Culture-independent evaluation of the appendix and rectum microbiomes in children with and without appendicitis

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.

Perforated Appendicitis in Children: Management, Microbiology, and Antibiotic Stewardship

Although appendicitis has been described for more than 300 years, its optimal management remains a topic of active investigation. Acute appendicitis is the most common cause of peritonitis in children, and rates of perforated appendicitis are much higher in children than in adults. Increased risk for perforated appendicitis in children is related to a delay in diagnosis due to age, size, access to care, and more. Surgical options include immediate appendectomy versus nonoperative management with intravenous antibiotics ± a drainage procedure, with a subsequent interval appendectomy. Microbiota of perforated appendicitis in children most often includes Escherichia coli, Bacteroides fragilis, Streptococcus, and more. Even though the most common organisms are known, there is a large variety of practice when it comes to postoperative antibiotic management in these patients. Studies discuss the benefits of mono- versus dual or triple therapy without a particular consensus regarding what to use. This is reflected across differing practices at various institutions. In this review, we aim to explore the implications of perforated appendicitis in pediatrics, common organisms seen, antibiotic regimen coverage, and the implications of variations of practice. Resistance to commonly used broad-spectrum antibiotics is evolving, therefore minimization of care variability is needed for improved patient outcomes and proper antibiotic stewardship.

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.

Colonoscopy in the diagnosis and management of appendiceal disease

In this editorial, we comment on the article published in the recent issue of the World Journal of Gastrointestinal Endoscopy. We focused on the understanding of appendiceal disease, and the various options for diagnosis and treatment via endoscopy. Some factors affecting the diagnosis and management of appendiceal diseases are also discussed. The existence of any organ has its natural rationality, and the appendix is such a magical organ. A growing number of experts and scholars have gradually come to a consensus that the appendix is not a useless evolutionary relic. There are many lymphocytes and lymph nodes in the appendix wall, which has a strong immune function, and this function is particularly important for children and adolescents. Many intestinal probiotics in the appendix are very helpful for maintaining the balance of the intestinal flora. With the continuous progress of endoscopic technology, endoscopic treatment involving preservation of the appendix has shown great advantages over surgery. In the diagnosis of appendiceal inflammation and neoplasms, colonoscopy, endoscopic retrograde appendicography and choledochoscopy help assess conditions of the appendix. Endoscopic retrograde appendicitis therapy, abscess drainage under colonoscopy, fenestration of abscess under colonoscopy, and endoscopic or natural orifice transluminal endoscopic surgery resection of appendiceal neoplasms are safe and effective endoscopic treatments for appendiceal disease. New breakthroughs in the application of endoscopy in the appendix are expected to occur in the near future.

Compilation of Evidence Supporting the Role of a T Helper 2 Reaction in the Pathogenesis of Acute Appendicitis

Despite being the most common abdominal surgical emergency, the cause of acute appendicitis (AA) remains unclear, since in recent decades little progress has been made regarding its etiology. Obstruction of the appendicular lumen has been traditionally presented as the initial event of AA; however, this is often the exception rather than the rule, as experimental data suggest that obstruction is not an important causal factor in AA, despite possibly occurring as a consequence of the inflammatory process. Type I hypersensitivity reaction has been extensively studied, involving Th2 lymphocytes, and cytokines such as IL-4, IL-5, IL-9 and IL-13, which have well-defined functions, such as a positive-feedback effect on Th0 for differentiating into Th2 cells, recruitment of eosinophils and the release of eosinophilic proteins and the production of IgE with the activation of mast cells, with the release of proteins from their granules. Cytotoxic activity and tissue damage will be responsible for the clinical manifestation of the allergy. AA histological features are similar to those found in allergic reactions like asthma. The intestine has all the components for an allergic immune response. It has contact with hundreds of antigens daily, most of them harmless, but some can potentially induce an allergic response. In recent years, researchers have been trying to assess if allergy is a component of AA, with their latest advances in the understanding of AA as a Th2 reaction shown by the authors of this article.

