Prevalence and Characterization of Plasmid-mediated Quinolone Resistance Genes among Escherichia coli Strains Isolated from Different Water Sources in Alborz Province, Iran

BACKGROUND: This study was conducted to investigate the prevalence of quinolone resistance associated (qnr) antibiotic resistance among Escherichia coli strains isolated from different water sources in Alborz province, Iran.METHODS: E. coli strains were isolated and identified by standard microbiological and biochemical tests from surface water sources in Alborz province, Iran in 2013. Fluoroquinolone-resistant isolates were determined using the antimicrobial susceptibility test determined by the Kirby–Bauer assay. Total genomic and plasmid DNA were extracted by boiling method. The presence of qnr genes in all nalidixic-acid and ciprofloxacin-resistant E. coli strains was determined by Polymerase Chain Reaction (PCR). The PCR amplicons were visualized after electrophoresis stained with ethidium bromide.RESULTS: One hundred E. coli strains were isolated from the water sources examined in this study. As much as 22.7% and 7.3% of the isolates were resistant to nalidixic acid and ciprofloxacin respectively. While qnrS, qnrB and qnrA genes were detected in 28%, 9% and 1% of fluoroquinolone-resistant isolates respectively. All fluoroquinolone-susceptible isolates however did not contain any of the qnr genes.CONCLUSION: This study reflects an increasing prevalence of fluoroquinolone-resistant E. coli strains in surface water sources. Underlining the importance of surface water sources as reservoirs for dissemination of potentially pathogenic E. coli and horizontal gene transfer between other waterborne bacterial species. Other possible mechanisms of resistance should also be investigated for better characterization of quinolone-resistant E. coli isolates. Therefore, immediate measures are needed to control and treat water sources more effectively.KEYWORDS: antibiotic resistance, E. coli, qnr genes, water sources

Investigation of Carbapenem-Resistant AcinetobacterBaumannii Resistance Rate in Clinical Specimens of Newborns at Imam Khomeini Hospital in Tehran

Background: Carbapenem-resistant Acinetobacter Baumannii (CRAB) hospital infection poses a serious threat to the health of the newborns in neonatal intensive care units (NICU). The present study was conducted to evaluate the prevalence and resistance of hospital infections in the NICU ward at Imam Khomeini hospital in Tehran.Materials and Methods: The blaOXA-51 like gene was investigated with polymerase chain reaction (PCR). Then, sensitivity of isolates to different antibiotics was assessed using disc diffusion method and broth micro dilutions to determine the minimum inhibitory concentrations (MICs). Pulsed field gel electrophoresis (PFGE) was used for typing of randomly collected CRAB infection at different wards of this hospital. Results: A total of 10 CRAB infections were isolatedduringthe6-month study period, and it was found that 100% of them were positive forblaOXA-51-like gene in PCR assay.  All  isolates were resistant to all tested antibiotics, except colistin, polymyxin B, and tigecycline. CRAB isolates had a high MIC values for imipenem, cefotaxim, and amikacin, showing multidrug resistant (MDR) phenotype. According to PFGE analysis,3palsotypes including clone A (7%), clone B (2%), and clone D (1%) were seen in the 10 CRAB isolates. Clone A was a dominant clone and spread in different wards of the hospital, especially in other ICUs and the emergency ward. Moreover, the similarity between the palsotypes showed the ability of transferring CRAB infection from different wards of the hospital to the NICU.Conclusions: Based on the results of this study, CRAB infection, with a high resistance rate, has the ability to enter into important wards such as NICU, and thus it is highly important to control the presence of these isolates in different parts of the hospital

Assessing the Genetic Diversity of Isolated Cd and Cu Resistant Non-fermenting Gram-negative Bacilli from Waste Water by Using Molecular Markers

