Iranian Journal of Microbiology最新文献

Background and objectives: Pseudomonas aeruginosa (P. aeruginosa), a multidrug-resistant bacterium, represents a considerable risk in healthcare environments owing to its capacity to induce various infections. The resistance of P. aeruginosa is frequently linked to efflux pumps that actively remove antibiotics from the bacterial cell. This study investigates novel amide compounds as potential alternatives to address P. aeruginosa isolates exhibiting multidrug resistance mediated by efflux pumps.

Materials and methods: Gram staining and biochemical assays revealed thirty-three multi-drug-resistant P. aeruginosa isolates from a tertiary care hospital Peshawar. After antibiotic susceptibility testing, efflux pumps were detected using Ethidium Bromide (EtBr) agar cartwheel technique and UV transilluminator. Novel amides were tested for efflux pump and anti-pseudomonal action against efflux pump-positive isolates utilizing agar well diffusion and micro broth dilution, including synergy with ciprofloxacin and gentamicin.

Results: Three high efflux pump activity P. aeruginosa isolates were chosen using ETBr agar cartwheel technique. Novel amides (ITC, ITD, ITE, DEP) block efflux pump, although TEM-cu is very antimicrobial. TEM-cu, DEP, ITC, and ITE have 0.19, 0.78, and 0.78 mg/ml MICs. Effectiveness against efflux pump-expressing P. aeruginosa is lowest with ITE (1.56 mg/ml). Together with ciprofloxacin and gentamicin, TEM-cu and DEP improved antimicrobial effectiveness.

Conclusion: TEM-cu is highly effective against efflux pump-positive P. aeruginosa, while amides like ITC, ITD, ITE, and DEP block these pumps. With significant reductions, DEP and TEM-cu improve ciprofloxacin and gentamicin efficacy. This method may help overcome P. aeruginosa efflux pump-mediated resistance.

Background and objectives: The aim of this study was to assess the effectiveness of a new linear epitope from the N-terminal domain (NTD) of the SARS-CoV-2 S protein in the diagnosis of COVID-19.

Materials and methods: Serum samples from patients were confirmed to have COVID-19 by means of RT-PCR. The linear epitope sequence of the NTD was amplified by RT-PCR, inserted into an expression vector, and produced in Escherichi coli (DE3) pLysS. Subsequently, the recombinant proteins were purified and refolded. The interaction between the purified protein and the antibodies in COVID-19 patient sera was evaluated using ELISA.

Results: Sequencing verified that the N-terminal linear epitope was successfully cloned into the PET-22b vector with a 6His-tag at the C-terminal end. The presence of a 25 kDa band on SDS-PAGE indicated the successful purification of the recombinant protein using Ni-NTA chromatography. The results of ELISA showed that the NTD linear epitope had strong sensitivity (88%) and specificity (96%) for identifying viral infection in COVID-19 patients' blood samples.

Conclusion: The findings of this study demonstrated that the NTD linear epitopes of the SARS-CoV-2 spike protein exhibit significant sensitivity and specificity for the diagnosis of COVID-19 infection using serological techniques. However, further evaluations involving larger sample sizes across diverse ethnic populations is essential.

Background and objectives: The public health concern about urinary tract infections (UTIs) exists due to mounting antibiotic resistance rates. The antimicrobial properties of Rosmarinus officinalis create strong opportunities as an alternative therapeutic option. This study evaluated the antibacterial properties along with anti-biofilm behavior of rosemary extract against typical uropathogens.

Materials and methods: This study collected samples from 500 UTI isolates for its cross-sectional research. The antibacterial activity of rosemary extract underwent testing for its effects on Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and Pseudomonas aeruginosa through combination tests with disk diffusion, MIC and MBC assays. Biofilm inhibition was assessed using the Tissue Culture Plate method with extract concentrations of 25, 50, and 100 µg/mL. Statistical analysis included one-way ANOVA, Tukey's post-hoc, and regression analysis.

Results: The rosemary extract exhibited varying antibacterial effects, with inhibition zones ranging from 10 mm in E. faecalis to 16 mm in E. coli. MIC values were 4 mg/mL for E. coli and 32 mg/mL for E. faecalis, while MBC values ranged from 8 to 64 mg/mL. A 100 µg/mL concentration reduced E. coli biofilm formation by 70%. In checkerboard assays, rosemary extract enhanced antibiotic activity against E. coli and showed additive effects with K. pneumoniae and E. faecalis.

Conclusion: R. officinalis extract demonstrates promising antibacterial and anti-biofilm activities, suggesting potential as an adjunct UTI treatment, comparable to co-trimoxazole. Further research is recommended.

