International Journal of Microbiology最新文献

The growing problem of antibiotic resistance has driven the search for new sources of antimicrobial agents. Plants, particularly those from the Malvaceae family, have showed promising potential in this field. The present study is based on Tarasa extracts, and the antimicrobial action was assessed using Staphylococcus aureus and Escherichia coli as experimental bacterial strains. N-hexane extracts of T. capitata, Tarasa operculata and Tarasa tenuis were analysed and showed, for the first time, antimicrobial activities against human pathogens. GC/MS analysis identified several chemical compounds in the extracts that could be responsible for their antimicrobial activity. These findings suggest that Tarasa species could be a valuable source of new antimicrobial compounds.

Cases of antibiotic-resistant Escherichia coli (E. coli) infections are becoming increasingly frequent and represent a major threat to our ability to treat cancer patients. The emergence of antimicrobial resistance threatens the treatment of E. coli infections. In this study, the antimicrobial profiles, virulent genes, and the frequency of extended-spectrum beta-lactamase (ESBL) gene carriage in fecal E. coli isolates from cancer patients at the Laquintinie Hospital in Douala (Cameroon) were determined. 507 participants were recruited from October 2021 to March 2023, of whom 307 (60.55%) had cancer and 200 (39.45%) did not. Two hundred and two E. coli were isolated from fecal samples of one hundred and fifteen cancer patients and 47 (87) noncancer patients using EMB LEVINE agar. The antimicrobial resistance profile of the isolates was determined using the Kirby-Bauer disk diffusion method. Virulence and resistance genes were detected by simplex polymerase chain reaction (PCR). E. coli showed significant rates of resistance to amoxicillin, cefotaxime, ceftazidime, piperacillin, tetracycline, and ciprofloxacin in cancer patients compared to noncancer patients. The rate of multidrug resistance (MDR) was significantly (p < 0.05) higher in cancer patients than in noncancer patients. Fifty-five enterovirulent E. coli were identified, of which 24 (43.63%) were EPEC, 13 (23.63%) were EAEC, 6 (10.90%) were ETEC, 10 (18.18%) were STEC, and 2 (3.63%) were EIEC. The frequency of beta-lactamase genes in the 55 ESBL-producing enterovirulent E. coli isolates was determined, and 94.54% harbored at least one ESBL gene, distributed as follows: 80.00% for bla _TEM, 67.27% for bla _CTX-M, 24.63 for bla _OXA, and 36.36% for bla _SHV genes. Several associations were observed between virulence factors, resistance genes, and the antimicrobial resistance phenotype. This study revealed the real existence of fecal carriage of ESBL-producing enterovirulent E. coli isolates from cancer patients with a high rate of MDR in the latter.

Alpha-glucosidase inhibitors are one of the therapies used for treating type 2 diabetes by inhibiting the absorption of carbohydrates in the gastrointestinal tract. In addition to antimicrobial activity, some probiotic species show α-glucosidase inhibitor activity, making them potential alternative therapies for type 2 diabetes. This study aimed to characterize probiotics from "trites," a traditional food from North Sumatra, Indonesia, that exhibit α-glucosidase inhibition, potentially useful for type 2 diabetes treatment. The probiotic potential of the isolates was evaluated through antagonistic activity, acid tolerance, bile tolerance, and susceptibility to antimicrobial agents. α-Glucosidase inhibition was tested with acarbose as a control. The best-performing isolate, LBSU8, was identified as Pediococcus acidilactici through 16S rRNA gene sequencing. Gene analysis using genome sequencing for LBSU8 revealed antimicrobial secondary metabolites, including RiPPs, polyketide, and NRP, while capsular polysaccharide might contribute to its antidiabetic activity. Though no specific α-glucosidase inhibitory secondary metabolites were identified, enzymes like dTDP-glucose 4,6-dehydratase, transketolase, and glucose-1-phosphate thymidylyltransferase may contribute to this activity. P. acidilactici LBSU8 shows potential as an alternative diabetes therapy in the food and drug industries. Further studies are needed to elucidate the exact mechanism behind its α-glucosidase inhibitory activity and to explore its efficacy in clinical settings.

