Search Results (132)

Background: Infections caused by antimicrobial-resistant bacteria are difficult to treat and increase the risk of death in animals. This report describes a fatal case of diarrhea in a horse that, despite intensive treatment including surgery and broad-spectrum antimicrobials (ceftiofur and amikacin), experienced a worsening of its condition and subsequent death. Methods: A fecal swab sample was subjected to microbiological culture for the identification of bacteria and assessment of their phenotypical antimicrobial susceptibility profiles using the disk-diffusion and broth microdilution methods. The double-disk synergy test, polymerase chain reactions for the detection of genes encoding extended-spectrum β-lactamases, and whole-genome sequence-based analysis were also performed. Results: Strains of Salmonella enterica and Escherichia coli were isolated, with the E. coli strain DSL-HVUVV-2025 presenting resistance to a third-generation cephalosporin. Accordingly, the bla_CTX-M-2 gene was identified in the DSL-HVUVV-2025 strain, which was submitted to whole-genome sequencing. Genomic analysis showed several antimicrobial resistance determinants, as well as virulence genes, including those associated with the enteroaggregative pathotype. The bla_CTX-M-2 gene was surrounded by an ISCR1 element and embedded in a complex class 1 integron that is part of the Tn7337 transposon. Strain DSL-HVUVV-2025 belonged to a novel sequence type. Conclusions: This case highlights the importance of monitoring antimicrobial resistance and performing genomic characterization of bacteria involved in equine diarrhea to guide effective clinical management in veterinary hospitals. It also reinforces the role of horses as potential carriers of WHO critical priority pathogens and the need for responsible antimicrobial use. Full article

Persistent diarrhea remains a significant cause of morbidity in young children, yet the role of gut microbiota has not been fully clarified. This prospective study evaluated the diversity and predicted functions of the gut microbiota in 30 children aged 6–24 months with persistent diarrhea of unknown etiology (patient group, PG) and 30 healthy controls (healthy group, HG). Nearly full-length 16S rRNA genes from fecal bacterial metagenomic DNA were sequenced and taxonomically annotated. Subsequently, all downstream analyses, including diversity assessment, differential abundance and functional prediction analyses, and data visualization, were performed using R software (version 4.5.0, 2025). The PG showed lower Shannon and higher Simpson indices than the HG (p < 0.05), reflecting reduced microbial diversity. At the phylum level, Firmicutes predominated in the PG, whereas Actinobacteriota, Bacteroidota, and Verrucomicrobiota were more abundant in the HG (|log₂FC| > 1 and FDR < 0.05). At the genus and species levels, the PG exhibited a marked depletion of essential commensals such as Bifidobacterium longum, Faecalibacterium, Lactobacillus, and Eubacterium, alongside an enrichment of opportunistic taxa including Klebsiella, Enterococcus lactis, and Streptococcus spp. (FDR < 0.05). Functional predictions using PICRUSt2 indicated an enrichment of carbohydrate metabolism and reductions in amino acid metabolism, B-vitamin pathways, and the biosynthesis of endogenous antibiotics (FDR < 0.05). These findings suggest that the PG harbors a dysbiotic gut microbiota characterized by reduced diversity, depletion of key commensal taxa, expansion of opportunistic bacteria, and potentially adverse shifts in metabolic functions. Full article

Bacteroides fragilis is a usually beneficial colonizer of the human gut that can also act as an opportunistic pathogen, causing infection and contributing to the development and progression of important diseases. The production and secretion of the B. fragilis toxin (BFT), the main virulence factor of this bacterium, distinguishes enterotoxigenic (ETBF) from non-toxigenic (NTBF) strains. Although NTBF does not produce the BFT, certain strains can exhibit unexpected pathogenic characteristics. The complex interactions between B. fragilis and the other intestinal bacteria, such as Clostridioides difficile, the leading cause of antibiotic-associated diarrhea in healthcare settings, highlights its ambivalent role of benefactor and pathogen. In fact, although B. fragilis plays a part in preventing colonization and infection due to C. difficile (CDI), both these anaerobic bacteria can contribute to the development and progression of colorectal cancer (CRC), one of the most prevalent malignant tumors of the digestive tract. This review provides an overview of the dual nature of B. fragilis, focusing on the peculiarities of ETBF and NTBF, delving into B. fragilis interaction with C. difficile and impacts on the host. Full article

