Toxin-producing Bacteria Research Articles

P1357 Association between stool infection and C - reactive protein levels in Ulcerative Colitis: A retrospective analysis in Albania

Abstract Background Stool infections complicate the management of Ulcerative Colitis (UC), worsening symptoms and treatment outcomes. This study aimed to explore the relationship between stool infections and C-reactive protein (CRP) levels, a marker of inflammation, in UC patients. Methods A retrospective study was conducted at the IBD Unit, Clinic of Gastroenterology, Tirana, Albania, between April and October 2024. A total of 25 active (mean total Mayo score 5.72 ±1.67) UC patients (15 females, 10 males, mean age 41.96 ± 13.99 years, disease duration 9.26 ± 11.59 years) were included. Stool samples were tested for pathogens, and CRP levels were measured. Demographic data, and treatment history (including corticosteroids, immunosuppressants, and antibiotics) were recorded. The relationship between CRP levels, stool infection status, and clinical variables was analyzed using Pearson correlation and logistic regression models. ANOVA was used to compare CRP levels between UC patients with and without stool infection. Results Stool infections were present in 10 of 25 patients (40%), with 6 (60%) having multiple infections. Identified pathogens included Clostridium difficile (3), Enteropathogenic E. Coli (4), Enterohemorrhagic E. Coli (1), Dientamoeba fragilis (2), Aeromonas species (2), Norovirus (2), Shiga toxin-producing bacteria (2), Salmonella (1), and Blastocystis species (1). Of the infected patients, 4 (40%) were on multiple drugs, (corticosteroid and immunosuppressant), and 1 (10%) had recent antibiotic use. The mean CRP level was significantly higher in the stool infection group (13.09 ± 13.73 mg/L vs 4.41 ± 4.75 mg/L (F = 5.163, p = 0.033). A significant correlation was seen between CRP levels and stool infection (r =0.420, p = 0.041). Logistic regression suggested that each 1-unit increase in CRP was associated with an increase of 11.5% in the odds of stool infection {Exp (B) = 1.115}, though this trend was not statistically significant (p = 0.076). Conclusion Stool infection is associated with higher CRP levels in UC patients, suggesting increased inflammation in the presence of infection. Although CRP levels correlate with infection status, they do not reliably predict stool infection risk in this cohort. This study highlights the common occurrence of stool infections among UC patients and the potential role of infection in disease activity, though further research is needed to clarify the predictive value of CRP and other biomarkers in UC management.

Growth, persistence and toxin production of pathogenic bacteria in plant-based drinking milk alternatives.

The present study investigated the microbiological safety of the increasingly popular plant-based milk alternatives. No (10/27) or only very low microbial counts (17/27) were detected in the tested products. These were mainly identified as spore formers via MALDI-ToF-MS. Three products contained Bacillus cereus group isolates, which were able to form considerable amounts of enterotoxins and exhibited cytotoxicity towards CaCo-2 cells. Preliminary tests showed good growth of B. cereus, Listeria monocytogenes, and Salmonella enterica in all tested products (maximum bacterial counts: 5×1012 cfu/mL). These experiments also revealed strain-, time-, and temperature-, but especially product-specific enterotoxin production of B. cereus. In propagation and persistence tests according to DIN EN ISO 20976-1:2019-09, rapid bacterial proliferation was also detected in all products. B. cereus generally showed lower bacterial counts (106-107 cfu/mL) compared to L. monocytogenes and S. enterica (108-109 cfu/mL), but was detectable in a larger number of products over the test period of 6 weeks. pH values decreased (20/27) over time and visual and/or olfactory alterations (24/27) were observed. The present study provides information on the occurrence, growth and persistence of pathogenic bacteria in plant-based drinking milk alternatives. It also points out that the accompanying changes in pH, odor, and appearance are not necessarily recognizable to the consumer. PRACTICAL APPLICATION: The present study contributes to the understanding of the microbial risk related to plant-based drinking milk alternatives. It is crucial that the manufacturer ensures that particularly spore formers have been effectively eliminated from the products. Among them, especially toxin-producing bacteria can pose a risk to the consumer, as these products promote proliferation and persistence of the bacteria.

Exploring Therapeutic Advances: A Comprehensive Review of Intestinal Microbiota Modulators.

