Iranian Journal of Microbiology
Volume:7 Issue: 1, Feb 2015

Carbapenem resistant Pseudomonas aeruginosa is a serious cause of nosocomial infections. The main purpose of the study is to determine the prevalence rate of imipenem resistant Pseudomonas aeruginosa carrying metallo- beta- lactamase (MBL) genes. 236 Pseudomonas aeruginosa isolates were collected from teaching hospitals of Ahvaz University of Medical Sciences during a period of 9 months in 2012. These strains were identified using conventional microbiological tests. The susceptibility of isolates to antibiotics were assessed using disk diffusion test. The IMP-EDTA combination disk phenotypic test was performed for detection of MBL producing strains. Finally, polymerase chain reaction (PCR) was performed to detect MBL genes, blaIMP-1, blaVIM-2 and blaSPM-1 in imipenem resistant strains. Out of 236 examined isolates, 122 isolates (51.4%) were resistant to imipenem. The IMP-EDTA combination test showed that among 122 imipenem resistant strains, 110 strains (90%) were phenotipically MBL producers. Additionally, the results of PCR method showed that 2 strains (1.6%) and 67strains (55%) of imipenem resistant Pseudomonas aeruginosa isolates contained blaVIM-2 and blaIMP-1 genes respectively. No SPM-1gene was found in the examined samples. Resistance of P. aeruginosa isolates to imipenem due to MBL enzymes is increasing in Ahavaz. Because of clinical significance of this kind of resistance, rapid detection of MBL producing strains and followed by appropriate treatment is necessary to prevent the spreading of these organisms.

Pseudomonas aeruginosa is one of the most important Gram negative opportunistic bacteria which causes infection among burn patients. Resistance to the antibiotics in this group of bacteria is increased due to the activity of extended spectrum β-lactamase (ESBLs) genes. In the current study, we investigated the prevalence of two genes (blaPER-1 & blaOxa10) related β-lactamase genes among imipenem resistance clinical isolates of P. aeruginosa in hospitalized patients. From May 2010 to March 2011, 270 P. aeruginosa isolated from hospitalized burned patients’ wounds in Shiraz Burn Hospital, were tested for Imipenem resistance by disk diffusion method. Presence of ESBLs exo-enzyme, blaPER-1 and blaOxa10 genes were also evaluated in the resistant isolate. 210 (77.7%) of 270 P. aeruginosa isolates were resistant to imipenem. blaPER-1 and blaOxa10 were detected among 168 (80.0%) of imipenem resistant isolates. Furthermore, 160 (76.2%) of them had blaOxa10 gene and 84 (40.0%) of them had blaPER-1 while 63 (30.0%) resistant isolates contained both genes simultaneously. This study showed a high prevalence of blaPER-1 and blaOxa10 genes in hospitalized burn patients in south west of Iran. Therefore, it’s highly recommended to perform such tests routinely to evaluate the resistance pattern in order to better antibiotic selection in the burned patients.

Streptococcus pneumoniae is the main causative agent of acute bacterial meningitis in the world. This study aimed to detect pneumoniae infection in cerebrospinal fluid (CSF) samples of patients with suspected meningitis. In this study, 200 CSF samples in patients with suspected meningitis and with negative bacterial cultures were tested. Demographic data of patients and the laboratory analysis of CSF samples were also collected in a questionnaire. Pneumococcal capsular gene spn9802 was examined by real-time PCR technique. Of 200 CSF samples from patients with the average age of 32.1±25.3 year old, 20 were positive for S. pneumoniae in patients with the average age of 35.05±24.6. The biochemical and cytological analysis of positive samples showed significant changes, including, 39.7 mg/DL protein, 46.2 mg/DL glucose and 1173 white blood cells per microliter of CSF on average. The results of this study showed the significant pneumococcal infection in culture negative CSF samples. The majority of this infection occurred in middle-aged patients and with a higher incidence rate in the winter. It seems that the traditional methods of cultivation are not sensitive enough to detect this bacterium in CSF. Alternatively, the molecular techniques such a real-time seem to be accurate, sensitive and rapid for the detection of this agent in CSF. The cytological and biochemical findings of CSF can provide valuable clues in the diagnosis of bacterial meningitis.