The emergence of antibiotic-resistant bacteria has resulted in a lack of available drugs that can be used to treat various diseases. Antimicrobial peptides (AMPs) are green and safe antibiotic alternatives. In 2022, an outbreak of an acute diarrheal disease caused by Gram-negative cocci named Neisseria occurred among domestic geese (Anser cygnoides orientalis) in Northeast China. In this study, we analyzed Neisseria S1, which caused diarrhea in geese, and determined whether AMP R7I designed in our laboratory can be used to treat Neisseria infection. This is the first report and isolation of enteropathogenic Neisseria, as well as the first report of Neisseria infection in Anser cygnoides orientalis. Peptide R7I has the capability to counteract Neisseria S1 infection both in vivo and in vitro. R7I induced the release of intracellular contents, leading to the death of Neisseria. Oral treatment of R7I modulated metabolic levels, antioxidant capacity, and immune responses and inhibited inflammation in Neisseria-infected geese. Furthermore, R7I significantly contributed to the recovery of intestinal homeostasis and regulated intestinal function via a signaling pathway related to metabolism in Neisseria infection. During our study of the mechanism of R7I against Neisseria infection, we preliminary found that R7I regulates lipid metabolism disorder and inflammation caused by Neisseria infection through the PPAR signaling pathway. In conclusion, R7I shows a strong ability against Neisseria infection, and it can be used as an oral antibiotic alternative in animal feed. Full article

Background/Objectives: Infant diarrhea is a major global cause of morbidity and mortality. While Bifidobacterium is linked to diarrhea, its preventive effects, underlying mechanisms, and potential synergistic benefits with prebiotics remain unclear. The objective of this study was to explore the efficacy of a synbiotic composed of Bifidobacterium animalis subsp. lactis BB-12 (BB-12) and 2′-fucosyllactose (2′-FL) in alleviating infant diarrhea. Methods: One-week-old C57BL/6J mice were used to construct a model of infant diarrhea via infection with enteropathogenic Escherichia coli (EPEC) O127. Mice were administered BB-12 (10⁸ CFU per mouse), 2′-FL (1 g/kg), or their combination (synbiotic) for three consecutive weeks. Results: Administration of the synbiotic not only markedly improved diarrhea, anxiety-like behavior, colon inflammation, and gut barrier function but also positively reshaped the microbial community. This was achieved through a significant rise in short-chain fatty acid (SCFA)-producing bacteria (e.g., Akkermansia and Paraprevotella), a rise in fecal SCFAs, and a reduction in harmful bacteria such as Escherichia. Conclusions: The synbiotic effectively relieves EPEC-induced infant diarrhea by regulating gut microbiota composition and metabolic functions. These findings highlight its potential as a dietary intervention in infant diarrhea and provide new insights into infant health applications. Full article

Persistent diarrhea of unknown etiology in children under 2 years of age is a common problem and poses a major challenge for the health sector. However, knowledge of the composition and dysbiosis of the intestinal phageome, phage-associated bacteriome in the persistent diarrhea remains limited. In this study, a process for phage enrichment and metagenomic extraction was developed and applied to recover gut phage metagenomes from 30 healthy children and 30 children with persistent diarrhea for high-throughput sequencing. Taxonomic annotation using Kraken2 revealed that, besides Norwalk virus, Primate bocaparvovirus 1 and Human-associated gemykibivirus 2, phage communities in the diarrhea group showed reduced diversity and contained sample-dependent phages targeting Salmonella enterica, Enterobacter, Shigella flexneri, Clostridioides difficile, Pseudomonas aeruginosa, Streptococcus miti, uropathogenic Escherichia coli and functioned balancing bacterial communities. Bacterial fraction in the metagenomic datasets reflected clear patterns of dysbiosis, including a severe deficiency of beneficial bacteria, an increase in Firmicutes, a marked decline in Actinobacteria, Bacteroidetes, Proteobacteria and sample-dependent enrichment of Enterococcus, Escherichia and Acinetobacter in diarrhea cases. This study, for the first time, investigated the dynamics of gut phageome, phage-associated bacteriome in children with persistent diarrhea of unknown causes in Vietnam, providing new insight for complementary treatment. Full article

