Acute appendicitis in children is associated with an abundance of bacteria from the phylum Fusobacteria

The microbiome of the appendix differs in patients with and without appendicitis: A prospective cohort study

BACKGROUND

Appendicitis seems to be a disease of infectious origin, but the detailed pathogenesis is unknown. We aimed to investigate the microbiome of the appendix lumen in patients with and without appendicitis, including a comparison of the subgroups of complicated versus uncomplicated appendicitis.

METHODS

This prospective observational cohort study included adult patients undergoing laparoscopic appendectomy for suspected appendicitis. According to histopathologic findings, the investigated groups consisted of patients with and without appendicitis, including subgroups of complicated versus uncomplicated appendicitis based on the surgical report. A swab of the appendix lumen was analyzed for genetic material from bacteria with shotgun metagenomics, and outcomes included analyses of microbiome diversity and differential abundance of bacteria.

RESULTS

A total of 53 swabs from patients with suspected appendicitis were analyzed: 42 with appendicitis (16 complicated) and 11 without appendicitis. When comparing patients with and without appendicitis, they were equally rich in bacteria (alpha diversity), but the microbiome composition was dissimilar between these groups (beta diversity) (P < .01). No consistent bacterial species were detected in all patients with appendicitis, but a least 3 genera (Blautia, Faecalibacterium, and Fusicatenibacter) and 2 species, Blautia faecis and Blautia wexlerae, were more abundant in patients without appendicitis. For the subgroups complicated versus uncomplicated appendicitis, both measures for microbiome diversity were similar.

CONCLUSION

The appendix microbiome composition of genetic material from bacteria in adult patients with and without appendicitis differed, but the microbiome was similar for patients with complicated versus uncomplicated appendicitis. Trial registration NCT03349814.

Appendectomy versus antibiotic treatment for acute appendicitis

BACKGROUND

Acute appendicitis is one of the most common emergency general surgical conditions worldwide. Uncomplicated/simple appendicitis can be treated with appendectomy or antibiotics. Some studies have suggested possible benefits with antibiotics with reduced complications, length of hospital stay, and the number of days off work. However, surgery may improve success of treatment as antibiotic treatment is associated with recurrence and future need for surgery.

OBJECTIVES

To assess the effects of antibiotic treatment for uncomplicated/simple acute appendicitis compared with appendectomy for resolution of symptoms and complications.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two trial registers (World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov) on 19 July 2022. We also searched for unpublished studies in conference proceedings together with reference checking and citation search. There were no restrictions on date, publication status, or language of publication.

SELECTION CRITERIA

We included parallel-group randomised controlled trials (RCTs) only. We included studies where most participants were adults with uncomplicated/simple appendicitis. Interventions included antibiotics (by any route) compared with appendectomy (open or laparoscopic).

DATA COLLECTION AND ANALYSIS

We used standard methodology expected by Cochrane. We used GRADE to assess the certainty of evidence for each outcome. Primary outcomes included mortality and success of treatment, and secondary outcomes included number of participants requiring appendectomy in the antibiotic group, complications, pain, length of hospital stay, sick leave, malignancy in the antibiotic group, negative appendectomy rate, and quality of life. Success of treatment definitions were heterogeneous although mainly based on resolution of symptoms rather than incorporation of long-term recurrence or need for surgery in the antibiotic group.

MAIN RESULTS

We included 13 studies in the review covering 1675 participants randomised to antibiotics and 1683 participants randomised to appendectomy. One study was unpublished. All were conducted in secondary care and two studies received pharmaceutical funding. All studies used broad-spectrum antibiotic regimens expected to cover gastrointestinal bacteria. Most studies used predominantly laparoscopic surgery, but some included mainly open procedures. Six studies included adults and children. Almost all studies aimed to exclude participants with complicated appendicitis prior to randomisation, although one study included 12% with perforation. The diagnostic technique was clinical assessment and imaging in most studies. Only one study limited inclusion by sex (male only). Follow-up ranged from hospital admission only to seven years. Certainty of evidence was mainly affected by risk of bias (due to lack of blinding and loss to follow-up) and imprecision. Primary outcomes It is uncertain whether there was any difference in mortality due to the very low-certainty evidence (Peto odds ratio (OR) 0.51, 95% confidence interval (CI) 0.05 to 4.95; 1 study, 492 participants). There may be 76 more people per 1000 having unsuccessful treatment in the antibiotic group compared with surgery, which did not reach our predefined level for clinical significance (risk ratio (RR) 0.91, 95% CI 0.87 to 0.96; I2 = 69%; 7 studies, 2471 participants; low-certainty evidence). Secondary outcomes At one year, 30.7% (95% CI 24.0 to 37.8; I2 = 80%; 9 studies, 1396 participants) of participants in the antibiotic group required appendectomy or, alternatively, more than two-thirds of antibiotic-treated participants avoided surgery in the first year, but the evidence is very uncertain. Regarding complications, it is uncertain whether there is any difference in episodes of Clostridium difficile diarrhoea due to very low-certainty evidence (Peto OR 0.97, 95% CI 0.24 to 3.89; 1 study, 1332 participants). There may be a clinically significant reduction in wound infections with antibiotics (RR 0.25, 95% CI 0.09 to 0.68; I2 = 16%; 9 studies, 2606 participants; low-certainty evidence). It is uncertain whether antibiotics affect the incidence of intra-abdominal abscess or collection (RR 1.58, 95% CI 0.61 to 4.07; I2 = 19%; 6 studies, 1831 participants), or reoperation (Peto OR 0.13, 95% CI 0.01 to 2.16; 1 study, 492 participants) due to very low-certainty evidence, mainly due to rare events causing imprecision and risk of bias. It is uncertain if antibiotics prolonged length of hospital stay by half a day due to the very low-certainty evidence (MD 0.54, 95% CI 0.06 to 1.01; I2 = 97%; 11 studies, 3192 participants). The incidence of malignancy was 0.3% (95% CI 0 to 1.5; 5 studies, 403 participants) in the antibiotic group although follow-up was variable. Antibiotics probably increased the number of negative appendectomies at surgery (RR 3.16, 95% CI 1.54 to 6.49; I2 = 17%; 5 studies, 707 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Antibiotics may be associated with higher rates of unsuccessful treatment for 76 per 1000 people, although differences may not be clinically significant. It is uncertain if antibiotics increase length of hospital stay by half a day. Antibiotics may reduce wound infections. A third of the participants initially treated with antibiotics required subsequent appendectomy or two-thirds avoided surgery within one year, but the evidence is very uncertain. There were too few data from the included studies to comment on major complications.

Causal effects of gut microbiota on appendicitis: a two-sample Mendelian randomization study

Background

Previous research has posited a potential correlation between the gut microbiota and the onset of appendicitis; however, the precise causal connection between appendicitis and the gut microbiota remains an unresolved and contentious issue.

Methods

In this investigation, we performed a Mendelian randomization (MR) analysis employing publicly accessible summary data extracted from genome-wide association studies (GWAS) to elucidate the potential causal nexus between the gut microbiota and the development of appendicitis. We initially identified instrumental variables (IVs) through a comprehensive array of screening methodologies, subsequently executing MR analyses using the Inverse Variance Weighted (IVW) technique as our primary approach, supplemented by several alternative methods such as MR Egger, weighted median, simple mode, and weighted mode. Additionally, we implemented a series of sensitivity analysis procedures, encompassing Cochran's Q test, MR-Egger intercept test, Mendelian Randomized Polymorphism Residual and Outlier (MR-PRESSO) test, and a leave-one-out test, to affirm the robustness and validity of our findings.

Results

Our investigation indicates that an elevated prevalence of Deltaproteobacteria, Christensenellaceae, Desulfovibrionaceae, Eubacterium ruminantium group, Lachnospiraceae NK4A136 group, Methanobrevibacter, Desulfovibrionales, and Euryarchaeota is inversely associated with the risk of appendicitis. Conversely, we observed a positive correlation between an increased abundance of Family XIII, Howardella, and Veillonella and the susceptibility to appendicitis. Sensitivity analyses have corroborated the robustness of these findings, and Mendelian randomization analyses provided no indications of reverse causality.

Conclusion

Our Mendelian randomization (MR) analysis has unveiled potential advantageous or detrimental causal associations between the gut microbiota and the occurrence of appendicitis. This study offers novel theoretical and empirical insights into the understanding of appendicitis pathogenesis, along with its implications for preventive and therapeutic strategies.

