The Association between Gut Microbiome and Post-Cholecystectomy Syndrome and Diarrhoea: A Review

Cholecystectomy is a common surgical gold-standard treatment for cholelithiasis and its complications. Generally, gallbladder removal has no long-term ramifications, and most patients recover quickly without impairment on daily living activities. Nonetheless, some patients are found to develop postcholecystectomy syndrome (PCS) or diarrhoea (PCD), which can be uncomfortable, inconvenient and impair living quality. There is neither clear aetiology, nor clear solution for PCS/PCD. The significance of gut microbiome in maintaining a healthy gastrointestinal system is well-established. Dysbiosis, an imbalance between commensal and pathogenic bacteria, can lead to multiple GIT disorders like IBS or functional dyspepsia and has a strong association with change in stool consistency [1-3]. Alteration in gut microbiota can easily occur with physical or chemical changes. An invasive procedure like cholecystectomy exposes the intestinal lumen to exogenous bacteria and causes inflammatory changes, while secretory pattern changes of bacteriostatic bile acid disrupt the pH and microbial composition of the intestinal lumen. As such, it is worth understanding GIT microbiota changes post-cholecystectomy. While the concept of gut microbiome changes potentially causing PCS/PCD is not unknown, there is lack of literature reviewing research on what these microbial alterations are and establishing their association with PCS/PCD. In this review, we consolidate previous findings on post-cholecystectomy microbial alterations, effectiveness of diet on PCS/PCD based on gut microbiota and discuss the overall link between gut microbiome and PCS/PCD. This can deepen insight into aetiologies of idiopathic PCS/PCD, provide better management of PCS/PCD-associated comorbidities, and potentially offer a resolution for PCS/PCD through prescription of probiotics and prebiotics.

The role of extracellular polymeric substances in biofilm community assembly and metabolic functions

<p>Compared with the chemically defined synthetic wastewater (SynWW), real wastewater has been reported to exhibit distinct effects on microbial community development. Whether and how soluble microbial products in real wastewater contribute to different effects of synthetic and real wastewater on the fate of exogenous bacteria remains elusive. In this study, using a model wastewater bacterium <em>Comamonas testosteroni</em>, we first examined the influences of microfiltration filter-sterilized real wastewater (MF-WW) and SynWW on the retention of <em>C. testosteroni</em> in established wastewater flocs during bioaugmentation. In bioreactors fed with MF-WW, augmentation of <em>C. testosteroni</em> to wastewater flocs resulted in a substantially higher abundance of the augmented bacterial cells than those fed with SynWW. To identify the soluble microbial products in MF-WW contributing to the observed differences between bioaugmentation reactors fed with MF-WW and SynWW, we examined the effect of MF-WW and SynWW on the growth, floc formation, and biofilm development of <em>C. testosteroni</em>. When <em>C. testosteroni</em> grew in MF-WW, visible flocs formed within 2 h, which is in contrast to cell growth in SynWW where floc formation was not observed. We further demonstrated that the observed differences were mainly attributed to the high molecular weight fraction of the soluble extracellular polymeric substances (EPS) in MF-WW, in particular, proteins and extracellular DNA. The DLVO analysis suggested that, in the presence of soluble EPS, the bacterial cell surface exhibits an increased hydrophobicity and a diminished energy barrier, leading to irreversible attachment of planktonic cells and floc formation. The RNA-seq based transcriptional analysis revealed that, in the presence of soluble EPS, genes involved in nonessential metabolisms were downregulated while genes coding for Cco (cbb3- type) and Cox (aa3-type) oxidases with different oxygen affinities were upregulated, facilitating bacterial survival in flocs. Taken together, this study reveals the mechanisms underlying the contribution of soluble EPS to the recruitment of exogenous bacteria by microbial aggregates and provides implications to bioaugmentation.</p> <p> </p> <p><strong>References:</strong></p> <ol> <li>Wu, Y., Zaiden, N., Liu, X., Mukherjee, M. and Cao, B., 2020. Responses of Exogenous Bacteria to Soluble Extracellular Polymeric Substances in Wastewater: A Mechanistic Study and Implications on Bioaugmentation. Environmental Science & Technology. In press</li> <li>Wu, Y., Cai, P., Jing, X., Niu, X., Ji, D., Ashry, N.M., Gao, C. and Huang, Q., 2019. Soil biofilm formation enhances microbial community diversity and metabolic activity. Environment international, 132, p.105116.</li> </ol>

