Enterotoxigenic Escherichia coli (ETEC) strains expressing F4 and F18 fimbriae are major causes of neonatal and post‑weaning diarrhea in swine. Although epithelial maturation influences susceptibility in vivo, its impact on ETEC-host interactions remains poorly defined. This study characterizes the genomic diversity, virulence traits, and antibiotic resistance profiles of emerging F18 ETEC isolates using whole-genome sequencing and a differentiated porcine intestinal cell model. Six ETEC genomes: three F18 strains (3EC1, 27EC1, 3247EC), a porcine F4 strain, human ETEC H10407, and the historical F18 strain E. coli Nysø were analyzed by comparative genomics for virulence factors, toxin genes, and antimicrobial resistance (AMR) determinants. Genome sequences were submitted to the Type (Strain) Genome Server (TYGS) for whole genome-based taxonomic classification. Antibiotic susceptibility was phenotypically confirmed by microdilution and disk diffusion assays. Adhesion assays were performed using IPEC‑1, IPEC‑J2, and Caco‑2 cells conditioned to Early (6 days post‑confluence, DPC), Mid (9 DPC), and Late (16 DPC) maturation states. Expression of F18‑binding receptors (FUT1, FUT2) was quantified by RT‑qPCR. IPEC‑1 cells exhibited significantly higher FUT1 and FUT2 expression than IPEC‑J2, corresponding to approximately two‑fold stronger adhesion by most F18 isolates. Strain 3EC1 showed a distinct adhesion peak at 9 DPC, approaching F4 levels, while F4 and H10407 consistently displayed the highest adhesion across all models. Phylogenetic analysis placed 27EC1 and 3247EC in a clade with the F4 strain, whereas 3EC1 clustered with human H10407 and the ancestral E. coli Nysø strain. Comparative genomic analysis revealed substantial heterogeneity among F18 strains in fimbrial loci, flagellin, lipopolysaccharide biosynthesis genes, and AMR genes. Strain 3EC1 uniquely carried stx2e, and 3EC1 and 3247EC were positive for non‑classical EAST1 variants. All F18 isolates encoded hlyE and were β‑hemolytic. Strain 3247EC harbored the largest AMR gene repertoire (28 resistance genes), with all three F18 isolates demonstrating resistance to multiple antibiotic classes. The IPEC‑1/IPEC‑J2 maturation model recapitulates age‑dependent susceptibility to ETEC, driven by FUT1/FUT2 expression levels. The co-occurrence of strong adhesion capacity, stx2e, and extensive antimicrobial resistance in F18 strains underscores the evolution in virulence and the public health relevance of AMR surveillance in swine. This integrated genomic and cell-based platform provides a refined model for studying porcine ETEC pathogenesis and informing the development of targeted intervention strategies.

Cryptosporidium spp. is an important intestinal protozoan parasite causing morbidity and mortality in immunocompromised patients, particularly those with HIV+/AIDS. A cross-sectional study was conducted on 161 HIV+/AIDS patients in Kurdistan Province, Iran, aiming to assess prevalence and genetic diversity of Cryptosporidium spp. among HIV+/AIDS patients. Stool samples were examined microscopically and by nested PCR targeting the GP60 gene. PCR-positive samples were sequenced, and phylogenetic and population genetic analyses were conducted using MEGA12 software. Of 161 faecal samples from HIV+/AIDS patients, seven (4.34%) and four (2.48%) positive samples were detected by PCR and microscopy, respectively (OR = 1.94, P = 0.536). Two factors showed a statistically significant association with a higher risk of Cryptosporidium infection, including using untreated drinking water and contact with animals. Patients using untreated water had a 30% infection rate, compared to 2.6% for those using purified water (OR = 15.19, P = 0.011). Patients with animal contact had a 33.3% infection rate, compared to 3.2% for those without animal contact (OR = 14.73, P = 0.047). No significant association was found with the patient's sex or urban/rural location. All isolates belonged to the C. parvum IId subtype. Phylogenetic analyses clustered all isolates within the IId clade, which are closely related to animal-derived subtypes. The genetic similarity with previously reported animal isolates raises the possibility of zoonotic transmission; however, in the absence of animal or environmental sampling, this hypothesis remains speculative and should be interpreted with caution. These findings highlight the need for screening of Cryptosporidium among vulnerable populations, especially HIV+/AIDS patients.

