Hossein Fazeli

Synthesis, antimicrobial evaluation and QSAR study of some 3-hydroxypyridine-4-one and 3-hydroxypyran-4-one derivatives.

A series of Mannich bases of 2-alkyl-3-hydroxy-pyridine-4-ones, namely 2-alkyl-3-hydroxy-5-N-piperidylmethyl or N,N-dialkylaminomethyl pyridine-4-ones 9, 10 and 15-18, two derivatives of N-aryl-2-methyl-3-hydroxy-pyridine-4-ones 19, 20 and two N-alkyl derivatives of maltol, 21 and 22 were prepared. They were screened for their antibacterial and antifungal activities against a variety of microorganisms using micro plate Alamar Blue((R)) assay (MABA) method. Multiple linear regressions (MLR) analysis was performed for the synthesized compounds as well as a series of pyridinone and pyranone derivatives 23-43 which have been synthesized and evaluated for antimicrobial activity by other researchers previously. Studied compounds showed a better quantitative structure-activity relationship (QSAR) model for the antimicrobial activity against Candida albicans and Staphylococcus aureus in comparison with other tested microorganisms.

Morphological and Bactericidal Effects of Different Antibiotics on Helicobacter pylori

Background: Helicobacter pylori (H. pylori) is a spiral Gram negative bacteria that can transform to the coccoid form in adverse conditions. Objectives: The aim of this study was to determine the in vitro morphological and bactericidal effects of metronidazole, amoxicillin and clarithromycin on H. pylori. Materials and Methods: The standard strain 26695 of H. pylori was cultured on Brucella agar (BA) and the minimum inhibitory concentrations (MICs) of three antibiotics were determined by E-test method. The bacteria were exposed to antibiotics at 1/2 MIC, MIC and 2X MIC concentrations in Brucella broth (BB). Induced coccoid forms were confirmed by Gram staining and light microscopy. The viability of cells as well as the susceptibility of viable coccoids to antibiotics were examined using the flow cytometry method. Results: All of the three antibiotics at sub-MIC induced coccoid forms. The highest rates of coccoids (> 90%) were induced at 0.008 μg/mL concentration (1/2 MIC) of amoxicillin, 72 hours postexposure. Metronidazole and clarithromycin with 1/2 MIC (0.5 and 0.125 µg/mL respectively) induced lower rates of coccoid forms (60% and 40% respectively). Potent bactericidal effects on coccoids were observed with Metronidazole at 2X MIC and clarithromycin at MIC (0.25 µg/mL) (80 - 90%). Amoxicillin with MIC and 2X MIC had no bactericidal effect on coccoid forms. Conclusions: Despite the good in vitro bactericidal effect of amoxicillin on spiral forms of H. pylori, this antibiotic has little effect on induced coccoids that may develop after the inappropriate in vivo antibacterial treatment. Hence, for successful therapy, it is essential not only to eradicate the spiral forms, but to eliminate the viable coccoids.

Antimicrobial activity of a UV-stable bacteriocin-like inhibitory substance (BLIS) produced by Enterococcus faecium strain DSH20 against vancomycin-resistant Enterococcus (VRE) strains.

BACKGROUND/PURPOSE The narrow spectrum of action of most bacteriocins is an important limitation for their application as antimicrobial agents. The current study describes a novel bacteriocin-like inhibitory substance (BLIS) that display extended spectrum antimicrobial activity against vancomycin-resistant Enterococcus (VRE) strains. METHODS Acquired resistance profiles of Enterococcus isolates determined based on the European Centre for Disease Prevention and Control (ECDC) and the Centers for Disease Control and Prevention (CDC) definition as multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug resistant (PDR). BLIS activity of Enterococcus isolates was investigated against Enterococcus faecalis (E. faecalis) ATCC 29212 as the indicator strain and clinical isolates including VRE, methicillin resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria containing Pseudomonas aeruginosa (P. aeruginosa), Klebsiella, Acinetobacter, and Escherichia coli (E. coli). RESULTS Among 273 Enterococcus isolates, 27 and 2 VRE isolates, respectively, were XDR and PDR and eight isolates had BLIS activity against the indicator strain. One of these isolates, identified as E. faecium strain DSH20 based on its phenotypical and biochemical properties, as well as its 16S rRNA gene sequence, had potent BLIS production against all 29 VRE strains, but had no activity against MRSA, P. aeruginosa, Klebsiella, Acinetobacter, and E. coli strains. It was heat stable up to 121°C for 15 minutes (autoclave condition), active within the pH range of 3-9 and had UV stability, but its activity disappeared by treatment with proteinase K, pepsin, and trypsin, demonstrating its proteinaceous nature. It was designated as an approximately 35kDa peptide using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method. CONCLUSION This peptide is a potential agent for use as an alternative antibacterial agent for the treatment of drug-resistant strains of VRE infection.

