فهرست مطالب

Medical Bacteriology - Volume:4 Issue: 5, 2016
  • Volume:4 Issue: 5, 2016
  • تاریخ انتشار: 1394/12/13
  • تعداد عناوین: 8
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  • Baharak Akhtardanesh, Reza Ghanbarpour, Elmira Yazdani Pages 1-6
    Background
    This study was set to detect extended-spectrum beta-lactamases (ESBLs) producing E. coli isolates and the genes underlying their resistance in relation to phylogenetic background from fecal samples of healthy owned cats.
    Methods
    A total of 50 E. coli isolates were confirmed by standard bacteriological tests. The phylogenetic analyses of the isolates were carried out by combinations of three genetic markers chuA, yjaA and DNA fragment TspE4.C2 by a triplex PCR method. The ESBL (blaCTXM, blaTEM, blaSHV, blaOXA) encoding genes were detected. To identify ESBL producing phenotypes, all selected isolates were screened with a double disk synergy test including cefotaxime, cefotaxime with clavulanic acid, ceftazidime and ceftazidime with clavulanic acid.
    Results
    Results showed that E. coli isolates fell into four phylogenetic groups (A, D, B1 and B2) with prevalence of 78%, 4%, 8%, 10% and five phylogenetic subgroups including A (74 %), A1 (4 %), B1 (8 %), B2–2 (6 %), B2–3 (4 %) and D1 (4 %), respectively. Among all E. coli isolates, 4% were positive for blaSHV, blaCTX-M-15 and blaOXA-1 genes which distributed in B2-2, B2-3, A0 subgroups, respectively. According to antibiotic susceptibility test, 20 isolates were resistant which belonged to D (D1 phylogenetic subgroup) and A (A0 phylogenetic subgroup) groups.
    Conclusion
    The results showed that healthy cats could be considered as potential source for the dissemination of ESBL-encoding genes. Further investigations in companion animals and their owners are needed to clarify the importance of spreading of these zoonotic strains.
    Keywords: Escherichia coli, Extendedspectrum β lactamase, Phylogenetic group, cat
  • Behzad Ghasemi, Hamid Beyzaei, Seyed Hadi Hashemi, Hamidreza Majidiani Pages 7-12
    Introduction
    Escherichia coli is one of the important pathogens in human with global importance. Because of the necessity for identification and the use of novel antibacterial compounds against E. coli, in this present study we focused on the antibacterial effects of synthesized thiazole, imidazole and tetrahydropyridine derivatives on E. coli.
    Methods
    For evaluation of antibacterial effect, the disk diffusion method was applied to measure the growth inhibition zone diameter and broth micro-dilution was performed to determine the minimum inhibitory concentration (MIC).
    Results
    Assessing the antibacterial effect showed that only 6d derivative of thiazole had inhibitory effect on E. coli and the other thiazole, imidazole and tetrahydropyridine derivatives lacked any inhibitory result on this organism. The inhibitory effect of 6d derivative of thiazole was MIC=125 and growth inhibition zone diameter of 16±0.1.
    Discussion
    The antibacterial effect of thiazole, imidazole and tetrahydropyridine derivatives differs from each other and chemical linkages such as oxygen to thiazole ring in 6d derivative, could have reinforced this effect. The next step is determination of the toxicity and therapeutic effects in the laboratory animals.
    Keywords: Antibacterial effect, imidazole, thiazole, tetrahydropyridine, Escherichia coli
  • Mohammad Mehdi Soltan Dallal, Enayatollah Kalantar, Laya Kafami Khorasani, Mohammad Hassan Hoshdar Tehrani, Monireh Zeinolabedini Zamani Pages 13-18
    Background
    Staphylococcus aureus strains exhibiting multiple antibiotic resistances are isolated from most communities and hospital infections. Treatment of patients with these infections has been difficult. The aim of this study was to detect and extract, the egg yolk immunoglobulin Y as a potential source of anti- S. aureus antibody.