Proteus appendicitidis sp. nov., isolated from the appendiceal pus of an appendicitis patient in Yongzhou, China

A Gram-negative, facultatively anaerobic, short rod-shaped bacterium, designated as strain HZ0627T, was isolated from the appendiceal pus of a patient with appendicitis in Yongzhou, Hunan, China. This strain was subjected to comprehensive phenotypic, phylogenetic, and genomic analyses using polyphasic taxonomic methods. Phylogenetic analysis of the 16S rRNA gene sequence revealed that this strain belonged to the genus Proteus and the family Morganellaceae, whereas that based on the rpoB gene sequence and phylogenomic analysis demonstrated that this strain was distinctly separated from other type strains of Proteus species. Moreover, whole-genome-based analyses, including in silico DNA-DNA hybridization (isDDH) and average nucleotide identity (ANI), revealed that strain HZ0627T had much lower isDDH rates (24.5-55.6%) and ANI (82.04-93.90%) than those of the thresholds (i.e., 70% and 95%, respectively) for species delineation, when compared to the type strains of other Proteus species. The cellular fatty acid profile of strain HZ0627T was dominated by C16:0 (34.5%), cyclo C17:0 (25.8%), C14:0 (12.6%), C16:1 iso I/14:0 3-OH (7.7%), C18:1ω7c/18:1ω6c (6.5%), and C16:1ω7c/16:1ω6c (4.9%), which clearly differentiated it from the documented type strains of Proteus species. In addition, several specific physiological traits, including optimal growth temperature, tolerance to sodium chloride, and carbon source utilization, differed from those of other Proteus species. Therefore, we propose the name Proteus appendicitidis sp. nov. for strain HZ0627T (= CCTCC AB 2022380T = KCTC 92986T), which represents the type strain of this novel Proteus species.

Diversity of the microbiota communities found in the various regions of the intestinal tract in healthy individuals and inflammatory bowel diseases

The severe and chronic inflammatory bowel diseases (IBD), Crohn disease and ulcerative colitis, are characterized by persistent inflammation and gut damage. There is an increasing recognition that the gut microbiota plays a pivotal role in IBD development and progression. However, studies of the complete microbiota composition (bacteria, fungi, viruses) from precise locations within the gut remain limited. In particular, studies have focused primarily on the bacteriome, with available methods limiting evaluation of the mycobiome (fungi) and virome (virus). Furthermore, while the different segments of the small and large intestine display different functions (e.g., digestion, absorption, fermentation) and varying microenvironment features (e.g., pH, metabolites), little is known about the biogeography of the microbiota in different segments of the intestinal tract or how this differs in IBD. Here, we highlight evidence of the differing microbiota communities of the intestinal sub-organs in healthy and IBD, along with method summaries to improve future studies.

Role of MAIT cells in gastrointestinal tract bacterial infections in humans: More than a gut feeling

Mucosa-associated invariant T (MAIT) cells are the largest population of unconventional T cells in humans. These antimicrobial T cells are poised with rapid effector responses following recognition of the cognate riboflavin (vitamin B2)-like metabolite antigens derived from microbial riboflavin biosynthetic pathway. Presentation of this unique class of small molecule metabolite antigens is mediated by the highly evolutionarily conserved major histocompatibility complex class I-related protein. In humans, MAIT cells are widely found along the upper and lower gastrointestinal tracts owing to their high expression of chemokine receptors and homing molecules directing them to these tissue sites. In this review, we discuss recent findings regarding the roles MAIT cells play in various gastrointestinal bacterial infections, and how their roles appear to differ depending on the etiological agents and the anatomical location. We further discuss the potential mechanisms by which MAIT cells contribute to pathogen control, orchestrate adaptive immunity, as well as their potential contribution to inflammation and tissue damage during gastrointestinal bacterial infections, and the ensuing tissue repair following resolution. Finally, we propose and discuss the use of the emerging three-dimensional organoid technology to test different hypotheses regarding the role of MAIT cells in gastrointestinal bacterial infections, inflammation, and immunity.