The gut microbiota establishes a mutually beneficial relationship with the host starting from birth, impacting diverse metabolic and immunological processes. Dysbiosis, characterized by an imbalance of microorganisms, is linked to numerous medical conditions, including gastrointestinal disorders, cardiovascular diseases, and autoimmune disorders. This imbalance promotes the proliferation of toxin-producing bacteria, disrupts the host's equilibrium, and initiates inflammation. Genetic factors, dietary choices, and drug use can modify the gut microbiota. However, there is optimism. Several therapeutic approaches, such as probiotics, prebiotics, synbiotics, postbiotics, microbe-derived products, and microbial substrates, aim to alter the microbiome. This review thoroughly explores the therapeutic potential of these microbiota modulators, analysing recent studies to evaluate their efficacy and limitations. It underscores the promise of microbiota-based therapies for treating dysbiosis-related conditions. This article aims to ensure practitioners feel well-informed and up to date on the most influential methods in this evolving field by providing a comprehensive review of current research.

Effects of Vibrio vulnificus and Microcystis aeruginosa co-exposures on microplastic accumulation and depuration in the Eastern Oyster (Crassostrea virginica)

Microplastics are ubiquitous in the aquatic environment, and bivalves such as the Eastern oyster (Crassostrea virginica) can accumulate these particles directly from the water column. Bivalves are concurrently exposed to pathogenic and toxin-producing bacteria, including Vibrio spp. and Microcystis spp., which have been shown to adversely impact filtration rates. Exposure to these bacteria could thus affect oysters’ ability to accumulate and depurate microplastics. As climate change creates conditions that favor Vibrio spp. and Microcystis spp. growth in estuaries, it is increasingly important to understand how these co-occurring biotic stressors influence microplastic contamination in bivalves. The objective of this study was to examine how co-exposures to Vibrio vulnificus and Microcystis aeruginosa influence microplastic accumulation and depuration in Eastern oysters. Oysters were exposed to nylon microplastics (5000 particles L−1) and either V. vulnificus, M. aeruginosa, or both species (104 colony-forming units or cells mL−1, respectively) and sampled over time up to 96 h. Following exposure, remaining oysters were allowed to depurate in clean seawater and sampled over time for up to 96 h. Microplastic concentrations in oysters were quantified and compared among treatments, and rate constants for uptake (ku) and depuration (kd) were calculated using nonlinear regression and two-compartment kinetic models. Overall, microplastic concentrations in oysters exposed to V. vulnificus (X‾ = 2.885 ± 0.350 (SE) particles g−1 w.w.) and V. vulnificus with M. aeruginosa (X‾ = 3.089 ± 0.481 particles g−1 w.w.) were higher than oysters exposed to M. aeruginosa (X‾ = 1.540 ± 0.235 particles g−1 w.w.) and to microplastics alone (X‾ = 1.599 ± 0.208 particles g−1 w.w.). Characterizing microplastic accumulation and depuration in oysters co-exposed to these biotic stressors is an important first step in understanding how contaminant loads in bivalves can change. With this research, the efficacy of depuration for commonly-consumed seafood species can be estimated.

Incidence of Colorectal Cancer After Intestinal Infection Due to Clostridioides difficile.

Clostridioides difficile (C. difficile or C. diff) is a toxin-producing bacteria that is notorious for causing life-threatening diarrhea. Recent literature has investigated various effects of Clostridioides difficile infection (CDI) in cancer patients, but research into the impact of CDI on the development of cancer and its effects on the microbiome is limited. CDI predominately affects the colon, which urges consideration into the sequalae of infection. This study investigated the correlation between CDI and the incidence of colorectal carcinoma (CRC). A retrospective study (2010 - 2020) was conducted using a Health Insurance Portability and Accountability Act (HIPAA) compliant national database. The International Classification of Disease ninth and 10th Codes (ICD-9, ICD-10), Current Procedural Terminology (CPT), and National Drug Codes were used to identify CRC diagnosis, CDI, and matching or control parameters. Patients were matched for age, sex, Charlson Comorbidity Index (CCI), region of residence, and CDI treatment. An additional, but separate, query was executed to include obese patients with and without CDI, who were similarly matched and assessed for CRC. Statistical analyses were implemented to assess significance and estimate odds ratios (ORs). CDI was associated with a decreased incidence of CRC (OR = 0.59, 95% confidence interval (CI): 0.55 - 0.63), and the difference was statistically significant (P < 2.2 × 10-16). CDI treatment, including appropriate antibiotics and fecal microbiota transplant (FMT), was controlled for in both infected and noninfected populations. Patients with a prior CDI who received relevant treatment were compared to patients with no history of CDI and received analogous treatment. Both populations subsequently developed CRC. Results remained statistically significant (P < 2.2 × 10-16) with a relative risk (RR) of 0.57 (95% CI: 0.54 - 0.60). Obesity was explored as a controlled variable in relation to CRC development in patients with and without prior CDI. Obese patients without a history of CDI were found to have a decreased risk of developing CRC. Results were statistically significant (P < 4.3 × 10-13) with an OR of 0.70 (95% CI: 0.63 - 0.77). This study shows a statistically significant correlation between CDI and decreased incidence of CRC. Additionally, there is a statistically significant correlation between obese patients with CDI and an increased incidence of CRC. Further research is needed to explore the mechanism of this striking relationship and the implications of CDIs on the microbiome.

