MicrobiologyOpen最新文献

Enterococcus faecalis (E. faecalis) is a notable public health bacterium since it can thrive on high-touch surfaces in restaurants. This study aimed to isolate E. faecalis, conduct antibiogram to determine resistance patterns, explore the virulence profile and observe biofilm-forming properties. A total of 90 samples were collected from BAU restaurants, including high-touch surfaces and popular food items. Initial isolation employed culture-based method followed by Gram's staining technique and biochemical tests. Molecular confirmation was achieved via polymerase chain reaction (PCR) targeting the ddl_{E. faecalis} gene specific for E. faecalis. Antibiogram was performed using the Disc Diffusion Test for commonly used antibiotics. Genotypic detection of antibiotic resistance and virulence profile were also explored by PCR. Lastly, the Congo Red (CR) test was done to examine the biofilm-forming isolates. Results indicated a prevalence (30%) of E. faecalis in both food and surface samples, with higher contamination rates in crowded areas. Antibiogram revealed high resistance to Penicillin (100%) and moderate to low resistance towards Tetracycline, Ciprofloxacin, Erythromycin and Chloramphenicol. Shockingly, bla_TEM gene was found in 81.48% of isolates, and 18.51% were detected as multidrug-resistant. We found a very high prevalence of the virulence genes fsrA, fsrB, fsrC, gelE, pil, agg, and ace. Finally, the CR test revealed 33.33% and 44.44% isolates as strong and intermediate biofilm formers respectively. This study reinforces the significance of routine surveillance in combating the spread of antimicrobial resistance through the food chain and the prospective use of E. faecalis as a contamination marker.

Antimicrobial-resistant and virulent Staphylococcus aureus strains are spreading across diverse environments and hosts, but studies on Brazilian wildlife remain limited. From April to December 2021, oropharyngeal swabs were collected from 197 wild birds spanning five orders, 25 families, and 54 species in São Camilo State Park, a protected Atlantic Forest fragment facing significant pressure from surrounding agricultural landscapes. S. aureus was detected in 12.2% of the birds, including 27 methicillin-susceptible S. aureus (MSSA) and two Methicillin-resistant (MRSA) isolates. MSSA strains showed high inducible Macrolide-Lincosamide-Streptogramin B (MLSB) resistance, with 37% carrying the blaZ gene for penicillin resistance, and antimicrobial-resistant isolates frequently harboring the scn gene. Genomic sequencing identified both MRSA strains as ST398, marking the first report of MRSA ST398 in Brazilian wildlife. These strains displayed a broad resistome, including genes for resistance to multiple antimicrobial classes, as well as a comprehensive virulome, although in vivo assays with Galleria mellonella suggested low virulence. Phylogenomic analysis clustered the MRSA strains with MSSA from swine in northeastern Brazil, suggesting that these strains likely originated in livestock, acquired the SCCmec element, and spread into natural ecosystems. These findings suggest a possible spillover of livestock-associated antimicrobial-resistant S. aureus into a protected forest fragment, highlighting the potential for anthropogenic microbial threats to reach wildlife and underscoring the importance of including wild species in antimicrobial resistance surveillance, especially in fragmented ecosystems increasingly exposed to human activities.

The present study examined the virulence factors, phylogroups, antimicrobial profiles, and ESBL-associated genes in Escherichia coli isolated from frequently touched surfaces (FTS) in Mymensingh Sadar, Bangladesh. A total of 105 swab samples from seven categories of publicly shared common touch surfaces were collected to assess microbial load, with E. coli identified through molecular assay. The isolates were screened for major diarrheagenic virulence genes and underwent phylogenetic grouping, followed by disk diffusion and double disk synergy tests to evaluate their antimicrobial resistance and ESBL potential. Microbial loads on these surfaces ranged from 6.4 to 8.56 Log₁₀ CFU/cm², with E. coli detected in 12 samples (11.43%). Among these, only two isolates carried diarrheagenic virulence factors (ipaH and daaD), classifying them as enteroinvasive and diffusely adherent E. coli, respectively. The isolates were distributed across all four phylogenetic groups, predominantly group A (n = 5; 41.7%). Notably, 10 out of 12 isolates (83.3%) were multidrug-resistant, exhibiting complete resistance to ampicillin, followed by cefotaxime and trimethoprim/sulfamethoxazole. Additionally, the double disk synergy test confirmed four isolates (33.3%) as ESBL producers. This study highlights the potential risk of human infection with diarrheagenic E. coli from FTS, which may lead to serious illness and limit treatment options.