Campylobacter jejuni is a leading cause of bacterial gastroenteritis but rarely causes bacteraemia, except in immunocompromised hosts. Carbapenem resistance in C. jejuni remains uncommon, and the clinical evolution of resistance during infection has not been well described. We report a case series of three immunocompromised adults with recurrent C. jejuni bacteraemia at a tertiary hospital in Singapore between 2024 and 2025. All three patients had underlying haematologic or autoimmune disorders associated with hypogammaglobulinaemia. Each experienced multiple episodes of C. jejuni bacteraemia despite prolonged carbapenem therapy, with isolates showing stepwise increases in meropenem minimum inhibitory concentrations (MICs) from ≤ 0.05mg/L to as high as 16mg/L. No abscesses or drainable foci were identified radiologically. Two patients received regular intravenous immunoglobulin (IVIG) replacement after low serum IgG levels were detected. In all cases, recurrences ceased after introduction of eravacycline therapy, with or without concurrent oral gentamicin, in combination with IVIG support. One patient later died of progression of underlying lymphoma. This series demonstrates the potential for acquired carbapenem resistance to develop in C. jejuni during recurrent bacteraemia in immunocompromised hosts. Eravacycline, alongside immunoglobulin replacement, may represent a viable therapeutic option in such refractory infections.

Shigella species are a significant global public health threat with the highest burden of Shigella-associated diarrhoea in children under five years of age, particularly in low- and middle-income countries. Given the high burden of shigellosis in these settings, there is a need for continuous surveillance to identify the prevalent species, risk factors, and determine appropriate intervention strategies. This study aimed to determine the prevalence of Shigella flexneri (S. flexneri) and Shigella sonnei (S. sonnei), assess risk factors and identify Antimicrobial Resistance (AMR) genes present in samples positive for either species among children under five in Mukuru informal settlement. Between August 2023 and November 2024, 386 children presenting with diarrhoea at any of the four selected health facilities in Mukuru were enrolled. Stool samples or rectal swabs were collected and subjected to TaqMan Polymerase Chain Reaction (TAC PCR) for the detection of S. flexneri, S. sonnei and selected AMR genes. Case Report Forms (CRF) and structured questionnaires were used to collect medical history, behavioural and socioeconomic data, respectively. The prevalence of S. flexneri and S. sonnei among the 386 participants was 15.54% (60/386). Positivity for S. flexneri and S. sonnei by age group was highest among children aged 12-23 months (24.84%, 40/161) and lowest among those aged 24-59 months (2.08%, 2/96). S. flexneri was the most prevalent species, with serotypes 2 and X being the most detected. Among the samples positive for S. flexneri and S. sonnei, the mphA gene was detected in 98.33% (59/60), the β-lactamase gene CTX-M1-9 was present in 85% (51/60), and CTX-M2-8-25 was identified in 26.67% (16/60) of samples. Age (aOR = 1.025, 95% CI: 1.003-1.047, P = 0.027) and obtaining vegetables from the market (aOR = 2.737, 95% CI: 1.081-6.930, P = 0.034) were significantly associated with shigellosis. These findings show that shigellosis due to S. flexneri and S. sonnei remains a significant contributor to the burden of diarrheal disease, particularly among young children. The high prevalence of AMR genes, especially mphA and CTX-M β-lactamases, indicates widespread resistance to macrolides and extended-spectrum β-lactams. Addressing this challenge may require a multifaceted approach, including enhanced antimicrobial resistance surveillance, strengthened Water, Sanitation, and Hygiene (WASH) interventions, and the potential deployment of Shigella vaccines among vulnerable populations.