Abstract B015: Toxin-producing bacterial therapy limits tumor growth in autochthonous mouse models of pancreatic ductal adenocarcinoma

Abstract Treating pancreatic ductal adenocarcinoma (PDAC) with systemic chemotherapeutic drugs has remained a challenge, due in part to the hypovascularized and poorly perfused nature of PDAC tumors, impeding the accumulation of systemically delivered drugs. Several clinical trials aimed at improving drug delivery in PDAC, through targeting of ECM components (HALO-301) or stromal angiogenic signaling (IPI-926-03) have unfortunately not been effective. However, the features that have interfered with systemic therapy in PDAC are potential advantages for the use of bacterial therapies, as bacteria can actively migrate through tissues, thrive in hypoxic microenvironments, and benefit from local immune suppression. Recent developments in the field of synthetic biology have made it possible to engineer complex logic circuits into bacteria, enabling the production of anticancer therapies directly within the tumor parenchyma. Furthermore, live bacteria, once colonized within the tumor niche, are capable of providing a stable source of anticancer compounds directly, rather than relying on repeated systemic doses. We have therefore worked to develop novel bacterial strains and demonstrate preclinical efficacy of a novel strain of therapeutic bacteria for targeting PDAC. We began by testing a range of bacteria-produced toxins and identified the pore-forming protein theta toxin as having the greatest effect in both 2D cell culture and PDAC explant (tissue slice) models. We then engineered a non-toxic probiotic bacteria, E. coli Nissle 1917, to produce either theta toxin or GFP. To assess preclinical efficacy, we performed intratumoral injections of live GFP- and theta-expressing bacteria into the “KPC” genetically engineered mouse model (Kras LSL.G12D/+; Tp53 LSL.R172H/+; PdxCre tg/+). While GFP-producing bacteria did not induce a change in tumor growth kinetics, treatment with theta toxin-producing bacteria demonstrated prolonged stabilization of tumor growth, increasing the median survival to 34 days compared to ~12 days for vehicle- or gemcitabine-treated controls and 18.5 days for GFP-producing bacteria without additional therapy. Strikingly, while there was minimal spread of bacteria to non-tumor tissues, we observed translocation of the bacteria to macro- and micro- metastatic lesions and distant papillomas following injection of the primary pancreatic tumor, indicating a mechanism for targeting both known and unknown metastases following local administration. Histological analyses demonstrated that diffuse populations of bacteria co-localized with regions of cell death, but that bacterial presence and evidence of increased cell death was not observed in healthy tissues, such as the lung, liver, intestine, and diaphragm. Additionally, bacterial treatment, independent of the payload, led to a modest influx of anti-tumor immune populations, suggesting potential synergy with immunotherapies. Together these data demonstrate potent preclinical activity of cytotoxic bacterial therapy as a novel strategy to circumvent the challenges of systemic treatment of PDAC. Citation Format: Amanda R. Decker-Farrell, Stephen A. Sastra, Tetsuhiro Harimoto, Marie C. Hasselluhn, Fangda Li, Rosa Vincent, Carmine F. Palermo, Edward R. Ballister, Tal Danino, Kenneth P. Olive. Toxin-producing bacterial therapy limits tumor growth in autochthonous mouse models of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B015.

Deazaflavin metabolite produced by endosymbiotic bacteria controls fungal host reproduction.

The endosymbiosis between the pathogenic fungus Rhizopus microsporus and the toxin-producing bacterium Mycetohabitans rhizoxinica represents a unique example of host control by an endosymbiont. Fungal sporulation strictly depends on the presence of endosymbionts as well as bacterially produced secondary metabolites. However, an influence of primary metabolites on host control remained unexplored. Recently, we discovered that M. rhizoxinica produces FO and 3PG-F420, a derivative of the specialized redox cofactor F420. Whether FO/3PG-F420 plays a role in the symbiosis has yet to be investigated. Here, we report that FO, the precursor of 3PG-F420, is essential to the establishment of a stable symbiosis. Bioinformatic analysis revealed that the genetic inventory to produce cofactor 3PG-F420 is conserved in the genomes of eight endofungal Mycetohabitans strains. By developing a CRISPR/Cas-assisted base editing strategy for M. rhizoxinica, we generated mutant strains deficient in 3PG-F420 (M. rhizoxinica ΔcofC) and in both FO and 3PG-F420 (M. rhizoxinica ΔfbiC). Co-culture experiments demonstrated that the sporulating phenotype of apo-symbiotic R. microsporus is maintained upon reinfection with wild-type M. rhizoxinica or M. rhizoxinica ΔcofC. In contrast, R. microsporus is unable to sporulate when co-cultivated with M. rhizoxinica ΔfbiC, even though the fungus was observed by super-resolution fluorescence microscopy to be successfully colonized. Genetic and chemical complementation of the FO deficiency of M. rhizoxinica ΔfbiC led to restoration of fungal sporulation, signifying that FO is indispensable for establishing a functional symbiosis. Even though FO is known for its light-harvesting properties, our data illustrate an important role of FO in inter-kingdom communication.