Natural products have emerged as potential alternatives to antibiotics in the treatment of bacterial diarrhea, due to their multi-targeting effects, low potential for inducing resistance, and favorable safety profiles. Currently, the search for natural product-based therapies has become an emerging focus in medical research. This growing interest is driven by the increasing awareness that the widespread and irrational use of antibiotics has contributed to the alarming rise in antibiotic-resistant bacterial strains, which in turn diminishes the efficacy of conventional drugs. Among these concerns, the limitations of antibiotics in managing bacterial diarrhea and the potential mechanisms by which natural products exert therapeutic effects are the main focus of this paper. Natural products, containing a wide array of bioactive compounds, can not only directly inhibit the growth of pathogenic bacteria, disrupt bacterial membrane synthesis, and reduce toxin production, but also modulate inflammatory responses, enhance immune function, repair intestinal barriers, and restore gut microbial ecology—highlighting their systemic and multi-targeted therapeutic potential. Therefore, this paper will elaborate on how natural products combat bacterial diarrhea from three aspects: the pathogen and pathogenesis of bacterial diarrhea, natural product-based therapeutic studies, and the underlying mechanisms of action, thereby proposing natural products as viable alternatives to antibiotics. Full article

Piglet diarrhea caused by weaning stress will increase the mortality rate and seriously affect swine industry production efficiency. Probiotic supplementation has been reported to effectively alleviate weaning diarrhea by inhibiting the colonization of pathogenic microorganisms; however, the underlying mechanisms remain unclear. In this study, we isolated a strain of Bacillus velezensis and conducted a series of in vivo and in vitro experiments to explore its effects on weaned piglets. The piglets were fed for a 28-day period, and the results showed that dietary supplementation of B. velezensis 411 significantly alleviated weaning diarrhea (p = 0.019) and improved the average daily gain (ADG) of piglets throughout the experimental period (p = 0.004). The intestinal antioxidant capacity of piglets was also significantly enhanced. Whole-genome sequencing revealed that B. velezensis 411 contains a protein-encoding circular chromosome, which is involved in biological processes such as sporulation and antibiotic secretion. Supplementation with B. velezensis 411 significantly increased the abundance of Akkermansia in intestine samples and significantly decreased the abundance of pathogenic bacteria, including Escherichia coli and Staphylococcus aureus, in piglets (p < 0.05). The transcriptomic results suggest that B. velezensis 411 supplementation may alter the composition of intestinal microorganisms through regulating the expression of MPEG1. Collectively, dietary B. velezensis can relieve diarrhea in piglets and improve their production performance by influencing the antioxidant capacity of the intestines and the balance of the intestinal flora. This study provides valuable insights into the potential application of Bacillus velezensis in mitigating weaning-associated issues in piglets. Full article

Background: The use of in-feed antibiotics was banned in numerous countries within the animal production industry as a result of the emergence of antibiotic-resistant bacteria and the presence of residual antibiotics. Bacteriophages, which are viruses that infect host bacterial cells, are considered the natural predators of bacteria. Over the past two decades, bacteriophages have garnered increasing attention for their potential in controlling pathogenic bacteria in weaned piglets. Aims: The aim of this overview was to update the progress of bacteriophage application in weaned piglets. Methods: For the section on bacteriophage application in weaned piglets, a systematic search was performed to identify relevant articles published before June 2025 in databases such as Web of Science. Results: In this review, we provide a brief overview of bacteriophages, followed by a summary of the isolation of specific bacteriophages in weaned piglets. In addition, we have summarized the application progress of bacteriophages in weaned piglets, including the effects of oral administration or dietary supplementation with bacteriophages on growth performance, diarrhea characteristics, intestinal morphology, intestinal pH, nutrient digestibility, inflammatory response, intestinal barrier function, and intestinal microecology. Conclusions: This updated overview novelly highlights the potential of bacteriophages as anti-pathogenic agents in mitigating infections caused by pathogenic bacteria in weaned piglets. This review could provide a scientific basis for controlling pathogenic bacteria infections in weaned piglets in the post-antibiotic era. Full article