The appendix and ulcerative colitis - an unsolved connection

The appendix is thought to have a role in the pathogenesis of ulcerative colitis, but the nature and basis of this association remains unclear. In this Perspective, we consider the biology of the appendix with respect to its immunological function and the microbiome, and how this relates to evidence that supports the involvement of the appendix in ulcerative colitis. In experimental models, removal of the inflamed appendix prevents colitis, and in human observational studies, appendectomy is associated with protection against ulcerative colitis. Further, among people who develop ulcerative colitis, appendectomy before diagnosis might influence the course and outcomes of the disease - some evidence suggests that it protects against colectomy but could increase the risk of colorectal cancer. Appendectomy after onset of ulcerative colitis seems to have disparate consequences. Clinical trials to understand whether appendectomy has a role in the treatment of ulcerative colitis are ongoing. Major questions about the role of the appendix in the pathogenesis of ulcerative colitis remain unanswered, and further research is needed to establish whether the connection is clinically relevant.

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.

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.

Research on the Gut Microbiota of Hainan Black Goat

The intestine of animals is a complex micro-ecosystem containing a large number of microbiomes, which is essential for the host's health development. The Hainan black goat with good resistance and adaptability is a unique species in Hainan, China. These unique physiological characteristics are inseparable from their intestinal microbiota. In this study, high-throughput sequencing was used to investigate bacterial communities in different segments of the intestinal tract of Hainan black goat. The results showed that the indices of Chao1 and ACE in the cecum and colon were significantly greater than those in the ileum (p = 0.007, 0.018). According to PCoA, the intestinal flora composition of the cecum and colon is almost equivalent. In contexts of the phylum, Firmicutes, Bacteroidota, and Pseudomonadota were the dominant phyla in the gut of the Hainan black goat. While in context of the genus, the dominant groups in the gut of black goats mainly include Ruminococcaceae_UCG-005, Bacteroides, Paeniclostridium, Christensenellaceae_R-7_group, Rikenellaceae_RC9_gut_group, and Eubacterium coprostanoligenes _group, Prevotella_1, they have different proportions in different intestinal segments. The gut microbiota of Hainan black goat is mainly Firmicutes, Bacteroidota, and Pseudomonadota. Influenced by the intestinal location where they colonize, the large intestine has a more complex intestinal flora than the small intestine. In contrast, there are only minor differences between the caecum and the colon in the large intestine.

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 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.

Appendix and Ulcerative Colitis: a Key to Explaining the Pathogenesis and Directing Novel Therapies?

The vermiform appendix is generally considered a redundant organ, but recent evidence suggests that the appendix could contribute to the pathogenesis of inflammatory bowel diseases, in particular ulcerative colitis (UC), and may even have a therapeutic role; however, mechanisms of the appendix involvement remain unclear. Here, we highlight current evidence on the link between the appendix and UC and consider plausible therapeutic implications. A literature search was conducted using PubMed and PubMed Central from inception to Nov 2021 using the terms "Appendix", "UC", "Appendix & UC," "Appendectomy", and "Peri-appendicular patch," including only articles published in English. Reference lists from the selected studies were manually searched and reviewed to gather additional related reports. Inflammation around the appendix ("peri-appendicular patch") has been frequently observed in UC patients without other cecal involvement, and this inflammation can even precede the onset of UC. Epidemiologic studies propose that appendectomy reduces the risk of developing UC or even the risk of flare after UC is diagnosed, although this remains controversial. We reviewed studies showing altered host-microbe interactions in the appendix in UC, which suggest that the appendix could act as a priming site for disease via alterations in the immune response and changes in microbiota carried distally to the colon. In summary, recent literature suggests a possible role for microbes and immune cells within the appendix; however, the role of the appendix in the pathogenesis of UC remains unclear. Further research could clarify the therapeutic potential related to this organ.

