Iranian Journal of Microbiology最新文献

Background and objectives: The increasing prevalence of fungal infections due to antifungal resistance underscores the need for novel treatment strategies. The present study aimed to investigate the inhibitory effects of soil-originated antagonistic bacteria against Aspergillus and Trichophyton species.

Materials and methods: Fifty soil samples collected from Isfahan and Khuzestan provinces by using the Zig-Zag method were cultured on glucose-yeast extract (GY) agar around fungal colonies to isolate antagonistic bacteria. Antifungal activity was assessed by measuring clear zones around the colonies of A. niger, A. fumigatus, T. rubrum, and T. mentagrophytes by co-culture linear method. Potent antagonistic bacteria were identified by 16S rRNA sequencing, and evaluated for antifungal activity using disk diffusion assays compared with amphotericin B and ketoconazole.

Results: Among 50 samples, fifteen showed antifungal effects, yielding 55 bacterial strains. Four isolates with strong antifungal activity against all tested fungi were identified as Bacillus subtilis, B. licheniformis, B. axarquiensis, and Bacillus sp. These bacteria were distributed in distinct clusters phylogenitically and showed diverse antifungal activity.

Conclusion: The results suggest the potential of soil-derived Bacillus species as promising antifungal agents. Further studies are recommended to identify their inhibitory metabolites, their ability as biocontrol agents against soil habitated fungi and to explore their mechanism of action and spectrum of activity.

Background and objectives: Q fever is a frequently occurring illness that is induced by the bacterium Coxiella burnetii (C. burnetii) that can infect humans and various animals. It targets the macrophage cells in the tissues, and circulating monocytes.

Materials and methods: This study was conducted between 2022 and 2023 in the West Azerbaijan and Ardabil provinces of northwestern Iran to examine the presence infection of C. burnetii. Specimens were obtained by swabbing from 140 mares (70 from each province) and 20 stallions (10 from each province) which were apparently healthy, and their DNA was analyzed using quantitative PCR assay detecting the IS1111 element of the bacterium.

Results: The findings indicated that a mere 0.625% of the examined specimens tested positive for C. burnetii. Among the entire set of specimens, a single female horse from the region of Ardabil was found to be the carrier of the bacterium.

Conclusion: This suggested that even though horses may not display any clinical symptoms, they can still harbor C. burnetii and contribute to its transmission. Therefore, the potential contribution of horses to Q fever transmission should be considered.

Background and objectives: The rapid emergence of resistant fungi is occurring worldwide, and this crisis has been attributed to the lack of new antifungal drug development. This issue emphasizes the need for innovation in finding novel antifungals. There is an increasing interest in using the natural products of plants with high biological activity as alternatives to synthetic drugs. This study aimed to evaluate the possible applicability of polyphenols as alternative antifungal drugs to treat resistant Candida infections.

Materials and methods: A panel of fluconazole-resistant (n=14) and fluconazole-susceptible (n=26) clinical Candida isolates was obtained from the reference culture collection. The determination of the minimum inhibitory concentrations (MICs) of fluconazole, tannic acid, rosmarinic acid, gallic acid, chlorogenic acid, caffeic, ferulic, and p-coumaric was carried out following the Clinical and Laboratory Standards Institute (CLSI) guidelines.

Results: The MIC values of 40 Candida species isolates ranged from 0.25 to >64 μg/mL for polyphenolic compounds. The highest inhibitory effect against Candida species was observed with tannic acid, followed by fluconazole. Non-albicans Candida groups were more sensitive to tannic acid compared to C. albicans isolates. Significant differences were observed in the MICs of fluconazole and tannic acid against non-albicans Candida isolates.

Conclusion: The increasing antifungal resistance highlights the importance of evaluating new drugs that are more robust against resistance. This study suggests that tannic acid could be considered a novel antifungal agent for managing fungal infections, including multidrug-resistant non-albicans Candida infections.

Background and objectives: Increased Pseudomonas aeruginosa antibiotic resistance limits treatment options and is associated with a higher level of mortality and mordacity. The purpose of this research was to identify class 1 and 2 integrons, carbapenemase, SHV, and TEM genes in extensively drug-resistant (XDR) P. aeruginosa isolated from infected burns and evaluate their in vitro cefiderocol activity.