Background and objectives: Probiotics are used for the treatment of yeast infections, they restore the balance in vaginal microbiome, adhere to epithelial cells, compete against pathogenic bacteria, acidify the environment, produce bacteriocins and modulate the immunity. The aim of the study was to investigate the anti-yeast activity (AYA) of the strain Lacticaseibacillus rhamnosus R-2002 against different Candida species.

Materials and methods: From 20 strains of lactic acid bacteria examined, only L. rhamnosus R-2002 strain demonstrated beneficial properties against yeast. The effects of temperature and pH on AYA and its relation to cell wall were revealed by bi-layer agar assay. The connection of AYA to the cell wall was determined with the sonicated cells.

Results: R-2002 inhibited the growth of C. albicans ATCC 10291, C. tropicalis G 31 and C. albicans G4 (both isolated from vaginal samples). R-2002 maintained its AYA between a wide range of pH and its anti-yeast component/s are extracellular. The tested strain demonstrated stability against the high concentrations of progesterone and metronidazole, making it a suitable candidate for the mitigation of vaginitis.

Conclusion: The present study summarizes all the positive features of the strain R-2002 and its potential as a therapeutic agent in the treatment of candidiasis.

Background and objectives: High-dose of carbapenems and combination therapies with new β-lactam/β-lactamase inhibitors and polymyxin B/tigecycline have been considered for treatment of carbapenem resistant Enterobacterales infection. The research was conducted to evaluate the in vitro potency of aminoglycosides, ceftazidime/avibactam/aztreonam and tigecycline against isolates of Enterobacteriaceae with multiple carbapenemase enzymes.

Materials and methods: 42 genotypically confirmed carbapenem resistant Enterobacterales (twenty-nine NDM producers, nine NDM and OXA-48 producers, three NDM and VIM producers and one NDM combined with VIM and OXA 48 producer) were included. Minimum inhibitory concentration for carbapenems, aminoglycosides and tigecycline was determined by Vitek 2. Ceftazidime/avibactam/aztreonam synergy was observed by disk diffusion methodology.

Results: The in vitro efficacy of aminoglycosides was observed against Escherichia coli (E. coli) isolates with NDM and VIM genes. Low tigecycline susceptibility was observed among Klebsiella pneumoniae (K. pneumoniae) isolates with NDM and OXA-48 genes. Ceftazidime -avibactam/aztreonam combination displayed good in vitro activity against dual carbapenemase producers of E. coli isolates (NDM with OXA-48 and NDM with VIM genes) and Klebsiella pneumoniae (combination of NDM, VIM and OXA-48 genes).

Conclusion: Ceftazidime/avibactam/aztreonam, aminoglycosides and tigecycline displayed in vitro activity against dual carbapenemase producers of E. coli and K. pneumoniae.

Considerable information is available about the acute respiratory symptoms of influenza A and B. However, rarely, these viruses can adversely affect the cardiovascular system. Few cases of pericardial effusion and cardiac tamponade due to the Influenza virus have been reported. To the best of our knowledge, we present the first case of a 23-year-old unvaccinated woman having concurrent influenza A and B infection manifesting as pericardial effusion and cardiac tamponade. The patient was treated with oseltamivir 75 mg, resulting in significant clinical improvement. This case emphasizes the importance of considering influenza as a possible cause of cardiac tamponade.

Background and objectives: Uropathogenic Escherichia coli (E. coli) (UPEC) accounts for 70-95% of community-acquired urinary tract infections (UTIs) and a significant proportion of nosocomial UTIs. This study aimed to characterize the phenotypic and genotypic characteristics of E. coli isolates from symptomatic UTI patients and evaluate their antimicrobial susceptibility patterns.

Materials and methods: A hospital-based observational study was conducted at Aarupadai Veedu Medical College and Hospital, Puducherry, India, from August 2022 to April 2024. A total of 106 UPEC isolates were obtained from symptomatic UTI patients. Antimicrobial susceptibility testing (AST) was performed using the Kirby-Bauer method, and virulence genes (hlyA, fimH, papC) were detected using PCR.

Results: The mean age of patients was 49.7 years, with a female predominance (69.8%). Diabetes mellitus was the most common comorbidity (29.2%). Fever (60.4%) and dysuria (38.7%) were the most common symptoms. AST showed high susceptibility (>90%) to amikacin, nitrofurantoin, meropenem, and piperacillin/tazobactam, while >60% resistance was observed to cefotaxime and ceftazidime. Phenotypically, 30.2% of the isolates produced mannose-resistant hemagglutinins, and 17.9% produced hemolysin. ESBL production was found in 46.3%. Biofilm production was moderate in 65.1%, weak in 30.2% and strong in 4.7% and significantly correlated with multidrug resistance (p<0.05). Genotypically, 80.2% had fimH, 51.9% had papC and 20.8% had hlyA. papC was associated with reduced cefotaxime susceptibility (p<0.05).