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.

RNA Sequencing in COVID-19 patients identifies neutrophil activation biomarkers as a promising diagnostic platform for infections

Infection with the SARS-CoV2 virus can vary from asymptomatic, or flu-like with moderate disease, up to critically severe. Severe disease, termed COVID-19, involves acute respiratory deterioration that is frequently fatal. To understand the highly variable presentation, and identify biomarkers for disease severity, blood RNA from COVID-19 patient in an intensive care unit was analyzed by whole transcriptome RNA sequencing. Both SARS-CoV2 infection and the severity of COVID-19 syndrome were associated with up to 25-fold increased expression of neutrophil-related transcripts, such as neutrophil defensin 1 (DEFA1), and 3-5-fold reductions in T cell related transcripts such as the T cell receptor (TCR). The DEFA1 RNA level detected SARS-CoV2 viremia with 95.5% sensitivity, when viremia was measured by ddPCR of whole blood RNA. Purified CD15+ neutrophils from COVID-19 patients were increased in abundance and showed striking increases in nuclear DNA staining by DAPI. Concurrently, they showed >10-fold higher elastase activity than normal controls, and correcting for their increased abundance, still showed 5-fold higher elastase activity per cell. Despite higher CD15+ neutrophil elastase activity, elastase activity was extremely low in plasma from the same patients. Collectively, the data supports the model that increased neutrophil and decreased T cell activity is associated with increased COVID-19 severity, and suggests that blood DEFA1 RNA levels and neutrophil elastase activity, both involved in neutrophil extracellular traps (NETs), may be informative biomarkers of host immune activity after viral infection.

The potential of rectal swabs to differentiate simple and complex appendicitis in children with a microbiota-based test

Currently, accurate biomarkers differentiating simple (phlegmonous) from complex (gangrenous and/or perforated) appendicitis in children are lacking. However, both types may potentially require different treatment strategies, and the search for diagnostic modalities remains warranted. Previously, we demonstrated a distinct microbiota (both an increased bacterial diversity and abundance) in the appendix of children with complex compared to simple appendicitis. From the same cohort of patients we have collected 35 rectal swabs under general anesthesia prior to appendectomy and microbiota analysis was performed by IS-pro, a 16S-23S rDNA-based clinical microbiota profiling technique. Using the obtained IS-profiles, we performed cluster analyses (UPGMA), comparison of diversity (Shannon Diversity Index) and intensity (abundance in relative fluorescence units) on phylum level, and comparison on species level of bacteria between simple and complex appendicitis. Regarding these analyses, we observed no clear differences between simple and complex appendicitis. However, increased similarity of the microbial composition of the appendix and rectal swab was found within children with complex compared to simple appendicitis. Furthermore, PLS-DA regression analysis provided clear visual differentiation between simple and complex appendicitis, but the diagnostic power was low (highest AUC 0.65).   Conclusion: Microbiota analysis of rectal swabs may be viable to differentiate between simple and complex appendicitis prior to surgery as a supervised classification model allowed for discrimination of both types. However, the current diagnostic power was low and further validation studies are needed to assess the value of this method. What is Known: • Simple and complex appendicitis in children may require different treatment strategies, but accurate preoperative biomarkers are lacking. • Clear differentiation can be made between both types in children based upon the microbial composition in the appendix. What is New: • Increased similarity was found between the microbial composition of the appendix and rectal swab within children with complex compared to simple appendicitis. • Using a supervised classification model rectal swabs may be viable to discriminate between simple and complex appendicitis, but the diagnostic power was low.

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.

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.

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.

Effect of mupirocin for Staphylococcus aureus decolonization on the microbiome of the nose and throat in community and nursing home dwelling adults

Objective

To characterize the microbial communities of the anterior nares (nose) and posterior pharynx (throat) of adults dwelling in the community and in nursing homes before and after treatment with intranasal mupirocin.

