سال:1399 | دوره: | شماره: |تعداد مقالات:8

Aims: 16S ribosomal RNA methyltransferases (RMTases) confer high-level resistance to aminoglycosides and are increasingly reported among Gram-negative bacilli, especially Klebsiella pneumoniae isolates. The objectives of the present study were to assess the resistance to aminoglycosides, the presence of RMTase genes, and the multilocus sequence typing (MLST) in urinary K. pneumoniae isolates. Materials & Methods: In this study, 100 K. pneumoniae isolates were tested for susceptibility to amikacin and gentamicin by broth microdilution test according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Then the prevalence of RMTase genes was determined, and alleles and ST type of two selected isolates were identified by MLST. Finally, the isolates were genetically typed using Enterobacterial Repetitive Intergenic Consensus (ERIC) method. Findings: Broth microdilution assay showed that resistance to amikacin and gentamicin was 70 and 52%, respectively. In addition, 40% of the strains were resistant to both aminoglycosides. Also, rmtC (59. 8%) gene was the most common type of RMTase genes investigated, followed by rmtA (51. 2%), rmtD (47. 6%), rmtF (43. 9%), rmtE (41. 5%), armA (41. 5%), and rmtB (7. 3%). K. pneumoniae isolates were assigned into two sequence types: ST51 and ST149. Using ERIC-PCR method, 3-7 different bands and 21 ERIC-PCR profiles were detected among the studied isolates. Conclusion: The high frequency of aminoglycoside resistance and the increased presence of 16S RMTases in K. pneumoniae strains are of great concern in Iran. Molecular typing showed high genetic diversity among the studied isolates. However, ST51 and ST149 were reported for the first time in Iran and could be considered as emerging strains.

Aims: Helicobacter pylori is a bacterium that colonizes the gastric mucosa and is the main cause of gastritis as well as ulcer and gastric cancer. Due to the clinical significance and international increase in H. pylori multidrug resistance, it is necessary to search for new strategies improving eradication rates. Natural compounds have been demonstrated to have antimicrobial effect and the ability to restore the efficacy of conventional drugs. The objective of this work was to evaluate the antimicrobial effect of the hydroalcoholic extract of Curcuma longa L. (Cu) against H. pylori isolates. Materials & Methods: The minimum bactericidal concentration of the extract was determined by means of the MTT assay; also, the combination and dose reduction indices for levofloxacin (LVX), metronidazole (MET), and rifampicin (RIF) antimicrobial agents were determined by checkerboard format. Interaction analysis was performed using the CompuSyn program. Findings: About 90% of H. pylori isolates studied (9/10) were sensitive to the hydroalcoholic extract. Synergism was observed in more than 50% of Cu-LVX, Cu-MET, and Cu-RIF combinations. Additionally, for different concentrations of the extract, reduction rates in antimicrobial agents were determined to be between 0. 5 and 360 times. Conclusions: The hydroalcoholic extract of turmeric showed a good potential to be used as an antimicrobial agent in the treatment of H. pylori infection, either alone or in combination with antibiotics used, suggesting the renewal of the effectiveness of conventional antimicrobials in reducing the phenomenon of antimicrobial resistance.

Aims: Antibiotic resistance is recognized as one of the most challenging public health problems in the world. The need for new antibacterial and antifungal drugs is justified because many pathogens are currently resistant to available drugs. Several components of 1, 3, 4‑ oxadiazoles have been shown to pose a wide range of antibacterial activities. Materials & Methods: The new derivatives of 1, 3, 4-oxadiazole were synthesized using a single-stage method. The structure of derivatives was evaluated by IR, H-NMR, C-NMR, and GC-Mass methods. Then to measure the antibacterial and antifungal activities of the prepared derivatives at a concentration of 0. 5 mg/mL, agar well diffusion method was employed, and the minimum inhibitory concentration (MIC) and the minimum bactericidal/fungicidal concentration (MBC/MFC) were determined with three replications. Findings: The study of antibacterial properties of the prepared derivatives showed the highest activity of the compounds 4b-g against Enterococcus faecalis strains, among which the compound 4g with IZ= 55. 66 ± 0. 5 mm and MIC=31. 25 mg/mL had the greatest effect compared to the others. Also, the compound 4f with MIC= 125 mg/mL had a powerful effect against E. faecalis strains. In the case of fungal samples, the highest activity of the compound 4b was with IZ=12. 33± 0. 5 mm against Candida glabrata and with IZ=13. 33± 0. 5 mm against C. krusei strains. Conclusion: The new 1, 3, 4‑ oxadiazole derivatives (4b, 4d, and 4g) with tolyl, dimetylphenyl, and methoxyphenyl groups were shown to be a promising compounds for pharmaceutical applications so that by adding other functional groups to their structure, it is possible to increase the destructive power of these compounds.

