce special MTB internal control, first individual PCR test primers was optimized for molecular detection of MTB, and then their sensitivity and specificity were measured. The composite primer for IC-MTB was also designed, replicated and colonized. The amplified IC-MTB was ligated to pTZ57R plasmid and was transformed into E. coli JM107. The minimum IC number in each PCR reaction was studied using dilution and PCR response spectrum with IC.Results: The size of MTB diagnostic products with individual primers and IC-MTB were was 245 bp and 660 bp, respectively, which is a suitable difference in the size aspect. Minimum IC number was identified 1000 for each reaction. Minimum and maximum sensitivity PCR test by IC for MTB DNA was determined 10 and 10 million bacteria, respectively. No unwanted products were observed in characteristic tests by different agents.Conclusion: Using an internal control as an inside control system we could detect the errors in MTB molecular diagnosis test. In fact, IC amplification is representative of correct procedure in amplification and detection steps.

Background & Objectives: Acinetobacter spp. is one of the most important ethiology of nosocomial infections worldwide. The presence of multiple antibiotic-resistant strains has limited effective treatments for Acinetobacter spp. The purposes of this study were to screen gyrA gene mutation in quinolone resistance clinical isolates of A. baumannii and their antimicrobial susceptibility pattern in Isfahan.Material & Methods: In this cross-sectional study, 70 isolates of Acinetobacter were collected from patients hospitalized in the ICU of Isfahan Alzahra Hospital. Biochemical tests were used for detection of isolates. Antimicrobial susceptibility tests were performed on all isolates using the Kirby-Bauer Disk diffusion method and employment of eight antibiotics. Minimum inhibitory concentrations (MIC) of ciprofloxacin and levofeloxacin resistant isolates were determined using the E-test method according to the CLSI guideline. Furthermore, a PCR-RFLP test was performed to investigate gyrA gene mutation in ciprofloxacin/ levofloxacin resistance isolates.Results: The most antibiotic resistance was related to ciprofloxacin (100%) and gentamicin (100%) while the lowest antibiotic resistances were observed in case of application of imipenem (8.92%) and meropenem (90%). Based on MIC test the ratio of resistance to ciprofloxacin and levofeloxacin antibiotics were 100% and 65.7%, respectively. Also, overall 66.7% of these isolates showed multidrug resistant and 93% of the isolates carry a mutation at position 83 in gyrA gene.Conclusion: The present study revealed that A. baumannii isolates carry a mutation in gyrA gene. This mutation causes increases in the microbial resistance to quinolone. Rapid detection of quinolone resistant A. baumannii isolates can help physicians to determine effective treatment for these infections.

Background & Objectives: Pseudomonas aeruginosa is an important cause of nosocomial infections in burnt patients. Antibiotic resistance through various mechanisms is one of challenges for treatment of these patients. The mex efflux pumps play a vital role in the development of multiple resistances to antimicrobial drugs. This study aimed to analyze the prevalence of genes responsible for efflux pumps mexA-B-oprM and to investigate their phenotypes in the isolates.Materials & Methods: In this cross-sectional study, 250 swabs were obtained from wounds of the patients suffering of burns levels 2 and 3 who admitted in Ghotbodin Shirazi hospital, Shiraz. Presence of P. aeruginosa isolates were confirmed by biochemical tests and PCR. Drug susceptibility, the phenotypic activity of efflux pumps and the presence of mex A, mex B genes were determined using disk diffusion method, cartwheel method and PCR methods, respectively.Results: In this study, 26.40% (66 cases) of patients with burn wounds were infected with P. aeruginosa. These bacteria were resistant to all antibiotics tested except for colistin. Totally, 66.66% of the isolates (44 cases) had an efflux pump, among them 42.92% and 87.87% of the isolates carried mexA and mexB genes, respectively.Conclusion: Our finding showed that genotypic method is very accurate and reliable than phenotypic methods for detection of efflux pumps in clinical isolates of P. aeruginosa. Due to presence of the efflux pump genes in more than 90% of the P. aeruginosa isolates, analysis of the presence of these genes is very important for suggestion of an effective treatment model for the patients with bacterial infection.

Background & Objectives: Dental caries, caused mainly by mutans Streptococci, is the most common chronic disease in the world. Employment of probiotics is a new emerged technique to prevent dental caries production, and Lactobacillus rhamnosus is one of the important common probiotics in this strategy. This study aimed to evaluate the effects of L. rhamnosus on the adhesion of oral Streptococci.Materials & Methods: This cross-sectional study was carried out on 40 isolates of mutans and non-mutans Streptococci isolated from dental plaque and caries of the volunteers who admitted in dental school of Islamic Azad University, Khorasgan. The biofilm formation ability of these strains was investigated and the strongest isolates in this term were selected. The effect of L. rhamnosus (ATCC4769) on the adhesion of Streptococci was investigated by several methods; 1: an equal volum of Lactobacillus and Streptococcus, 2: application of Lactobacilli 30 minutes before induction of Streptococci into the system, 3: probiotic pellet 4: a supernatant of the overnight culture of probiotic.Results: Overall, L. rhamnousus led to reduction of Streptococci adhesion to surface using all four strategies. The second method was the most effective, its effect was more efficient on S. mutans adhesion than non-mutans. There was no significant difference between third and fourth methods, but effect of both methods on S. mutans was more than other Streptococci.Conclusion: Application of L. rhamnousus as probiotic could reduce the adhesion of mutans and non-mutans Streptococci to dental surfaces and therefore can reduce dental decay.