Introduction: One of the best methods to remove pollutions resulted from heavy metals in industrial wastewater is biological removing. The first step in this way is identifying and clustering microorganisms especially, resistant bacteria to these metals. Material and methods: In this research, 17 non-fermenting gram-negative bacilli were isolated and identified from industrial wastewater. Their MIC was determined by different concentrations of Cu and Cd. With CTAB and Dellaporta, methods were extracted bacterial DNA. Then evaluated genetic diversity by 7 RAPD, 3 ISSR markers. The similarity matrix was calculated by using NTSYS-pc software based on Jaccard’s coefficient for genotypes and dendrogram was drawn in UPGMA method. Results: 133 bands were identified by using 10 markers that they included 122 polymorphic bands and 11 monomorphic bands. This markers show high level of polymorphism among the bacteria studied. Discussion and Conclusion: In the study cluster analysis and dendrogram drawn based on RAPD and ISSR markers together, there was a significant match between genetic diversity of markers and genetic diversity based on the MIC values. The combined use of both markers for genetic clustering based on resistance to copper and cadmium was more accurate. Principal component analysis was performed to complete the results of cluster analysis and 2-D, 3-D plots were drawn. The results of comparing these two methods showed that these markers had been properly selected for studying genetic diversity, and it was recommended using cluster analysis

RAPD PCR Profile, Antibiotic Resistance, Prevalence of armA

The increasing prevalence of multidrug-resistant Klebsiella pneumoniae strains isolated from hospitals shows the limitation of recent antibiotics used for bacterial eradication. In this study, 81 K. pneumoniae isolates were collected from three hospitals in Tehran. Antibiotic susceptibility test showed the highest rates of resistance to cefotaxim (85.5%) and ceftazidime (78.3%), and the lowest rates of resistance were detected for colistin (16.9%), streptomycin (16.8%), and chloroamphenicol (21.7%). Eleven different resistance patterns were observed. Sixty-six out of 81 isolates (81.5%) were found to be multidrug resistant (MDR), and 35.8% of them belonged to A3 resistance pattern. 7.4% and 66.7% were KPC enzyme and armA gene positive, respectively. RAPD PCR assay of these bacteria showed 5 clusters, 16 single types, and 14 common types, and there was not any correlation between genetic patterns of the isolates and presence of resistance agents. Simultaneous detection of resistance-creating agents could be an important challenge for combination therapy of MDR K. pneumoniae-caused infections

High prevalence of OXA-type carbapenemases among Acinetobacter baumannii strains in a teaching hospital of Tehran

Nosocomial infection caused by carbapenem-resistant Acinetobacter baumannii (CRAB) has created a public health concern all around the world. In this study, 100 isolates of CRAB from hospitalized patients during 2015–2016 at Imam Khomeini Hospital were investigated to determine the rates of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains using Kirby–Bauer disk diffusion method. The minimum inhibitory concentrations (MICs) of six antibiotics were determined by broth microdilution method. Multiplex polymerase chain reaction (PCR) was performed to detect blaOXA-51 like and blaOXA-58 like, blaOXA-23 like, and blaOXA-24 like that are encoding resistance to carbapenems. All CRAB isolates were MDR and XDR and 2% of them were pandrug-resistant (PDR), whereas colistin, polymyxin B, and tigecycline were the most effective agents. All isolates were positive for blaOXA-51 like by PCR. The frequency of blaOXA-23 like and blaOXA-24 like was 81% and 22%, respectively. Findings of this study showed that very few therapeutic options remained for the treatment of CRAB infections and blaOXA-23 like is a dominant resistance gene in CRAB at this hospital

Use of cost effective and rapid molecular tools for identification of Candida species, opportunistic pathogens

