Iranian Journal of Microbiology最新文献

Background and objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of illness from consuming contaminated food. MRSA is mainly known for its ability to develop resistance to antibiotics including methicillin. This research examined the antimicrobial resistance pattern, enterotoxigenic dispensation, virulence factors, and biotyping for MRSA isolates.

Materials and methods: Susceptibility of S. aureus isolates to 13 types of antibiotics were assessed, and the genes associated with the resistance were investigated. Disk diffusion was used to identify the phenotypic tenet of antibiotic resistance. PCR is instrumental in detecting genes that confer resistance to antibiotics, virulence and enterotoxin genes.

Results: S. aureus were found in 167 out of 363 nugget and salad samples, representing 46% of the total sample count. Seventy-eight isolates (46.71%) were identified as MRSA bacteria. Its prevalence in different sources was as follows: 10% in bovine, 0% in ovine, 30% in poultry, and 56% in humans. MRSA displays high prevalence of resistance to cefotaxime and tetracycline (100%). coa was the most prevalent virulence factor (100%) in MRSA.

Conclusion: Distribution of antibiotic resistance genes in MRSA, highlights a serious health issue, as the presence of different antibiotic resistance genes exacerbates multidrug resistance in MRSA isolates.

Background and objectives: Urinary tract infections (UTIs) are common in pregnancy and can cause maternal and fetal complications. Proteus mirabilis is a significant pathogen in recurrent UTIs due to its virulence factors. This study investigated the virulence genes and antibiotic resistance patterns of P. mirabilis isolates from pregnant women with UTIs in Erbil, Iraq.

Materials and methods: This cross-sectional study (September 2024-January 2025) included 120 urine specimens from pregnant women (15-44 years) with UTI symptoms. Bacterial identification was performed using culture, biochemical tests, as well as the Vitek 2 system. Virulence genes were detected by PCR, and antimicrobial susceptibility was assessed by standard methods.

Results: Of the 120 samples, 103 (85.8%) showed bacterial growth; 8 (6.7%) were positive for P. mirabilis, while 95 (79.1%) yielded other bacteria. The most affected age group was 25-34 years (52.5%), predominantly in the second trimester (42.5%) and urban residents (60.8%). Antimicrobial resistance was significant to ampicillin, trimethoprim-sulfamethoxazole, amoxicillin/clavulanic acid, and cephalosporins, although susceptibility was observed with several antibiotics. All P. mirabilis isolates harbored the UreC gene, and 75% possessed the MrpA virulence gene.

Conclusion: Multidrug-resistant P. mirabilis with key virulence genes was detected in pregnant women with UTIs. Regular screening and resistance monitoring are essential for effective management.

Background and objectives: Dermatophytosis is a significant worldwide health concern, particularly in tropical and subtropical regions. Tinea unguium (TU) and Tinea capitis (TC) are among the most prevalent clinical manifestations of dermatophytosis caused by several dermatophyte fungi. This study investigated the molecular epidemiology and distribution of dermatophytes causing TU and TC in Tehran, Iran.

Materials and methods: From March 2023 to March 2024, a clinical mycology center in Tehran received 342 suspected cases of TU and TC. The diagnostic methods included the conventional and molecular methods by sequencing the ITS region of ribosomal DNA.

Results: Overall prevalence of dermatophytosis was 59/342 (17.2%) among suspected patients by direct examination. TU and TC were diagnosed in 31/59 (53%) and 28/59 (47%), respectively. The final prevalence among suspected patients was 43/342 (12.5%) by PCR-sequencing, and TC accounted for the largest group of them, 25/43 (58%). Females represented the largest group of suspected TU cases (204/303, 67%; mean age: 57 years), while males predominated among TC patients (28/39, 74%; mean age: 10 years). PCR-sequencing revealed Trichophyton tonsurans was the most common agent of TC, 22/25 (88%), and Trichophyton indotineae emerged as a notable cause of TU in 5/18 (28%) of confirmed cases.

Conclusion: In our study, T. tonsurans remained the predominant cause of TC, while T. indotineae emerged as a significant cause of TU. Agreement between conventional and molecular methods was substantial (κ=0.73, 95% CI: 0.61-0.85), with 81.8% misidentification of the T. mentagrophytes complex but complete accuracy for T. tonsurans and Microsporum canis.

