Letters in Applied Microbiology最新文献

Foodborne diseases are a major public health concern, and food handlers play a key role in the transmission of pathogenic and antimicrobial-resistant microorganisms. This study evaluated the occurrence and antimicrobial resistance profiles of Staphylococcus aureus among 50 food handlers working in the food and nutrition unit of a public hospital in Rio de Janeiro, Brazil. Samples from hands and nasal cavities were analyzed using culture-based methods and identified by MALDI-TOF mass spectrometry. Staphylococcus aureus was detected in 12% of hand samples and 22% of nasal swabs. High resistance rates were observed for penicillin, erythromycin, and ampicillin. Methicillin-resistant S. aureus (MRSA) represented 29% of hand isolates and 47% of nasal isolates, and 26% were multidrug resistant. These findings indicate that food handlers may act as reservoirs and transmission sources of antimicrobial resistance in hospital food service settings, highlighting the need for continuous monitoring, strict hygiene practices, and antimicrobial stewardship programs.

This study investigates the antibacterial effects of two widely used preservatives into foods, pharmaceuticals, and personal care products, sodium benzoate and phenoxyethanol on Gram-positive bacteria Staphylococcus aureus (ATCC 6538) and Gram-negative bacteria Pseudomonas aeruginosa (MTCC 1688). Despite their wide-spread usage, the exact antibacterial mechanisms of these preservatives are not yet fully understood. Our study demonstrated that the presence of SB and POE lead to extensive cellular rupture, membrane damage, and intracellular content leakage in bacteria. The results were validated through biochemical assays and visualised by transmission electron microscopy. The key findings from this study reveals that P. aeruginosa when treated with SB leads to cell shrinkage, whereas POE treatment leads to cellular bulging, under varied concentrations. Further analysis demonstrates that both compounds induce intracellular aldehyde accumulation leading to an increase in oxidative stress. This increase in oxidative stress can cause protein cross-linking, DNA and membrane destabilization, leading to cellular disruption. In summary, this study sheds light on the mechanisms behind the antibacterial effects and preservative's efficacy of these well-established compounds, offering valuable information for their ongoing use and potential enhancement in microbial control strategies.

When cultivation-based microbiology is used to isolate strains from environmental samples, the cultured populations may not represent ecologically relevant taxa in the source community. To address this, we employed pre-cultivation metabarcoding to establish a baseline community profile and detect cultivation bias. Using time-resolved cultivation of marine sediment bacteria, we demonstrated the need for initial community characterization. Sediment-derived microbiomes were cultured in Marine Broth 2216 and analyzed using 16S rRNA gene metabarcoding at 0, 6, 12, 18, and 24 h. A rapid 10-fold reduction in alpha diversity was observed within the 6 h (from 1029 amplicon sequence variants to 34-106), with the genus Vibrio reaching near-complete dominance (>95%) from 18 to 24 h, while environmentally dominant taxa such as Acinetobacter were quickly excluded. This dramatic shift illustrates that, without baseline characterization, cultivation-induced artifacts cannot be clearly distinguished from ecologically meaningful patterns. Fast-growing generalists can quickly outcompete ecologically significant taxa, distorting isolation outcomes and hindering the recovery of functionally important microorganisms. We show that metabarcoding at 0 h can identify cultivation biases, help interpret isolation results, and suggest targeted strategies for recovering ecologically relevant taxa. This integrated approach facilitates more accurate recovery and analysis of functionally significant microbial diversity.

The increasing demand for multifunctional and eco-friendly dermatological products has driven the search for natural bioactive agents from microbial fermentation. In this study, the fermented products derived from (XOS) and (Glc) by Lactiplantibacillus plantarum S61, previously isolated and characterized in our laboratory, were evaluated for their dermatoprotective and cosmeceutical potential. The obtained metabolites displayed potent antimicrobial activity against major skin pathogens. Inhibition zones ranged from 12 to 14.02 mm against C. glabrata, 11 to 19.90 mm against C. albicans, and up to 20.01 mm against Staphylococcus aureus and Micrococcus luteus, with minimum inhibitory concentrations as low as 4.16%. Beyond antimicrobial effects, the fermented supernatants exhibited remarkable anti-aging activities, effectively inhibiting tyrosinase and elastase enzymes responsible for pigmentation and skin elasticity loss. The IC₅₀ values for tyrosinase inhibition were 52.49 µg mL-1 (Glc) and 26.81 µg mL-1 (XOS), while elastase inhibition reached 85.46 µg mL-1 and 35.07 µg mL-1, respectively. Moreover, the samples demonstrated photoprotective properties, with Sun Protection Factor values of 7.357 (Glc) and 11.589 (XOS), corresponding to 86.40% and 91.37% Ultraviolet B protection. These findings highlight the XOS fermented product of L. plantarum S61 as a promising multifunctional ingredient for sustainable cosmeceutical formulations combining antimicrobial, anti-aging, and photoprotective benefits.