Methods

Staphylococcus aureus-colonized adults were recruited from the community (n = 25) and from nursing homes (n = 7). S. aureus colonization was confirmed using cultures. Participants had specimens taken from nose and throat for S. aureus quantitation using quantitative PCR for the nuc gene and bacterial profiling using 16S rRNA gene sequencing over 12 weeks. After two baseline study visits 4 weeks apart, participants received intranasal mupirocin for 5 days with 3 further visits over a 8 week follow-up period.

Results

We found a decrease in the absolute abundance of S. aureus in the nose for 8 weeks after mupirocin (1693 vs 141 fg/ul, p = 0.047). Mupirocin caused a statistically significant disruption in bacterial communities of the nose and throat after 1 week, which was no longer detected after 8 weeks. Bacterial community profiling demonstrated that there was a decrease in the relative abundance of S. aureus (8% vs 0.3%, p<0.01) 8 weeks after mupirocin and a transient decrease in the relative abundance of Staphylococcus epidermidis in the nose (21% vs 5%, p<0.01) 1 week after mupirocin.

Conclusions

Decolonization with mupirocin leads to a sustained effect on absolute and relative abundance of S. aureus but not for other bacteria in the nose. This demonstrates that a short course of mupirocin selectively decreases S. aureus in the nose for up to 8 weeks.

Apple cider vinegar soaks do not alter the skin bacterial microbiome in atopic dermatitis

INTRODUCTION

Atopic dermatitis is a common skin disease characterized by altered cutaneous immunity in which patients often exhibit lower skin microbiota diversity compared to healthy skin and are prone to colonization by Staphylococcus aureus. Apple cider vinegar has been shown to have antibacterial effects; however, its effects on the skin microbiome have not previously been well-described.

OBJECTIVES

We aimed to examine the effects of topical dilute apple cider vinegar soaks on Staphylococcus aureus abundance, skin bacterial microbiome composition, and skin bacterial microbiome diversity in atopic dermatitis participants compared to healthy skin.

METHODS

Eleven subjects with atopic dermatitis and 11 healthy controls were enrolled in this randomized, non-blinded, single-institution, split-arm pilot study. Subjects soaked one forearm in dilute apple cider vinegar (0.5% acetic acid) and the other forearm in tap water for 10 minutes daily. Skin bacteria samples were collected from subjects' volar forearms before and after 14 days of treatment. 16S sequencing was used to analyze Staphylococcus aureus abundance and skin bacterial microbiome composition, and alpha diversity of microbiota were determined using Shannon diversity index.

RESULTS

There was no difference in skin bacterial microbiome in atopic dermatitis subjects after 2 weeks of daily water or apple cider vinegar treatments (p = 0.056 and p = 0.22, respectively), or in mean abundance of S. aureus on apple cider vinegar-treated forearms (p = 0.60). At 2 weeks, the skin bacterial microbiomes of healthy control subjects were not significantly different from the skin bacterial microbiome of atopic dermatitis subjects (p = 0.14, 0.21, 0.12, and 0.05).

CONCLUSIONS

Our results suggest that daily soaks in 0.5% apple cider vinegar are not an effective method of altering the skin bacterial microbiome in atopic dermatitis. Further studies are needed to explore the effects of different concentrations of apple cider vinegar on skin microflora and disease severity.

TRIAL NUMBER

UVA IRB-HSR #19906.

Metagenomic NGS optimizes the use of antibiotics in appendicitis patients: bacterial culture is not suitable as the only guidance

BACKGROUND

Previous treatment guidelines have suggested that bacteria are associated with the severity of appendicitis, and the use of postoperative antibiotics should be guided according to the bacteria culture results derived from intraoperative samples. However, this approach has many limitations. Patients were commonly administrated antibiotics during the perioperative period, which can lead to inaccurate culture result.

AIM

To assess the relationship between pathogenic bacteria and appendicitis and optimize the process of antibiotic selection.

