Infectious Disorders of the GI Tract

Causal associations of genetically predicted gut microbiota and blood metabolites with inflammatory states and risk of infections: a Mendelian randomization analysis

Background

Inflammation serves as a key pathologic mediator in the progression of infections and various diseases, involving significant alterations in the gut microbiome and metabolism. This study aims to probe into the potential causal relationships between gut microbial taxa and human blood metabolites with various serum inflammatory markers (CRP, SAA1, IL-6, TNF-α, WBC, and GlycA) and the risks of seven common infections (gastrointestinal infections, dysentery, pneumonia, bacterial pneumonia, bronchopneumonia and lung abscess, pneumococcal pneumonia, and urinary tract infections).

Methods

Two-sample Mendelian randomization (MR) analysis was performed using inverse variance weighted (IVW), maximum likelihood, MR-Egger, weighted median, and MR-PRESSO.

Results

After adding other MR models and sensitivity analyses, genus Roseburia was simultaneously associated adversely with CRP (Beta IVW = -0.040) and SAA1 (Beta IVW = -0.280), and family Bifidobacteriaceae was negatively associated with both CRP (Beta IVW = -0.034) and pneumonia risk (Beta IVW = -0.391). After correction by FDR, only glutaroyl carnitine remained significantly associated with elevated CRP levels (Beta IVW = 0.112). Additionally, threonine (Beta IVW = 0.200) and 1-heptadecanoylglycerophosphocholine (Beta IVW = -0.246) were found to be significantly associated with WBC levels. Three metabolites showed similar causal effects on different inflammatory markers or infectious phenotypes, stearidonate (18:4n3) was negatively related to SAA1 and urinary tract infections, and 5-oxoproline contributed to elevated IL-6 and SAA1 levels. In addition, 7-methylguanine showed a positive correlation with dysentery and bacterial pneumonia.

Conclusion

This study provides novel evidence confirming the causal effects of the gut microbiome and the plasma metabolite profile on inflammation and the risk of infection. These potential molecular alterations may aid in the development of new targets for the intervention and management of disorders associated with inflammation and infections.

Network-wide analysis of the Serosep EntericBio Gastro Panel 2 for the detection of enteric pathogens in Public Health Wales microbiology laboratories

Introduction. A retrospective data analysis of 34 months (spanning 2016-2020) of 961573 diagnostic results obtained before and after nucleic acid amplification testing (NAAT) implementation, across the Public Health Wales microbiology network.Hypothesis / Gap Statement. This is the first network-wide analysis of the implementation of enteric NAAT in diagnostic microbiology.Aim. To assess the outcome of replacing microscopy and bacterial culture with NAAT as the primary test in the diagnosis of: Campylobacter spp., Salmonella sp., Shigella spp., Shiga toxin-producing Escherichia coli (STEC), Cryptosporidium spp. and Giardia duodenalis infections.Methodology. Following NAAT introduction, bacterial culture was performed as a secondary test, to provide further information from NAAT positive samples for epidemiological purposes. Primary detection rates and overall bacterial culture rates were calculated for each target pathogen using both testing regimes (Stage I) including a comparison of in-patient and out-patient diagnoses (Stage II).Results. Stage I analysis showed that the primary detection rate significantly increased for Campylobacter spp. (P<0.0001), Salmonella sp. (P=0.0151), Shigella spp. (P<0.0001), STEC (P<0.0001), Cryptosporidium spp. (P<0.0001) and Giardia duodenalis (P<0.0001) when using NAAT compared to microscopy or bacterial culture. A significant decrease was seen in the overall rate of Campylobacter spp. isolation by bacterial culture (P<0.0001), whilst other targets remained unaffected. Stage II analysis showed that NAAT positive out-patient samples were more likely to be supplemented by a positive bacterial culture than NAAT positive in-patient samples for Campylobacter spp. (P<0.0001), Salmonella sp. (P=0.0004) and STEC (P=0.0039). However, Shigella spp. was more frequently isolated from NAAT positive in-patient samples (P=0.0005). A notable increase was seen for G. duodenalis detection from in-patient samples (P=0.0002). Reference laboratory data showed the NAAT assay can detect at least 53 serotypes of STEC but may not be able to detect some of the rarer species of Cryptosporidium seen in human infections.Conclusion. The implementation of NAAT has significantly increased the primary detection rate of all target enteric pathogens in Wales and information gleaned previously from direct culture is largely unaffected.