    Methods
    Specific IgY was produced by immunizing hens with formalin-killed S. aureus. The specificity of serum`s antibody was confirmed by ELISA method. The antibodies were extracted from egg yolk by polyethylene glycol (PEG) precipitation. Proteins were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).
    Results
    Chicken egg yolk antibodies (IgY) were raised against S. aureus in the serum after injections. Up to 104 dilution specific antibodies were determined in serum.
    Conclusion
    The results of the ELISA indicates the specificity of the immunoglobulin Y to the target antigen. In order to find a viable alternative to antibiotic treatments, more research must be done on the ability of these antibodies to inhibit the growth of S. aureus.
    Keywords: Staphylococcus aureus, Serum, ELISA, Polyethylene Glycol
  • Mohammad Khalili Pages 19-23
    Background
    Q fever is a zoonotic disease caused by inhalation of the bacterium Coxiella burnetii. Ruminant livestock are common reservoirs for C. burnetii, and bacteria present in aerosols derived from the waste of infected animals can infect humans. C. burnetii is thought to infect humans primarily via airborne transmission.
    Methods
    64 environmental swab samples were collected from 24 sheep and goat farms in Southeast Kerman province (Iran).
    Results
    In this study touchdown nested trans- PCR were used for detection of C. burnetii in environmental samples. We detected C. burnetii DNA in inhalable dust samples collected at 5 farms.
    Conclusion
    This first report in Iran highlighted presence of C. burnetii in dust originated from goat and sheep farms and that role in human infections with disseminating by wind.
    Keywords: Coxiella burnetii, Dust, PCR, Kerman, Iran
  • Hashem Fakhre Yaseri, Mehdi Shekaraby, Hamid Reza Baradaran, Seyed Kamran Soltani Arabshahi Pages 24-30
    Background
    Helicobacter pylori strains have two classical virulence genes, the cytotoxinassociated A (cagA) gene and the vacuolating cytotoxin A (vacA) gene, which are located in the cag pathogenicity island (cagPAI). Serum immunoglobulin G (IgG) antibodies to H. pylori, especially, the CagA antigen may be a reliable marker for selection of dyspeptic patients for upper endoscopy.
    Methods
    Serum sample of 129 dyspeptic patients with positive H. pylori, were tested for serum IgG Anti-CagA antibody by ELISA. The presence of the cagA and vacA genotypes were determined using polymerase chain reaction (PCR) on biopsy samples taken via endoscopy.
    Results
    Positive serum IgG anti-CagA antibodies in patients with cagA+/vacA+ and cagA+/vacA- genotypes were 22/23 (95.6%) and 18/19 (94.7%), respectively. In addition, serum IgG anti-CagA antibodies in patients with cagA-/vacA+ and cagA-/vacA- genotypes were 22/47 46.8%) and 33/40 (82.5%), respectively.
    Conclusions
    It can be concluded that the serum IgG anti-CagA antibody alone could select patients with dyspepsia following upper endoscopy. The assessment of vacuolating cytotoxin activity of H. Pylori is, therefore, not required, even when vacA gene is positive. This hypothesis needs to be studied in a large number of patients with dyspepsia.
    Keywords: Dyspepsi, cagA, vacA
  • Vajihe Karbasizade, Leila Heidari, Reyhaneh Jafari Pages 31-36
    Background
    Acinetobacter baumannii as one of the causes of nosocomial infections has become resistant to almost all antimicrobial agents. The emergence of resistance to carbapenems, one of the last drugs on the shelf, is the major concern about A. baumannii antimicrobial resistance. Resistance to carbapenems is mediated by production of class B and D carbapenemases. The aim of this study was to detect the resistance genes including blaOXA-23, 24, 51, and 58 in A. baumannii isolates from nosocomial infections in Isfahan hospitals.