Changes in the gut microbiota (GM) are closely linked to colorectal cancer (CRC) development, influencing tumor cell proliferation and apoptosis. Prebiotics, probiotics, and synbiotics have been proposed as modulators of GM and potential regulators of tumor progression through key molecular markers, such as p53 and Ki-67. In this sense, a scoping review was performed following PRISMA-ScR guidelines to map available evidence on the impact of prebiotics, probiotics, and synbiotics on p53 and Ki-67 expression in CRC. Search was conducted in PubMed, SciELo, BVS/Lilacs, Embase, and Web of Science databases without date or language restrictions. Nineteen studies were included (18 preclinical and one randomized clinical trial). Ten studies assessed p53, seven evaluates Ki-67, and two examined both markers. Most preclinical studies suggested that biotic supplementation modulates apoptosis and proliferation-related pathways, often through p53 activation or Ki-67 suppression, although directionality varied across strains and models. Biotic interventions appear to influence tumor proliferation markers in CRC with strain- and model-dependent manner. Nevertheless, the evidence remains limited by heterogeneity of the study design, dosage, exposure time, and biomarker assessment. Well-designed and strain-resolved clinical trials are required to clarify whether these findings have translational and therapeutic relevance in CRC management.

Burkholderia cepacia (B. cepacia) is Gram-negative, multidrug-resistant bacteria that can infect neonates and hospitalized patients, often spreading through contaminated medical devices. It causes various infections including sepsis, and it is difficult to treat due its antibiotic resistance. Over a three-year period (2021-2023), data from the ICU at Hevi Pediatric Teaching Hospital were reviewed and analyzed. Sepsis cases were identified based on clinical signs and confirmed through blood culture. B. cepacia identification and sensitivity test were confirmed using the VITEK system. Out of a total 1046 blood samples, 524 (50.1%) demonstrated positive bacterial growth, among which 142 (27.1%) identified as B. cepacia sepsis. The total neonatal cases counted for 123, 112 (91.1%) occurred in males and 11(8.9%) in females. Early-onset sepsis (EOS, ≤72 h) accounted for 49 cases (39.8%) and late-onset sepsis (LOS, > 72 h) for 74 (60.2%). The overall in-hospital mortality rate was 10.6% (13/123). Notably, B. cepacia isolates exhibited extensive multidrug resistance. Only a limited number of antimicrobials, including meropenem (3% resistance), ceftazidime (5%) and trimethoprim/sulfamethoxazole (9%) demonstrated promising results. These findings underscore an urgent need for coordinated interventions, emphasizing prudent antibiotic use and the strengthening of antimicrobial stewardship program to mitigate further resistance.

This study evaluated the protective effect of combining Bifidobacterium bifidum with the prebiotics inulin and isomalto-oligosaccharides against enterohemorrhagic Escherichia coli infection and investigated the underlying mechanisms, using an integrated strategy of in vitro screening followed by in vivo validation. Among ten prebiotics screened, IMO and inulin were identified as optimal for promoting B. bifidum proliferation and acetate production (>2.5-fold), with IMO further enhancing bacterial adhesion to Caco-2 cells (4-fold). In a murine infection model, B. bifidum alone reduced total intestinal EHEC colonization, whereas inulin alone was ineffective. The combination of IMO and B. bifidum markedly suppressed EHEC colonization, particularly in the colon (5-fold reduction), while inulin provided no added benefit. Although fecal acetate levels were elevated in synbiotic groups, no linear correlation with EHEC clearance was observed, suggesting that protection may rely on mechanisms other than bulk acetate production-such as localized metabolite delivery or microbial ecological interactions. These findings demonstrate that an IMO-based synbiotic can effectively limit EHEC colonization through multifactorial modulation of the gut ecosystem. The presented strategy offers a rational framework for designing synbiotics to prevent foodborne infections.