The increasing prevalence of multidrug-resistant (MDR) uropathogenic Escherichia coli (UPEC) strains, particularly those producing β-lactamase enzymes, complicates urinary tract infection (UTI) treatment and poses a significant public health threat. This study investigates the antibacterial potential of actinomycete extracts against MDR UPEC isolates while characterizing their phylogenetic diversity and β-lactamase profiles. From 300 clinical UTI samples collected in Babil Province, Iraq, 50 UPEC isolates were confirmed via standard microbiological and biochemical assays. Phylogenetic analysis, utilizing PCR-based detection of chuA, yjaA, and TspE4.C2 loci, revealed that most isolates belonged to the virulent B2 group. Antibiotic susceptibility testing showed 64% of isolates were MDR, with high resistance to cephalosporins and fluoroquinolones. Screening for β-lactamase genes identified blaCTX-M-I, blaTEM, and blaOXA as prevalent resistance determinants. Actinomycete isolates from soil samples produced ethyl acetate extracts that exhibited potent antibacterial effects against MDR UPEC, with inhibition zones exceeding 15 mm. These findings highlight actinomycetes as a promising source of novel antimicrobials to combat β-lactamase-producing UPEC, emphasizing the need for further compound characterization.

Multidrug-resistant (MDR) Escherichia coli (E. coli) represents a significant public health concern, particularly when harboring virulence genes such as clbA, which encodes the genotoxin colibactin. This study assessed the distribution of the clbA gene among MDR E. coli isolates from normal individuals, cancer patients, and clinical patients, and examined its association with antimicrobial resistance patterns. A total of 115 MDR E. coli isolates were collected from January to December 2024 at two healthcare centers in Nepal. The clbA gene was detected in 13.0% (15/115) of isolates, with a significantly higher prevalence in clinical patients (25.0%) compared to cancer patients (8.6%) and normal individuals (5.0%) (p = 0.0105). clbA-positive isolates exhibited markedly increased resistance to critical antibiotics, including imipenem (100% vs. 15.0%, p = 0.003), meropenem (100% vs. 12.5%, p = 0.001), and amikacin (100% vs. 10.0%, p = 0.050), compared to clbA-negative strains. These findings suggest that the presence of the colibactin-encoding clbA gene in MDR E. coli is linked to heightened antimicrobial resistance, especially in clinical settings, underscoring the need for targeted molecular surveillance and infection control strategies.

We characterized the secreted Trypanosoma cruzi P21 protein and hypothesized its role in parasite invasion and multiplication. To investigate the role of T. cruzi P21 protein in host-parasite interactions, specifically focusing on the low-virulence G strain. P21 knockout parasites were generated using CRISPR/Cas9. Cell invasion, multiplication, egress, and tissue parasitism were assessed in vitro and in vivo, comparing knockout and control parasites. P21 knockout significantly reduced parasite invasion and multiplication in Vero cells. In vivo, knockout parasites also showed reduced heart tissue parasitism in infected mice, despite no observable systemic parasitemia. Accordingly, P21 knockout trypomastigote egress was reduced in Vero cells. P21 plays a pleiotropic role in T. cruzi infection, differentially impacting parasite biology in the low-virulent G strain. In the G strain, P21 promotes invasion and persistence, potentially through mechanisms distinct from its role in the Y strain previously described. This highlights its potential as a therapeutic target for Chagas disease, warranting further investigation into strain-specific functions.

Antibiotics are widely used in animal production for disease treatment, prevention, and as growth promoters at subtherapeutic doses. Across Africa, various antibiotic classes, including beta-lactams, macrolides, tetracyclines, phenicols, fluoroquinolones, aminoglycosides, and polymyxins, have been incorporated into animal feed to enhance growth and productivity. However, the continuous supplementation of animal feed with antibiotics exerts selective pressure on bacteria, accelerating the development of antibiotic resistance. This misuse in animal agriculture significantly contributes to the growing global threat of antibiotic resistance, affecting animal, human, and environmental health. Resistant strains of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Salmonella species have been widely reported in animal, human, and environmental samples. The transmission of antibiotic-resistant bacteria from animals to humans can occur through direct contact. It can also result from exposure to contaminated manure, wastewater, or consumption of contaminated animal products. This poses a major public health challenge in Africa. To mitigate antibiotic resistance, the use of antibiotics as growth promoters in animal farming must be restricted. Alternative feed additives such as probiotics, prebiotics, and phytobiotics have shown potential as sustainable replacements. Educating farmers on antibiotic risks and sustainable alternatives is crucial. Furthermore, governments must implement strict regulations to control the sale and misuse of antibiotics in livestock production. The review aims to present the harm of antibiotic misuse in livestock farming and emphasize the need for alternative growth promoters, ultimately reducing the burden of resistance across the continent.