Molecular epidemiology and mechanisms of antimicrobial resistance in Pseudomonas aeruginosa isolates causing burn wound infection in Iran

Abstract In this study, the contributions of different resistance mechanisms in Pseudomonas aeruginosa isolates were investigated among burned patients. The real-time reverse transcription polymerase chain reaction was performed to determine the expression level of mexY, ampC, and oprD for isolates. Also the isolates were typed by multilocus sequence typing (MLST). Seventy-five per cent of clinical isolates were multidrug resistant. The blaOXA group-I and blaPER alleles were identified in 28 and 10 P. aeruginosa isolates, respectively. The majority of blaPER positive isolates belonged to the same MLST clone and was identified as ST235. The types of remaining isolates were ST360 and ST861. Among 10 blaPER positive isolates, eight isolates demonstrated reduced oprD expression and mexY overexpression. Our data further highlight the epidemic potential of the international clone ST235. According to the results, different resistant mechanisms identified among ST235 isolates that were resistant to ceftazidime, imipenem, ciprofloxacin, and amikacin.

The study of mutation in 23S rRNA resistance gene of Helicobacter pylori to clarithromycin in patients with gastrointestinal disorders in Isfahan - Iran

Background: Helicobacter pylori antimicrobial resistance is an important factor responsible for treatment failure. The purpose of this study was evaluating the prevalence of point mutations in clarithromycin-resistant clinical isolates of H. pylori in Isfahan city of Iran. Materials and Methods: Thirty isolates of H. pylori from 130 biopsy specimens were isolated by culture and confirmed by biochemical and PCR tests. The MIC of clarithromycin antibiotic for 30 clinical isolates of H. pylori was determined by E-test method. The point mutations in the 288 bp of 23S rRNA gene of H. Pylori were investigated in four clarithromycin-resistant clinical isolates by PCR followed by sequencing. Results: Among 30 isolates of H. pylori, 4 cases were resistant to clarithromycin. One point mutation was found at position T2243C in the 23S rRNA gene in all resistance isolates. Conclusions: In our study, H. pylori resistance to clarithromycin associated with point mutation at position 2243 (T2243C).

Efflux pump regulatory genes mutations in multidrug resistance Pseudomonas aeruginosa isolated from wound infections in Isfahan hospitals

Background: Multidrug resistance Pseudomonas aeruginosa (MDR-P. aeruginosa) is a worldwide threat for public health. Hyperexpression of efflux pump systems (MexAB-OprM and MexCD-OprJ), which is a well-known mechanisms for MDR emerging, is controlled by regulatory genes, mexR and nfxB, respectively. The aim of this study was to evaluate point mutations in mexR and nfxB genes in MDR- P. aeruginosa isolated from wound infections. Materials and Methods: A total of 34 P. aeruginosa cultures obtained from wound infections were analyzed. Among them eight isolates identified as MDR-P. aeruginosa and were subjected to determination of mutations in mexR and nfxB genes. Results: We detected eight-point mutations in mexR and 12-point mutations in nfxB. The most common mutations were common G327-A (eight isolates), G384-A (eight isolates), G411-A (eight isolates). Mutations in A371-C and A372-C were the predominant substitution which was seen in nfxB. Amino acid substitutions were also found at position 124 and 126 for NfxB and MexR, respectively. Conclusions: P. aeruginosa isolates with mutation in efflux pump regulatory genes such as mexR and nfxB could be a main factor contributed to antibiotic resistance and must be considered in antibiotic treatment.

Distribution of the Strains of Multidrug-resistant, Extensively Drug-resistant, and Pandrug-resistant Pseudomonas aeruginosa Isolates from Burn Patients