Aims: In the past decade, drug resistance in Gram negative bacilli has become a serious problem. The production of extended spectrum beta-lactamase (ESBL), AmpC beta-lactamase, and metallo beta-lactamase (MBL) enzymes in Klebsiella pneumoniae strains is the mechanism of drug resistance among these commonly isolated Gram negative bacteria from clinical specimens. The aim of this study was to assess the frequency of β-lactamase enzymes, including extended spectrum β-lactamases (ESBLs), metallo-β-lactamases (MBLs), and AmpC beta-lactamases, in K. pneumonia strains isolated from urine samples referred to medical laboratories in Aliabad. Materials & Methods: A total of 780 urine samples were collected from patients suspected of having UTI from March to June 2017. In positive urine samples, K. pneumonia isolates were identified by biochemical tests. Antibiotic resistance pattern was determined by disk diffusion method, and phenotypic confirmatory test was performed for detecting ESBLs, MBLs, and AmpC BLs producers. Findings: Out of 378 positive samples for UTI, 97 K. pneumonia strains were isolated. Most of the isolates (more than 90%) were resistant to ampicillin and amoxicillin; however, imipenem and amikacin were effective antibiotics against the isolates. The frequency of ESBLs, MBLs, and AmpC BLs producers was determined as 33. 3, 21. 3, and 5. 1%, respectively. Conclusions: In this study, 14 isolates were simultaneously positive for ESBL and AmpC BL production, and 2 isolates were co-producer of ESBL and MBL. This finding could have a great impact on the management and treatment of UTI cases. Therefore, detection of beta‑ lactamases is of great importance for controlling and reducing the spread of ESBL, AmpC BL, and MBL producing strains.

Background: Due to the side effects of chemical and synthetic antibiotics and the increase in bacterial resistance, extensive research has been conducted to obtain natural compounds without side effects from natural sources such as insects, especially Diptera order, because these insects require to live and survive on rotting food and be in direct contact with pathogenic and dangerous microorganisms because of their special diet. Materials & Methods: In this study, hemolymphs were extracted from Musca domestica, Drosophila melanogaster, and Sarcophaga nodosa, and then the anti-bactericidal activity of these extracts against important pathogenic bacteria was investigated separately by the minimum inhibitory concentration (MIC) method using resazurin indicator. Findings: S. nodosa and M. domestica larvae were not able to prevent the growth of any of the bacteria. D. melanogaster larvae extract completely inhibited the growth of Escherichia coli and Pseudomonas aeruginosa bacteria at all densities, while Staphylococcus aureus was completely resistant to all concentrations. The minimum inhibitory concentration of D. melanogaster larvae extract against two bacteria of Listeria monocytogenes and Salmonella typhimurium was determined as 125 and 500 μ L/mL, respectively. D. melanogaster pupae extract was unable to inhibit the growth of E. coli and S. typhimurium but prevented the growth of P. aeruginosa at all concentrations. Also, the minimum inhibitory concentration of this extract against both S. aureus and L. monocytogenes was determined as 1000 μ L/mL. Conclusion: These outcomes show that D. melanogaster holds a high potential of antibacterial effects, and the purification and evaluation of this extract active substances are recommended for future utilization as antibacterial agents and food preservatives to fight pathogenic and toxigenic microorganisms.