One of the main pillars of human health depends on healthy nutrition. Chicken makes up a significant part of human nutrition particularly in societies experiencing economic inflation and severe disruptions to people's livelihoods. So livestock and poultry pose a crucial impact on food safety and immunity. Probiotics have acquired worldwide acceptance as a healthy ingredient for usage as a potential feed supplement to reduce foodborne diseases and confirm food hygiene from farm to fork. Feed additives containing live yeast, e.g. Saccharomyces boulardii, and yeast derivative products can increase feed intake and intestinal health, and improve productivity. This probiotic, non-pathogenic yeast possesses several health-beneficial properties for poultry and livestock. However, it was previously believed that yeast did not have an effective probiotic effect in chicken and poultry. In this review, the advantages of using Saccharomyces boulardii has been introduced as a probiotic for poultry and livestock. This comprehensive analysis explores the multifaceted applications of probiotics in animal feed from health and AMR perspectives, examining their mechanisms of action, benefits, and potential to transform sustainable animal production practices.

Background and objectives: The increasing incidence of antifungal-resistant Candida infections, particularly among cancer patients, emphasizes the urgency of exploring alternative therapeutic strategies. This study aimed to assess the in vitro antifungal efficacy of three anticancer agents-tamoxifen, panobinostat, and miltefosine-both individually and in combination with the antifungals fluconazole and itraconazole, against fluconazole-resistant Candida strains.

Materials and methods: A total of 21 clinical Candida isolates (C. albicans, C. parapsilosis, C. glabrata, C. tropicalis, and C. auris) were evaluated. Antifungal susceptibility testing was conducted following the microdilution protocol outlined by CLSI.

Results: The combination of panobinostat with fluconazole exhibited full synergistic activity against C. albicans and C. tropicalis. Conversely, antagonistic effects were observed with C. parapsilosis and C. glabrata, while C. auris displayed an indifferent response. Panobinostat paired with itraconazole showed synergy exclusively against C. albicans. Similarly, miltefosine combined with itraconazole demonstrated synergism with C. albicans, but no interaction was found with fluconazole. Tamoxifen in conjunction with itraconazole revealed a synergistic response against C. albicans, antagonism with C. tropicalis, and indifference with other species.

Conclusion: Certain combinations of antifungals and anticancer agents could potentiate antifungal activity against resistant Candida isolates. Therefore, precise species-level identification is vital for tailoring effective combination therapies, particularly in immunocompromised individuals.

Background and objectives: White basil (Ocimum gratissimum L. Lamiaceae) essential oil exhibits potent antibacterial effects but its aqueous insolubility and high volatility restrict its applications. This study aimed to develop a nanodispersed mouthwash containing white basil essential oil, optimizing of surfactant/co-surfactant type and ratio, assess its physicochemical stability and antibacterial efficacy against Streptococcus mutans ATCC 25175.

Materials and methods: Formulations combining white basil essential oil, Tween-80, isopropanol, Labrasol and water were prepared. Particle size, zeta potential, and pH were measured. Stability was evaluated under accelerated (40°C, 75% RH) and stressed (60°C, 75% RH) conditions over three months. Antimicrobial efficacy was assessed via minimum bactericidal concentration (MBC) after 30-second exposure.

Results: Characterization of the optimized formulation revealed an average particle size of 128 nm, neutral zeta potential, pH 3.42. Stability testing demonstrated thermodynamic resistance under all storage conditions for three months without phase separation or significant size change. The MBC against Streptococcus mutans was 0.4% w/v essential oil following 30 seconds of exposure. A corresponding mouthwash with 0.4% w/v essential oil demonstrated equivalent bactericidal activity.

Conclusion: Nanodispersion offers a promising strategy for white basil essential oil in mouthwash formulations. The developed formulation shows favorable stability and rapid bactericidal action, supporting further evaluation for clinical and commercial development.

Background and objectives: Group B Streptococcus (GBS) is a common bacterium found in the gastrointestinal tract and genitalia of both humans and animals. GBS infections can lead to a range of conditions, including meningitis, pneumonia, and sepsis. The present study aimed to analyze the colonization rate, antibiotic susceptibility, and serotypes of GBS in pregnant women in Urmia, Iran.

Materials and methods: Following GBS isolation from pregnant women and confirming its presence through PCR, antibiotic susceptibility testing was conducted to assess resistance patterns, followed by amplification of resistance genes (mefA, ermB, ermTR, linB) and molecular serotyping to determine the genetic characteristics of the strains.

Results: Out of 400 samples, 31 (7.75%) were positive for GBS, with 22 (70.97%) showing multidrug resistance. Clindamycin had the highest resistance rate (80.65%), while penicillin showed the lowest (3.23%). Serotypes II and V were the most common (38.71% each), followed by Ia (19.35%) and III (3.23%). The ermB gene was detected in 4 strains, while mefA, ermTR, and linB were not found.

Conclusion: Optimal management of GBS infections in pregnant women necessitates ongoing surveillance and antibiotic stewardship, considering penicillin resistance and observed resistance patterns.