Haemolysin Ahh1 secreted from Aeromonas dhakensis activates the NLRP3 inflammasome in macrophages and mediates severe soft tissue infection

Severe soft tissue infections caused by Aeromonas dhakensis, such as necrotizing fasciitis or cellulitis, are prevalent in southern Taiwan and around the world. However, the mechanism by which A. dhakensis causes tissue damage remains unclear. Here, we found that the haemolysin Ahh1, which is the major virulence factor of A. dhakensis, causes cellular damage and activates the NLR family pyrin domain containing 3 (NLRP3) inflammasome signalling pathway. Deletion of ahh1 significantly downregulated caspase-1, the proinflammatory cytokine interleukin 1β (IL-1β) and gasdermin D (GSDMD) and further decreased the damage caused by A. dhakensis in THP-1 cells. In addition, we found that knockdown of the NLRP3 inflammasome confers resistance to A. dhakensis infection in both THP-1 NLRP3-/- cells and C57BL/6 NLRP3-/- mice. In addition, we demonstrated that severe soft-tissue infections treated with antibiotics combined with a neutralizing antibody targeting IL-1β significantly increased the survival rate and alleviated the degree of tissue damage in model mice compared control mice. These findings show that antibiotics combined with therapies targeting IL-1β are potential strategies to treat severe tissue infections caused by toxin-producing bacteria.

Atypical Haemolytic Uraemic Syndrome in an Infant with Ventricular Septal Defect: A Case Report

Atypical Haemolytic Uraemic Syndrome (aHUS) is a rare type of thrombotic microangiopathy that occurs without Shiga toxin producing bacteria. It is a condition related to complement regulation, which may be genetic or acquired. The complement system’s alternative pathway is commonly implicated, with around 6-10% of cases being caused by autoantibodies directed against factor H. While it typically affects children between 9 to 13-years-old, it can also occur in adults. Many patients do not have circulating Complement Factor H-related proteins 1 and 3 due to a homozygous deletion involving CFHR1 and CFHR3. Authors hereby report a case of a six-month-old female child who was diagnosed with Ventricular Septal Defect (VSD) at one and a half months of age. She presented with pneumonia and subsequently developed haemolytic anaemia with thrombocytopenia, oliguria, and acute kidney failure. She was diagnosed with Antifactor H antibody-mediated HUS. She was treated with plasma therapy, but the patient succumbed due to multiorgan dysfunction.

Cholera: An Overview with Reference to the Syrian Outbreak.

Cholera is an acute type of diarrheal disease caused by intestinal infection with the toxin-producing bacteria Vibrio cholerae. The disease is still endemic in almost 69 countries, accounting for around 2.86 million cases and 95,000 deaths annually. Cholera is associated with poor infrastructure, and lack of access to sanitation and clean drinking water. The current cholera outbreak in Syria is associated with more than 10 years of conflict, which has devastated infrastructures and health services. There were 132,782 suspected cases reported between August 25, 2022 and May 20, 2023 in all 14 governorates, including 104 associated deaths. The recent earthquake in the region has complicated the situation, with an increase in cholera cases, and hindrance to a response to the disease. Climate change has driven a number of large cholera outbreaks around the world this year. The World Health Organization prequalifies three oral cholera vaccines. Cholera treatment mainly depends on rehydration, with the use of antibiotics in more severe infections. This review gives an overview of cholera bacteriology, pathogenesis, epidemiology, clinical manifestations, diagnosis, management, and prevention in light of global climate change and the ongoing outbreak in Syria, which poses a significant public health threat that requires urgent attention.