Aims: Recently, overuse and misuse of antibiotics have led to the development of multidrug-resistant bacteria and infectious diseases caused by these organisms, increasing morbidity and mortality rate in patients. Pseudomonas aeruginosa as a common Gram-negative pathogen is predominantly responsible for hospital-acquired infections. In this study, the prevalence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) P. aeruginosa strains isolated from clinical specimens of patients admitted to a teaching hospital in Gorgan, Iran, was determined. Materials & Methods: Clinical samples of blood, urine, burn wound, eye, and secretions (pleural fluid, tracheal or bronchial aspirates and sputum) were collected from all hospitalized patients during a three-month period from April to June 2019. Using conventional biochemical methods, P. aeruginosa strains were identified, and the antibiotic resistance pattern was determined by Kirby-Bauer disc diffusion method. Findings: A total of 40 (25. 4%) P. aeruginosa strains were isolated from 377 clinical specimens. Most of the P. aeruginosa strains were isolated from wound (35%) and urine (30%) samples. Most of the P. aeruginosa positive samples were recovered from intensive care unit (32. 5%) and burn ward (30%). The highest susceptibility was shown to fosfomycin (100%), and the lowest susceptibility was observed to ceftazidime (87. 5%), followed by aztreonam (60%). Based on the results, 52. 5 and 20% of the isolates were MDR and XDR, respectively. All of the MDR isolates exhibited susceptibility to colistin. No PDR phenotype was observed. Conclusion: Continuous monitoring of drug resistant strains among clinical isolates of P. aeruginosa must be done to adopt effective strategies to decrease the threat of antimicrobial resistance.

Aims: Daily consumption of milk containing antibiotic residues has become a great public health concern. This study aimed to evaluate the antibiotic residues in cattle raw milk using Copan milk test and specific enzyme-linked immunosorbent (ELISA) kits. Materials & Methods: In this study, 92 milk samples were collected from Qazvin province, Iran in two seasons during 2019. All the samples were analyzed by the Copan milk test and competitive ELISA kits to evaluate gentamicin, tetracycline, tylosin, chloramphenicol, penicillin, and sulfonamide residues in milk. Findings: The results showed that 45 milk samples (48. 91%) were positive for the presence of antibiotic residues. Samples collected in summer were significantly (p<. 05) more contaminated with antibiotic residues (30. 43%) than those collected in winter (18. 47%). The highest mean contamination was related to sulfonamide (13. 72± 1. 21 ng/mL), followed by gentamicin (13. 24± 2. 81 ng/mL) and tylosin (13. 15± 1. 37 ng/mL) residues, and the lowest mean contamination was related to penicillin residues (0. 007± 0. 002 ng/mL). The limit of detection (LOD) was 2, 2. 5, 0. 02, 8, 0. 4, 0. 08, and 13 ng/mL for gentamicin, tylosin, chloramphenicol, sulfamethazine, tetracycline, penicillin, and flumequine, respectively. Chloramphenicol residues were above the maximum residue limit (MRL) according to the Codex and European Commission (EC) (0 ng/mL) in all the samples. Sulfonamides residues were above the Codex MRL (25 ng/mL) in 33. 33% of the samples. Conclusion: The results shows that monitoring of antibiotic residues in milk and dairy products is necessary. Indeed, examining the amount of antibiotic residues in dairy products could be an important aspect of their monitoring.

Background: The outbreak of novel coronavirus (2019-nCoV), which began in Wuhan, China, has rapidly spread in many countries and is currently considered a pandemic. The virus (SARS-CoV-2) causes severe acute respiratory syndrome and is related to SARS-CoV and MERS-CoV. Methods: In this review, an introduction to SARS-CoV-2 was provided comprising the following items: general features; pathogenesis; the existing knowledge on immunological properties; transmission routs; diagnostic features, especially discussion about new approaches for treatment and prevention; and different diagnostic methods including nucleic acid based assays, serological testing, and MALDI TOF-MS and LC-MS technologies. Findings and Conclusion: Introducing the different methods for SARS-CoV-2 detection may be useful to provide new insights into the development and improvement of detection primers, probes, methods/techniques, potential targets for drug designation, and therapeutic candidates against the virus.