Chlamydophila psittaci is a lethal bacterium that causes endemic avian chlamydiosis, and respiratory psittacosis. Laboratory diagnosis of Chlamydophila psittaci is difficult by culture. This study was design to investigate the presence of Chlamydophila psittaci in collected pharyngeal swabs from asyptomatic pigeons by PCR. Pharyngeal samples from pigeons with no symptoms of disease (n=280) were collected during hot and cold seasons in different parts of Ahvaz. DNA was extracted from specimens and subjected to PCR targeting pmp genes and 16s-23s rRNA intergenic spacer of Cp. psittaci and chlamydiales specific primers. Of 280 samples 2 (0.7%) harbor were positive for chlamydiales (16s-23s intergenic spacer) and Cp. psittaci specific genes (pmp gene). In this research the pigeons were asymptomatic carriers for Cp. psittaci in their respiratory discharges. These results suggest that Cp. psittaci infection of human can occur in very close and continuous contact with pigeons.

Due to the evolution of multidrug-resistant strains, screening of natural resources, especially actinomycetes, for new therapeutic agents discovery has become the interests of researchers. In this study, molecular, chemical and biological screening of soil actinomycetes was carried out in order to search for peptide-producing actinomycetes. 60 actinomycetes were isolated from soils of Iran. The isolates were subjected to molecular screening for detection NRPS (non-ribosomal peptide synthetases) gene. Phylogenic identification of NRPS containing isolates was performed. Chemical screening of the crude extracts was performed using chlorine o-dianisidine as peptide detector reagent and bioactivity of peptide producing strains was determined by antimicrobial bioassay. High pressure liquid chromatography- mass spectrometry (HPLC-MS) with UV-visible spectroscopy was performed for detection of the metabolite diversity in selected strain. Amplified NRPS adenylation gene (700 bp) was detected among 30 strains. Phylogenic identification of these isolates showed presence of rare actinomycetes genera among the isolates and 10 out of 30 strains were subjected to chemical screening. Nocardia sp. UTMC 751 showed antimicrobial activity against bacterial and fungal test pathogens. HPLC-MS and UV-visible spectroscopy results from the crude extract showed that this strain has probably the ability to produce new metabolites. By application of a combined approach, including molecular, chemical and bioactivity analysis, a promising strain of Nocardia sp. UTMC 751 was obtained. This strain had significant activity against Staphylococcus aureus and Pseudomonas aeruginosa. Strain Nocardia sp. UTMC 751 produce five unknown and most probably new metabolites with molecular weights of 274.2, 390.3, 415.3, 598.4 and 772.5. This strain had showed 99% similarity to Nocardia ignorata DSM 44496 T.

The efficacy of Mentha piperita L, Zataria multiflora Boiss and Thymus vulgaris L essential oils (EOs) was evaluated for controlling the growth of Phytophthora drechsleri, the causative agent of damage to many crops that is consumed directly by humans. The EOs used in this study was purchased from Magnolia Co, Iran. The pour plate method in petri dishes containing Potato Dextrose Agar (PDA) was used to evaluate the antifungal properties of EOs. The minimal inhibitory concentrations (MIC), minimum fungicidal concentration (MFC) as well as mycelial growth inhibition (MGI) were measured. The IC50 value (the concentration inhibited 50% of the mycelium growth) was calculated by probit analysis.Results and The fungal growth was significantly reduced by increasing concentrations of tested EOs. The complete reduction was obtained with Shirazi thyme at all concentrations, whereas the complete reduction for peppermint and thyme was observed at 0.4% and 0.8% (v/v) concentrations, respectively. Meanwhile, the minimum inhibition was observed when 0.1% peppermint (MGI values of 9.37%) was used. The IC50, MIC and MFC values of Shirazi thyme was 0.053, 0.1% and 0.2%, respectively. Similarly, MIC and MFC values of peppermint and thyme were recorded 0.4% and 0.8%, respectively. The results obtained from this study may contribute to the development of new antifungal agents to protect the crops from this pathogenic fungus and many agricultural plant pathogens causing drastic crop losses.

The genus Xanthomonas is composed of phytopathogenic bacterial species. In addition to causing crops diseases, most of the Xanthomonas species especially Xanthomonas campestris produce xanthan gum via an aerobic fermentation process. Xanthan gum is, an important exopolysaccharide from Xanthomonas campestris, mainly used in the food, petroleum and other industries. the purpose of this study was assessment of relationship between genetic diversity and xanthan production in Xanthomonas spp. In this study 15 strains of Xanthomonas spp. which had previously been isolated from soils of vegetable farms, were discriminated from each other using Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR and 16S rDNA sequencing methods. Xanthan production of strains was measured in 250 ml flask. The results of ERIC PCR and xanthan production was compared. ERIC-PCR patterns not only could differentiate all Xanthomonas campestis from the control i.e. Xanthomonas translucent but also discriminate strains of Xanthomonas to three clusters with 40% similarity based on Jaccard’s coefficient. This clustering of the strains was in agreement with other characteristics including xanthan production and biochemical features. The results showed that genomic fingerprinting conferred adequate genetic data for discriminating between strains of the species Xanthomonas campestris. The data indicated a partial relationship between ERIC-PCR patterns and xanthan production by the strains. Further development of experiments may result in making good prediction about xanthan production capabilitymof the Xanthomonas strains on the basis of ERIC-PCR method.