Cell surface-associated polysaccharides, including cell wall polysaccharides (CWPSs), capsular polysaccharides (CPSs), and exopolysaccharides (EPSs), play vital roles in bacterial interactions with their environment, influencing critical aspects of dairy fermentations, such as phage–host dynamics. Pseudolactococcus laudensis and Pseudolactococcus raffinolactis (formerly Lactococcus laudensis and Lactococcus raffinolactis) are emerging dairy-associated species whose CWPSs remain uncharacterized. This study analyzed the complete genomes of 21 P. laudensis and seven P. raffinolactis strains to investigate the genetic diversity underlying CWPS and EPS production. Eight novel cwps genotypes (E–L) were identified, significantly expanding the known diversity within the dairy-associated (pseudo)lactococci. Notably, E and G genotypes diverge from the classical rhamnan-PSP organization, suggesting a CWPS biosynthesis pathway distinct from the dual-chain assembly found in previously studied Lactococcus. Additionally, eps loci were identified in 25 of the 28 strains, uncovering 11 distinct genotypes (I–XI) with evidence of horizontal gene transfer. Their integration into chromosomal genomic islands highlights their mobility and potential role in evolutionary adaptation. Chemical analysis revealed unprecedented CWPS structures. P. laudensis DSM 28961 (type E) presented a 6-deoxy-α-l-talan polysaccharide and a β-(1,4)-galactan, marking the first instance of d-talose replacing rhamnose and the first homopolysaccharide in (pseudo)lactococcal CWPS, respectively. These were structurally independent, confirming a novel CWPS organization and biosynthetic pathway. Conversely, P. raffinolactis DSM 20443 (type I) exhibited a typical rhamnan-PSP structure, composed of a variably glycosylated rhamnan and a glucose-lactose hexapolysaccharide, respectively. This study provides the first resolved CWPS structures for the Pseudolactococcus genus, expanding the understanding of polysaccharide biosynthesis in Lactic Acid Bacteria.

Gastric cancer (GC) persists as the third most prevalent malignancy in China. GC exhibits distinct features when stratified by Lauren/ZJU subtypes. The interdependence of microbes, metabolites, and tumor evolution is recognized. Nevertheless, the specific microbial and metabolite disparities related to the Lauren and ZJU subtypes of GC have yet to be thoroughly investigated. In this study, we employed 16S sequencing of microbial communities and conducted untargeted metabolomic assessments on tumor tissues and their matched normal controls from 50 GC patients. We observed variations in microbial composition and metabolite landscapes across subtypes, irrespective of the Lauren or ZJU classification. We explored the associations and differences between the Lauren and the ZJU classification. It was found that both classifications share differential microbiota, including Fusobacterium and Haemophilus. Additionally, 38 of the top 50 differential metabolites are common to both classifications. However, distinct classifications also exhibit unique differential microbiota and metabolite characteristics. Among them, Eubacterium_ventriosum_group and N6-Succinyl Adenosine are both characteristic differences of the ZJU classification. Multivariate survival analysis disclosed that Eubacterium_ventriosum_group positively correlates with poor prognosis, whereas N6-Succinyl Adenosine negatively correlates with poor prognosis. Our research delineates the microbiota and metabolites specific to different subtypes of GC and investigates the interplay between these differential elements, as well as their prognostic significance. We have identified two distinct features that are both associated with the ZJU classification, suggesting that the ZJU classification is more closely related to prognosis.

The human gastrointestinal tract provides a complex environment for bacterial pathogens, necessitating their adaptation to host defenses and microbiota. Shigella, a Gram-negative bacterium responsible for bacillary dysentery, has evolved sophisticated mechanisms to regulate its virulence in response to intestinal signals. This study focuses on the role of peptidoglycan recognition protein 4 (PGLYRP4), a component of the host's innate immune system, in modulating Shigella's virulence. We demonstrate that PGLYRP4, at sub-bactericidal concentrations, significantly induces the transcription of the virulence regulator virF, through the CpxA/R TCS activation, therefore enhancing Shigella's infectivity without compromising bacterial viability. Moreover, our findings suggest that Shigella has developed an increased capacity to respond to oxidative stress, including that induced by PGLYRP4, through the basal upregulation of genes involved in detoxifying reactive oxygen species. This adaptation likely helps the pathogen counteract the bactericidal effects of PGLYRP4. Based on the results of our experiments and the literature, we hypothesize that Shigella uses PGLYRP4, which is produced by stimulated enterocytes in response to cytokines released by pyroptotic macrophages, as a molecular cue to enhance its ability to invade enterocytes. This study contributes to improving our understanding of bacterial pathogens' adaptation strategies by showing that they can evolve to compete more effectively with their hosts by using factors of the hosts' arsenal.