Materials and methods: By using the disc diffusion method, the antimicrobial susceptibility of 110 P. aeruginosa isolates collected from infected burns were evaluated. XDR P. aeruginosa were screened phenotypically for carbapenemase and extended spectrum β-lactamases (ESBLs) production. Both MIC Test Strip and disc diffusion were employed to test the cefiderocol susceptibility. PCR was used to assess carbapenemase, SHV and TEM genes and integrons class 1 and 2.

Results: From the 110 P. aeruginosa, 54 isolates (49%) were XDR. TEM gene was detected in 35 isolates. Among XDR isolates, carbapenemase genes were detected in 31.5%, with NDM being predominant Thirty XDR isolates had class1 integrons. All isolates were sensitive to cefiderocol and its MIC₅₀/MIC₉₀ was 0.5/1.5mg/L (range 0.064-1.5mg/L).

Conclusion: Nearly half the P. aeruginosa isolates from burn infections were extensively drug-resistant. Cefiderocol's in vitro activity demonstrated that it is a promising therapy alternative for treating extensively drug-resistant P. aeruginosa in burn patients.

Background and objectives: The rapid emergence of resistant fungi is occurring worldwide, and this crisis has been attributed to the lack of new antifungal drug development. This issue emphasizes the need for innovation in finding novel antifungals. There is an increasing interest in using the natural products of plants with high biological activity as alternatives to synthetic drugs. This study aimed to evaluate the possible applicability of polyphenols as alternative antifungal drugs to treat resistant Candida infections.

Materials and methods: A panel of fluconazole-resistant (n=14) and fluconazole-susceptible (n=26) clinical Candida isolates was obtained from the reference culture collection. The determination of the minimum inhibitory concentrations (MICs) of fluconazole, tannic acid, rosmarinic acid, gallic acid, chlorogenic acid, caffeic, ferulic, and p-coumaric was carried out following the Clinical and Laboratory Standards Institute (CLSI) guidelines.

Results: The MIC values of 40 Candida species isolates ranged from 0.25 to >64 μg/mL for polyphenolic compounds. The highest inhibitory effect against Candida species was observed with tannic acid, followed by fluconazole. Non-albicans Candida groups were more sensitive to tannic acid compared to C. albicans isolates. Significant differences were observed in the MICs of fluconazole and tannic acid against non-albicans Candida isolates.

Conclusion: The increasing antifungal resistance highlights the importance of evaluating new drugs that are more robust against resistance. This study suggests that tannic acid could be considered a novel antifungal agent for managing fungal infections, including multidrug-resistant non-albicans Candida infections.

Background and objectives: Staphylococcus aureus (S. aureus) is one of the predominant biofilm producing pathogen in leprosy foot ulcer (LFU). The objective of this study was to identify the transcriptome profile through Next Generation Sequencing (NGS) approach in mature biofilm of leprosy foot ulcer isolate of S. aureus.

Materials and methods: A cross-sectional study was conducted from July 2019 to May 2022 and a total of twenty-seven S. aureus isolates were collected from the foot ulcers of leprosy patients. All S. aureus isolates were screened for biofilm formation in vitro. Initially, two potential biofilm producing isolates and two planktonic cells were selected for transcriptome comparison.

Results: With reference to transcriptome profile, out of 2,842 genes, 2,688 genes in mature biofilm and 2,685 genes in planktonic cells were expressed. Among them, forty-five differentially expressed genes with 32 and 13 genes showing up and down regulation respectively were obtained.

Conclusion: The research emphasizes the need for continued exploration into the mechanisms of biofilm formation by S. aureus, particularly in the context of leprosy foot ulcers. Understanding these pathways not only aids in grasping the complexity of chronic infections but also paves the way for innovative therapeutic approaches aimed at mitigating biofilm-related complications in clinical settings.

Background and objectives: Due to the persistence of residual fungal elements, onychomycosis tends to have a high recurrence rate. It is essential to determine the etiology and frequency of onychomycosis across various factors. This study aimed to assess the prevalence of onychomycosis and identify its fungal agents in cancer patients undergoing chemotherapy.

Materials and methods: This cross-sectional study was conducted on cancer patients attending the Oncology Clinic and Cancer Institute of Tehran University of Medical Sciences. Among the 165 patients meeting the inclusion criteria, 75 individuals with nail alterations were referred to a dermatologist. Each patient's information, including demographics, disease-related data, and details about nail involvement, was recorded. When onychomycosis was suspected, nail samples were collected from the deepest part and examined using a light microscope after clarifying with 15% potassium hydroxide (KOH) to detect fungal elements.