Transcription activator-like effector protects bacterial endosymbionts from entrapment within fungal hyphae

As an endosymbiont of the ecologically and medically relevant fungus Rhizopus microsporus, the toxin-producing bacterium Mycetohabitans rhizoxinica faces myriad challenges, such as evading the host's defense mechanisms. However, the bacterial effector(s) that facilitate the remarkable ability of M.rhizoxinica to freely migrate within fungal hyphae have thus far remained unknown. Here, we show that a transcription activator-like (TAL) effector released by endobacteria is an essential symbiosis factor. By combining microfluidics with fluorescence microscopy, we observed enrichment of TAL-deficient M.rhizoxinica in side hyphae. High-resolution live imaging showed the formation of septa at the base of infected hyphae, leading to the entrapment of endobacteria. Using a LIVE/DEAD stain, we demonstrate that the intracellular survival of trapped TAL-deficient bacteria is significantly reduced compared with wild-type M.rhizoxinica, indicative of a protective host response in the absence of TAL proteins. Subversion of host defense in TAL-competent endobacteria represents an unprecedented function of TAL effectors. Our data illustrate an unusual survival strategy of endosymbionts in the host and provide deeper insights into the dynamic interactions between bacteria and eukaryotes.

Particular genomic and virulence traits associated with preterm infant-derived toxigenic Clostridium perfringens strains

Clostridium perfringens is an anaerobic toxin-producing bacterium associated with intestinal diseases, particularly in neonatal humans and animals. Infant gut microbiome studies have recently indicated a link between C. perfringens and the preterm infant disease necrotizing enterocolitis (NEC), with specific NEC cases associated with overabundant C. perfringens termed C. perfringens-associated NEC (CPA-NEC). In the present study, we carried out whole-genome sequencing of 272 C. perfringens isolates from 70 infants across 5 hospitals in the United Kingdom. In this retrospective analysis, we performed in-depth genomic analyses (virulence profiling, strain tracking and plasmid analysis) and experimentally characterized pathogenic traits of 31 strains, including 4 from CPA-NEC patients. We found that the gene encoding toxin perfringolysin O, pfoA, was largely deficient in a human-derived hypovirulent lineage, as well as certain colonization factors, in contrast to typical pfoA-encoding virulent lineages. We determined that infant-associated pfoA+ strains caused significantly more cellular damage than pfoA− strains in vitro, and further confirmed this virulence trait in vivo using an oral-challenge C57BL/6 murine model. These findings suggest both the importance of pfoA+C. perfringens as a gut pathogen in preterm infants and areas for further investigation, including potential intervention and therapeutic strategies.

Safety and Tolerability of SER-109 as an Investigational Microbiome Therapeutic in Adults With Recurrent Clostridioides difficile Infection

A safe and effective treatment for recurrent Clostridioides difficile infection (CDI) is urgently needed. Antibiotics kill toxin-producing bacteria but do not repair the disrupted microbiome, which promotes spore germination and infection recurrence. To evaluate the safety and rate of CDI recurrence after administration of investigational microbiome therapeutic SER-109 through 24 weeks. This phase 3, single-arm, open-label trial (ECOSPOR IV) was conducted at 72 US and Canadian outpatient sites from October 2017 to April 2022. Adults aged 18 years or older with recurrent CDI were enrolled in 2 cohorts: (1) rollover patients from the ECOSPOR III trial who had CDI recurrence diagnosed by toxin enzyme immunoassay (EIA) and (2) patients with at least 1 CDI recurrence (diagnosed by polymerase chain reaction [PCR] or toxin EIA), inclusive of their acute infection at study entry. SER-109 given orally as 4 capsules daily for 3 days following symptom resolution after antibiotic treatment for CDI. The main outcomes were safety, measured as the rate of treatment-emergent adverse events (TEAEs) in all patients receiving any amount of SER-109, and cumulative rates of recurrent CDI (toxin-positive diarrhea requiring treatment) through week 24 in the intent-to-treat population. Of 351 patients screened, 263 were enrolled (180 [68.4%] female; mean [SD] age, 64.0 [15.7] years); 29 were in cohort 1 and 234 in cohort 2. Seventy-seven patients (29.3%) were enrolled with their first CDI recurrence. Overall, 141 patients (53.6%) had TEAEs, which were mostly mild to moderate and gastrointestinal. There were 8 deaths (3.0%) and 33 patients (12.5%) with serious TEAEs; none were considered treatment related by the investigators. Overall, 23 patients (8.7%; 95% CI, 5.6%-12.8%) had recurrent CDI at week 8 (4 of 29 [13.8%; 95% CI, 3.9%-31.7%] in cohort 1 and 19 of 234 [8.1%; 95% CI, 5.0%-12.4%] in cohort 2), and recurrent CDI rates remained low through 24 weeks (36 patients [13.7%; 95% CI, 9.8%-18.4%]). At week 8, recurrent CDI rates in patients with a first recurrence were similarly low (5 of 77 [6.5%; 95% CI, 2.1%-14.5%]) as in patients with 2 or more recurrences (18 of 186 [9.7%; 95% CI, 5.8%-14.9%]). Analyses by select baseline characteristics showed consistently low recurrent CDI rates in patients younger than 65 years vs 65 years or older (5 of 126 [4.0%; 95% CI, 1.3%-9.0%] vs 18 of 137 [13.1%; 95% CI, 8.0%-20.0%]) and patients enrolled based on positive PCR results (3 of 69 [4.3%; 95% CI, 0.9%-12.2%]) vs those with positive toxin EIA results (20 of 192 [10.4%; 95% CI, 6.5%-15.6%]). In this trial, oral SER-109 was well tolerated in a patient population with recurrent CDI and prevalent comorbidities. The rate of recurrent CDI was low regardless of the number of prior recurrences, demographics, or diagnostic approach, supporting the beneficial impact of SER-109 for patients with CDI. ClinicalTrials.gov identifier: NCT03183141.