Background & Objectives: Beta-lactam antibiotics are currently the most common treatment for bacterial infections. The production of beta-lactamase enzymes are the most important reason of bacterial resistance to these antibiotics. The aim of this study was to investigate the presence of ampC and esbls genes in E. coli isolated from human and poultry.Materials & Methods: In this cross-sectional study, 400 urine samples were collected from medical centers and also 200 swab poultry cloaca samples were collected from poultry farms located in Tehran province. Phenotypic identification of the beta-lactamase producing strains was performed using disk diffusion method. The presence of ampC and esbls genes in bacteria was studied using PCR approach.Results: A total of 120 (30%) human sample and 50 (25%) poultry samples were infected to E. coli. Phenotyping evaluation showed that 54 cases (45%) of the human samples carried esbls beta-lactamase gene while 2 cases (1.67%) carried ampC beta-lactamase gene. In poultry samples, 3 cases (21.4%) were confirmed for ESBLs enzymes and none of them carried ampC gene. Based on genotyping analysis 2 (1.67%) of the strains isolated from human samples carried ampC gene.Conclusion: Based on the results of this study, the ampC beta-lactamase gene was found in human samples, but more accurate studies are required for poultry. Due to high risk factor of the betalactamase producing organisms in nosocomial infections further studies is suggested to prevent their spread in community.

Background & Objectives: Oil pollutions are one of the major problems threatening environment. Biodegradation using hydrocarbon-degrading indigenous bacteria is considered as a convenient method both economically and environmentally. The genus Alcanivorax is known as a petroleum hydrocarbon degrader in petroleum-contaminated marine environments. The purpose of this study was to evaluate the capacity of Alcanivorax dieselolei, isolated from the coastal sediments of Persian Gulf for crude oil biodegradation.Material & Methods: In this applied-fundamental study, first oil degrading bacteria were isolated from the coastal sediments of Persian Gulf and were enriched in media. The isolated bacterium was identified using molecular identification based on 16S rRNA sequence. The oil degrading ability of the isolates was assessed using various concentrations of crude oil.Results: Based on molecular approaches the isolated bacterium was identified as Alcanivorax dieselolei. This bacterium was able to disintegrate oil droplets stably in less than one minute. Results showed that the biodegradation rates at 1, 2.5 and 5% concentrations of crude oil were68.37, 67.97 and 13.2% respectively.Conclusion: Since Alcanivorax genus is an indigenous bacterium in hydrocarbon polluted marine environments and its capability in biodegradation of crude oil has been proved, using this bacterium to remove oil pollutants is certainly possible.

Background & Objectives: Ectomyelois ceratoniae is one of the main pests of pomegranate. By now, no pesticides showed efficient effects on this pest. Biological control, such as changes in the reproduction ability, is a new emerged strategy for control of the population of this pest. This study was aimed to identify the symbiont bacteria in Ectomyelois ceratoniae and to determine their taxonomic classification.Materials & Methods: In this study, totally 100 infected pomegranate were randomly collected from different parts of Fars providence. After DNA extraction from ovum of the insects, a PCR approach was used to identify any symbiont bacteria in this samples. Following sequencing of the products and their analysis on gene banks, the taxonomic classification of Wolbachia was determined using ClusalX and Tree View.Results: In this study only one sample collected from shiraz was contaminated to Wolbachia. After amplification of wsp gene, OCR produced a 513 bp fragment which is available in gene bank under accession number KF007903. Analysis of the fragment in gene bank showed that this bacterium belonged to subclass Fur8 from group B, referred to as Wolbachia pipientis.Conclusion: According to our knowledge, the present study is the first report of the presence of Wolbachia in E. ceratoniae. Since the sampling were performed through June to August, the low prevalence of the bacterium Wolbachia sp. in these area can be due to effects of temperature, which is an inhibitory factor for growth of the bacterium in the insect.

Background & Objectives: Due to pleomorphic feature of Cyanobacteria in different conditions, confirmation of their identification required several phytochemical, physiologic, molecular and genetic analysis after preliminary morphological analysis. This study is the first report in Iran in which was aimed to identify Cyanobacteria Leptolyngbya sp. Isc25 based on molecular approaches and to analyze their morphologic response to monochromatic red, green and blue light rays.Material & Methods: In order to investigate the morphologic responses of Leptolyngbya sp. Isc25, the purified isolate of this Cyanobacterium in BG11 media were exposed first to autotrophic conditions (white light) and then to to monochromatic red, green and blue light rays. The morphological responses, flock production, structural changes, biometry and situation of trichome of Leptolyngbya sp. were evaluated using light microscopy and scanning electron microscopy (SEM) at different time periods, daily, weekly and monthly.Results: Based on the morphologic and biometric analysis of the samples using light and scanning electron microscopy, the morphology and growth factor of this Cyanobacteria was affected by different environmental factors, and the best adaptation is obtained in green and red lights in comparison to blue light. Leptolyngbya sp. produced special cells with red pigments in their wall in case of exposure to green and red lights, which confirmed the variability of this species.Conclusion: The results show that Leptolyngbya sp. has morphological diversity and response differently in each light condition.