Iranian Journal of Microbiology最新文献

Background and objectives: Today, medicinal plants and their derivatives are considered to reduce the prevalence of antibiotic resistance. The aim of this study was to investigate the effect of Mentha longifolia essential oil on oqxA efflux pump gene expression and biofilm formation in ciprofloxacin-resistant Klebsiella pneumoniae strains.

Materials and methods: A total of 50 clinical strains of K. pneumoniae resistant to ciprofloxacin were studied. The minimum inhibitory concentration (MIC) of M. longifolia essential oil and its synergistic effect with ciprofloxacin were determined using the microbroth dilution method and the fractional inhibitory concentration (FIC) method. Minimum biofilm inhibition concentration (MBIC) of M. longifolia essential oil was detected. The effect of essential oils on the expression level of the oqxA gene was detected by Real-time PCR.

Results: M. longifolia essential oil showed inhibitory activity against ciprofloxacin-resistant strains of K. pneumoniae. When M. longifolia essential oil was combined with ciprofloxacin, the MIC was reduced 2-4 times. In 28% of the strains, M. longifolia with ciprofloxacin showed a synergistic effect. M. longifolia essential oil reduces the strength of biofilm formation and alters the biofilm phenotype. A significant decrease in oqxA gene expression was observed in all isolates after treatment with M. longifolia essential oil.

Conclusion: Based on the results of this study, it was observed that supplementing M. longifolia essential oil can help reduce ciprofloxacin resistance and inhibit biofilm formation in fluoroquinolone-resistant K. pneumoniae strains.

Background and objectives: This study evaluated the efficacy of the TrueLab™ Real Time mini-PCR system in providing rapid and accurate diagnostic results for tuberculosis (TB) detection in India. The goal is to improve case detection and accelerate treatment in settings with limited resources.

Materials and methods: This prospective study was conducted by the Department of Microbiology on 120 patients, age ranging from >=15 years with at least two clinical symptoms of pulmonary TB. Molbio and Universal Cartridge Based Sample Prep were the 2 methods used for processing sputum samples. The diagnosis was based on the MTB Real Time PCR test, which has a detection limit of 100 CFU/mL. Patients under 15 years, samples lacking clinical background, saliva specimens or extra-pulmonary TB cases were excluded from the study.

Results: A total of 44.17% samples were positive for TB with maximum positivity in the age group 31-45 years. Positivity rate was found to be higher in females. In 4.17% of cases there was rifampicin resistance, which was significantly high in previously treated cases. Comparison of Truenat with Ziehl-Neelsen and fluorescent method revealed that it was more sensitive and less time consuming.

Conclusion: Truenat MTB/RIF is a sensitive detection system for TB with rapid results, which serves as an important tool in the early management of tuberculosis patients and drug-resistant-TB cases.

Background and objectives: SARS-CoV-2 is a newly discovered viral infection. It's still unclear how antibodies react in infected individuals, and there is not enough evidence to support the clinical use of antibody examination. This study evaluates the diagnostic value of serologic tests for diagnosing COVID-19.

Materials and methods: 32 patients for whom serologic testing was performed within 7 to 21 days from symptom onset and whether they were diagnosed with COVID-19 by both PCR and lung HRCT as gold standard tests at the same time, were included in the study.

Results: Serologic tests (IgM / IgG) compared to PCR and lung HRCT scan to diagnose COVID-19, were 89.3% specific and 59.6% sensitive. Positive predictive value (PPV) was 95% and negative predictive value (NPV) was 37%. The diagnostic accuracy index of the serologic test was 0.745 (CI 0.651-0.838) (p-value <0.001).

Conclusion: Serologic testing can be a complementary alternative for SARA-CoV-2 nucleic acid RT-PCR, although it cannot replace it completely. IgG/IgM combo test kits and RT-PCR together can give more insight into the diagnosis of SARS-CoV-2.

Background and objectives: This study aimed to evaluate the frequency of multidrug-resistant (MDR) bacteria in biliary samples, MDR-bacteria risk factors, and the relationship between MDR-bacteria positivity and some clinical outcomes.

Materials and methods: The study was conducted between May 2018 and May 2023, including patients over the age of 18 who had positive culture results in biliary samples. The frequency of MDR-bacteria in biliary samples was evaluated. Risk factors for MDR bacteria were assessed using univariate and multivariate analyses. MDR and non-MDR groups were compared inappropriate empirical antibiotic treatment, total antibiotic treatment duration, length of stay, and in-hospital mortality.