A study on toxin genes and cytotoxicity levels of Bacillus cereus in various ready-to-eat foods and pastry products in Turkey

Bacillus cereus is a spore-forming and toxin-producing gram-positive bacteria widely isolated from soils, meat, milk, and vegetables. It is recognized as one of the pathogenic bacteria that can lead to food poisoning and food spoilage in food service systems due to its ease of contamination of foods and lack of guarantee of elimination by pasteurization and sanitation practices. B. cereus causes two types of diseases mainly characterized by diarrhea and vomiting type syndrome with the toxins it produces. Toxins produced by B. cereus are mainly heat-stable emetic toxin and three different heat-labile enterotoxins. Foodborne illnesses of the diarrheal type are caused by the single protein toxin; cytotoxin K (CytK), and both tripartite toxins; hemolysin BL (Hbl), and the non-hemolytic enterotoxin (Nhe), whereas the emetic type, is caused by an emetic toxin cereulide. In this study, 225 ready-to-eat foods and pastry products were analyzed for B. cereus, its toxin profiles, and cytotoxicity effects. Multiplex PCR is used to identify the presence of the Hbl, CytK, and emetic toxin encoding genes. Component-specific antibody-based ELISA tests were utilized to determine the Hbl-L2 and NheB components. Cytotoxic activity of the B. cereus isolates on Vero cells was also identified. In total, B. cereus was detected in 37 out of 225 (16.4%) food samples. From the positive 37 B. cereus isolates, the ces gene was not identified, whereas 91.9% (34) Nhe, 56.8% (21) Hbl, and 8.1% (3) CytK encoding genes revealed positive results on PCR analysis. PCR results were also compatible with ELISA and Cytotoxicity tests. In a nutshell, 16.4% prevalence of B. cereus in foods is insufficient, and the presence or absence of toxin genes may not yield reliable results. It is critical to detect pathogenic B. cereus toxin gene profiles as well as toxin production ability at the same time. This study presents for the first time, data from a cell culture cytotoxicity test using specific monoclonal antibody-based sandwich ELISA and multiplex PCR for ready-to-eat foods and pastry products in Turkey

Traditional Chinese Medicine: An Exogenous Regulator of Crosstalk between the Gut Microbial Ecosystem and CKD.

Chronic kidney disease (CKD) is often accompanied by an imbalance in the gut microbial ecosystem. Notably, the imbalanced gut microbiota and impaired intestinal barrier are the keys to the crosstalk between the gut microbial ecosystem and CKD, which was the central point of previous studies. Traditional Chinese medicine (TCM) has shown considerable efficacy in the treatment of CKD. However, the therapeutic mechanisms have not been fully elucidated. In this review, we explored therapeutic mechanisms by which TCM improved CKD via the gut microbial ecosystem. In particular, we focused on the restored gut microbiota (i.e., short-chain fatty acid- and uremic toxin-producing bacteria), improved gut-derived metabolites (i.e., short-chain fatty acid, indoxyl sulfate, p-Cresyl sulfate, and trimethylamine-N-oxide), and intestinal barrier (i.e., permeability and microbial translocation) as therapeutic mechanisms. The results found that the metabolic pattern of gut microbiota and the intestinal barrier were improved through TCM treatment. Moreover, the microbiota-transfer study confirmed that part of the protective effect of TCM was dependent on gut microbiota, especially SCFA-producing bacteria. In conclusion, TCM may be an important exogenous regulator of crosstalk between the gut microbial ecosystem and CKD, which was partly attributable to the mediation of microbiota-targeted intervention.

Application of Procalcitonin for the Rapid Diagnosis of Clostridioides difficile Infection in Patients with Inflammatory Bowel Disease.