Background: Pseudomonas aeruginosa is an opportunistic and Gram-negative pathogen that is used as the most important factor in burn wound infections, and due to the rapid acquisition of multidrug resistance (MDR), it causes high mortality rates in these sectors. Thus, diagnosis and assessment of antibiotic resistance patterns are very important in these patients. The aim of this study was to evaluate antibiotic resistance pattern and determining P. aeruginosa MDR. Materials and Methods: In this study, phenotypic, biochemical, and polymerase chain reaction tests were used to identify P. aeruginosa from 120 wound burn samples that 96 samples were detected to P. aeruginosa species. In the next step, according to the Clinical and Laboratory Standard Institute standard guidelines, antibiogram test was performed by disk diffusion method for amikacin, ciprofloxacin, norfloxacin, gentamicin, cefepime, aztreonam, meropenem, colistin, ceftazidime, and piperacillin-tazobactam antibiotics. Antibiotic data were analyzed by WHONET software; finally, the rate of antibiotic resistance and MDR strains was determined. Results: The highest antibiotic resistance belonged to amikacin (94.8%) and norfloxacin (90.6%); in contrast, colistin (8.3%) had the lowest and the MDR strains were MDR (95.8%) and extensively drug resistance (XDR) (87.5%). Conclusion: In this study, there was MDR with an alarming rate including MDR (95.8%), XDR (87.5%), and pan-drug resistance (0%). As a result, given antibiotics to patients should be controlled by the antibiogram results to avoid increasing MDR strains.

Antibiotic Resistance Patterns and Genetic Diversity in Clinical Isolates of Pseudomonas aeruginosa Isolated From Patients of a Referral Hospital, Isfahan, Iran

Background: Pseudomonas aeruginosa is a well-known opportunistic pathogen, which affects hospitalized patients in different wards due to its natural resistance to drugs. Objectives: The purpose of the current study was to determine the antibiotic susceptibility profiles and genetic relatedness in P. aeruginosa isolated from patients admitted to a referral hospital in Isfahan, Iran. Materials and Methods: Out of 150 analyzed samples, 54 P. aeruginosa isolates were recovered and were subjected to antibiotic resistance patterns and genetic diversity determination by Kirby-Bauer’s disk diffusion method and RAPD-PCR, respectively. Results: The highest percentage of resistance was observed against ceftazidime and imipenem with 30 (55.6%) isolates; meanwhile all isolates were sensitive to polymyxin B. Twenty-eight (51.8%) isolates revealed resistance to all applied antibiotics. RAPD-PCR (Random Amplified Polymorphic DNA- Polymerase Chain Reaction) results showed 54 unique genotypes, which were divided into 39 clusters. Conclusions: Although different source of P. aeruginosa may involve in patient colonization, genetically related strains were isolated from different wards and or the same ward of the hospital. Our results pointed to the restriction of currently used antibiotics in studied hospital. We hope that our results cast light on the control and transmission of the infection in the investigated hospital.

Molecular identification of Acinetobacter baumannii isolated from intensive care units and their antimicrobial resistance patterns

Background: Acinetobacter baumannii is one of the most important pathogens in hospital-acquired infections especially in intensive care units (ICUs). This opportunistic pathogen can be easily isolated from water, soil, and hospital facilities. A. baumannii as a nosocomial opportunistic pathogen is resistant to a wide range of antibiotics and responsible for multiple infections, including bacteremia, pneumonia, meningitis, urinary tract infections, and surgical wounds. The aim of this study was to determine frequency and resistance patterns of A. baumannii isolated in ICUs of Isfahan Hospitals. Materials and Methods: During 1 year period (2012-2013), 350 specimens were collected from ICUs of Isfahan hospitals. The isolates were characterized as A. baumannii by conventional phenotypic, biochemical tests and confirmed by PCR for OXA-51-like gene. Susceptibility of isolates was determined by standard disk diffusion method according to CLSI. Results : From total of 350 specimens, 43 isolates were A. baumannii. The antimicrobial patterns of isolates showed that 53.5% of isolates were resistant to amikacin, 83.7% to tetracyclin, 86% to ceftazidime, 90.7% to Trimethoprim sulfametoxazol, 93% to imipenem, cefepime, meropenem, ampicillin-sulbactam. All isolates were resistant to ciprofloxacin. Conclusion: This study showed a high resistance of A. baumannii to a wide range of antimicrobial agent. It is necessary to adopt appropriate strategies to control the spread of the bacteria in care unit centers and wards.

Isolation of bacteriophages against multidrug resistant Acinetobacter baumannii

Increasing multiple drug resistant (MDR) strains of Acinetobacter baumannii has aggravated curiosity in development of alternative therapy. Bacteriophages are often considered as alternative agents for controlling A. baumannii infections. In the present study two lytic phages for MDR A. baumannii were isolated and their efficacy and host ranges were evaluated. The phages were isolated from hospital wastewater. Electron microscopy revealed that IsfAB78 might belong to Myoviridae and IsfAB39 to Podoviridae. Initial characterization of phages showed that they have narrow host range and failed to infect relative and non- relative bacteria. Both phages decreased the A. baumannii turbidity significantly, indicating that these isolated phages may be considered as candidates for phage therapy.