فهرست مطالب

Medical Bacteriology - Volume:5 Issue: 5, 2016
  • Volume:5 Issue: 5, 2016
  • تاریخ انتشار: 1395/09/28
  • تعداد عناوین: 6
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  • Laila Goudarzi, Rouha Kasra Kermanshahi, Zahra Mousavinezhad, Mohammad Mehdi Soltan Dallal Pages 1-12
    Background
    Proteus spp. belongs to the family of Enterobacteriaceae. These bacteria are Gram-negative and motile microorganisms and known as the third most common causes of urinary tract infections. The aim of the current study was to investigate the effects of some secondary metabolites from probiotic strains of Lactobacillus spp. on swarming and growth of Proteus mirabilis and P. vulgaris.
    Methods
    After determination of optimal conditions for the growth and production of antimicrobials, bacteriocins and biosurfactants were partially purified from Lactobacillus culture supernatants. Then, effects of the purified compounds on growth and swarming migration of Proteus spp. were examined in the presence of various concentrations of semi-purified compounds.
    Results
    Results showed that the partially purified bacteriocins inhibited Proteus spp. swarming distance and had a significant reduction on the bacterial growth curves. Biosurfactants in a solvent form did not have any considerable effects on factors produced by Proteus spp.
    Conclusion
    According to the results, the secondary metabolites, especially bacteriocins or bacteriocin-like substances derived from Lactobacillus strains, can inhibit or reduce growth and swarming migration of Proteus spp. which are considered as the bacteria major virulence factors.
    Keywords: Bacteriocin, Biosurfactant, Proteus, Swarming
  • Abdol Rasoul Sobhani, Mahin Mallaei, Samaneh Kazemi Pages 13-20
    Background
    The increasing bloodstream infection mainly in developing countries is one of the most important health care systems concern. And, the choice of antimicrobial treatment for septicemia is often empirical and based on the knowledge of local antimicrobial activity patterns of the most common bacteria causing such bloodstream infections. This study was carried to identify the microbial profile in the blood culture isolates and their antibiotic susceptibility patterns.
    Methods
    This retrospective cross sectional study was done at Razi Hospital, Rasht, Iran over a period of thirteen months from August 2012 to September 2013. Bacteria were identified by various biochemical tests and antimicrobial susceptibility testing of the isolates was performed by Kirby-Bauer disc diffusion method.
    Results
    Out of 953 identified isolates, Gram-negative isolates 482 (50.58%) were followed by Gram-positive isolates 471 (49.42%). Among Gram-positive organisms Staphylococcus epidermidis was the highest with 255 (54%) records and in Gram-negative bacteria Pseudomonas spp. was highest with 241 (50%) records. There were 467 (49.0%) positive blood culture reports for males and 487 (51.0%) for females. Pseudomonas spp. (134 reports) and S. epidermidis (162 reports) were the most common pathogens in male and woman, respectively. In 15-44 years old age group, Pseudomonas spp. and in 45-75
    Conclusion
    It can be concluded that bacterial resistance to antibiotics which used against bloodstream infections can make complication in treatment of infection cause by these pathogens.
    Keywords: Anti-Bacterial Agents, Blood-Borne Pathogens, Bacteria
  • Maryam Dehghani, Azam Haddadi, Mahmoud Shavandi Pages 21-28
    Background
    AmpC β-lactamases are important cephalosporinases chromosomally encoded in many of Enterobacteriaceae and a few other organisms where they mediate resistance to cephalothin, cefazolin, cefoxitin and penicillins. The six different families of plasmid-mediated AmpC β-lactamases have been described, but no phenotypic test can discriminate among them. AmpC multiplex PCR has been successfully used to discriminate plasmid-mediated ampC specific families in organisms such as Klebsiella pneumonia and Escherichia coli. The aim of this study was to indicate the prevalence of AmpC β-lactamase genes by specifically designed primers through PCR test.
    Methods
    243 total clinical urine samples were collected, and 227 isolates were identified as Escherichia coli based on standard biochemical tests. Subsequently, the isolates were screened by disc diffusion and combined disc test for β-lactamase production. Resistant isolates were evaluated by PCR for ampC family determination.
    Results
    Antibiotic resistance pattern were observed as follows: cefepime (%25), ceftazidime (%31), ceftriaxone (%37), cefotaxime (%38). The ratio of isolates was detected as ESBLs and AmpC producers were 34% and 5.2%, respectively. PCR performed on 12 selected isolates via phenotypic tests and the results revealed that among 12 isolates, 11 contained blaCMY-42.
    Conclusion
    Unfortunately, antibiotic resistance has become an increasingly critical problem in many countries like Iran and occurrence of isolates co-expressing AmpC-β-lactamases and ESBLs can create serious problems in the future. As antibiotic options in the treatment of AmpC β-lactamases and ESBLs producing organisms are extremely limited, molecular screening by laboratories is suggested to reduce the risk of therapeutic defeat.
    Keywords: Antibiotic Resistance, AmpC β, lactamases, ESBLs
  • Zahra Tahanasab, Sina Mobasherizadeh, Mehdi Moghadampour, Aliakbar Rezaei, Nafiseh Maleki, Jamshid Faghri Pages 29-38
    Background
    This study was to evaluate the prevalence of CTX-Mand TEM type ESBLs-producing K. pneumoniae and determination of MDR, XDR, and PDR phenotypes of these isolates as well as find out the genetic relationship and molecular typing of these isolates using phenotypic and genotypic methods.