Association between Dietary Factors and Constipation in Adults Living in Luxembourg and Taking Part in the ORISCAV-LUX 2 Survey

Constipation, a disorder of bowel movements, is among the most frequent gastrointestinal complaints in Western countries. Dietary constituents such as inadequate fiber intake have been related to constipation, but discrepancies exist in the findings regarding dietary factors. This study investigated the association between dietary patterns and bowel movements in adults living in Luxembourg. Data from 1431 participants from ORISCAV-LUX 2 (a cross-sectional survey) who completed a 174-item food frequency questionnaire (FFQ) were analyzed. A questionnaire-based constipation score was assessed by a validated scoring system. Confounders such as physical activity and serum/urine indicators were assessed. Women had higher constipation scores than men (p < 0.001). In food group-based regression models, a negative association was found between higher constipation score and intake of grains (Beta = −0.62, 95%CI: −1.18, −0.05) and lipid-rich foods (Beta = −0.84, 95%CI: −1.55, −0.13), while a positive association was found for sugary products (Beta = 0.54, 95%CI: 0.11, 0.97) (p < 0.05). In a nutrient-based regression model, a positive association was found between constipation score and total energy (Beta = 5.24, 95%CI: 0.37, 10.11) as well as sodium intake (Beta = 2.04, 95%CI: 0.21, 3.87), and a negative one was found for total fats (Beta = −4.17, 95%CI: −7.46, −0.89) and starch (Beta = −2.91, 95%CI: −4.47, −1.36) (p < 0.05). Interestingly, neither fruits and vegetables or dietary fiber were significantly associated with constipation. Thus, grains, lipid-rich foods, total fats and starch were associated with a lower constipation score, while sugary products, sodium, and higher energy intake were correlated with higher constipation.

Lymphogranuloma venereum proctitis mimicking inflammatory bowel diseases in 11 patients: a 4-year single-center experience

Lymphogranuloma venereum (LGV) is a sexually transmitted disease caused by Chlamydia trachomatis (CT) serovars L1–L3. Our study wants to underline the similarities between rectal LGV and idiopathic inflammatory bowel diseases (IBD), which can share clinical, endoscopic and histopathological findings.

Clinical and Pathological Features of Ulcerative Colitis in Patients with and without Clostridium Difficile Infection; An Observational Study

BACKGROUND

A dramatic rise in the rate of clostridium difficile infection (CDI) in patients with inflammatory bowel disease (IBD) has been reported in recent years.

METHODS

In this observational case control study, 65 patients were included and were divided into two groups of IBD + CDI as case group and IBD without CDI as control group.

RESULTS

35 patients who had positive test for clostridium difficile were assigned to the case group. The control group consisted of 30 patients with negative test for clostridium difficile. Pancolitis was seen in the cases more statistically significant than the controls and proctitis was seen more among the controls than the cases (p = 0.001). The cases were on immunosuppressive (p = 0.001) and antibiotic (p = 0.02) therapy more than the controls. Colonoscopic findings revealed more severe and extensive inflammation among the cases versus milder inflammation among the controls, but these differences were not statistically significant (p = 0.2). Colectomy was seen in 10% of controls and none of the cases and this difference was statistically significant (p value = 0.05). More fecal calprotectin were seen among the cases than the controls and this difference was statistically significant (p < 0.05)

CONCLUSION

This study showed more clostridium difficile infection among the patients on antibiotic or immunosuppressive therapy. Pathological investigation revealed more severe and extensive inflammation among the cases than the controls. Cases had clinically more severe signs and symptoms with higher mayo scores than the controls. ESR (Erythrocyte sedimentation rate) and fecal calprotectin were higher in patients with positive clostridium difficile infection and serum albumin was lower in such patients.

Histologic findings and clinical characteristics in acutely symptomatic ulcerative colitis patients with superimposed Clostridium difficile infection

OBJECTIVES

To examine biopsy specimens for histologic features suggestive of Clostridium difficile infection in patients with ulcerative colitis (UC).

METHODS

Nine patients with UC had colonic biopsy specimens taken during a symptomatic flare that coincided with positive C difficile (C difficile+) tests. Twenty-eight controls were biopsied during a UC flare but tested negative for C difficile. We reviewed the slides for evidence of pseudomembranes, ischemic-like changes, degree of colitis, and lamina propria hemorrhage.

RESULTS

In C difficile+ patients, 4 (44.4%) of 9 had microscopic pseudomembranes compared with 11% in controls (P < .05). Other histologic/clinical features were not predictive.

CONCLUSIONS

Although the presence of microscopic pseudomembranes suggests C difficile infection in patients with UC, sensitivity and specificity are poor; biopsy findings do not reliably detect this infection in patients with UC.

Interobserver variability and feasibility of polymerase chain reaction-based assay in distinguishing ischemic colitis from Clostridium difficile colitis in endoscopic mucosal biopsies

Polymerase chain reaction (PCR)-based assays using stool samples are currently the most effective method of detecting Clostridium difficile. This study examines the feasibility of this assay using mucosal biopsy samples and evaluates the interobserver reproducibility in diagnosing and distinguishing ischemic colitis from C difficile colitis. Thirty-eight biopsy specimens were reviewed and classified by 3 observers into C difficile and ischemic colitis. The findings were correlated with clinical data. PCR was performed on 34 cases using BD GeneOhm C difficile assay. The histologic interobserver agreement was excellent (κ= 0.86) and the agreement between histologic and clinical diagnosis was good (κ = 0.84). All 19 ischemic colitis cases tested negative (100% specificity) and 3 of 15 cases of C difficile colitis tested positive (20% sensitivity). C difficile colitis can be reliably distinguished from ischemic colitis using histologic criteria. The C difficile PCR test on endoscopic biopsy specimens has excellent specificity but limited sensitivity.