Role of Hydrogen Sulfide in Inflammatory Bowel Disease

Hydrogen sulfide (H2S), originally known as toxic gas, has now attracted attention as one of the gasotransmitters involved in many reactions in the human body. H2S has been assumed to play a role in the pathogenesis of many chronic diseases, of which the exact pathogenesis remains unknown. One of them is inflammatory bowel disease (IBD), a chronic intestinal disease subclassified as Crohn's disease (CD) and ulcerative colitis (UC). Any change in the amount of H2S seems to be linked to inflammation in this illness. These changes can be brought about by alterations in the microbiota, in the endogenous metabolism of H2S and in the diet. As both too little and too much H2S drive inflammation, a balanced level is needed for intestinal health. The aim of this review is to summarize the available literature published until June 2023 in order to provide an overview of the current knowledge of the connection between H2S and IBD.

A comprehensive microbial analysis of pediatric patients with acute appendicitis

BACKGROUND

Pathogenesis of pediatric acute appendicitis (AA) is yet to be elucidated. Therefore, we performed a comprehensive microbial analysis of saliva, feces, and appendiceal lumen of AA patients using 16S ribosomal RNA (rRNA) gene amplicon sequencing to elucidate the pathogenesis of pediatric AA.

METHODS

This study included 33 AA patients and 17 healthy controls (HCs) aged <15 y. Among the AA patients, 18 had simple appendicitis, and 15 had complicated appendicitis. Salivary and fecal samples were obtained from both groups. The contents of the appendiceal lumen were collected from the AA group. All samples were analyzed using 16S rRNA gene amplicon sequencing.

RESULTS

The relative abundance of Fusobacterium was significantly higher in the saliva of AA patients as compared to that in HCs (P = 0.011). Bacteroides, Escherichia, Fusobacterium, Coprobacillus, and Flavonifractor were significantly increased in the feces of AA patients, as compared to that in HCs (P = 0.020, 0.010, 0.029, 0.031, and 0.002, respectively). In the appendiceal lumen, Bacteroides, Parvimonas, Fusobacterium, and Alloprevotella were the top bacterial genera with an average relative abundance >5% (16.0%, 9.1%, 7.9%, and 6.0%, respectively).

CONCLUSIONS

The relative abundance of Fusobacterium was high in the appendiceal lumen of pediatric AA patients. Moreover, the relative abundance of Fusobacterium was significantly higher in the saliva and feces of pediatric AA patients than in those of healthy children. These results suggest that ectopic colonization of oral Fusobacterium in the appendix might play an important role in the pathogenesis of pediatric AA.

Association of the Bacteria of the Vermiform Appendix and the Peritoneal Cavity with Complicated Acute Appendicitis in Children

BACKGROUND

Primary infection has been questioned as the pathogenetic cause of acute appendicitis. We attempted to identify the bacteria involved and to investigate if their species, types, or combinations affected the severity of acute appendicitis in children.

METHODS

Samples from both the appendiceal lumen and the peritoneal cavity of 72 children who underwent appendectomy were collected to perform bacterial culture analysis. The outcomes were studied to identify if and how they were associated with the severity of the disease. Regression analysis was performed to identify any risk factors associated with complicated appendicitis.

RESULTS

Escherichia coli, Pseudomonas aeruginosa, and Streptococcus species were the most common pathogens found in the study population. The same microorganisms, either combined or separate, were the most common in the appendiceal lumen and the peritoneal cavity of patients with complicated appendicitis. Gram-negative bacteria and polymicrobial cultures in the peritoneal fluid and in the appendiceal lumen were associated with complicated appendicitis. Polymicrobial cultures in the peritoneal cavity presented a four times higher risk of complicated appendicitis.

CONCLUSIONS

Polymicrobial presentation and Gram-negative bacteria are associated with complicated appendicitis. Antibiotic regimens should target the combinations of the most frequently identified pathogens, speculating the value of early antipseudomonal intervention.

Investigation of VGLL3 and sub-target genes in the aetiology of paediatric acute appendicitis: a prospective case-control study

PURPOSE

Vestigial like family member 3 (VGLL3) and its sub-target genes show considerable transcriptomic overlap in terms of several autoimmune and inflammatory diseases. Herein, we investigated the role of VGLL3 rs13074432 polymorphism and its sub-target genes in the aetiology of acute appendicitis (AA).

METHODS

In this prospective case-control study, we included 250 patients (age, 0-18 years) who underwent appendectomy with the diagnosis of AA (patient group; blood and appendix tissue samples) and 200 healthy children (control group; only blood samples) without appendectomy. ELISA method was used for protein-level detection of VGLL3 and sub-target genes expression change in obtained tissue samples, and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used for mRNA level detection. Genotyping analyses were performed on DNA samples isolated from blood using TaqMan SNP genotyping test.

RESULTS

The frequency of TT variant genotype (p < 0.001) and T allele (p = 0.002) showed a significant decrease in the patient group compared with the control group. No significant correlation was observed between the expression of VGLL3 in the appendiceal tissue and patient clinical and demographic data (p > 0.050).

CONCLUSION

This study revealed that the VGLL3 gene and its sub-target genes are associated with AA aetiology.

Non-culture-based studies of the appendiceal microbiota: a systematic review

Aims: To review studies examining the appendiceal microbiota and microbial changes in acute appendicitis. Methods: After a systematic literature search, 11 studies examining the appendiceal microbiota (414 samples) using non-culture-based methods were included. Results: The appendiceal microbiota showed decreased α-diversity compared with fecal microbiota. Inflamed and uninflamed appendices showed differences in β-diversity, and there was an increased abundance of oral-associated bacteria in inflamed versus uninflamed appendices. Conclusion: The appendiceal microbiota exhibits lower α-diversity than the fecal microbiota, with an increased abundance of oral-associated bacteria. Compared with uninflamed appendices, the appendix microbiota in acute appendicitis also showed increased abundance of oral-associated bacteria, but no bacterial profile unique to either complicated or uncomplicated appendicitis was found.

Microbiome Structure and Mucosal Morphology of Jejunum Appendix and Colon of Rats in Health and Dysbiosis

Gut microbiota contributes to human health. Plenty of studies demonstrate that antibiotics can disrupt gut ecosystem leading to dysbiosis. Little is known about the microbial variation of appendix and its up/downstream intestine after antibiotic treatment. This study aimed to investigate the microbiome and mucosal morphology of jejunum, appendix, and colon of rats in health and dysbiosis. A rodent model of antibiotic-induced dysbiosis was employed. Microscopy was used to observe mucosal morphological changes. 16S rRNA sequencing was performed for identifying bacterial taxa and microbiome structure. The appendices of dysbiosis were found enlarged and inflated with loose contents. Microscopy revealed the impairment of intestinal epithelial cells. High-throughput sequencing showed the Operational Taxonomic Units changed from 361 ± 33, 634 ± 18, 639 ± 19 in the normal jejunum, appendix, colon to 748 ± 98, 230 ± 11, 253 ± 16 in the disordered segments, respectively. In dysbiosis, Bacteroidetes translocated inversely from the colon and appendix (0.26%, 0.23%) to the jejunum (13.87% ± 0.11%); the relative abundance of all intestinal Enterococcaceae increased, while Lactobacillaceae decreased. Several bacterial clusters were found correlated to the normal appendix, whereas nonspecific clusters correlated to the disordered appendix. In conclusion, species richness and evenness reduced in the disordered appendix and colon; similar microbiome patterns were shared between the appendix and colon regardless of dysbiosis; site-specific bacteria were missing in the disordered appendix. Appendix is likely a transit region involving in upper and lower intestinal microflora modulation. The limitation of this study is all the data were derived from rats. We must be cautious about translating the microbiome results from rats to humans.

Gut microbiota of Parkinson's disease in an appendectomy cohort: a preliminary study

In patients with Parkinson's disease (PD), α-synuclein pathology is thought to spread to the brain via the dorsal motor nucleus of the vagus nerve. The link between the gut microbiome and PD has been explored in various studies. The appendix might play an important role in immunity by maintaining the microbiota as a reservoir. In recent times, appendectomy has been linked to a lower risk of PD, possibly owing to the role of the appendix in altering the gut microbiome. We aimed to elucidate whether the gut microbiota affects PD development in the appendectomy cohort. We analyzed the fecal microbial composition in patients with PD and healthy controls with and without a history of appendectomy. The abundance of microbes from the family Enterobacteriaceae was higher in feces samples from patients with Parkinson's disease compared to that in samples collected from healthy controls. Furthermore, there was a significant phylogenetic difference between patients with PD and healthy controls who had undergone appendectomy. There was a significant phylogenetic difference between patients with PD and HCs who had undergone APP. These results suggest the correlation between gut microbiota and PD in patients who have undergone APP.