Background: The incidence of Clostridioides difficile infection (CDI) has increased in recent years in patients with inflammatory bowel disease (IBD). C. difficile is a toxin-producing bacterium, and CDI results in the worsening of underlying IBD, increasing the risk of IBD treatment failure, surgery, and hospitalization. Because the symptoms of CDI overlap with those of IBD, it is challenging to make a differential diagnosis. Therefore, early, rapid, and reliable diagnostic tools that can identify CDI in IBD patients would be valuable to clinicians. Methods: This study retrospectively collected 135 patients with IBD. Among them, 44 patients were diagnosed with CDI, and 42 patients were diagnosed with viral or fungal infections. A total of 49 patients without infections were defined as the control group. The diagnostic values of procalcitonin (PCT), C-reactive protein (CRP), and white blood cell (WBC) count in the peripheral blood were examined. Results: In this study, PCT levels were significantly higher in patients with CDI than in non-CDI patients (including patients with viral/fungal infections and the control group; p &lt; 0.001 and p &lt; 0.05, respectively). CRP levels were significantly higher in patients with CDI than in non-CDI patients (p &lt; 0.05). The area under the curve (AUC) of PCT and WBC count were compared using DeLong's test: the AUCs of PCT vs. CRP for the detection of the IBD-CDI group and the control group was 0.826 [95% confidence interval (CI) 0.743-0.909] vs. 0.663 [95% confidence interval (CI) 0.551-0.774] (p &lt; 0.05), respectively. WBC count was inferior as a diagnostic tool for CDI. The sensitivity was 59.09% (95% CI: 43.2% to 73.7%), the specificity was 89.80% (95% CI: 77.8% to 96.6%), and the positive likelihood ratio LR (+) was 5.79 for PCT for the diagnosis of CDI. Conclusions: The present study demonstrates the superiority of PCT over CRP and WBC count for the rapid diagnosis of CDI in IBD patients.

Optimising Antimicrobial Stewardship to Tackle Clostridioides difficile Infection and Improve Patient Outcomes

Clostridioides difficile, formerly known as Clostridium difficile, is a Gram-positive spore-forming and toxin-producing bacterium that causes diarrhoea in vulnerable patient groups. It is a common hospital-acquired infection but also occurs in the community. Typically, C. difficile colonises the gut in patients experiencing gut dysbiosis, for example, following antimicrobial treatment or chemotherapy. Cases of C. difficile are increasing worldwide, both in healthcare settings and in the community, and are an indicator of widespread antibiotic use. Antimicrobial stewardship (AMS) combines local, national, and international guidelines for good antimicrobial practice, effective monitoring of antimicrobial resistance, and control of antibiotic use. Such strategies are vital in the international drive to stem the rise in antimicrobial resistance and control hospital-acquired infections such as C. difficile. However, implementation of such strategies is often lacking. Resourcing issues and a lack of awareness of current best practices among physicians, prescribers, and the general public are significant barriers to implementation. EMJ spoke with two infectious disease experts: Benoît Guery, University Hospital of Lausanne, Switzerland, and Javier Cobo Reinoso, Hospital Universitario Ramón y Cajal, Madrid, Spain. They highlighted the challenges that face medical practitioners, infectious disease experts, hospital managers, and healthcare providers in developing and implementing effective antimicrobial strategies that support better patient outcomes. The two experts also discussed the changes required to ensure that good AMS can be implemented at local, national, and international levels.

Paeniclostridium sordellii uterine infection is dependent on the estrous cycle.

Human infections caused by the toxin-producing, anaerobic and spore-forming bacterium Paeniclostridium sordellii are associated with a treatment-refractory toxic shock syndrome (TSS). Reproductive-age women are at increased risk for P. sordellii infection (PSI) because this organism can cause intrauterine infection following childbirth, stillbirth, or abortion. PSI-induced TSS in this setting is nearly 100% fatal, and there are no effective treatments. TcsL, or lethal toxin, is the primary virulence factor in PSI and shares 70% sequence identity with Clostridioides difficile toxin B (TcdB). We therefore reasoned that a neutralizing monoclonal antibody (mAB) against TcdB might also provide protection against TcsL and PSI. We characterized two anti-TcdB mABs: PA41, which binds and prevents translocation of the TcdB glucosyltransferase domain into the cell, and CDB1, a biosimilar of bezlotoxumab, which prevents TcdB binding to a cell surface receptor. Both mABs could neutralize the cytotoxic activity of recombinant TcsL on Vero cells. To determine the efficacy of PA41 and CDB1 in vivo, we developed a transcervical inoculation method for modeling uterine PSI in mice. In the process, we discovered that the stage of the mouse reproductive cycle was a key variable in establishing symptoms of disease. By synchronizing the mice in diestrus with progesterone prior to transcervical inoculation with TcsL or vegetative P. sordellii, we observed highly reproducible intoxication and infection dynamics. PA41 showed efficacy in protecting against toxin in our transcervical in vivo model, but CDB1 did not. Furthermore, PA41 could provide protection following P. sordellii bacterial and spore infections, suggesting a path for further optimization and clinical translation in the effort to advance treatment options for PSI infection.