Results: 342 microorganisms were isolated from 202 patients. Escherichia coli was the most commonly (37.2%) isolated Gram-negative microorganism, and Enterococcus spp. was the most commonly (70.2%) isolated Gram-positive microorganism. The incidence of MDR microorganisms was 42.3%. Gastrointestinal malignancy (OR: 1.96; 95% CI, 1.03-3.71) and previous antibiotic use (OR: 2.26; 95% CI, 1.09-4.68) were independent risk factors for MDR-bacteria. In the MDR group, inappropriate empirical antibiotic treatment (56.6% vs. 41%, p = 0.091), total antibiotic treatment duration (13 vs. 8 days, p = 0.054), length of stay (24 vs. 15 days, p = 0.001), and in-hospital mortality (27.3% vs. 22.3%, p = 0.416) were higher compared to the non-MDR group.

Conclusion: MDR-bacteria positivity is associated with inappropriate antibiotic treatment, prolonged hospitalization, and increased mortality. Screening, antibiotic prophylaxis, and empirical treatment approaches should be carefully performed in patients with malignancy and recent antibiotic use, which are significant risk factors for MDR-bacteria.

Background and objectives: The most common cause of healthcare-associated diarrhea is Clostridium difficile infection (CDI), which causes severe and recurring symptoms. The increase of antibiotic-resistant C. difficile requires alternate treatments. Postbiotics, metabolites produced by probiotics, fight CDI owing to their antibacterial capabilities. This study aims to evaluate the antibacterial, antibiofilm, and anti-toxigenic potential of postbiotics in combating CDI.

Materials and methods: GC-MS evaluated postbiotics from Bifidobacterium bifidum and Lactobacillus plantarum. Disk diffusion and broth microdilution determined C. difficile antibacterial inhibition zones and MICs. Microtiter plates assessed antibiofilm activity. MTT assay evaluated postbiotics anti-viability on HEK293. ELISA testing postbiotic detoxification of toxins A and B. Postbiotics were examined for tcdA and tcdB genes expression using real-time PCR.

Results: The most identified B. bifidum and L. plantarum postbiotic compounds were glycolic acid (7.2%) and butyric acid (13.57%). B. bifidum and L. plantarum displayed 13 and 10 mm inhibition zones and 2.5 and 5 mg/ml MICs against C. difficile. B. bifidum reduced biofilm at 1.25 mg/ml by 49% and L. plantarum by 31%. MTT assay showed both postbiotics had little influence on cell viability, which was over 80%. The detoxification power of postbiotics revealed that B. bifidum decreased toxin A and B production more effectively than L. plantarum, and also their related tcdA and tcdB genes expression reduction were statistically significant (p < 0.05).

Conclusion: Postbiotics' ability to inhibit bacterial growth, biofilm disruption, and toxin reduction makes them a promising adjunctive for CDI treatment and a good solution to pathogens' antibiotic resistance.

Background and objectives: Rifampicin (RIF) and isoniazid (INH), two most potent antibiotics, are prescribed to cure tuberculosis. Mycobacterium tuberculosis, the causative agent of multidrug-resistant tuberculosis (MDR-TB), is resistant to these first-line drugs. Here, two molecular techniques were demonstrated such as PCR sequencing-based and GeneXpert assay for rapidly identifying MDR-TB.

Materials and methods: Pulmonary samples (sputum) were collected from 55 MDR-TB suspected patients from the National Tuberculosis Reference Laboratory (NTRL), Dhaka where the research work was partially accomplished and continued in the department of Microbiology, University of Dhaka, Bangladesh. We strived for sequencing technique as well as GeneXpert assay to identify mutations in rpoB and katG genes in MTB strains and sputum directly. Culture-based drug susceptibility testing (DST) was performed to measure the efficacy of the molecular methods employed.

Results: When analyzed, rpoB gene mutations at codons 531 (54.54%), 526 (14.54%), and 516 (10.91%) were found by sequencing in 80% of the samples. Nucleotide substitution at katG315 (AGC→ACC) was spotted in 16 (76.19%) out of 21 samples. When comparing the sequencing results with DST, sensitivity and specificity were investigated to determine drug-resistance (rifampicin-resistance were 98 and 100% whereas isoniazid-resistance were 94 and 100% respectively). Additionally, as a point of comparison with DST, only 85.45% of RIF mono-resistant TB cases were accurately evaluated by the GeneXpert assay.

Conclusion: This research supports the adoption of PCR sequencing approach as an efficient tool in detecting MDR-TB, counting the higher sensitivity and specificity as well as the short period to produce the results.

Background and objectives: Colorectal cancer (CRC) is a heterogeneous disease of the colon or rectum arising from adenoma precursors and serrated polyps. Recently, probiotics have been proposed as an effective and potential therapeutic approach for CRC prevention and treatment. Probiotics have been shown to alleviate inflammation by restoring the integrity of the mucosal barrier and impeding cancer progression.