Acute appendicitis manifests as two microbiome state types with oral pathogens influencing severity

Mounting evidence suggests that acute appendicitis (AA) is not one but two diseases: complicated appendicitis, which is associated with necrosis leading to perforation or periappendicular abscess, and uncomplicated appendicitis, which does not necessarily result in perforation. Even though AA is the most frequent cause of surgery from abdominal pain, little is known about the origins and etiopathogenesis of this disease, much less regarding the different disease types. In this study, we investigated the microbiome (inter-domain amplicon and metagenome sequencing) of samples from the appendix, rectum and peritoneum of 60 children and adolescents with AA to assess the composition and potential function of bacteria, archaea and fungi. The analysis of the appendix microbial community revealed a shift depending on the severity of the AA. This shift was reflected by two major community state types that represented the complicated and uncomplicated cases. We could demonstrate that complicated, but not uncomplicated, appendicitis is associated with a significant local expansion of oral, bacterial pathogens in the appendix, most strongly influenced by necrotizing Fusobacterium spp., Porphyromonas and Parvimonas. Uncomplicated appendicitis, however, was characterized by gut-associated microbiomes. Our findings support the hypothesis that two disease types exist in AA, which cannot be distinguished beyond doubt using standard clinical characterization methods or by analysis of the patient's rectal microbiome. An advanced microbiome diagnosis, however, could improve non-surgical treatment of uncomplicated AA.

The vermiform cecal appendix, expendable or essential? A narrative review

PURPOSE OF REVIEW

The vermiform cecal appendix is a small thin pouch-like tube of intestinal tissue situated in the lower right abdomen. It is attached at the junction of the large intestine between the ascending colon and small intestine. Historically, the appendix has been labeled redundant with no significant function, a remnant of evolution. This idea was thought to represent a function that may have been critical for survival that became nonsignificant over time. Evolutionary biologists deemed it to be a vestigial organ that early in human evolution was a dedicated organ that was useful and exploited by herbivorous ancestors.

RECENT FINDINGS

Currently, the vermiform cecal appendix has generated significant renewed research interest. As such it has been reported to present a site with a high concentration of lymphoid tissue and a biofilm microbiome that approximately mirrors that which is found in the large bowel.

SUMMARY

Research suggests that the vermiform cecal appendix may be the site of a safe-house biofilm that could re-inoculate the large bowel. Given that the appendix has no known role in digestion, the network of lymphoid tissue and microbiome could constitute an initial site of bacterial translocations that can influence early life ontology and immunological tolerance. A dysbiotic microbiome in the appendix is posited to trigger inflammatory sequelae.

Appendiceal microbiome in uncomplicated and complicated acute appendicitis: A prospective cohort study

Background

Uncomplicated and complicated acute appendicitis seem to be two different forms of this common abdominal emergency. The contribution of appendiceal microbiota to appendicitis pathogenesis has been suggested, but differences between uncomplicated and complicated appendicitis are largely unknown. We compared the appendiceal microbiota in uncomplicated and complicated acute appendicitis.

Methods

This prospective single-center clinical cohort study was conducted as part of larger multicenter MAPPAC trial enrolling adult patients with computed tomography or clinically confirmed uncomplicated or complicated acute appendicitis. The microbial composition of the appendiceal lumen was determined using 16S rRNA gene amplicon sequencing.

Results

Between April 11, 2017, and March 29, 2019, 118 samples (41 uncomplicated and 77 complicated appendicitis) were available. After adjusting for age, sex, and BMI, alpha diversity in complicated appendicitis was higher (Shannon p = 0.011, Chao1 p = 0.006) compared to uncomplicated appendicitis. Microbial compositions were different between uncomplicated and complicated appendicitis (Bray-Curtis distance, P = 0.002). Species poor appendiceal microbiota composition with specific predominant bacteria was present in some patients regardless of appendicitis severity.

Conclusion

Uncomplicated and complicated acute appendicitis have different appendiceal microbiome profiles further supporting the disconnection between these two different forms of acute appendicitis.

Study registration

ClinicalTrials.gov NCT03257423.

Characteristics of appendicitis after immune checkpoint inhibitor therapy among cancer patients

PURPOSE

Immune checkpoint inhibitor (ICI) therapy has revolutionized cancer care but is associated with immune-related adverse events (irAEs). Recent case reports raised the concern that acute appendicitis may be an irAE. In this study, we sought to describe the disease course of post-ICI therapy appendicitis and its associated complications.

METHODS

Adult patients who had an International Classification of Diseases code for appendicitis within the first 2 years after initiating ICI therapy from January 2010 to April 2021 and who had imaging evidence of appendicitis were studied retrospectively.

RESULTS

13,991 patients were identified who had ICI exposure during the study period, 44 had codes for appendicitis, 10 of whom met the inclusion criteria. Their median age at the time of diagnosis was 59 years. The median time from ICI therapy initiation to appendicitis onset was 188 days. The most common presenting symptoms were abdominal pain (70%) and fever (40%). Abscesses were present in two patients, and a perforation was present in one. All 10 patients received broad-spectrum antibiotics. Five patients needed surgery or interventional radiology drainage. Nine patients had resolution of appendicitis symptoms after treatment.

CONCLUSION

Post-ICI therapy appendicitis is rare but presents similarly to and has similar complications rates as conventional appendicitis. Appendectomy remains the mainstay of treatment, but its use can be limited in cancer patients. The decision to continue ICI therapy remains at the discretion of the clinician. Further studies are needed to bring awareness to and advance the understanding of this clinical entity.

The microbiome in adult acute appendicitis

Acute appendicitis is a common acute surgical emergency; however, the pathogenesis of adult appendicitis remains poorly understood. The microbiome is increasingly thought to play a key role in inflammatory disease of the bowel and similarly, may play a role in appendicitis. This study aimed to characterise the microbiome of adult acute appendicitis in a prospective cohort. We recruited 60 adults with acute appendicitis and 20 healthy controls. Rectal swabs were taken from each patient. After DNA extraction, 16S rRNA amplicon sequencing was carried out for analysis of diversity and taxonomic abundance. Phylogenetic sequencing of the samples indicated that there is a difference between the microbial composition of those with acute appendicitis and healthy controls, with a statistically significant decrease in alpha diversity in rectal swabs of appendicitis patients compared to healthy controls. At the genus level, we saw an increased abundance of potential pathogens, for example, Parvimonas and Acinetobacter, and a decrease in commensal taxa such as Faecalibacterium, Blautia and Lachnospiraceae in appendicitis patients compared to healthy controls. There was a reduction in diversity and loss of commensals in the microbiome of those with acute appendicitis, which may play a role in the cascade leading to acute appendicitis or the result of this.

The Gut Microbiota and Inflammatory Factors in Pediatric Appendicitis

Background. The study analyzed gut microflora’s composition and investigated the associations between the associations between gut dysbiosis and inflammatory indicators in pediatric patients with acute appendicitis. Methods. High-throughput sequencing and bioinformatics analysis were used to investigate the composition and diversity of gut microflora in 20 pediatric patients with acute appendicitis and 11 healthy children. Endpoints measured were operational taxonomic units (OTU) of gut microflora. The OTU and its abundance analysis, sample diversity analysis, principal component analysis of samples, differential analysis, and analysis of biomarkers were performed. Results. Overall fecal microbial richness and diversity were similar in patients and controls. Yet richness within the group of Bilophila, Eggerthella, Clostridium, Parvimonas, Megasphaera, Atopobium, Phascolarctobacterium, Adlercreutzia, Barnesiella, Klebsiella, Enterococcus, and Prevotella genera was higher in patients. Adlercreutzia was significantly positively correlated with IL-10, while the three other genera, comprising Klebsiella, Adlercreutzia, and Prevotella, were positively correlated with B cells level. Conclusion. Gut microbiome components are significantly different in pediatric patients with acute appendicitis and healthy children. The differential abundance of some genera is correlated with the production of inflammatory markers in appendicitis.