Rhodococcus equi-a facultative intracellular pathogen of macrophages-causes bronchopneumonia in foals and patients who are immunocompromised. Virulent strains of R. equi possess a virulence-associated plasmid, which encodes a 15- to 17-kDa surface protein called virulence-associated protein A (VapA). VapA expression is regulated by temperature and pH. Two transcriptional regulators, VirR and VirS, are involved in the transcriptional regulation of vapA. VirR regulates VapA expression through VirS. However, whether VirR directly regulates virS transcription is unclear. In this study, we examined VirR binding to the promoter region of the icgA operon, which contains virS, using the electrophoretic mobility shift assay and DNase I footprinting. VirR bound DNA fragments containing the virR-icgA intergenic region. Transcription from the promoter in this region was VirR-dependent and regulated by temperature and pH. The VirR-binding site contained the LysR-type transcriptional regulator-binding consensus motif, T-N₁₁-A. A point mutation (L98E) in the putative ligand-binding pocket of VirR constitutively activated the icgA promoter. However, no apparent difference was observed in the electrophoretic mobility shift assay and DNase I footprinting using the icgA promoter when L98E VirR was compared with wild-type VirR. A bacterial two-hybrid system identified an interaction between VirR and RpoA. Our data reveal that VirR binds the promoter of the icgA operon and directly activates its transcription. Furthermore, the regulation of VapA expression in response to temperature and pH is mediated by VirR.

Multidrug-resistant (MDR) Acinetobacter baumannii poses a significant therapeutic challenge due to its resistance to multiple antibiotics and its ability to form biofilm. This study aimed to characterize MDR A. baumannii isolates for their biofilm-forming capabilities and the presence of common biofilm-related genes at a tertiary care university hospital in Nepal. In addition, it assessed the efficacy of various compounds, particularly essential oils, in inhibiting biofilm formation. Identification and antibiotic sensitivity testing of A. baumannii isolates from clinical specimens were conducted according to the guidelines of the American Society for Microbiology. Isolates were screened for motility profiles, biofilm production in a microtiter plate assay, and the presence of biofilm-related gene(s) by conventional polymerase chain reaction. The ability of cinnamaldehyde, ethylenediaminetetraacetic acid (EDTA), Tween 80, amino acids (glycine and glutamic acid), and natural plant extracts to inhibit biofilm formation was also tested using the microtiter plate system. Out of the total 200 A. baumannii isolates, 195 were MDR, with 192 able to produce biofilms. Among them, 83.1% were strong biofilm producers. In this study, 42.0% and 66.2% of the isolates exhibited twitching motility and surface-associated motility, respectively. Thirty MDR A. baumannii isolates from medical devices contained biofilm-related genes csuE, ompA, bap, and bla _PER-1, in 90.0%, 53.3%, 46.6%, and 26.6% of strains, respectively. Cinnamaldehyde (0.875 mg/mL) was the most effective compound, inhibiting biofilm formation by 77.3%, followed by ethanolic extract of onion (77.2%), 0.5% Tween 80 (76.8%), and essential oil of ginger (70.8%). The majority of A. baumannii clinical isolates were strong biofilm producers and often possessed the biofilm-related genes csuE and ompA. Essential oils at 200 mg/L, along with Tween 80, were the most effective (≥ 67%) at inhibiting the formation of biofilms. These findings help to understand biofilm production and provide valuable insights into MDR A. baumannii isolates in this clinical setting.

Fermented foods, particularly fermented dairy products, offer significant health benefits but also present serious concerns. Probiotic bacteria, such as lactic acid bacteria (LAB), found in these foods have been strongly linked to the selection and dissemination of antibiotic resistance genes (ARGs). This study aims to examine the potential risks associated with fermented foods, despite their importance in human nutrition, by analyzing the entire production chain from raw material acquisition to storage. Focusing on cheese production as a key fermented food, the study will investigate various aspects, including dairy farm management, milk acquisition, milk handling, and the application of good manufacturing practices (GMP) and good hygiene practices (GHP) in cheese production. The findings of this review highlight that ARGs found in LAB are similar to those observed in hygiene indicator bacteria like E. coli and pathogens like S. aureus. The deliberate use of antibiotics in dairy farms and the incorrect use of disinfectants in cheese factories contribute to the prevalence of antibiotic-resistant bacteria in cheeses. Cheese factories, with their high frequency of horizontal gene transfer, are environments where the microbiological diversity of raw milk can enhance ARG transfer. The interaction between the raw milk microbiota and other environmental microbiotas, facilitated by cross-contamination, increases metabolic communication between bacteria, further promoting ARG transfer. Understanding these bacterial and ARG interactions is crucial to ensure food safety for consumers.