METHODS

A nonconsecutive case series analysis was conducted from January to July 2017. Nineteen patients were divided into two groups according to their postoperative histological results (Non-perforated: phlegmonous/Perforated: gangrenous, n = 9/10) and postoperative bacterial culture results (Negative/Positive, n = 8/11). Patients were administrated same antibiotics during the perioperative period. During appendectomy, the diseased appendixes were collected, and whole metagenomic sequencing was used to identify the pathogenic bacteria in the specimens. Conventional technology was used to culture bacteria from appendix samples.

RESULTS

We identified 361 species in the appendix samples. Six species in the appendix samples had relative abundances > 5%. No significant differences were observed in the bacterial composition of the two assayed groups. In particular, according to the grouping of culture results, the sequencing analysis results were completely different from those of the culture-based method.

CONCLUSION

In clinical practice, because patients are regularly administrated antibiotics during the perioperative period, these antibiotics inevitably affect the results of bacterial culture. Therefore, bacterial culture results are not suitable for exclusively guiding the use of antimicrobial agents after appendicitis. Next-generation sequencing has numerous advantages, such as precisely characterizing the profiles of microbiota and their antibiotic resistance in appendicitis patients. Based on the above results, we propose that a combination of bacterial culture and next-generation sequencing should be used to improve the efficacy of antibiotic therapy.

Bulleidia extructa: An underappreciated anaerobic pathogen

Bulleidia extructa is a rarely recognized anaerobic Gram-positive bacterium with an oral and gastroenterological ecological niche. It is difficult to isolate due to slow growth in culture and usually requires identification techniques such as 16S rRNA gene sequencing or matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). While most often isolated from infections related to the oral cavity (gingivitis, periodontitis, brain and lung abscess), it has also been recovered from cases of prosthetic joint hip infections after unprophylaxed dental procedures.

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.

Gut Microbiota Dysbiosis Is Associated with Elevated Bile Acids in Parkinson's Disease

The gut microbiome can impact brain health and is altered in Parkinson’s disease (PD). The vermiform appendix is a lymphoid tissue in the cecum implicated in the storage and regulation of the gut microbiota. We sought to determine whether the appendix microbiome is altered in PD and to analyze the biological consequences of the microbial alterations. We investigated the changes in the functional microbiota in the appendix of PD patients relative to controls (n = 12 PD, 16 C) by metatranscriptomic analysis. We found microbial dysbiosis affecting lipid metabolism, including an upregulation of bacteria responsible for secondary bile acid synthesis. We then quantitatively measure changes in bile acid abundance in PD relative to the controls in the appendix (n = 15 PD, 12 C) and ileum (n = 20 PD, 20 C). Bile acid analysis in the PD appendix reveals an increase in hydrophobic and secondary bile acids, deoxycholic acid (DCA) and lithocholic acid (LCA). Further proteomic and transcriptomic analysis in the appendix and ileum corroborated these findings, highlighting changes in the PD gut that are consistent with a disruption in bile acid control, including alterations in mediators of cholesterol homeostasis and lipid metabolism. Microbially derived toxic bile acids are heightened in PD, which suggests biliary abnormalities may play a role in PD pathogenesis.

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.

An observational study of innate immune responses in patients with acute appendicitis

Acute appendicitis is a common surgical emergency worldwide. Exaggerated immune responses could be associated with appendicitis. This study aimed at characterizing immune responses towards a large variety of gut commensals and pathogens, and pattern recognition receptor (PRR) ligands, and investigating the course of systemic inflammation in a prospective cohort of acute appendicitis patients. PBMC responses of 23 patients of the cohort and 23 healthy controls were characterized more than 8 months post-surgery. Serum cytokine levels were measured in 23 patients at the time of appendicitis and after one month. CRP, WBC and percentage of neutrophils were analyzed in the total cohort of 325 patients. No differences in PBMC responses were found between patients and controls. Stronger IL-10 responses were found following complicated appendicitis. A trend towards lower IL-8 responses was shown following gangrenous appendicitis. Serum IL-10 and IL-6 were significantly elevated at presentation, and IL-6, IL-8 and TNF-α levels were higher in complicated appendicitis. Routine biomarkers could predict severity of appendicitis with high specificities, but low sensitivities. Cytokine responses in patients following acute appendicitis did not differ from healthy controls. Higher serum cytokine levels were found in acute complicated and gangrenous cases. Further research into discriminative biomarkers is warranted.