The Periodontal Pathogen Fusobacterium nucleatum Exacerbates Alzheimer's Pathogenesis via Specific Pathways

Alzheimer's Disease (AD) is the most common form of dementia in older adults and has a devastating impact on the patient's quality of life, which creates a significant socio-economic burden for the affected individuals and their families. In recent years, studies have identified a relationship between periodontitis and AD. Periodontitis is an infectious/inflammatory disease that destroys the supporting periodontal structure leading to tooth loss. Dysbiosis of the oral microbiome plays a significant role in the onset and development of periodontitis exhibiting a shift to overgrowth of pathobionts in the normal microflora with increasing local inflammation. Fusobacterium nucleatum is a common pathogen that significantly overgrows in periodontitis and has also been linked to various systemic diseases. Earlier studies have reported that antibodies to F. nucleatum can be detected in the serum of patients with AD or cognitive impairment, but a causal relationship and a plausible mechanism linking the two diseases have not been identified. In this study, we conducted both in vivo and in vitro experiments and found that F. nucleatum activates microglial cells causing morphological changes, accelerated proliferation and enhanced expression of TNF-α and IL-1β in microglial cells. In our in vivo experiments, we found that F. nucleatum-induced periodontitis resulted in the exacerbation of Alzheimer's symptoms in 5XFAD mice including increased cognitive impairment, beta-amyloid accumulation and Tau protein phosphorylation in the mouse cerebrum. This study may suggest a possible link between a periodontal pathogen and AD and F. nucleatum could be a risk factor in the pathogenesis of AD. We are currently further identifying the pathways through which F. nucleatum modulates molecular elements in enhancing AD symptoms and signs. Data are available via ProteomeXchange with identifier PXD033147.

Association of Gut Microbiota and Biochemical Features in a Chinese Population With Renal Uric Acid Stone

Previous studies suggest that patients with nephrolithiasis exhibit dysbiosis in their gut microbiota, but those studies were conducted in calcium oxalate stone patients. We aimed to explore the association of gut microbiota and biochemical features of renal uric acid stone (UAS) patients in a Chinese population and identify the related bacteria that may affect the pathopoiesis of UAS. A case-control study of 117 patients with UAS, 123 patients with gout, and 135 healthy controls were included from January 2014 to October 2020. For each subject, data on demographics, biochemical parameters of blood and urine were analyzed. Fifteen patients with gout, 16 patients with UAS, 17 UAS patients with gout, and 17 healthy subjects were enrolled and provided fecal samples. The characteristics of gut microbiota were explored by using 16S ribosomal RNA (rRNA) gene sequencing and analyzed by using a combination of software mother and R. Hyperuricemia was the main risk factor for the development of gout and UAS. Obesity, dyslipidemia, and aciduria were unique risk factors for UAS patients. The richness, diversity, and relative abundance of dominant bacteria at the phylum and genus levels of gut microbiota in UAS patients were significantly distinct from other subjects. Abundance of Bacteroides and Fusobacterium was significantly positively correlated with the serum uric acid (UA) level of UAS patients. Fusobacteria was involved in the metabolism and degradation of certain short-chain fatty acids, amino acids, and sugars in pathopoiesis of UAS, and inhibited their synthesis pathways. Fusobacteria may be related to the pathogenesis of UAS, and this finding contributes to the personalized treatment of UAS from the perspective of maintaining micro-ecological equilibrium in gut.

Cluster of Acute Appendicitis Among High School Tibetan Students in Nanchang, China: Investigation, Control, and Prevention

Objective

Infectious etiology of acute appendicitis is a current hot topic. The most of study on appendicitis came from sporadic patients and focused on clinical treatment rather than control and prevention of appendicitis in the population. The present study aims to investigate the epidemiological features of cluster of acute appendicitis, risk factors, and evaluate effectiveness of control and prevention in population.

Methods

We conducted longitudinal study on a cluster of acute appendicitis among Tibetan students at a high school in eastern China, which was divided into three stages: 1. We retrospectively collected epidemiological data and clinical data to explore risk factor and possible transmission route in August of 2005; 2. We conducted targeted measures from August of 2005 and analyzed incidence trend from 2000 to 2010; 3. Since no new patients occurred in 2011, we conducted surveillance from the beginning of 2012 until July 2018.

Results

Among 973 Tibetan students, there were 120 patients with more female patients (102 of 499, 20.4%) than male patients (18 of 474, 3.8%) from January of 2000 to December of 2010. The 4-year cumulative incidence rates in female students enrolled in 2001, 2002, 2003, 2004, 2005, 2006 were 26.8% (11 of 41), 27.1% (13 of 48), 44.7% (21 of 47), 42.4% (14 of 33), 23.1% (9 of 39), and 19.3% (11 of 57), respectively before their graduation. There was a clustering feature. Mutual contact with patients before the onset of symptoms was an important risk factor (Adjusted OR 4.89, 95% CI: 1.67–14.35). Transmission route may be fecal-oral infection. Before conducting targeted measures, the incidence rate increased from 2000 and peaked in 2005. After conducting targeted measures, the incidence rate decreased year by year until 2010. Under surveillance from January of 2012 to July of 2018, only four sporadic patients occurred at this school.

Conclusion

This cluster of acute appendicitis had features of an infectious disease in epidemiology, which can be controlled and prevented by targeted measures. Our study may also be used for prevention of sporadic patients and be generalized in general population as cluster of appendicitis occurred in many provinces of China.

The appendix‐mucosal immunity and tolerance in the gut: consequences for the syndromes of appendicitis and its epidemiology

The cause of appendicitis is unknown. A review is presented across diverse sources relating to the biology of the appendix and its perturbations. A mechanistic model of the function of the appendix is presented, and its application to the syndromes and consequences of appendicitis is described.

Larger Physique as a Risk Factor for Infantile Appendicitis: A Retrospective Study

The clinical features and risk factors of acute appendicitis in infants are unclear. Our aim was to evaluate the association between anthropometrics and the occurrence of infantile appendicitis. This was a retrospective study of infants (<6 years of age) and school-age children (6-10 years of age) of Asian ethnicity who required hospitalization for appendicitis at our two participating institutions between 2004 and 2018. The Z-score for height, body weight, and body mass index (BMI) was compared between the two groups, as well as between patients presenting with perforated and non-perforated appendicitis. The analysis included data from 73 infants and 362 school-age children. Z-scores were greater in infants than in school-age children for height (0.37 versus -0.03, p = 0.003) and body weight (0.12 versus -0.36, p = 0.023), with no between-group difference for the Z-score of BMI. There was no difference in Z-scores for height, weight, and BMI between the perforated and non-perforated appendicitis infant groups. Infants presenting with acute appendicitis were characterized by a larger physique but with normal proportion. This trend was not observed in school-age children. Therefore, larger infants presenting with abdominal pain should be screened for appendicitis.

Structural and biochemical analyses of the tetrameric carboxypeptidase S9Cfn from Fusobacterium nucleatum

As one of the most abundant bacteria in the human oral cavity, Fusobacterium nucleatum is closely involved in various oral diseases and is also a risk factor for other diseases. The peptidases of F. nucleatum can digest exogenous peptides into amino acids to satisfy its nutrient requirements. Here, a putative F. nucleatum peptidase, termed S9Cfn, which belongs to the S9C peptidase family was identified. Enzymatic activity assays combined with mass-spectrometric analysis revealed that S9Cfn is a carboxypeptidase, but not an aminopeptidase as previously annotated. The crystal structure of the S9Cfn tetramer was solved at 2.6 Å resolution and was found to contain a pair of oligomeric pores in the center. Structural analysis, together with site-directed mutagenesis and enzymatic activity assays, revealed a substrate-entrance tunnel that extends from each oligomeric pore to the catalytic triad, adjacent to which three conserved arginine residues are responsible for substrate binding. Moreover, comparison with other S9 peptidase structures indicated drastic conformational changes of the oligomeric pores during the catalytic cycle. Together, these findings increase the knowledge of this unique type of tetrameric carboxypeptidase and provide insight into the homeostatic control of microbiota in the human oral cavity.

Optimal First-Line Antibiotic Treatment for Pediatric Complicated Appendicitis Based on Peritoneal Fluid Culture

PURPOSE

Consensus is lacking regarding the optimal antibiotic treatment for pediatric complicated appendicitis. This study determined the optimal first-line antibiotic treatment for pediatric patients with complicated appendicitis based on peritoneal fluid cultures.

METHODS

This retrospective study examined the cases of pediatric patients who underwent appendectomy for complicated appendicitis at our institution between 2013 and 2019. Peritoneal fluid specimens obtained during appendectomy were cultured for the presence of bacteria.