Regional differences in the gut microbiota and CRC incidence and mortality rates are well-documented. However, studies on the microbiota associated with CRC in Indonesia remain scarce. This study aimed to chracterize the gut microbiota profile of CRC in Indonesia. We collected stool samples from 14 patients with CRC (CRC), 19 patients with non-CRC bowel diseases (non-CRC), and 16 healthy controls (HC). The gut microbiota profiles across the three groups were analyzed using 16 S rRNA gene amplicon sequencing. Data analysis was performed using several software packages: QIIME2, ANCOM-BC2, and PICRUSt2. In comparison to the non-CRC and HC groups, patients with CRC demonstrated significant differences in both alpha and beta diversity. The CRC group had lower evenness and richness than the HC group. Firmicutes and Bacteroidota were identified as the predominant phyla across all groups. The differential abundance analysis identified four beneficial genera that were substantially reduced in Indonesian CRC patients: Roseburia, Dialister, Agathobacter, and Muribaculaceae. No genera were found to be significantly enriched in CRC. Functional prediction analysis revealed multiple pathways such as mTOR, mRNA surveillance, basal transcription factors, phagosome, and proteasome, were reduced in CRC. Conversely, CRC demonstrated a significant upregulation of pathways related to lipid metabolism and the biosynthesis of flavonoids, stilbenoids, diarylheptanoids, and gingerols. Our study revealed distinct gut microbiota profiles in Indonesian CRC patients, highlighting the significance of decreased abundance of certain beneficial taxa.

Klebsiella pneumoniae, K. quasipneumoniae, and K. variicola are members of the K. pneumoniae species complex (KpSC) with distinct genotypes, virulence, and antibiotic resistance traits. However, their distribution and characteristics in Taiwan remain unknown. We evaluated 809 KpSC isolates (377 from bacteremia and 432 from urinary tract infections) collected at National Cheng Kung University Hospital (NCKUH) (1999-2022), identified by multiplex PCR and 16S rDNA sequencing, and characterized by antimicrobial susceptibility testing, virulence gene profiling, capsular typing, biofilm assays, and Galleria mellonella larvae infection models. Among the 809 KpSC isolates, 752 (93.0%) were identified as Klebsiella pneumoniae, 37 (4.6%) as K. quasipneumoniae, and 20 (2.4%) as K. variicola. MALDI-TOF was unable to identify any of the 37 K. quasipneumoniae isolates correctly, but it accurately identified 17 of the 20 K. variicola isolates. K62 was the most prevalent capsular type among K. pneumoniae isolates (7/50, 14%), while K54 was the most common among K. quasipneumoniae isolates (5/37, 13.5%). Among the 20 K. variicola isolates, K35 and K49 were the major capsular serotypes, each represented by three isolates (3/20, 15%). Notably, 16.8% of KpSC isolates could not be assigned to any serotype based on wzi sequencing. The prevalence of iucA, iroB, irp1, irp2, prmpA, prmpA2, and peg-344 was significantly higher in K. pneumoniae than in K. quasipneumoniae and K. variicola. In contrast, only kfuBC was more common in K. variicola than in K. pneumoniae and K. quasipneumoniae. The virulence score was highest in K. pneumoniae (6.2 genes), followed by K. quasipneumoniae (4.6 genes) and K. variicola (4.4 genes) (p = 0.002). K. pneumoniae demonstrated significantly higher resistance rates to gentamicin (p = 0.005), ciprofloxacin (p = 0.013), levofloxacin (p = 0.003), and sulfamethoxazole/trimethoprim (p = 0.036), compared to K. quasipneumoniae and K. variicola. The biofilm formation capacity of K. pneumoniae was found to be higher than that of K. quasipneumoniae and K. variicola. However, on day seven, the survival rate of larvae infected with K. pneumoniae was 25.1%, while only 9.7% and 8.5% of larvae survived in K. quasipneumoniae and K. variicola, respectively (p < 0.0001). K. pneumoniae, K. quasipneumoniae, and K. variicola in Taiwan exhibit distinct genotypic and phenotypic characteristics. K. quasipneumoniae and K. variicola displayed higher mortality in larvae infection model, underscoring the importance of continued surveillance of their dissemination.