Parkinson's disease (PD) and Alzheimer's disease(AD) have significant gut-brain axis interaction via microbial dysbiosis. In this study, Iranian patients with PD (n = 25), ad (n = 25), and neurological disorders (ND, n = 20) were compared with healthy controls (HC, n = 20) in terms of gut microbiota abundance, short-chain fatty acid levels, and gut inflammation markers (calprotectin and zonulin). Stool and blood samples were collected from all participants and analyzed using real-time PCR, high-performance liquid chromatography, and enzyme-linked immunosorbent assay. Significant reductions in Bacteroidetes, Faecalibacterium prausnitzii, Bacteroides spp., Bifidobacterium spp., and Lactobacillus spp. were observed in PD and ad patients versus HC. Enterobacteriaceae levels were elevated in PD, ad, and ND groups, while Proteobacteria were significantly higher only in ND patients. ad patients showed reduced Actinobacteria and increased Akkermansia muciniphila compared to HC. Inflammatory markers calprotectin and zonulin were markedly elevated in all patient groups, indicating intestinal inflammation. These findings suggest that microbial dysbiosis, particularly in PD and ad, may contribute to gut barrier dysfunction and systemic inflammation. Due to sample size and methodological limitations, future studies should incorporate advanced sequencing and longitudinal designs to validate these associations and explore therapeutic implications.

Rice (Oryza sativa) sustains more than half of the global population but is particularly vulnerable to water limitation in rainfed upland and lowland ecosystems. Endophytic microbiomes represent a sustainable strategy for improving drought resilience, yet their diversity and functional potential in traditional rice landraces remain underexplored. This study investigated endophytic bacterial communities associated with indigenous upland and lowland cultivars of West Bengal, India, using 16S rRNA amplicon sequencing, predictive functional profiling, culture-based screening, and biochemical validation. Distinct microbial assemblages revealed for diverse agro-ecosystems, with upland cultivars enriched in stress-adapted taxa such as Proteobacteria, Actinobacteria, and Firmicutes. PICRUSt2 predictions indicated higher representation of KEGG pathways associated with osmolyte biosynthesis, antioxidant defense, and compatible solute metabolism in upland microbiomes. Culture isolates, notably Enterobacter sp. KNR1 and Klebsiella sp. GBR1, exhibited strong tolerance to PEG-induced osmotic stress, producing elevated proline, glycine betaine, EPS, and IAA, alongside efficient root colonization in susceptible rice. Collectively, these findings establish indigenous upland rice as a reservoir of functionally resilient endophytes and provide a foundation for developing microbial consortia to enhance rice performance under water-limited conditions.

Clostridioides difficile is an opportunistic pathogen of the gastrointestinal tract that can cause illnesses ranging from diarrhea to pseudomembranous colitis. Recurrent Clostridioides difficile infection remains a major clinical challenge, with substantial relapse rates after standard antibiotic therapy. Emerging evidence suggests that rifaximin can be used after the conventional therapy to reduce risk of the recurrence. However, rifaximin resistance in Clostridioides difficile remains the primary concern. The aim of this systematic review and meta-analysis is to estimate the risk of rifaximin resistance in Clostridioides difficile infection and among different ribotypes. The search included PubMed, Scopus, Web of Science, and Cochrane Library for studies reporting rifaximin resistance in Clostridioides difficile isolates. After systematically screening 731 records from all databases and excluding 664 studies, a total of 67 studies were included in the meta-analysis. The findings of the meta-analaysis indicated a resistance rate of 15.1% (95%CI,12.0%-18.9%) for rifaximin and/or rifampicin and 12.8% (95%CI,8.8%-18.2%) for rifaximin alone. Ribotype-specific analysis revealed high rifaximin resistance in RT017(72.3%), RT027(47.0%), and RT018(20.9%), while RT012, RT002, RT112, and RT014/020 demonstrated low resistance. The study finding indicate that rifaximin/rifamycin resistance in Clostridioides difficile is concerning and not randomly distributed but is more frequently associated with certain ribotypes.