RESULTS

Eighty-six pediatric patients were diagnosed with complicated appendicitis. Of them, bacteria were identified in 54 peritoneal fluid samples. The major identified bacteria were Escherichia coli (n=36 [66.7%]), Bacteroides fragilis (n=28 [51.9%]), α-Streptococcus (n=25 [46.3%]), Pseudomonas aeruginosa (n=10 [18.5%]), Enterococcus avium (n=9 [16.7%]), γ-Streptococcus (n=9 [16.7%]), and Klebsiella oxytoca (n=6 [11.1%]). An antibiotic susceptibility analysis showed E. coli was inhibited by sulbactam/ampicillin in 43.8% of cases versus cefmetazole in 100% of cases. Tazobactam/piperacillin and meropenem inhibited the growth of 96.9-100% of the major identified bacteria. E. coli (100% vs. 84.6%) and P. aeruginosa (100% vs. 80.0%) were more susceptible to amikacin than gentamicin.

CONCLUSION

Tazobactam/piperacillin or meropenem is a reasonable first-line antibiotic treatment for pediatric complicated appendicitis. In the case of aminoglycoside use, amikacin is recommended.

Appendectomy Is Associated With Alteration of Human Gut Bacterial and Fungal Communities

Recent research has revealed the importance of the appendix in regulating the intestinal microbiota and mucosal immunity. However, the changes that occur in human gut microbial communities after appendectomy have never been analyzed. We assessed the alterations in gut bacterial and fungal populations associated with a history of appendectomy. In this cross-sectional study, we investigated the association between appendectomy and the gut microbiome using 16S and ITS2 sequencing on fecal samples from 30 healthy individuals with prior appendectomy (HwA) and 30 healthy individuals without appendectomy (HwoA). Analysis showed that the gut bacterial composition of samples from HwA was less diverse than that of samples from HwoA and had a lower abundance of Roseburia, Barnesiella, Butyricicoccus, Odoribacter, and Butyricimonas species, most of which were short-chain fatty acids-producing microbes. The HwA subgroup analysis indicated a trend toward restoration of the HwoA bacterial microbiome over time after appendectomy. HwA had higher gut fungi composition and diversity than HwoA, even 5 years after appendectomy. Compared with those in samples from HwoA, the abundance correlation networks in samples from HwA displayed more complex fungal–fungal and fungal–bacterial community interactions. This study revealed a marked impact of appendectomy on gut bacteria and fungi, which was particularly durable for fungi.

Microbial Epidemiology of Acute and Perforated Appendicitis: A Post-Hoc Analysis of an EAST Multicenter Study

BACKGROUND

There are significant practice variations in antibiotic treatment for appendicitis, ranging from short-course narrow spectrum to long-course broad-spectrum. We sought to describe the modern microbial epidemiology of acute and perforated appendicitis in adults to help inform appropriate empiric coverage and support antibiotic stewardship initiatives.

METHODS

This is a post-hoc secondary analysis of the Multicenter Study of the Treatment of Appendicitis in America: Acute, Perforated, and Gangrenous (MUSTANG) which prospectively enrolled adult patients (age ≥ 18 years) diagnosed with appendicitis between January 2017 and June 2018 across 28 centers in the United States. We included all subjects with positive microbiologic cultures during primary or secondary (rescue after medical failure) appendectomy or percutaneous drainage. Culture yield was compared between low- and high-grade appendicitis as per the AAST classification.

RESULTS

A total of 3,471 patients were included: 230 (7%) had cultures performed, and 179/230 (78%) had positive results. Cultures were less likely to be positive in grade 1 compared to grades 3, 4, or 5 appendicitis with 2/18 (11%) vs 61/70 (87%) (p < .001). Only 1 subject had grade 2 appendicitis and culture results were negative. E. coli was the most common pathogen and cultured in 29 (46%) of primary appendectomy samples, 16 (50%) of secondary, and 44 (52%) of percutaneous drainage samples.

CONCLUSION

Culturing low-grade appendicitis is low yield. E. coli is the most commonly cultured microbe in acute and perforated appendicitis. This data helps inform empiric coverage for both antibiotics alone and as an adjunct to operative or percutaneous intervention.

Porphyromonas gingivalis outside the oral cavity

Porphyromonas gingivalis, a Gram-negative anaerobic bacillus present in periodontal disease, is considered one of the major pathogens in periodontitis. A literature search for English original studies, case series and review articles published up to December 2019 was performed using the MEDLINE, PubMed and GoogleScholar databases, with the search terms "Porphyromonas gingivalis" AND the potentially associated condition or systemic disease Abstracts and full text articles were used to make a review of published research literature on P. gingivalis outside the oral cavity. The main points of interest of this narrative review were: (i) a potential direct action of the bacterium and not the systemic effects of the inflammatory acute-phase response induced by the periodontitis, (ii) the presence of the bacterium (viable or not) in the organ, or (iii) the presence of its virulence factors. Virulence factors (gingipains, capsule, fimbriae, hemagglutinins, lipopolysaccharide, hemolysin, iron uptake transporters, toxic outer membrane blebs/vesicles, and DNA) associated with P. gingivalis can deregulate certain functions in humans, particularly host immune systems, and cause various local and systemic pathologies. The most recent studies linking P. gingivalis to systemic diseases were discussed, remembering particularly the molecular mechanisms involved in different infections, including cerebral, cardiovascular, pulmonary, bone, digestive and peri-natal infections. Recent involvement of P. gingivalis in neurological diseases has been demonstrated. P. gingivalis modulates cellular homeostasis and increases markers of inflammation. It is also a factor in the oxidative stress involved in beta-amyloid production.

Association Between NEDD4L Variation and the Genetic Risk of Acute Appendicitis: A Multi-institutional Genome-Wide Association Study

Importance

The familial aspect of acute appendicitis (AA) has been proposed, but its hereditary basis remains undetermined.

Objective

To identify genomic variants associated with AA.

Design, Setting, and Participants

This genome-wide association study, conducted from June 21, 2019, to February 4, 2020, used a multi-institutional biobank to retrospectively identify patients with AA across 8 single-nucleotide variation (SNV) genotyping batches. The study also examined differential gene expression in appendiceal tissue samples between patients with AA and controls using the GSE9579 data set in the National Institutes of Health's Gene Expression Omnibus repository. Statistical analysis was conducted from October 1, 2019, to February 4, 2020.

Main Outcomes and Measures

Single-nucleotide variations with a minor allele frequency of 5% or higher were tested for association with AA using a linear mixed model. The significance threshold was set at P = 5 × 10-8.

Results

A total of 29 706 patients (15 088 women [50.8%]; mean [SD] age at enrollment, 60.1 [17.0] years) were included, 1743 of whom had a history of AA. The genomic inflation factor for the cohort was 1.003. A previously unknown SNV at chromosome 18q was found to be associated with AA (rs9953918: odds ratio, 0.99; 95% CI, 0.98-1.00; P = 4.48 × 10-8). This SNV is located in an intron of the NEDD4L gene. The heritability of appendicitis was estimated at 30.1%. Gene expression data from appendiceal tissue donors identified NEDD4L to be among the most differentially expressed genes (14 of 22 216 genes; β [SE] = -2.71 [0.44]; log fold change = -1.69; adjusted P = .04).

Conclusions and Relevance

This study identified SNVs within the NEDD4L gene as being associated with AA. Nedd4l is involved in the ubiquitination of intestinal ion channels and decreased Nedd4l activity may be implicated in the pathogenesis of AA. These findings can improve the understanding of the genetic predisposition to and pathogenesis of AA.

Acute appendicitis is associated with appendiceal microbiome changes including elevated Campylobacter jejuni levels

OBJECTIVES

To compare the appendiceal microbiomes and examine the prevalence of Campylobacter species in the appendices of adult subjects with confirmed acute non-perforated appendicitis and controls with healthy appendices.

DESIGN

Archived samples of formalin-fixed paraffin-embedded appendiceal tissues were obtained from 50 consecutive female subjects who underwent appendectomy for acute, non-perforated appendicitis, and 35 consecutive female controls who underwent incidental appendectomy during gynaecological surgery.

RESULTS

16S rRNA gene sequencing revealed that the relative abundances (RAs) of the major phyla in appendiceal tissues (Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria) were similar in both groups. Beta diversity was significantly different due to differences in Bacteroidetes and Proteobacteria (p<0.0001). Within Proteobacteria, RAs of classes Alphaproteobacteria (~21%, fold change (FC)=1.31, false discovery rate (FDR) p value=0.03) and Epsilonproteobacteria (~1%, FC=0.25, FDR p value>0.05) were increased in acute appendicitis samples. RAs of unknown genera from families Burkholderiaceae and Enterobacteriaceae were decreased in appendicitis samples, and 14 genera were increased, including Neisseria, Acinetobacter and Campylobacter. Quantitative PCR revealed that levels of Campylobacter jejuni DNA, but not other Campylobacter species or pathogens tested, were significantly higher in appendicitis samples than in controls (p=0.013). Using a cut-off of 0.31 pg/µL, 40% of appendicitis cases and 6% of controls were positive for C. jejuni, indicating specificity of 93.7% (95% Cl 79.2 to 99.2), sensitivity of 40.9% (95% Cl 24.7 to 54.5), and OR of 10.38 (Fisher's p value=0.0006, 95% Cl 2.3 to 47.4).