Results: The prevalence of onychomycosis was 37.6% (n=62). Among the 75 patients with nail alterations and suspected onychomycosis, 17.3% (n=13) tested negative for pathogenic agents. The most common pathogen was Candida albicans, present in 21% (13/62) of patients with positive onychomycosis. The prevailing nail alteration was onycholysis, affecting 45.3% (34/75) of patients.

Conclusion: Onychomycosis exhibits associations with variables such as gender, age, cancer and chemotherapy.

Background and objectives: As a Gram-positive bacterium, Streptococcus agalactiae or Group B Streptococcus (GBS) is normally found as a transient flora of the gastrointestinal and genitourinary tracts of women. The high prevalence of GBS in the urethra warrants investigation of UTIs and antibiotic resistance frequency associated with GBS. Given the paucity of research on antibiotic resistance of GBS in Iran, the present study investigated the UTIs associated with GBS and the antibiotic susceptibility patterns associated with GBS.

Materials and methods: This study included 65 GBS strains collected from urine samples obtained from the Bouali Laboratory Complex, one of the largest laboratories in western Iran. VITEK 2 GP ID cards were used to identify all GBS isolates. VITEK 2 susceptibility testing for Gram-positive bacteria was performed according to the manufacturer's instructions using the AST-ST card. MIC method was performed after the detection of GBS strains.

Results: We found that 53 (81.5%) of the GBS isolates showed resistance to tetracycline; 47 (72.3%), 40 (61.5%), and 30 (46.15%) of these had a resistance to erythromycin, clindamycin and ampicillin respectively.

Conclusion: In the present study, the VITEK 2 system was validated as a user-friendly system that can serve as a rapid and accurate tool for identification and antimicrobial susceptibility testing of GBS.

Background and objectives: Wheat and its derived products are high-risk commodities for aflatoxin contamination. The objective of this study was to investigate the effect of using Saccharomyces cerevisiae, Lactobacillus plantarum, and the dough fermentation and baking periods on reducing aflatoxin B₁ (AFB₁), ochratoxin A (OTA), and zearalenone (ZEA) toxins.

Materials and methods: Toast bread flour contaminated with AFB₁, OTA and ZEA (10,10 and 400 ng/g) were separately treated with S. cerevisiae and L. plantarum (at a concentration of 10⁸ CFU/g). The reduction of mycotoxins was examined immediately after dough preparation, at the end of fermentation, and after baking.

Results: The type of microorganism, fermentation and baking significantly affected the reduction of mycotoxins (AFB₁, OTA, and ZEA). After baking, neither AFB₁ nor OTA were detected in any of the toast bread samples, with a 100% reduction observed in all treatments. In contrast, the percentage reduction of ZEA after baking compared with immediately after dough preparation ranged from 98.90% to 100%, and the percentage reduction of ZEA at the end of fermentation compared with immediately after dough preparation ranged from 97.80% to 99.57%.

Conclusion: The findings of this study suggest that L. plantarum and S. cerevisiae can be used as additives or processing agents to decrease mycotoxins in fermented wheat foods.

Background and objectives: The COVID-19 pandemic was mitigated by the rapid development and deployment of vaccines. While vaccines reduce infection severity, breakthrough infections (BTIs) still occur. The CDC defines BTI as a positive SARS-CoV-2 test ≥14 days post-vaccination. This study investigates the occurrence of COVID-19 BTIs at a tertiary care hospital in Puducherry, South India.

Materials and methods: This retrospective study analysed hospital tested qRT-PCR data of individuals from the ICMR portal (March 2021-March 2022). Demographic and vaccination details were extracted.

Results: Among 8001 tested individuals, 1452 were vaccinated. The BTI rate decreased from 16.6% to 1.2% after the first dose and from 58% to 40% after the second one. Odds ratio indicated a 74% reduction in infection risk for vaccinated individuals compared to unvaccinated. Males had higher infection rates than females, regardless of vaccination status.

Conclusion: Our study demonstrates a higher BTI rate after one vaccine dose compared to two doses. The BTI rate also increased four months post-vaccination, even with two doses, potentially due to waning immunity and the emergence of new variants. Therefore, continued adherence to preventive measures in conjunction with vaccination is crucial for minimizing COVID-19 transmission.