Abstract B028: Bacterial cytotoxin therapy limits tumor growth for pancreatic ductal adenocarcinoma

Abstract Treating pancreatic ductal adenocarcinoma (PDAC) with systemic chemotherapeutic drugs has remained a challenge, due in part to the hypovascularized and poorly perfused nature of PDAC tumors, impeding the accumulation of systemically delivered drugs. Several clinical trials aimed at improving drug delivery in PDAC, through targeting of ECM components (HALO-301) or stromal angiogenic signaling (IPI-926-03) have unfortunately not been effective. However, the features that have interfered with systemic therapy in PDAC are potential advantages for the use of bacterial therapies, as bacteria can actively migrate through tissues, thrive in hypoxic microenvironments, and benefit from local immune suppression. Recent developments in the field of synthetic biology have made it possible to engineer complex logic circuits into bacteria, enabling the production of anticancer therapies directly within the tumor parenchyma. Furthermore, live bacteria, once colonized within the tumor niche, are capable of providing a stable source of anticancer compounds directly, rather than relying on repeated systemic doses. We have therefore worked to develop novel bacterial strains and demonstrate preclinical efficacy of a novel strain of therapeutic bacteria for targeting PDAC. We began by testing a range of bacteria-produced toxins and identified the pore-forming protein theta toxin as having the greatest effect in both 2D cell culture and PDAC explant (tissue slice) models. We then engineered a non-toxic probiotic bacteria, E. coli Nissle 1917, to produce either theta toxin or GFP following induction with acyl-homoserine lactone (AHL). To assess preclinical efficacy, we performed intratumoral injections of live GFP- and theta-expressing bacteria into the “KPC” genetically engineered mouse model (Kras LSL.G12D/+; Tp53 LSL.R172H/+; PdxCre tg/+). While GFP-producing bacteria did not induce a change in tumor growth kinetics, treatment with theta toxin-producing bacteria demonstrated prolonged stabilization of tumor growth, increasing the doubling time from 13.7 days (GFP) to 32.5 days (theta) without additional therapy. Indeed, one theta-treated KPC animal lived 113 days following a single bacterial injection, compared to a median of ~12 days for vehicle- or gemcitabine-treated historical controls. Histological analyses demonstrated that diffuse populations of bacteria co-localized with regions of tumor necrosis and cell death, but that bacterial presence and evidence of increased cell death was not observed in healthy tissues, such as the lung, liver, intestine, and diaphragm. Strikingly, while there was minimal spread of bacteria to non-tumor tissues, we observed translocation of the bacteria to regions of liver metastases and distant papillomas following injection of the primary pancreatic tumor, suggesting a mechanism for targeting both known and unknown metastases following local administration. Together these studies demonstrate potent preclinical activity of cytotoxic bacterial therapy as a novel strategy to circumvent the challenges of systemic treatment of PDAC. Citation Format: Amanda R. Decker, Tetsuhiro Harimoto, Steve A. Sastra, Tal Danino, Kenneth Olive. Bacterial cytotoxin therapy limits tumor growth for pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B028.

Toxoflavin contamination in rice samples from rice processing complexes in South Korea

Toxoflavin contamination was investigated in broken rice produced as a by-product of domestic rice processing complexes (RPCs) in 2011 in South Korea. Of the 68 RPCs investigated, toxoflavin contamination was confirmed in 12 from three provinces: Gangwon, Gyeonggi, and Gyeongsang. Isolation of toxoflavin-producing bacteria independent of toxoflavin contamination was also performed in this study. We obtained 25 toxoflavin-producing bacterial isolates from rice samples; these samples were collected from the same 12 RPCs mentioned above. All 25 toxoflavin-producing bacteria were identified as Burkholderia glumae by 16S rRNA gene sequencing. Toxoflavin-producing ability differed slightly among the 25 isolates, but they all inhibited rice seed germination and induced seed rot. This is the first report of toxoflavin contamination and the toxin-producing bacterium B. glumae in broken rice produced during the rice milling process. Because toxoflavin has stable physical properties even above a boiling temperature of 100°C, it can pose a problem even if rice is cooked or processed. These results will serve as baseline data aiding comprehensive management of toxoflavin contamination during the post-harvest storage and processing of rice.