CONCLUSIONS

Our findings indicate that Campylobacter jejuni may be a significant cause of acute appendicitis. This supports earlier studies and suggests that targeted antibiotic therapies could be an alternative treatment for a subset of non-complicated acute appendicitis cases.

Determination of the Role of Fusobacterium Nucleatum in the Pathogenesis in and Out the Mouth

INTRODUCTION

One of the most important types of microorganisms in the oral cavity in both healthy and non-healthy individuals is Fusobacterium nucleatum. Although present as a normal resident in the oral cavity, this Gram-negative pathogen is dominant in periodontal disease and it is involved in many invasive infections in the population, acute and chronic inflammatory conditions, as well as many adverse events with a fatal outcome.

AIM

To determine the role of F. nucleatum in the development of polymicrobial biofilms thus pathogenic changes in and out of the oral media.

MATERIAL AND METHOD

A systematic review of the literature concerning the determination and role of F. nucleatum through available clinical trials, literature reviews, original research and articles published electronically at Pub Med and Google Scholar.

CONCLUSION

The presence of Fusobacterium nucleatum is commonly associated with the health status of individuals. These anaerobic bacteria plays a key role in oral pathological conditions and has been detected in many systemic disorders causing complex pathogenethic changes probably due to binding ability to various cells thus several virulence mechanisms. Most common diseases and conditions in the oral cavity associated with F.nucleatum are gingivitis (G), chronic periodontitis (CH), aggressive periodontitis (AgP), endo-periodental infections (E-P), chronic apical periodontitis (PCHA). The bacterium has been identified and detected in many systemic disorders such as coronary heart disease (CVD) pathological pregnancy (P); polycystic ovary syndrome (PCOS), high-risk pregnancy (HRP), colorectal cancer (CRC); pre-eclampsia (PE); rheumatoid arthritis (RA); osteoarthritis (OA).

Impact of Appendectomy on Gut Microbiota

Background: Considered vestigial from the classic point of view, the vermiform appendix has long been the subject of intensive studies. The recent understanding of appendix function in the context of unique architecture and bacterial complexity and density allows considering it as a safehouse for intestinal biodiversity. Methods: This review analyzes and assesses the current state of scientific knowledge regarding the role of the vermiform appendix in normal gut microbiota maintenance as a crucial factor of host homeostasis. It also highlights the difference in microbial composition between the large bowel and the appendix, as well as the association between the surgical excision, appendectomy, and dysbiosis-induced diseases. In addition, the review discusses the results of epidemiologic studies on appendectomy as a risk factor for the initiation of gastrointestinal carcinogenesis. It also highlights the association between appendectomy and a series of chronic inflammatory and neurologic disorders, including inflammatory bowel disease.

Antibiotics during childhood and development of appendicitis-a nationwide cohort study

BACKGROUND

Appendicitis is a common disease with a lifespan risk of approximately 8%. The full range of specific causes for the disease remains elusive, but an aberrant microbiota have been identified as a potential risk factor.

AIM

To investigate if use of antibiotics in a paediatric population increases the risk of appendicitis in childhood and adolescence METHODS: We conducted a cohort study from 1 January 1995 to 31 December 2014. A total of 1 385 707 children (0-19 years of age) including 7 406 397 antibiotic prescriptions and 11 861 cases of appendicitis were included. Primary outcome was appendicitis requiring appendectomy according to previous use of antibiotics. Appendicitis and appendectomy were identified from nationwide hospital records, and exposure to antibiotics was identified from nationwide prescription register. Rate ratios (RRs) with 95% confidence intervals were estimated from Poisson and logistic regression models.

RESULTS

Children who received at least one course of antibiotics were at increased risk of developing appendicitis compared to unexposed children (adjusted RR 1.72 [95% confidence interval 1.61-1.85]), mean age of developing appendicitis was 9.8 years (SD 4.1 years). The RR of appendicitis increased by 1.04 (1.04-1.04) per antibiotic course. A higher risk of appendicitis was observed in children exposed to antibiotics within the first 6 months of life (RR 1.46 [1.36-1.56]) and children exposed to broad-spectrum antibiotics (RR 1.33 [1.27-1.39]). After adjustment for number of antibiotic courses, the association between early age of antibiotic exposure and risk of appendicitis and the association between exposure to broad-spectrum antibiotics and the risk of appendicitis both disappeared.

CONCLUSION

Children who receive antibiotics are at increased and dose-dependent risk of appendicitis. The underlying mechanisms merit further investigation.

Contrasting gut microbiota in captive Eurasian otters (Lutra lutra) by age

Understanding the gut microbiota characteristics of endangered species such as the Eurasian otter (Lutra lutra), especially in their early stages of life, could be essential for improving their management and ex situ conservation strategies. Here, we analyzed the gut microbiota diversity, composition, and function of captive Eurasian otters at different ages using high-throughput 16S rRNA gene sequencing. We found that: (1) Clostridiaceae was abundant in all age stages; (2) Lactococcus in cubs is thought to predominate for digesting milk; (3) bacteria associated with amino acid metabolism increase with age, while bacteria associated with carbohydrate metabolism decrease with age, which is likely due to decrease in dietary carbohydrate content (e.g., milk) and increase in dietary protein contents (e.g., fishes) with age; and (4) fish-related bacteria were detected in feces of healthy adults and juveniles. Overall, the gut microbiota of captive Eurasian otters was taxonomically and functionally different by age, which is thought to be attributed to the difference in the diet in their life stages. This study provided baseline information regarding the gut microbiota of Eurasian otters for the first time and contributes to improvement in their management in captivity.

Could Periodontal Disease through Periopathogen Fusobacterium Nucleatum be an Aggravating Factor for Gastric Cancer?

Periodontal disease affects the supporting tissues of the teeth, being a chronic inflammatory disease caused by specific microorganisms from subgingival biofilm. Fusobacterium nucleatum is a Gram-negative anaerobic bacterium that acts as a periodontal pathogen, being an important factor in linking Gram-positive and Gram-negative bacteria in the periodontal biofilm, but its involvement in systemic diseases has also been found. Several studies regarding the implication of Fusobacterium nucleatum in gastro-enterological cancers have been conducted. The present review aims to update and systematize the latest information about Fusobacterium nucleatum in order to evaluate the possibility of an association between periodontal disease and the evolution of gastroenterological cancers through the action of Fusobacterium nucleatum, highlighting gastric cancer. This would motivate future research on the negative influence of periodontal pathology on the evolution of gastric cancer in patients suffering from both pathologies.

Association between Appendectomy and Demyelinating Disorders in Subjects 40 Years and Older

Background

The association between appendectomy and multiple sclerosis (MS) is unknown. In this study, we explored the association between appendectomy and MS and neuromyelitis optica spectrum disorder (NMOSD).

Patients and Methods

MS and NMOSD patients older than 40 were identified from neurology records from hospitals in Malaysia. The diagnoses were based on the Revised McDonald (2010) and Wingerchuk (2015) criteria. Controls were sampled from Malaysia's normal population. Individuals were interviewed telephonically or face-to-face. The age inclusion criterion (over 40) differentiated high or low lifetime risk of appendicitis, as appendicitis incidence is rare after 40.

Results

49 MS, 71 NMOSD, and 880 controls met the inclusion criteria. Seventy-two individuals (9 MS, 4 NMOSD, 59 control) had undergone appendectomy. Appendectomy rates were 18.37% in the MS group (95% CI 7.5-29.2%), 5.6% in the NMOSD group (0.3%, 11%), and 6.7% among controls (5.1%, 8.4%), (MS vs NMOSD P = 0.036, MS vs controls P = 0.007). Binary regression analysis showed that MS was an independent risk factor for appendectomy (OR 2.938, 95% CI 1.302, 6.633, P = 0.009). NMOSD showed no association with appendectomy.

Conclusion

MS is positively associated with appendectomy, unlike ulcerative colitis, which is negatively associated. We hypothesize that there is a commonality in the microflora in persons who have had these two illnesses.

