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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.

 

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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.

 

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Background: In recent years, the widespread prevalence of Multidrug-Resistant (MDR) Staphylococcus aureus strains and the increase in the number of Extensively Drug-Resistant (XDR) and Pandrug-Resistant (PDR) phenotypes amongst S. aureus strains have become one of the greatest challenges. This study aimed to determine the incidence of MDR, XDR, and PDR phenotypes in S. aureus strains in a teaching hospital in Gorgan, Golestan province, Iran.
Materials & Methods: Clinical samples of blood, urine, wound, and sputum were collected from all hospitalized patients during April to June 2019. S. aureus strains were identified using conventional biochemical methods, and antibiotic susceptibility assessment was performed by Kirby-Bauer disc diffusion method.
Findings: A total of 73 isolates were identified as S. aureus. The majority of S. aureus isolates were collected from wound specimens (31 out of 73). Most of the isolates were recovered from internal ward (35 out of 73), followed by intensive care unit (ICU) (16 out of 73). The highest susceptibility was observed to glycopeptides category (100%), and the lowest susceptibility was observed to erythromycin (54.7%), followed by cefoxitin (49.3%). Out of the 73 isolates, 32 (43.8%) were found to be methicillin-resistant S. aureus (MRSA) isolates. Among MRSA isolates, 96.8 and 12.5% were MDR and XDR, respectively. All of the MRSA isolates, were susceptible to vancomycin. No PDR phenotype was observed among the isolates as all of them were sensitive to vancomycin (100%).
Conclusion: Based on the obtained results, the highest and lowest antibiotic resistance was observed against erythromycin and vancomycin, respectively, which is consistent with similar studies conducted in the country. Therefore, these antibiotics should not be used in the empirical therapy of S. aureus infections

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Background: This study aimed to determine antibacterial activity of ethanolic extract of Matricaria chamomilla (chamomile) against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) Pseudomonas aeruginosa strains isolated from clinical specimens.
Materials & Methods: The plant samples were collected, and the flowers and leaves were separated and dried completely in the shade. After grinding, extraction was performed using the maceration method. The extracts of both flowers and leaves were dried at 37°C for 24 hrs. About 500 mg of the dried plant extract was dissolved in 10 mL of 5% dimethyl sulfoxide and sterilized by filtration through a 0.45 µm membrane filter. For the antibacterial assay, agar well diffusion and broth microdilution methods were used.
Findings: No inhibitory effect was observed for both extracts against MDR P. aeruginosa isolates in agar well diffusion method. In broth microdilution method, the leaves extract showed inhibitory effect, and its MIC and MBC were determined at 12.5 and 25 mg/mL concentrations, respectively. The flowers extract showed antibacterial activity against most MRSA isolates. The extract of leaves demonstrated inhibitory effect on 7 MRSA isolates. The MIC and MBC of flowers extract were determined at concentrations of 6.25 and 12.5 mg/mL for most MRSA isolates, while MIC and MBC of leaves extract were 12.5 and 25 mg/mL for a few MRSA isolates, respectively.
Conclusion: In this study, the ethanolic extract of chamomile leaves showed antibacterial activity against MDR P. aeruginosa isolates; meanwhile, the flowers extract showed better activity against MRSA isolates.

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Backgrounds: Staphylococcus aureus is one of the major causes of nosocomial infections. Biofilm formation is an important virulence factor of S. aureus, leading to its high resistance to antibiotics and evasion from host defenses. This study aimed to assess the prevalence and antimicrobial resistance profile of biofilm-producing S. aureus strains and characterize genes involved in biofilm formation.
Materials & Methods: A total of 79 S. aureus strains were isolated from 1000 clinical samples and characterized using phenotypic, biochemical, and molecular tests. The biofilm production ability of isolates was examined using the microtiter assay. Moreover, the expression of genes involved in biofilm production (psm A and psm B) was screened using real-time PCR. Finally, antibiotic susceptibility testing was done using the Kirby-Bauer method and interpreted according to the CLSI M100 standard.
Findings: Out of 79 S. aureus isolates, 43 (54.4%) isolates were strong biofilm producers, 21 (26.6%) isolates were weak biofilm producers, and 15 (19%) isolates were non-adhesive. The results of real-time PCR showed that 55 (86%), 60 (93.7%), and 46 (58.2%) isolates were positive for psm A, psm B, and both genes, respectively. The results of antibiotic susceptibility testing showed that all the isolates were resistant to two or more antibiotics.
Conclusion: The high prevalence of biofilm-forming S. aureus strains in hospital environments could be a major health challenge with serious outcomes for hospitalized patients. Thus, it is necessary to disinfect hospital environments to reduce the risk of infection and spread of these microorganisms.