    Methods
    Non-repetitive 96 K. pneumonia isolates were isolated from hospitalized patients in Al-Zahra hospital of Isfahan, Iran. The antibiotic susceptibility test was assessed for 20 antibiotics using Kirby-Bauer disk diffusion method. The frequency of ESBL-producing isolates was determined by phenotypic confirmatory test. All ESBLs-producing isolates were assessed for blaTEM and blaCTX-M genes using PCR method. Molecular typing was performed by enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR).
    Results
    Among 96 isolates, 58 isolates (60.4%) were ESBL-producers. In this study, 85.7% and 30.3% of ESBL-producing isolates showed MDR and XDR phenotypes, respectively. No PDR isolate was found. PCR amplification on ESBL-producing isolates showed that 47 (81%) isolates were carried blaTEM gene, while blaCTX-M was detected in all isolates (100%). ERIC-PCR typing was characterized the high genetic similarity among ESBL-producing K. pneumonia isolates and revealed 32 band pattern for the isolates.
    Conclusion
    This study showed high prevalence of important ESBL genes (blaCTX-M and blaTEM genes) among the K. pneumoniae isolated from in-patients. Constant following of ESBLs, also identification of their types, in bacteria isolated from hospitalized patients has an important clinical impact. It can provide valuable information for the choice of appropriate antibacterial therapy and decrease of antibiotic resistance.
    Keywords: Klebsiella pneumoniae, MDR, ESBLs, TEM, CTX-M, ERIC-PCR
  • Maryam Moghadasi, Mohsen Mirzaee, Mohammad Reza Mehrabi Pages 39-45
    Background
    Klebsiella pneumoniae is among the most common and significant agents of community and hospital-acquired infections. Plasmid mediated quinolone resistance (PMQR) was increasingly identified in Enterobacteriaceae family worldwide. Plasmid-mediated quinolone resistance (PMQR) was first reported in 1998 from a Klebsiella pneumoniae isolate in the USA. Till date, five Qnr proteins have been identified; QnrA, QnrB, QnrC, QnrD and QnrS. Quinolone are broad spectrum antibiotics the resistant to which has increasingly been reported among many bacterial species including Klebsiella. The aim of this study was the antibiotic resistance profile was determined based on resistance and molecular characterization of qnrB and qnrC genes in Klebsiella pneumoniae clinical isolated.
    Methods
    In this cross sectional study, 94 samples of K. pneumoniae were collected. Isolates were screened for quinolone antibiotics resistance using disk diffusion method according to clinical and laboratory standards institute (CLSI) guidelines. Isolates with resistance to at least one of the quinolone antibiotics, examined for presence of the qnrB and qnrC genes.
    Results
    Based on the obtained results by the Agar disk diffusion test, 29.78%, 27.65%, 28.72% and 27.65% of the isolates were resistant to nalidixic acid, ciprofloxacin, norfloxacin and ofloxacin, respectively. Of these 46.66% carried qnrB, 3.33% carried qnrC genes.
    Conclusion
    The identification of qnrB gene among quinolone-resistant K. pneumoniae isolates shows that the emergence of PMQR in this region requires serious preventive measures.
    Keywords: Klebsiella pneumoniae, Quinolone Resistance, qnr Genes
  • Moslem Papizadeh, Hossein Nahrevanian, Mahdi Rohani, Seyed Nezamedin Hosseini, Seyed Abbas Shojaosadati Pages 46-59
    Probiotics, living microorganisms which when used in adequate amounts, have health benefits on the host, have attracted a considerable deal of interest in the biotechnology market. Various prokaryotic and eukaryotic microbes have been studied for probiotic purposes in human and animals. Lactobacillus and Bifidobacterium are the main probiotic genera; however, there are reports on the probiotic potential of strains belonging to Bacillus, Lactococcus, Pediococcus and also some yeast species. Lactobacillus species are regarded as the most investigated beneficial microbes for human and either animal probiotic development due to: a) anti-inflammatory effects, b) anti-allergic features, c) secretion of antimicrobial compounds, d) develops in aerobic and anaerobic conditions, and e) many Lactobacilli have been Generally Recognized As Safe (GRAS) by the Food and Drug Administration (FDA). Among Lactobacilli, Lactobacillus rhamnosus Gorbach-Goldin (GG) is known among the most in-detail studied strains and is regarded as a top well-researched and commercialized probiotic strain in the industrial biotechnology. Strain GG is a commercially significant probiotic which was originally isolated from the healthy human gastrointestinal tract in 1983. The documents studied this strain were reviewed here and it is shown that such successful strains in the probiotic market have been extensively studied from the probiotic traits and safety point of views and a minor part of the documents concerned the bioprocessing issues. Also, we showed that the beneficial and negative effects of this strain has been investigated in various clinical trial systems when it became commercialized. Various aspects of this strain are here reviewed, comparatively.
    Keywords: Lactobacillus rhamnosus Strain GG, Generally Recognized as Safe (GRAS), Industrial Strain, Probiotics