A clinical prediction model for complicated appendicitis in children younger than five years of age

Background

No reliably specific method for complicated appendicitis has been identified in children younger than five years of age. This study aimed to analyze the independent factors for complicated appendicitis in children younger than five years of age, develop and validate a prediction model for the differentiation of simple and complicated appendicitis.

Methods

A retrospective study of 382 children younger than five years of age with acute appendicitis from January 2007 to December 2016 was conducted with assessments of demographic data, clinical symptoms and signs, and pre-operative laboratory results. According to intraoperative findings and postoperative pathological results, acute appendicitis was divided into simple and complicated appendicitis. Univariate and multivariate analyses were used to screen out the independent factors of complicated appendicitis, and develop a prediction model for complicated appendicitis. Then 156 such patients from January 2017 to December 2019 were collected as validation sample to validate the prediction model. Test performance of the prediction model was compared with the ALVARADO score and Pediatric Appendicitis Score (PAS).

Results

Of the 382 patients, 244 (63.9%) had complicated appendicitis. Age, white blood cell count, and duration of symptoms were the independent factors for complicated appendicitis in children younger than five years of age. The final predication model for complicated appendicitis included factors above. In validation sample, the prediction model exhibited a high degree of discrimination (area under the curve [AUC]: 0.830; 95% confidence interval [CI]: 0.762–0.885) corresponding to a optimal cutoff value of 0.62, and outperformed the PAS (AUC: 0.735; 95% CI: 0.658–0.802), ALVARADO score (AUC: 0.733; 95% CI: 0.657–0.801).

Conclusion

Age, white blood cell count, and duration of symptoms could be used to predict complicated appendicitis in children younger than five years of age with acute appendicitis. The prediction model is a novel but promising method that aids in the differentiation of acute simple and complicated appendicitis.

Impact of host intraspecies genetic variation, diet, and age on bacterial and fungal intestinal microbiota in tigers

The bacterial microbiota in the gut varies among species, as well as with habitat, diet, age, and other factors. Intestinal microbiota homeostasis allows a host to adjust metabolic and immune performances in response to environmental changes. Therefore, potential implications of the gut microbiota in sustaining the health of the host have gained increasing attention in the field of endangered animal conservation. However, the effect of host intraspecies genetic variation on the gut microbiota is unknown. Moreover, little is known about the complexity of the gut mycobiota. Tigers are listed as endangered species, raising worldwide concern. Potential influences of subspecies, diet, and age on the gut microbiota in tigers were investigated in this study to provide a better understanding of the response of the tiger gut microbiota to external changes. The results revealed that the impacts of the factors listed above on gut bacterial and fungal communities are versatile. Host intraspecies genetic variation significantly impacted only fungal alpha diversity of the gut microbiota. Differences in diet, on the other hand, had a significant impact on alpha diversity of the gut microbiota, but exerted different effects on beta diversity of gut bacterial and fungal communities. Host age had no significant impact on the diversity of the gut fungal communities, but significantly impacted beta diversity of gut bacterial communities. This comprehensive study of tiger gut microbiota is an essential reference for tiger conservation when considering feeding and management strategies, and will contribute to a better understanding of the mycobiota in wildlife.

The neglected role of Enterobius vermicularis in appendicitis: A systematic review and meta-analysis

Although the main cause of appendicitis is unclear, infection with Enterobius vermicularis is suggested as a neglected risk factor. Since, there is no comprehensive analysis to estimate the prevalence of E. vermicularis in appendicitis; therefore, we conducted a global-scale systematic review and meta-analysis study to estimate the prevalence of E. vermicularis infection in appendicitis cases. PubMed, Scopus, Web of Science and Google Scholar databases were systematically searched for relevant studies published until 15 August 2019. Pooled prevalence of E. vermicularis infection was estimated using the random effects model. Data were classified based on the continents and countries. Moreover, subgroup analyses regarding the gender, the human development index (HDI), and income level of countries were also performed. Fifty-nine studies involving 103195 appendix tissue samples belonging to the individuals of appendicitis were included. The pooled prevalence of E. vermicularis infection was (4%, 95%CI, 2–6%), with the highest prevalence (8%, 95% CI: 0–36%) and lowest prevalence (2%, 95% CI: 1–4%) in Africa and Americas continents, respectively. With respect to countries, the lowest and highest prevalence rates were reported from Venezuela (<1%, 95% CI: 0–1%) and Nigeria (33%, 95% CI: 17–52%), respectively. Indeed, a higher prevalence was observed in females, as well as in countries with lower levels of income and HDI. Our findings indicate the relatively high burden of E. vermicularis infection in appendicitis cases. However, our findings suggest the great need for more epidemiological studies to depth understand overlaps between E. vermicularis infection and appendicitis in countries with lower HDI and income levels.

Microbiota of Children With Complex Appendicitis: Different Composition and Diversity of The Microbiota in Children With Complex Compared With Simple Appendicitis

BACKGROUND

Two types of appendicitis are hypothesized, simple and complex, with potential different treatment strategies. To improve differentiation, underlying pathogeneses need to be further unraveled.

AIM

To determine if the microbial composition in the appendix differs between children with simple and complex appendicitis.

METHODS

Two-center, prospective cohort study including 40 children (0-17 years old) undergoing appendectomy for suspected appendicitis. Appendix tissue was used for IS-pro analysis to identify bacterial species by their length of 16S-23S rDNA interspacer (IS) region. Cluster analysis, based on IS-profiles, and correspondence with type of appendicitis, using Fisher exact test, was performed. Simple and complex appendicitis were compared regarding bacterial presence, intensity and diversity, using Fisher exact test and Mann-Whitney U test, respectively.

RESULTS

Appendicitis was confirmed in 36 of 40 patients (16 simple, 20 complex). Cluster analysis identified 2 clusters, encompassing 34 patients. Distribution of simple and complex appendicitis was 12 (80%) and 3 (20%) versus 3 (16%) and 16 (84%) patients for clusters 1 and 2, respectively (P < 0.001). Complex appendicitis was on phylum level characterized by an increased intensity (Bacteroidetes P = 0.001, Firmicutes, Actinobacteria, Fusobacteria and Verrucomicrobia (FAFV) P = 0.005 and Proteobacteria P < 0.001) and diversity (Bacteroidetes P = 0.001 and Proteobacteria P = 0.016) and an increased abundance of 5 species (Alistipes finegoldii P = 0.009, Bacteroides fragilis P = 0.002, Escherichia coli P = 0.014, Parvimonas micra P = 0.022 and Sutterella spp P = 0.026).

CONCLUSIONS

The microbial composition of the appendix differs between children with simple and complex appendicitis, regarding both composition and diversity. Future research should focus on the role of these bacteria in the pathogenesis of both types and its implications for preoperative diagnostics.

The role of Fusobacterium nucleatum in colorectal cancer: from carcinogenesis to clinical management

Colorectal cancer (CRC) is a common malignant tumor that affects people worldwide. Metagenomic analyses have shown an enrichment of Fusobacterium nucleatum (F. nucleatum) in colorectal carcinoma tissue; many studies have indicated that F. nucleatum is closely related to the colorectal carcinogenesis. In this review, we provide the latest information to reveal the related molecular mechanisms. The known virulence factors of F. nucleatum promote adhesion to intestinal epithelial cells via FadA and Fap2. Besides, Fap2 also binds to immune cells causing immunosuppression. Furthermore, F. nucleatum recruits tumor-infiltrating immune cells, thus yielding a pro-inflammatory microenvironment, which promotes colorectal neoplasia progression. F. nucleatum was also found to potentiate CRC development through toll-like receptor 2 (TLR2)/toll-like receptor 4 (TLR4) signaling and microRNA (miRNA)-21 expression. In addition, F. nucleatum increases CRC recurrence along with chemoresistance by mediating a molecular network of miRNA-18a*, miRNA-4802, and autophagy components. Moreover, viable F. nucleatum was detected in mouse xenografts of human primary colorectal adenocarcinomas through successive passages. These findings indicated that an increased number of F. nucleatum in the tissues is a biomarker for the diagnosis and prognosis of CRC, and the underlying molecular mechanism can probably provide a potential intervention treatment strategy for patients with F. nucleatum-associated CRC.