Clostridioides difficile infection (CDI) appears mainly as nosocomial antibiotic-associated diarrhea, and community-acquired infection is increasingly being recognized. The threshold of asymptomatic colonization and the clinical manifestation of CDI need further elucidation. Community-acquired CDI (CA-CDI) should be considered when the disease commences within 48 h of admission to hospital or more than 12 weeks after discharge. Although CDI is not established as a food-borne or zoonotic disease, some data support that direction. The spores’ ability to survive standard cooking procedures and on abiotic surfaces, the formation of biofilms, and their survival within biofilms of other bacteria render even a low number of spores capable of food contamination and spread. Adequate enumeration methods for detecting a low number of spores in food have not been developed. Primary care physicians should take CA-CDI into consideration in the differential diagnosis of diarrhea, as there is a thin line between colonization and infection. In patients diagnosed with inflammatory bowel disease and other comorbidities, C. difficile can be the cause of recurrent disease and should be included in the estimation of diarrhea and worsening colitis symptoms. In the community setting, it is difficult to distinguish asymptomatic carriage from true infection. For asymptomatic carriage, antibiotic therapy is not suggested but contact isolation and hand-washing practices are required. Primary healthcare providers should be vigilant and implement infection control policies for the prevention of C. difficile spread. Full article

Enterotoxigenic Escherichia coli (ETEC), a common intestinal pathogen, can colonize the intestines and induce diarrhea in piglets, which brings great economic losses to the swine industry. Antibiotics are recommended to the treatment for diarrhea caused by ETEC in weaned piglets. However, with the emergence and spread of multidrug-resistant ETEC, there is an urgent need to develop alternatives to antibiotics. Due to the unique antibacterial mechanism of targeting bacterial membranes, antimicrobial peptides (AMPs) are promising candidates. In this study, the activity of crude recombinant porcine β-defensin 2 (rPBD2) expressed in Pichia pastoris (P. pastoris) was measured in vitro. Mice infected with ETEC were orally administered 16, 8, and 4 AU crude rPBD2 for 7 consecutive days to evaluate its anti-infective activity in vivo. The results showed that in addition to broad antibacterial activity against Gram-positive and -negative bacteria, crude rPBD2 displayed high tolerance to temperatures ranging from 20 to 60 °C, a broad range of pH, trypsin, pepsin, and physiological concentrations of salts. In an ETEC-induced mouse model, the oral administration of crude rPBD2 decreased diarrhea scores and the intestinal/carcass ratio and alleviated body weight loss. Additionally, crude rPBD2 decreased bacterial loads in stools and the colon (HP group), and the levels of serum pro-inflammatory cytokines IL-6 (HP group) and TNF-α (HP and MP groups), and increased the villus height and the ratio of villus height to crypt depth (VH/CD) in the ileum (HP and MP groups). Our study provides a cost-effective way for PBD2 production and identifies it as a promising candidate to combat ETEC-induced infection. Full article

Background/Objectives: Acute diarrheal illnesses are a major cause of hospital admissions, particularly in immunocompromised patients. Traditional diagnostic methods are slow and often insensitive, delaying treatment. In contrast, PCR panels provide rapid, sensitive detection of multiple pathogens. This study evaluates stool PCR testing in hospitalized adults and its impact on clinical decisions and antimicrobial stewardship. Methods: We conducted a retrospective study at Bistrița County Hospital, Romania (September 2023–September 2024), including 75 adults with acute diarrhea and negative conventional stool tests. PCR testing (VIASURE panels I and II) detected 11 bacteria, 6 viruses, and 5 parasites. Clinical and therapeutic data were analyzed, and logistic regression identified predictors of PCR positivity and adverse outcomes. Results: PCR was positive in 78% of cases, with Campylobacter spp. (57.6%) and Clostridioides difficile (20.3%) being the most common. Bloody diarrhea independently predicted PCR positivity (OR 9.78, p = 0.047). Immunosuppression and end-stage liver disease were linked to worse outcomes. PCR results led to antimicrobial therapy adjustments in 40 patients (p = 0.001), correcting inappropriate antibiotic use in 66% of those receiving empirical treatment. Targeted therapy significantly reduced antimicrobial duration from 7 to 5 days (p = 0.00001). Conclusions: Stool PCR testing enhances pathogen detection, guides targeted therapy, and reduces inappropriate antibiotic use, supporting antimicrobial stewardship and improving outcomes in selected hospitalized patients. Full article

