Vol 4 No 1-2 (2015)

Published: 2015-11-23

Original Articles

  • XML | PDF | downloads: 169 | views: 188 | pages: 1-7
    Introduction: One of the most important agents in hospital-acquired infections isStaphylococcus aureus. Treatment of methicillin-resistant S. aureus (MRSA) infections withdecreased susceptibility to vancomycin has recently been more difficult. The aim of this studywas to evaluate the possible presence of vancomycin intermediate S. aureus (VISA) andvancomycin- resistant S. aureus (VRSA) and also to determine the frequency of MRSA inclinical specimens.Methods: In this study, 195 S. aureus isolates were collected from the patients were examined.All of the isolates were identified using standard biochemical tests. Susceptibility of S. aureusisolates against 10 antibiotics was detected by disk diffusion method and was followed by E-testand vancomycin screen agar methods. Minimum inhibitory concentration (MIC) of vancomycinwas determined according to the CLSI guidelines. Also, detection of mecA gene was performedby PCR and finally, the results were compared.Results: All of the isolates were susceptible to vancomycin (i.e. MIC range of vancomycin wasbetween 0.25-2 µg/ml). Out of 195 S. aureus isolates, 99 isolates (50.8%) were resistant tomethicillin, and mecA gene was detected in 96 isolates. These results also showed that thehighest and lowest resistance rate of isolates was to penicillin (96.9%) and chloramphenicol(0%), respectively.Conclusion: Our findings showed that vancomycin can still be used as a valuable drug fortreatment of S. aureus infections in our region. However, periodic evaluation of vancomycinMIC of S. aureus isolates is critical for monitoring MRSA and preventing the spread of VISA orVRSA among patients.
  • XML | PDF | downloads: 279 | views: 222 | pages: 8-14
    Introduction: Nocardia is saprophytic soil bacterium of the actinomycetes families. Nocardiahas high diversity of species and due to species diversity of Nocardia, phenotypic tests areessential for early identification of Nocardia species.Methods: 155 soil samples from different regions of North Khorasan province in Iran werecollected, including: urban and rural areas. Isolation of Nocardia was performed by paraffinbaiting Technique. Identification of Nocardia species was performed by phenotypic methodsthat are including: hydrolysis of the amino acids, acid production of carbohydrates and, growthat 35° C and 45°C.Results: 11 Nocardia species (7%) were identified . These bacteria were related to the gardens,the sands soils, and soil of town square. No growth was observed at 45°C. As the result, ourisolates were identified as Nocardia asteroides complex.Conclusion: Isolation and identification of Nocardia spp. from soil of different regions in NorthKhorasan province in Iran can help to enhance our understanding of epidemiological andecological of the pathogenic Nocardia species.
  • XML | PDF | downloads: 288 | views: 223 | pages: 15-20
    Introduction: Streptococcus pneumoniae cause morbidity and mortality in infants and youngerchildren. Because of high prevalence of penicillin resistance, rapid and reliable diagnostictechniques for penicillin non-susceptible S. pneumoniae (PNSSP) are important for preventionand treatment. We investigated the association of the restriction length polymorphism (RFLP)patterns for pbp2b to distinguish between penicillin susceptible and resistant S. pneumoniaeisolates.Methods: In this study, a total of 70 pneumococcal isolates were collected from different clinicalsources. MIC of these isolates was determined and pbp2b gene was amplified by PCR and theywere digested by HaeІІІ enzyme.Results: Of the 70 isolates, 86% (60) and 14% (10) pneumococcal isolates were found to bePNSSP (penicillin intermediate S. pneumoniae (PISP) and penicillin resistant S. pneumoniae(PRSP)) and penicillin susceptible S. pneumoniae (PSSP). In addition, 10 RFLP patterns (A-J)which were based on the HaeІІІ digestion of pbp2b gene were observed. All PSSP isolatesshowed that they belonged to pattern D, whereas, all PNSSP showed 10 different patterns.Conclusion: In general, the present study suggests that RFLP can be a powerful tool indifferentiation between the penicillin resistant and susceptible strains.
  • XML | PDF | downloads: 175 | views: 180 | pages: 21-26
    Introduction: Antibiotics have the potential to adversely affect the microbial community. Foranaerobic digestion, a sufficient methanogenic population needs to be preserved in the system.The main aim of this study was determination of inhibitory concentration of oxytetracycline onmethanogenic bacteria.Methods: A 120 mL jacketed bioreactor with a 90 mL working volume was inoculated granularsludge from an anaerobic digester, substrate and different concentration of oxytetracycline with10 days cycles and intermittent mixing. The reactor was operated at 35 ± 2 ° C. The inhibitoryeffect of antibiotic was evaluated by monitoring biogas production.Results: Based on the findings from each batch, complete inhibitory concentration of oxytetracycline was in concentration of 800 mg L-1. Significant relation was seen betweeninoculated antibiotic concentrations and methane production (r=-0.86).Conclusion: The addition of antibiotics to the biomass affected the utilization of fatty acids,resulting in unfavorable effects on methanogenesis. Thus, overusing of antibiotics can adverseeffects of intestinal flora.
  • XML | PDF | downloads: 307 | views: 280 | pages: 35-42