Prospective multicentre cohort trial on acute appendicitis and microbiota, aetiology and effects of antimicrobial treatment: study protocol for the MAPPAC (Microbiology APPendicitis ACuta) trial

INTRODUCTION

Based on the epidemiological and clinical data, acute appendicitis can present either as uncomplicated or complicated. The aetiology of these different appendicitis forms remains unknown. Antibiotic therapy has been shown to be safe, efficient and cost-effective for CT-confirmed uncomplicated acute appendicitis. Despite appendicitis being one of the most common surgical emergencies, there are very few reports on appendicitis aetiology and pathophysiology focusing on the differences between uncomplicated and complicated appendicitis. Microbiology APPendicitis ACuta (MAPPAC) trial aims to evaluate these microbiological and immunological aspects including immune response in the aetiology of these different forms also assessing both antibiotics non-responders and appendicitis recurrence. In addition, MAPPAC aims to determine antibiotic and placebo effects on gut microbiota composition and antimicrobial resistance.

METHODS AND ANALYSIS

MAPPAC is a prospective clinical trial with both single-centre and multicentre arm conducted in close synergy with concurrent trials APPendicitis ACuta II (APPAC II) (per oral (p.o.) vs intravenous+p.o. antibiotics, NCT03236961) and APPAC III (double-blind trial placebo vs antibiotics, NCT03234296) randomised clinical trials. Based on the enrolment for these trials, patients with CT-confirmed uncomplicated acute appendicitis are recruited also to the MAPPAC study. In addition to these conservatively treated randomised patients with uncomplicated acute appendicitis, MAPPAC will recruit patients with uncomplicated and complicated appendicitis undergoing appendectomy. Rectal and appendiceal swabs, appendicolith, faecal and serum samples, appendiceal biopsies and clinical data are collected during the hospital stay for microbiological and immunological analyses in both study arms with the longitudinal study arm collecting faecal samples also during follow-up up to 12 months after appendicitis treatment.

ETHICS AND DISSEMINATION

This study has been approved by the Ethics Committee of the Hospital District of Southwest Finland (Turku University Hospital, approval number ATMK:142/1800/2016) and the Finnish Medicines Agency. Results of the trial will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03257423.

Diversity and composition of intertidal gastropod microbiomes across a major marine biogeographic boundary

Marine biogeographic boundaries act as barriers to dispersal for many animal species, thereby creating distinctive faunas on either side. However, how such boundaries affect the distributions of microbial taxa remains poorly known. To test whether biogeographic boundaries influence the diversity and composition of host-associated microbiota, we analysed the microbiomes of three species of common intertidal gastropods at two sites separated by the biogeographic boundary at Point Conception (PtC), CA, using 16S rRNA gene sequencing. Our results show that each host species shows microbiome compositional specificity, even across PtC, and that alpha diversity does not change significantly across this boundary for any of the gastropod hosts. However, for two of the host species, beta diversity differs significantly across PtC, indicating that there may be multiple levels of organization of the marine gastropod microbiome. Overall, our results suggest that while biogeographic boundaries do not constrain the distribution of a core set of microbes associated with each host species, they can play a role in structuring the transient portion of the microbiome.

Dietary Factors in Sulfur Metabolism and Pathogenesis of Ulcerative Colitis

The biogeography of inflammation in ulcerative colitis (UC) suggests a proximal to distal concentration gradient of a toxin. Hydrogen sulfide (H₂S) has long been considered one such toxin candidate, and dietary sulfur along with the abundance of sulfate reducing bacteria (SRB) were considered the primary determinants of H₂S production and clinical course of UC. The metabolic milieu in the lumen of the colon, however, is the result of a multitude of factors beyond dietary sulfur intake and SRB abundance. Here we present an updated formulation of the H₂S toxin hypothesis for UC pathogenesis, which strives to incorporate the interdependency of diet composition and the metabolic activity of the entire colon microbial community. Specifically, we suggest that the increasing severity of inflammation along the proximal-to-distal axis in UC is due to the dilution of beneficial factors, concentration of toxic factors, and changing detoxification capacity of the host, all of which are intimately linked to the nutrient flow from the diet.

Early gut microbiota signature of aGvHD in children given allogeneic hematopoietic cell transplantation for hematological disorders

BACKGROUND

The onset of acute Graft-versus-Host Disease (aGvHD) has been correlated with the gut microbiota (GM) composition, but experimental observations are still few, mainly involving cohorts of adult patients. In the current scenario where fecal microbiota transplantation has been used as a pioneer therapeutic approach to treat steroid-refractory aGvHD, there is an urgent need to expand existing observational studies of the GM dynamics in Hematopoietic Stem Cell Transplantation (HSCT). Aim of the present study is to explore the GM trajectory in 36 pediatric HSCT recipients in relation to aGvHD onset.

METHODS

Thirty-six pediatric patients, from four transplantation centers, undergoing HSCT were enrolled in the study. Stools were collected at three time points: before HSCT, at time of engraftment and > 30 days following HSCT. Changes in the GM phylogenetic structure were studied by 16S rRNA gene Illumina sequencing and phylogenetic assignation.

RESULTS

Children developing gut aGvHD had a dysbiotic GM layout before HSCT occurred. This putative aGvHD-predisposing ecosystem state was characterized by (i) reduced diversity, (ii) lower Blautia content, (iii) increase in Fusobacterium abundance. At time of engraftment, the GM structure underwent a deep rearrangement in all patients but, regardless of the occurrence of aGvHD and its treatment, it reacquired a eubiotic configuration from day 30.

CONCLUSIONS

We found a specific GM signature before HSCT predictive of subsequent gut aGvHD occurrence. Our data may open the way to a GM-based stratification of the risk of developing aGvHD in children undergoing HSCT, potentially useful also to identify patients benefiting from prophylactic fecal transplantation.

Gut microbiota in children and altered profiles in juvenile idiopathic arthritis

Microbial diversity plays a key role in the maintenance of intestinal homeostasis and in the development of the immune system in the gut mucosa. Maybe one of the most important function of our gut microbiota is the immune system education, in particular the discrimination of friends from foes that occurs during childhood. In addition to bacterial antigens, several metabolites of microbial origin have a crucial role in training of the immune system, such as Short Chain Fatty Acids (SCFAs). There are many evidences on the role of the gut microbiota in rheumatic diseases, in particular modifications of microbiota composition causing dysbiosis that, in turn, can induce gut permeability, and thus immunological imbalance and trigger inflammation. In particular, immune cells can reach extra-intestinal sites, such as joints and trigger local inflammation. Childhood is a crucial period of life for development and evolution of the gut microbiota, especially for the acquisition of fundamental functions such as immunotolerance of commensal microorganisms. For this reason, gut dysbiosis is gaining interest as a potential pathogenetic factor for Juvenile Idiopathic Arthritis (JIA). Here we summarized the studies conducted on JIA patients in which a pro-arthritogenic microbial profiles has been observed; this, together with a depletion of microbial biodiversity, clearly distinguish patients' from healthy subjects' microbiota. Further studies are however needed to better clarify the role of microbiota in JIA pathogenesis.

The vermiform appendix: an immunological organ sustaining a microbiome inoculum

The hominoid vermiform appendix has been characterized as a diverticulum of the caecum and describes an entity at the juxtaposition of the colon in the confluence of tanias. The independent development of the lymphoid follicle centres of the appendix is progressed at birth in the presence of the intestinal commensal microbiome, an obligatory prompt for the diversification of intestinal and extra-intestinal mucosal immunological tissue. In the vermiform appendix, this activity is centred on further developing the inventory of primary antibodies and the maturation of T- and B-lymphocyte cells in the follicles within the lymphoid tissue. Furthermore, the columnar epithelia, enterocytes and goblet cells comprise the complement of cells that occupy the lamina propria and muscularis mucosae of the vermiform appendix's mucosa, while macrophages and an abundance of immunoglobulin A and immunoglobulin G generating plasma cells seed the lamina propria Intraepithelial immune cells consisting predominantly of specific CD8⁺ T regulatory lymphocytes occupy sites in the appendix analogous to those present in the intestinal epithelia of the caecal colon. The complement of bacterial genera concealed in the vermiform appendix is posited extant as a biofilm inoculum of the intestinal commensal microbiome. This facilitates re-inoculation of the proximal colon and to a lesser degree the terminal ilium post an intestinal perturbation such as occurs with daily lifestyle stressors, dietary choices and the short-term administration of antibiotics rather than an infectious fulminant colitis. A plausible appreciation results of the importance of multiple immunological aspects of a healthy vermiform appendix and the provision of a commensal biofilm to the gut that repairs a dysbiotic microbiome contributing to balancing intestinal pro- and anti-inflammatory activity for maintaining homeostasis in the gut. Since the composition of the gut microbiome can vary over the short-term and long-term, it is plausible that the appendix inoculum may be instrumental in maintaining the intestinal microbiome.