Evaluation of Gentamicin Exposure Effects on Human gut Microbiota using the Simulator of Human Intestinal Microbial Ecosystem (SHIME)

Background: Antibiotics are emerging toxic contaminant that have potential public health risk worldwide. They may cause the human intestinal microbial disorder, as well as the spreading of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Most of the intestinal bacteria are not cultivable for the moment, tracking the special gene-labeled plasmid from the exogenous bacteria would help obtain the direct evidence of the horizontal transfer of ARGs in the intestinal flora. However, to date, there are only a few research reports applying the exogenous labeled bacteria to study the transfer of ARGs among intestinal bacteria. Therefore, for the first time, this study evaluated the in vitro ability of gentamicin on colonization of exogenous bacteria and plasmid in the simulated human gut. Results: This study indicated that exposure to gentamicin may be conducive to the colonization of exogenous bacteria and plasmid, as well as the conjugation of plasmid to gut microbiota. Gentamicin exposure was also confirmed to reduce the gene numbers of human disease-related pathways and promote the drug resistance in the gut microbiota. The effects on the genetic level might attribute to microbiota shift, as co-occurrence patterns suggested that Bacteroides attributed to the ARGs enrichment and Klebsiella played a crucial role in human disease-related pathways reduction after gentamicin treatment. Conclusion: These results may open up new perspectives for assessing the direct effects of antibiotics on the intestinal microbiota. These suggested side-effects should be considered for antibiotics prescription.

CLINICAL STUDY ON CELLULITIS IN A TERTIARY CENTRE

INTRODUCTION: Cellulitis is a non-suppurative, invasive infection caused by bacteria that is characterized by specifically affecting the dermis and subcutaneous fatty layer by normal skin flora or exogenous bacteria. The lower limbs are affected commonly following a breach due to cracks, breaks, blisters, surgical wounds, ulcers in the skin. Untreated conditions will lead to sequential changes causing severe morbidity and sometimes mortality. AIM: To study the age and sex distribution, risk factors, treatment modalities of patients admitted as cellulitis cases in Department of General Surgery,Government Tirunelveli Medical College Hospital from August 2017 to February 2018. RESULTS: In this study on 100 patients, 76 had lower limb cellulitis and 24 had upper limb cellulitis. Age group commonly affected was from 40 - 60 yrs of age.Most of the patients had Grade III cellulitis. Among the patients with risk factors of Diabetes mellitus, snake bites, the site of bite or the toes or the metatarsal below showed lytic changes, or destruction due to the gangrenous changes. It is observed that 75 patients in the study group required surgical debridement,48 of them required decompression of the muscular compartment by means of a fasciotomy.

DAV131A Protects Hamsters from Lethal Clostridioides difficile Infection Induced by Fluoroquinolones

ABSTRACT Fluoroquinolone treatments induce dysbiosis of the intestinal microbiota, resulting in loss of resistance to colonization by exogenous bacteria such as Clostridioides difficile that may cause severe diarrhea in humans and lethal infection in hamsters. We show here that DAV131A, a charcoal-based adsorbent, decreases the intestinal levels of the fluoroquinolone antibiotics levofloxacin and ciprofloxacin in hamsters, protects their intestinal microbiota, and prevents lethal infection by C. difficile.

Microbial Simulation Experiment on Enhancing Coalbed Methane Production

Coalbed Methane(CBM) production enhancement for single wells is a big problem to CBM industrialization. Low production is due to insufficient gas generation by thermogenic. Luckily, Biogenic gas was found in many areas and its supply is assumed to improve coalbed methane production. Therefore, microbial simulation experiment will demonstrate the effectiveness of the assumption. From microbial simulation experiment on different coal ranks, it is found that microbes can use coals to produce biogas under laboratory conditions. With different temperatures for different experiments, it turns out that the gas production at 35 ℃ is greater than that at 15℃,indicating that 35℃ is more suitable for microbes to produce gas. According to quantitative experiments, adding exogenous nutrients or exogenous bacteria can improve CBM production. Moreover, the production enhancement ratio can reach up to 115% under the condition of adding exogenous bacterial species, while the ratio for adding nutrients can be up to 144%.