    Introduction: Biofilm producing Staphylococcus aureus is known as one of the majorcausative agents of infections, failure of implanted devices and persistent infectionamong hospitalized patients. The aim of the present study was to determine thefrequency of biofilm producing S. aureus isolates amongst the clinical specimens.Methods: This cross-sectional study was conducted during 2012 to 2013 in twoteaching hospitals in Shiraz, southwest of Iran. Totally, 345 S. aureus isolates fromvarious clinical specimens were included. Biofilm producing isolates werephenotypically detected using Congo Red Agar (CRA) and genotypically by PCRassay for the icaA and icaD genes.Results: Of the 345 S. aureus isolates, 42.3% were methicillin-resistant S. aureus(MRSA) and subsequently 57.7% were methicillin susceptible isolates. The results ofCRA plates showed that 77 (52.7%) and 74 (37.2%) of MRSA and MSSA werebiofilm producing isolates. The frequency of icaA/D genes among MRSA and MSSAisolates was 127 (87%) and 167 (83.9%), respectively.Conclusion: Such a high rate of icaA/D harboring S. aureus among clinical isolatessuggest the risk for establishing persistent infections in the hospital settings.
  • XML | views: 261 | pages: 27-34
    Introduction: ESBLs are a B -lactamases which had ability to hydrolyse third-generationcephalosporins and aztreonam. ESBLs producer bacteria are resistant to a wide variety ofantimicrobials and they made a serious global health concern for treatment strategies. So, aim ofthis study as to molecular detection of ESBLs in bacteria isolated from blood cultures inhospitals from Kurdistan Province, Iran.Methods: Biochemical test, antimicrobial susceptibility test by disc method, ESBL detection byNCCLs Phenotypic and PCR method for ESBL detection were applied. Results were analyzedby using SPSS 11.5 (p < 0.05).Results: 96 S. epidermidis isolated from blood cultures, E. coli, Enterobacter spp., Klebsiellaspp., P. aeruginosa, Salmonella spp., C. freundii, S. maltophilia, also S. aureus, andS.epidermis. Maximum resistance was 75% for CP and minimum resistance was 25% for GM.Of the 96 isolates, 20 (20.83%) produced ESBLs. Also 11.46%, 20.83%, 12.5%, 9.38% and2.08% were positive for TEM, CTX-M, SHV, OXA-1 and OXA-2 ensymes, respectively.Conclusion: Inappropriate therapy for infections with ESBL producers is cause of prolongshospital stay and mortality. So, more research on drug resistance with ESBL is necessary.
  • XML | PDF | downloads: 228 | views: 274 | pages: 43-52
    Introduction: Staphylococcus aureus is a prominent human pathogen. One of the drugs used inthe treatment of staphylococcal infections (particularly infections of skin and soft tissue), isclindamycin. Resistance to clindamycin includes two types: inducible and constitutive. Routinelaboratory methods of antibiotic susceptibility testing cannot detect the inducible type and Dtest is required for its detection. The purpose of this systematic review was to determine therelative prevalence of this type of resistance in Iran.Methods: Search terms "inducible clindamycin resistant", "D-test", "Staphylococcus aureus"and "Iran" were used to find relevant articles in PubMed, Google Scholar and two Persiansearch engines. Also, the abstracts of the recent national microbiology congresses were checked.All studies used D-test to find iMLSB (inducible macrolide, lincosamide and streptograminBresistance) phenotype among clinical isolates (not nasal swabs) of S. aureus, were included. Inorder to perform meta-analysis, we used “comprehensive meta-analysis” software (ver. 2).Results: In total, 9 articles and 8 abstracts related to the topic of the study were found. Randomeffects meta-analyses showed a pooled estimate for percentage of iMLSB phenotype among2683 samples of S. aureus was about 10% (95% confidence interval: 0.07-0.12). Using the fixedeffect model, the odds of positive iMLSB in methicillin-resistant S. aureus was about 5 timesmore likely to occur in comparison with methicillin-susceptible S. aureus (95% CI: 3.49 to7.76).Conclusion: Fortunately, the relative frequency of inducible resistance to clindamycin in ourcountry is relatively low. However, we believe that D-test should be performed for allerythromicin-resistant isolates in order to identify inducible resistance to clindamycin.Moreover, reevaluation of inducible resistance to clindamycin in forthcoming years is highlyrecommended.
  • XML | PDF | downloads: 134 | views: 187 | pages: 53-57
    Introduction: Due to more resistance of pathogenic bacteria to new and currentantibiotics researchers are looking to find the agents of herbal with antimicrobialactivities in order to replace chemical drugs.Methods: The herbal extract of Withani somnifera was done by using a rotary vacuum,20 strains of Pseudomonas aeruginosa were isolated from urinary infections hospitalizedpatients in city of Zabol hospital. The MIC Withani somnifera were determined bydilution method in various concentrations. Sensitivity of strains to multiple antibioticswas evaluated by standard disk diffusion Kirby-Bauer.Results: The result showed that P. aeruginosa were resistance to 4 of the agentsincluding ampicillin (85%), nitrofurantoin (65%), nalidixic acid (65%), ciprofloxacin(15%) and for 5 strains of Pseudomonas showed MIC with activity of 100 ppm.Conclusion: This study has suggested the effect of winter cherry extract on P.aeruginosa in the in vitro assay. It s effectiveness of on in vivo system can be examinedin future.