Background and objectives: Hypermucoviscous Klebsiella pneumoniae exhibits distinct phenotypic and genetic characteristics that distinguish it from the classic K. pneumoniae pathogen. The aim of current study was to investigate some phenotypic and genetic markers used for hmKp identification.

Materials and methods: Seventy-one K. pneumoniae isolates were obtained from the respiratory care unit in Al-Diwanyiah Teaching Hospital Diwanyah, Iraq, from the first of November 2024 to the first of March 2025. The bacteria were identified, and antibiotic sensitivity testing was performed using VITEK 2 ID-GN and AST cards. Hypermucoviscosity was assessed using the string test, and an investigation into several adherence and virulence genes was conducted for all isolates. Then, multi-locus sequence typing was performed for hypermucoviscous K. pneumoniae isolates.

Results: 3 (4.22%) of 71 isolates were hypermucoviscous. The virulence and adherence genes were present in 100% of the isolates, whereas rmpA was only found in hypermucoviscous isolates. The results showed that the hmKp isolates were members of clonal group 147 (CG147) and were assigned to sequence type (ST) 293.

Conclusion: The string test is the primary phenotypical diagnosis for hmKp, while the genetically encoded rmpA gene is the most reliable genetic marker for hmKp identification. However, MLST is not beneficial for identification. The central positioning of ST392 within the MST highlights its potential role as an emerging high-risk clone.

Background and objectives: Ventilator-associated pneumonia (VAP) caused by carbapenem-resistant Gram-negative bacteria is a serious ICU challenge. This study determined the prevalence, antimicrobial susceptibility profiles, and phenotypic carbapenemase resistance mechanisms of Gram-negative isolates from VAP patients in two tertiary hospitals in Karachi, Pakistan.

Materials and methods: We included 104 consecutive cases of VAP (July 2021-January 2023). A total of 67 carbapenem-resistant Gram-negative isolates were identified and tested. Antibiotic susceptibility was assessed by disk diffusion and broth micro dilution, according to CLSI and EUCAST guidelines. Modified and enhanced carbapenem inactivation methods (mCIM/eCIM) were used to distinguish metallo-β-lactamase (MBL) and serine carbapenemase production.

Results: The mean age was 44.6 ± 18.3 years; 52.2% were male. Early-onset VAP accounted for 37.3% and late-onset for 62.7%. The most frequent pathogens were Acinetobacter baumannii (49.3%, 33/67) and Klebsiella pneumoniae (20.9%, 14/67). Notably, 67% of isolates produced MBLs, and 33% produced serine carbapenemases (phenotypically). The prevalence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan drug-resistant (PDR) phenotypes was 42.6%, 31.3%, and 19.4%, respectively.

Conclusion: VAP in our ICUs was dominated by A. baumannii and K. pneumoniae with high levels of MBL-mediated resistance. These findings highlight the urgent need for surveillance, stewardship, and new therapeutic options.

Background and objectives: Probiotics are effective in improving inflammatory bowel disease (IBD). This study assessed the effect of mesalazine and two candidate probiotics on the improvement of acetic acid (AA)-induced colitis model.

Materials and methods: Lactobacillus plantarum MS1and Lactobacillus delbrueckii YN1 were used for IBD model in rat. Twenty-five male Wistar rats weighing 250 ± 50 grams were used in 5 classified groups: Control (CO); Colitis (CL); Colitis, Probiotic (CLP); Colitis, Mesalazine (CLM); Colitis, Probiotic, Mesalazine (CLPM) and the treatment period was 3 weeks. The rats were treated with mesalazine 30 mg/kg and probiotic 10⁹ CFU/ml after induction of colitis. Histopathological and immunological analyses were performed to evaluate the effects of probiotic bacteria on IBD.

Results: The results showed that the probiotic bacteria reduced inflammation (P<0.05), extent (P<0.01), crypt abscesses (P<0.01), edema (P<0.05), inflammatory cell infiltration (P<0.5), and increased mucosa (P<0.001) in rats. Mesalazine administration in animals with colitis did not have a significant effect. Administration of probiotics in both CLP and CLPM groups reduced extent, crypt abscesses, edema, and inflammatory cell infiltration and showed an important role in the down-regulation of consolidation of pro-inflammatory factors (TNFα, IL-6, and IL-17), as well as up-regulation of anti-inflammatory factors such as IL-10.

Conclusion: Lactobacillus plantarum MS1 and Lactobacillus delbrueckii YN1 have shown significant potential in alleviating AA-induced colitis symptoms. Their administration leads to a marked reduction in pro-inflammatory cytokines such as TNF-α, IL-17, and IL-6, while enhancing IL-10 levels, indicating their promise as therapeutic candidates for inflammatory bowel disease (IBD).