Background and Purpose :Candidiasis is a widespread fungal infection caused by different Candida species. Rapid identification of Candida species in clinical laboratory is becoming increasingly important since the identification and discrimination of ethological agents for early treatment. We aimed at molecular identification of commonly Candida species isolated from clinical samples by using both PCR-RFLP assay and amplification of hwp1 gene. Materials and Methods: Clinical samples comprising of vaginal specimens ,cutaneous, sputum, bronchoalveolar lavage (BAL,( and blood cultures were recovered from suspected patients. Candida isolates were initially identified phenotypically and confirmed by molecular approaches based on restriction fragment length polymorphism (PCR-RFLP (with MspI restriction enzyme. Amplification of hwp1 gene was performed for discrimination of C. albicans from C. dubliniensis and C. africana. Results: The most abundant species were C. albicans (n=67; 44.6 %), C. glabrata (n=10; 20 %), C. tropicalis (n=20; 13.3 %), C. krusei (n=12; 8 %), C. parapsilosis (n=11; 7.3 %). Out of 67 C. albicans species, 6 species identified as C. dubliniensis and 4 species identified as C. africana. Conclusion: High frequency of non-albicans Candida species and differences in levels of susceptibility to the antifungal agents are important issues in medicine .Therefore, to manage the Candida-related infections properly, molecular diagnostic methods would be fast, reliable and even cost-effective approaches for identification of Candida species

Study of Relationship between Genetic Pattern and Susceptibility to Terbinafine in Clinical Isolated of Trichophyton rubrum

Background & objectives: Trichophyton rubrum is one of the most common pathogeniccause of dermatophytosis. One of the drugs which have been prescribed widely for fungal infections is terbinafine which belongs to allylamines group of antifungal agents. Recently molecular typing methods have been developed for answering the epidemiological questions and disease recurrence problems. Current study has been conducted on 22 isolates of Trichophyton rubrum obtained from patients randomly. Our aim was the investigation of correlation between genetic pattern and sensitivity to Terbinafine in clinical isolates of Trichophyton rubrum.   Methods: Firstly the genus and species of isolated fungi from patients have been confirmed by macroscopic and microscopic methods, then, the resistance and sensitivity of isolates against drug have been determined using culture medium containing defined amount of drug. In next step fungal DNA has been extracted by RAPD-PCR (random amplified polymorphic DNA) with random sequences of 3 primers.   Results: Each primer produced different amplified pattern, and using each 3 primers differences have been observed in genetic pattern of resistant and sensitive samples using each 3 primers, but there was no bond with 100% specificity.   Conclusion: The 12 sensitive isolates which didn’t grow in 0.1 mg concentration of drug, also had limited growth at the low concentration of drug. Ten resistant isolates which grew in 0.1mg/ml of drug, in lower concentration of drug were resisted. RAPD analysis for molecular typing of Trichophyton rubrum seems to be completely suitable

Prevalence and Characterization of Plasmid-mediated Quinolone Resistance Genes among Escherichia coli Strains Isolated from Different Water Sources in Alborz Province, Iran

BACKGROUND: This study was conducted to investigate the prevalence of quinolone resistance associated (qnr) antibiotic resistance among Escherichia coli strains isolated from different water sources in Alborz province, Iran.METHODS: E. coli strains were isolated and identified by standard microbiological and biochemical tests from surface water sources in Alborz province, Iran in 2013. Fluoroquinolone-resistant isolates were determined using the antimicrobial susceptibility test determined by the Kirby–Bauer assay. Total genomic and plasmid DNA were extracted by boiling method. The presence of qnr genes in all nalidixic-acid and ciprofloxacin-resistant E. coli strains was determined by Polymerase Chain Reaction (PCR). The PCR amplicons were visualized after electrophoresis stained with ethidium bromide.RESULTS: One hundred E. coli strains were isolated from the water sources examined in this study. As much as 22.7% and 7.3% of the isolates were resistant to nalidixic acid and ciprofloxacin respectively. While qnrS, qnrB and qnrA genes were detected in 28%, 9% and 1% of fluoroquinolone-resistant isolates respectively. All fluoroquinolone-susceptible isolates however did not contain any of the qnr genes.CONCLUSION: This study reflects an increasing prevalence of fluoroquinolone-resistant E. coli strains in surface water sources. Underlining the importance of surface water sources as reservoirs for dissemination of potentially pathogenic E. coli and horizontal gene transfer between other waterborne bacterial species. Other possible mechanisms of resistance should also be investigated for better characterization of quinolone-resistant E. coli isolates. Therefore, immediate measures are needed to control and treat water sources more effectively.KEYWORDS: antibiotic resistance, E. coli, qnr genes, water sources </jats:p