Background: Fetal complications can occur if pregnant women with urinary tract infection (UTI) are not treated. We aimed to determine the magnitude of UTI, drug resistance profile, and fetal outcomes among pregnant women in Adare General Hospital, Hawassa, Ethiopia. Methods: Facility-based cross-sectional study was conducted among 308 pregnant women using questionnaire and review of medical records. From 308 randomly selected pregnant women, clean catch midstream urine samples were collected, processed, and inoculated onto MacConkey and blood agars and after incubation, the colonies were further confirmed by using standard biochemical tests. A binary logistic regression model was used to compute the explanatory variables with the outcome variable. A p value less than 0.05 was considered statistically significant. Results: The overall prevalence of UTI was 13.6% with a 95% CI: 10-18. Out of 42 samples, 39 (92.8%) UTI infections in women between the ages of 15 and 34 were identified. The three most common bacterial isolates were Escherichia coli, Staphylococcus aureus, and Staphylococcus saprophyticus. The majority of the Gram-negative bacteria isolates were resistant to ampicillin (96.2%) and trimethoprim-sulfamethoxazole (39%), while the Gram-positive bacteria were resistant to tetracycline (75%) and trimethoprim-sulfamethoxazole (68.8%). Of the total 308 pregnant women who participated in the study, there were 51 (16.6%) poor fetal outcomes. In this study, the presence of bacteriuria had a significant association with poor fetal outcomes (p value = 0.001). The mother's age, gravidity, level of education, occupation, marital status, and previous UTI history were not associated with the current UTI status. Conclusions: Poor fetal outcomes are strongly associated with UTI during pregnancy. Early detection of UTI and treatment after culture and antibiotic susceptibility testing should be a priority for the management of UTIs in pregnancy to avoid poor fetal outcomes.

Uropathogenic Escherichia coli (UPEC) strains are the main bacteria that cause urinary tract infections (UTIs). UPEC are a significant public health hazard due to their high proliferation, antibiotic resistance, and infection recurrence. The ability to form biofilms is a mechanism of antibiotic resistance, which requires the expression of different genes such as fimH, ihf, upaB, and upaH. Despite the relevance of biofilm formation in bacterial pathogenicity, differences in the expression level of these genes among bacterial growth conditions have been little studied. Here, we have characterized the expression of fimH, ihf, upaB, and upaH genes in biofilms and suspension-grown bacteria of different E. coli strains. These included the UPEC CFT073, the multidrug-resistant strain CDC-AR-0346, and clinical isolates obtained from UTI patients. The expression of fimH, ihf, upaB, and upaH was markedly heterogeneous in clinical isolates, both in terms of transcript levels and response to suspension or biofilm conditions. That expression pattern was distinct from the one in UPEC CFT073, where upaB and upaH were upregulated and ihf and fimH were slightly downregulated in biofilm. In conclusion, the data presented here show that the pattern of biofilm-associated genes in the clinical isolates from UTI patients is not fully related to the reference strain of UPEC CFT073. However, analysis of a larger number of samples is required.

Research into biologically natural substances with antitumor properties, known for their potential to induce fewer side effects and exhibit specificity toward cancerous cells, remains imperative. The pressing demand for novel agents in cancer therapy underscores the intensive investigation of natural products from microorganisms. Penicillium aurantiogriseum, frequently isolated from food and feed, emerges as a promising candidate against pathogenic bacteria and fungi. This species harbors numerous mycotoxins that warrant extensive clinical study due to their potential in cancer treatment. Identifying mycotoxins with anticancer properties produced by P. aurantiogriseum could unveil novel therapeutic targets and enrich the pharmacological landscape. This review provides a comprehensive overview of the utilization of P. aurantiogriseum mycotoxins in cancer research and elucidates therapeutic agents' advantages and limitations. P. aurantiogriseum produces at least 15 mycotoxins with potent anticancer effects mediated through diverse mechanisms, including enzyme inhibition (e.g., pseurotin), induction of apoptosis (e.g., auranthine, aurantiamides A, aurantiomides A-C, penicillic acid, penitrem, verrucisidinol, acetate verrucosidinol, and chaetoglobosin A), and cell-cycle arrest (e.g., anicequol, aurantiamine, and Taxol). Although certain mycotoxins, such as Taxol, Anacin, and Compactin, are used in commerce, many others remain relatively unexplored. The mycotoxins derived from P. aurantiogriseum hold considerable potential for cancer treatment, offering novel therapeutic avenues and enhancing current treatments through synergistic combinations and advanced delivery systems.