    Methods
    A total number of 456 clinical specimens were collected from nosocomial infections and evaluated in order to isolate A. baumannii strains. After identification of the isolates, the antibiotic sensitivity to carbapenems was assessed using disk diffusion method. The resistance genes of bla OXA-23, 24, 51, and 58 were detected by multiplex PCR method.
    Results
    Fifty A. baumannii isolates were isolated from clinical specimens. Fifty two percent of the isolates showed phenotypic resistance to the carbapenems (imipenem and meropenem). According to PCR results, 88% of resistant isolates had ≥1 blaOXA gene. The frequency of resistant isolates bearing blaOXA-23, blaOXA-24 and blaOXA-58 were 77%, 38% and 15% respectively.
    Conclusions
    This study showed the high frequency of carbapenem resistance genes among A. baumannii isolates. Therefore, adopting an appropriate strategy to confine the spreading of these strains and also implementing new treatment regimens are necessary.
    Keywords: Acinetobacter baumannii, Nosocomial infection, OXA, Type carbapenemase, imipenem, meropenem
  • Tanaz Zabihi, Vajihe Karbasizade, Ali Mohammad Ahadi Pages 37-41
    Background
    These days, the antibiotic resistance of Pseudomonas aeruginosa isolates to imipenem has significantly increased. Therefore the study of resistance to imipenem in this organism to imipenem in determining the appropriate treatment is crucial and necessary. The goal of this study is to compare three phenotypic methods of E-test, disk diffusion and micro broth dilution in the study of resistance to imipenem in clinical isolates of P. aeruginosa.
    Methods
    Within a 6-month interval, 120 clinical specimens were collected and evaluated. All isolates were identified as P. aeruginosa by standard biochemical tests and amplification of 16S rRNA gene. Three phenotypic methods of E-test, disk diffusion, and micro broth dilution were used to determine imipenem resistance in P. aeruginosa isolates.
    Results
    Of the 96 P. aeruginosa isolates studied for their resistance to imipenem by the use of E-test, disk diffusion and micro broth dilution methods, 38.5% of the strains in micro broth dilution method and 33.3% in the two methods of E-test and disk diffusion were resistant to imipenem. The rate of sensitivity and specificity of disk diffusion and E-test methods were 100%, 90.1%, and they were 100% and 83.1% for micro broth dilution, respectively.
    Conclusions
    With regard to the results obtained from the comparison of the three methods 100% agreement were observed among the antimicrobial susceptibility results obtained by the Etest and disk diffusion methods (P ≥ 0.05). Therefore, the use of disk diffusion method can be an appropriate replacement for E-test method with regard to its being easy and cost effective.
    Keywords: Disk Diffusion test, imipenem, Pseudomonas aeruginosa
  • Mohammad Mehdi Soltan Dallal, Abbas Rahimi Foroushani, Sara Sharifi, Yazdi, Mohammad Kazem Sharifi, Yazdi, Noushin Arfatahery Pages 42-46
    Background
    During fishing and transport, preservation and quality of fish products are important as well as storage to prevent the growth of pathogenic and toxin producing bacteria. Staphylococcus aureus is one of the most common causes of sea food-borne diseases worldwide due to contamination of food by preformed enterotoxins. The aim of this study was to compare the prevalence and contamination of S. aureus in marine and farmed shrimps in Tehran fishery center.
    Methods
    A total of 300 samples, including 150 marine, 150 farmed shrimps were selected during September 2013 to December 2014. Isolation and identification of S. aureus from isolated samples were carried out according to conventional methods, and antibiotic susceptibility test was performed by modified Kirby-Bauer disc diffusion method.
    Results
    The results of this study showed that 30% of marine and 20% off armed shrimps were contaminated with S. aureus. The highest resistance was observed with penicillin and ampicillin, whereas 100% were sensitive to vancomycin, clindamycin, ciprofloxacin, and rifampin.
    Conclusions
    Due to relatively high contamination of shrimp by S. aureus more attention should be given during processing and manufacturing.
    Keywords: Staphylococcus aureus, Sea food, shrimp