Materials and methods: In this study, we aimed to investigate the immunomodulatory effects of live and UV-killed Bacillus subtilis natto on the inflammatory response in CRC. Caco-2 cells were exposed to various concentrations of live and UV- killed B. subtilis natto, and cell viability was assessed using MTT assay. Gene expression analysis of IL-10, TGF-β, TLR2 and TLR4 was performed using RT-qPCR.

Results: Our findings showed that both live and UV-killed B. subtilis natto caused significant reduction in inflammatory response by decreasing the gene expression of TLR2 and TLR4, and enhancing the gene expression of IL-10 and TGF-β in Caco-2 cells as compared to control group.

Conclusion: The results of this study suggest that live and UV-killed B. subtilis natto may hold potential as a therapeutic supplement for modulating inflammation in CRC.

Background and objectives: Urinary tract infections (UTIs), one of the most prevalent bacterial infections, are facing limited treatment options due to escalating concern of antibiotic resistance. Urine cultures significantly help in identification of etiological agents responsible for these infections. Assessment of antibiotic susceptibility patterns of these bacteria aids in tackling the emerging concern of antibiotic resistance and establishment of empirical therapy guidelines. Our aim was to determine various agents responsible for urinary tract infections and to assess their antibiotic susceptibility patterns.

Materials and methods: This cross-sectional study was performed over a period of six months from January 2023 to July 2023 in Department of Microbiology of Pakistan Institute of Medical Sciences (PIMS).

Results: Out of 2957 positive samples, Gram negative bacteria were the most prevalent in 1939 (65.6%) samples followed by Gram positive bacteria in 418 (14.1%) and Candida spp. in 269 (9.1%) samples. In gram negative bacteria, Escherichia coli (E. coli) was the most prevalent bacteria isolated from 1070 samples (55.2%) followed by Klebsiella pneumoniae in 397 samples (20.5%). In Gram positive bacteria, Enterococcus spp. was the most common bacteria in 213 samples (51%) followed by Staphylococcus aureus in 120 samples (28.7%). Amikacin was the most sensitive drug (91%) for Gram negative bacteria. Gram positive bacteria were most susceptible to linezolid (97%-100%).

Conclusion: The generation of a hospital tailored antibiogram is essential for the effective management of infections and countering antibiotic resistance. By adopting antimicrobial stewardship strategies by deeper understanding of sensitivity patterns, we can effectively combat antibiotic resistance.

Background and objectives: Leptospirosis is an infectious zoonotic disease that can result in severe complications. It is widespread, especially in hot and humid climates such as the northern region of Iran. The immune responses to leptospirosis are multifaceted. Lipl41 is an outer membrane protein that is expressed during infection and is highly conserved among pathogenic species. This makes it a good candidate for diagnosis and induction of specific immune responses. The aim of the present study was to evaluate immune responses against recombinant Lipl41 in mice.

Materials and methods: After immunizing of different groups of mice with recombinant Lipl41 (rLipl41), the levels of specific antibodies and cytokine profiles interferon-gamma/interleukin-4 (IFN-γ/IL-4) were measured.

Results: The results revealed that rLipl41 showed a significant increase in antibody levels compared with the control groups (P< 0.05). Although the level of IL-4 in the groups that received Lipl41 was similar to that in the other control groups, the IFN-γ levels showed a significant increase (P<0.05).

Conclusion: It has been concluded that recombinant Lipl41 protein could strongly stimulate specific immune responses and be considered a potential candidate for vaccine development and diagnostic research.

Background and objectives: Herpes zoster, or shingles, is caused by the varicella-zoster virus (VZV), which initially presents as chickenpox in children. VZV is a global health concern, especially in winter and spring, affecting 10-20% of adults over 50 and posing a 30% risk for the general population. This study used PCR to detect VZV, confirming results with duplicated DNA samples and identifying 234 bp fragments by targeting the gpB gene.

Materials and methods: This study examined 50 herpes zoster cases from October 2020 to April 2021, involving 30 males and 20 females aged 10 to 90, diagnosed by dermatologists. Data were collected via a questionnaire. PCR detected VZV by amplifying the gpB and MCP genes from skin lesion samples. Six positive 234-bp PCR products were sequenced at Macrogen Inc. in Seoul, South Korea.

Results: Six DNA samples with 234 bp amplicons were sequenced, showing 99-100% similarity to human alpha herpesvirus sequences in the gpB gene. NCBI BLAST matched these sequences to a reference (GenBank acc. MT370830.1), assigning accession numbers LC642111, LC642112, and LC642113. Eight nucleic acid substitutions caused amino acid changes in the gpB protein: isoleucine to threonine, serine to isoleucine, and threonine to Proline. These variants were deposited in NCBI GenBank as gpB3 samples.

Conclusion: The study found high sequence similarity to known VZV sequences, identifying six nucleic acid variations and eight SNPs. Notable amino acid changes in the gpB protein were deposited in NCBI GenBank as the gpB3 sample.