DNA molecular weight marker is widely used in molecular biology experiments incurring considerable costs on low-budget settings. Here a PCR-supported procedure is described that uses 10 primer pairs targeting chromosomal DNA from the harmless vaccinal Bacillus anthracis Sterne 34F2 strain as template. A single PCR protocol is used to reproduce all the 10 fragments of a 100 bp DNA size marker.Results and The unpurified amalgam of 10 PCR products can be directly loaded to agarose gels. This work was intended to develop a reasonably cost-effective DNA ladder that is useful for researchers in laboratories with limited funding.

Salmonellosis can be acquired through consumption of infected raw or undercooked eggs. The aim of this study was isolation and identification of Salmonella spp from the eggshells and the egg contents samples of Tabriz retails. A total number of 150 samples of eggs were analyzed for the presence of Salmonella spp. using conventional culture method and multiplex-PCR. Two (1.33%) out of 150 samples from eggshells were determined as contaminated with Salmonella spp. Salmonella spp was not isolated from the egg contents. Salmonella serovar was determined as enteritidis and typhimurium. The results of the present study provide the recent dataset of the prevalence of S. enteritidis and S. typhimurium in eggs at retail shops in the northwest of Iran. It is important to remember that control is required at all levels in the food chain and by separating cooked and raw.

Over the last two decades, both the incidence of nosocomial candidaemia and the proportion of blood stream infection due to Candida spp. other than Candida albicans have increased. The aims of this study was to identify different species of Candida and risk factors associated with bloodstream infection and detection of biofilm production. This study was conducted in an 840 bedded tertiary care hospital, over a period of one year. All blood isolates received from patients during this period were screened for candidemia prospectively. Speciation was carried out by standard microbiological method. Biofilm production detection was done by Brachini et al method. A total of 80 cases of candidemia were identified. Most important risk factor was placement of vascular access devices in all the age groups. Candida albicans accounted for 22 isolates (27.5%) whereas non-albicans Candida spp. accounted for 58 isolates (72.5%). Biofilm production was found in 31 strains (38.75%). Biofilm production was seen more in non-albicans Candidaspp. (83.87%) especially in C. tropicalis (66.67%, 8 of 12). Non-albicansspecies of Candida were most frequently recovered in our study. So, the epidemiology of Candida infection is changing. Non–albicans Candida spp have the capacity to produce significant amount of biofilm which may be the cause of their reduced susceptibility to antifungal agents.

Given the importance of rapid diagnosis for fungal rhinosinusitis, this study aimed to evaluate the use of nested PCR to identify Aspergillus and Mucor species in clinical samples from patients with suspected fungal rhinosinusitis. Functional endoscopic sinus surgery specimens were collected from 98 patients with rhinosinusitis from 2012 to 2013. All samples were ground and cultured on sabouraud dextrose agar. The isolated fungi were identified based on their macroscopic and microscopic features. Fungal DNA was extracted from the tissue samples and nested PCR was performed with two sets of primers for Mucor and Aspergillus. Direct microscopic showed that 5.1% contained fungal components and 9.2% exhibited growth of fungi in culture. The most common agents isolated were Aspergillus fumigatus (n= 3), Aspergillus flavus (n=2), Penicillium sp (n=3) and Alternaria sp. (n=1). Mucor sp. was identified in the pathology smear from 1 patient. Positive results for fungal rhinosinusitis were obtained for a total of 10.2% by culture or pathology smear. Positive PCR results were obtained in 72 samples for Aspergillus and 31 samples for Mucor. Our results suggest that endoscopic sinus surgery specimens are not suitable for nested PCR, probably because of the accumulation of fungi that contaminate the environmental air. This drawback is a limiting factor for diagnosis with nasal cavity specimens. Therefore, molecular methods and conventional culture techniques are helpful complementary diagnostic methods to detect fungal rhinosinusitis and determine appropriate management for these patients.