Waterborne pathogens seriously threaten human life and can cause diarrhea, gastrointestinal disorders, and more serious systemic infections. These pathogens are usually caused by contaminated water sources that contain disease-causing microorganisms, such as bacteria, viruses, and parasites, which cause infection and disease when they enter the human body through drinking water or other means. Due to the wide range of transmission routes and the high potential risk of waterborne pathogens, there is an urgent need for an ultrasensitive, rapid, and specific pathogenic microorganism monitoring platform to meet the critical monitoring needs of some water bodies’ collection points daily monitoring needs. Microfluidics-based pathogen surveillance methods are an important stage towards automated detection through real-time and multi-targeted monitoring, thus enabling a comprehensive assessment of the risk of exposure to waterborne pathogens and even emerging microbial contaminants, and thus better protection of public health. Therefore, this paper reviews the latest research results on the isolation and detection of waterborne pathogens based on microfluidic methods. First, we introduce the traditional methods for isolation and detection of pathogens. Then, we compare some existing microfluidic pathogen isolation and detection methods and finally look forward to some future research directions and applications of microfluidic technology in waterborne pathogens monitoring. Full article

Shiga toxin-producing Escherichia coli (STEC) is an important pathogen that can cause asymptomatic infections, diarrhea, hemorrhagic colitis (HC), and life-threatening hemolytic uremic syndrome (HUS) in humans. Shiga toxins (Stxs) are the major virulence factors encoded by prophages, which play a crucial role in STEC pathogenesis and evolution. In this study, seven Stx phages were obtained from STEC isolates derived from four asymptomatic food handlers, two diarrheal patients, and one outbreak-related HUS case in China. These phages exhibited three morphologies: an icosahedral head with either a short or a long tail, and an elongated head with a long tail. Of these seven phages, three were sequenced; two showed a complete identity with their respective prophage sequences, while phage phiXuzhou21-Stx2a lacked a 6011 bp region-encoding integrase, excisionase, and hypothetical proteins. Comparative genome analysis revealed that the induced seven phages primarily varied in their regulatory regions, whereas the short-tailed phages showed high similarity in their morphogenesis-related regions. In addition, five of the seven phages demonstrated the ability to convert non-pathogenic E. coli strains into Stx-producing transduced strains. Under inducing conditions, Stx expression levels were significantly increased in these transduced strains. These findings underscore the diversity and adaptability of Stx phages and emphasize the importance of understanding their genetic and molecular interactions with host bacteria. Full article

Background: The mixed type of irritable bowel syndrome (IBS-M) is characterized by recurrent constipation and diarrhea. The cause of the variability of these symptoms is not sufficiently understood. The aim of this study was to perform metagenomic and metabolic assessment of the gut microbiome in constipation and diarrheal period of IBS-M. Methods: This study included 30 women, aged 28–47 years old, with the symptoms which aligned with those of IBS-M, according to the Rome IV Criteria. Results: In both periods of the disease, the dysbiosis index (DI), the Shannon diversity index (SDI), the hydrogen–methane and ammonia breath tests, as well as the selected bacterial metabolites (-p-hydroxyphenyl acetic acid (HPA), 3-indoxyl sulfate (Indican, 3-IS)), and hippuric acid (A) in urine, were determined. The dysbiosis index (DI) in the period of constipation was 3.73 ± 0.90 points, and in the diarrheal period it did not change significantly 3.93 ± 0.75 points (p > 0.05). During the diarrheal period, the diversity of bacteria increases from 2.16 ± 0.59 to 2.74 ± 0.50 points on the Shannon dietary index (p < 0.001). The gut microbiome profile also changed, especially during the diarrheal period where an abundance of Bifidobacterium spp. and Lactobacillus spp. decreased significantly. In addition, during this period, the levels of hydrogen and ammonia in breath air increased, while the methane level decreased. The differences also concern the results of urinary metabolites, especially related to hippuric acid and indican. During the diarrheal period, the levels of hydrogen and ammonia ions increased, while the methane level decreased. The differences also concern the results of urinary metabolites, especially related to hippuric acid and indican. Conclusions: In patients with IBS-M, periodic changes in the profile and metabolism of the gut microbiome occur, which coexist with recurrent symptoms such as constipation and diarrhea. Full article