The human gut microbiota is essential for supporting the host's health and immune system. Imbalances in this microbiota, known as dysbiosis, are associated with numerous inflammatory and autoimmune diseases. Despite extensive research on bacterial components, the significant modulatory role of eukaryotic gut inhabitants, particularly intestinal parasites, remains largely overlooked. While traditionally viewed as pathogens, emerging evidence highlights a profound duality in their role, suggesting they are integral and active modulators of the gut microbiota and challenging the conventional view of parasitism. For instance, helminths often induce microbial diversity and promote the expansion of anti-inflammatory microbes. Conversely, pathogenic protozoa are generally associated with reduced microbial diversity, fostering the growth of pathobionts and leading to significant gut dysbiosis. However, these interactions are highly context-dependent, and a comprehensive understanding is hindered by varied findings and limited data, particularly concerning protozoan infections. Furthermore, while mechanistic evidence is robust, human intervention studies remain limited. This narrative review synthesises the complex interrelationship between intestinal parasites and the human gut microbiota, distinguishing the distinct dynamics of helminthic and protozoan infections. Specifically, this review examines the inherent duality of intestinal parasites by investigating parasite-specific factors, including species, parasite burden, and coinfections, which can impact gut microbial composition and function. Ultimately, this review provides a comprehensive framework for understanding the profound influence of the gut ecosystem, shifting the paradigm beyond solely pathogenic views.

Giardia lamblia is a globally prevalent gastrointestinal parasite. Breastfeeding provides protective effects against infections, but the impact of early life stress, such as maternal separation, on G. lamblia infection remains unclear. This study examines how Maternal Separation During Breastfeeding (MSDB) affects G. lamblia infection in Wistar rats. In a Wistar rat model, MSDB led to a significant increase in G. lamblia cyst shedding, with early effects more evident in males and delayed effects in females. Additionally, infected MSDB rats showed elevated eosinophil infiltration in the intestinal mucosa-consistent with heightened immune response-along with altered villus/crypt ratios in non-infected separated animals, particularly in males. Our findings demonstrate that maternal separation during breastfeeding intensifies the severity of G. lamblia infection. This suggests that early-life maternal interactions may play a protective role in host resistance specifically against G. lamblia, highlighting the relevance of early-life conditions in shaping outcomes of giardiasis.

Antimicrobial resistance, particularly in clinical Enterococcus isolates, poses a serious global health threat because of difficult-to-treat nosocomial infections. The emergence of vancomycin-resistant enterococci (VRE), mediated by VanA or VanB operons, has significantly limited treatment options. This study aimed at identifying antibiotic resistance and virulence genes in enterococci and exploring potential correlations between these genetic traits. A total of 100 suspected enterococci were gathered from two hospitals and identified through phenotypic methods and the VITEK 2 Compact system. The Kirby-Bauer disk diffusion and MIC by microbroth dilution methods were employed for antimicrobial susceptibility. The gelatinase production and biofilm were evaluated phenotypically, while the presence of vancomycin resistance (vanA, vanB) and virulence (esp, gelE, hyl) genes was confirmed by PCR and sequenced for genetic characterization. Sixty-five Enterococcus isolates were characterized, with E. faecium (50.7%) and E. faecalis (41.5%) being the predominant species. Linezolid, teicoplanin, and chloramphenicol still retain good activity with 6.15%, 10.7%, and 29.2% resistance, respectively. About 40% of isolates were VRE, and all harbored the vanA gene. Biofilm formation and gelatinase production were most prevalent in E. faecium and E. faecalis, indicating enhanced virulence. Sequencing confirmed the chromosomal location and identity of the resistance and virulence genes, supporting their accurate detection and distribution among different Enterococcus species. Statistical analysis revealed that both esp and gelE genes were significantly associated with biofilm formation and gelatinase activity; however, esp showed a positive correlation with vanA and vancomycin resistance, while gelE demonstrated a negative correlation. Even though vanA is typically linked to high levels of resistance to both teicoplanin and vancomycin, only seven out of the twenty-six isolates that were vanA-positive showed phenotypic resistance to teicoplanin. Enterococcus faecium and E. faecalis were identified as predominant multidrug-resistant species carrying multiple virulence determinants, with esp and gelE strongly linked to biofilm formation and gelatinase activity. Linezolid, teicoplanin, and chloramphenicol remained the most effective agents. Our findings demonstrate the coexistence of resistance and virulence traits, along with unexpected genotype-phenotype variations, underscoring the need for integrated molecular and phenotypic approaches in surveillance and clinical management.