Conclusion: The study highlights the significance of phenotypic and genotypic characterization in understanding UPEC virulence and resistance patterns, and emphasizes the need for targeted empiric therapy to improve UTI management.

Postbiotics, which consist of beneficial compounds produced by probiotic bacteria, have emerged as promising natural preservatives in food applications. This article examines the health-promoting properties of postbiotics and their role in improving food preservation and formulating nutrient-enriched foods. An organized investigation of published works was carried out through key research databases, including ScienceDirect, Scopus, PubMed, and Google Scholar, using keywords such as "Postbiotics," "Biopreservation," "Food Safety," "Functional Foods," "Antimicrobial Activity," "Anti-inflammatory," and "Bioactivities". The findings reveal that postbiotics exert antimicrobial effects through multiple mechanisms, including the production of organic acids, bacteriocins, fatty acids, antimicrobial peptides, hydrogen peroxide, and vitamins. These bioactive substances actively suppress the proliferation of harmful and spoilage-causing microbes, consequently prolonging the preservation period of food items. Furthermore, postbiotics have been integrated into functional foods to modulate the host immune response and mitigate inflammatory conditions. Emerging applications of postbiotics also include their use in active food packaging systems, biofilm eradication, and cosmetic formulations. Although research on postbiotics is advancing, further investigations are required to elucidate the mechanisms of postbiotics and optimize their applications in both clinical and non-clinical contexts. This review emphasizes the potential of postbiotics to enhance food safety, improve nutritional quality, and contribute to overall health promotion.

Background and objectives: Pseudomonas aeruginosa (P. aeruginosa) is one of the most common causes of hospital-acquired infections. It is associated with high morbidity and healthcare costs, especially when appropriate antibiotic treatment is delayed. Antibiotic selection for patients with P. aeruginosa infections is challenging due to the bacteria's inherent resistance to many commercially available antibiotics. This study investigated antibiotic-resistance genes in isolated bacteria, which play a key role in disease pathogenesis.

Materials and methods: 100 samples out of the 140 samples collected from urinary tract infections (UTIs) cases between December 15^th, 2022, and April 15^th, 2023, were included in the study. Identification of bacterial isolates was based on colony morphology, microscopic examination, biochemical tests, and the Vitek-2 system. Antibiotic resistance genes; Aph(3)-llla, ParC, Tet/tet(M), and aac(6´)-Ib-cr were tested by polymerase chain reaction (PCR).

Results: The obtained results were based on bacterial identifications of 81 clinical samples. Only 26 (32%) of these isolates were P. aeruginosa, 21 (26%) were Escherichia coli, and 18 (22.2%) were other bacteria. These isolates were used to detect four genes including tet(M), Aph(3)-llla, Par-c, and aac(6´)-Ib-cr. Four types of primers were used for PCR detection. The results showed that 11/14 (78.57%) carried the tet(M) gene, 10/14 (71.42%) carried the Aph(3)-llla gene, 14/14 (100%) carried the Par-c gene, and 10/14 (71.42%) of the isolates carried the aac(6´)-Ib-cr gene. The biofilm formation examining the esp gene, showed that 9 (64.28) isolates carried this gene.

Conclusion: The inability of antibiotics to penetrate biofilms is an important factor contributing to the antibiotic tolerance of bacterial biofilms.

Background and objectives: Human papillomavirus (HPV) is a significant etiological agent in cervical cancer. This study aimed to evaluate the performance of PCR-ELISA for detecting HPV genotypes 11, 16, and 18 compared to the conventional hybridization methods.

Materials and methods: PCR-ELISA was designed and optimized to detect target HPV genotypes using biotin-labeled probes. Sensitivity, specificity and reproducibility were assessed through intra-assay and inter-assay variability tests. Additionally, a cost-benefit analysis was performed to compare PCR-ELISA with RT-PCR and gel electrophoresis.

Results: PCR-ELISA demonstrated high sensitivity (HPV18: 94.92%, HPV16: 98.36%, HPV11: 93.75%) and specificity (100% for all genotypes), with Kappa values ranging from 0.84 to 0.92, indicating strong agreement with the reference standard. Reproducibility analysis showed intra-assay CVs below 5% for most samples and inter-assay CVs within acceptable limits. The cost-benefit analysis revealed significant reductions in reagent and equipment costs compared to RT-PCR, making PCR-ELISA a cost-effective alternative.

Conclusion: PCR-ELISA offers a reliable, sensitive and cost-effective method for HPV detection, particularly in resource-limited settings. Its simplicity and compatibility with existing workflows makes it a promising tool for routine diagnostic applications.