The Appendix in Parkinson's Disease: From Vestigial Remnant to Vital Organ?

Parkinson’s disease (PD) has long been considered a brain disease, but studies now point to the gastrointestinal (GI) tract as a potential starting point for PD. In particular, the human vermiform appendix has been implicated in PD. The appendix is a tissue rich in immune cells, serving as part of the gut-associated lymphoid tissue and as a storehouse for the gut microbiome. The functions of the appendix converge with recent evidence demonstrating that gut inflammation and shifts in the microbiome are linked to PD. Some epidemiological studies have linked removal of the appendix to lowered PD risk, though there is controversy among these associations. What is apparent is that there is an abundance of aggregated forms of α-synuclein in the appendix relevant to PD pathology. α-Synuclein pathology is thought to propagate from gut to brain via the vagus nerve, which innervates GI tract locations, including the appendix. Remarkably, α-synuclein aggregates in the appendix occur not only in PD patients, but are also present in healthy individuals. This has led to the proposal that in the appendix α-synuclein aggregates are not unique to PD. Moreover, the molecular events leading to PD and the mechanisms by which α-synuclein aggregates transfers from gut to brain may be identifiable in the human appendix. The influence of the appendix on GI inflammation, autoimmunity, microbiome storage, and the lymphatic system may be yet unexplored mechanisms by which the appendix contributes to PD. Overall, the appendix represents a promising tissue site to advance our understanding of PD pathobiology.

The value of post-operative antibiotic therapy after laparoscopic appendectomy for complicated acute appendicitis: a prospective, randomized, double-blinded, placebo-controlled phase III study (ABAP study)

BACKGROUND

Approximately 30% of appendectomies are for complicated acute appendicitis (CAA). With laparoscopy, the main post-operative complication is deep abscesses (12% of cases of CAA, versus 4% for open surgery). A recent cohort study compared short and long courses of postoperative antibiotic therapy in patients with CAA. There was no significant intergroup difference in the post-operative complication rate (12% of organ/space surgical site infection (SSI)). Moreover, antibiotic therapy is increasingly less indicated for other situations (non-complicated appendicitis, post-operative course of cholecystitis, perianal abscess), calling into question whether post-operative antibiotic therapy is required after laparoscopic appendectomy for CAA.

METHODS/DESIGN

This study is a prospective, multicenter, parallel-group, randomized (1:1), double-blinded, placebo-controlled, phase III non-inferiority study with blind evaluation of the primary efficacy criterion. The primary objective is to evaluate the impact of the absence of post-operative antibiotic therapy on the organ/space surgical site infection (SSI) rate in patients presenting with CAA (other than in cases of generalized peritonitis). Patients in the experimental group will receive at least one dose of preoperative and perioperative antibiotic therapy (2 g ceftriaxone by intravenous injection every 24 h up to the operation) and metronidazole (500 mg by intravenous injection every 8 h up to the operation) and, in the post-operative period, a placebo for ceftriaxone (2 g/24 h in one intravenous injection) and a placebo for metronidazole (1500 mg/24 h in three intravenous injections, for 3 days). In the control group, patients will receive at least one dose of preoperative and perioperative antibiotic therapy (2 g ceftriaxone by intravenous injection every 24 h up to the operation) and metronidazole (500 mg by intravenous injection every 8 h up to the operation) and, in the post-operative period, antibiotic therapy (ceftriaxone 2 g/24 h and metronidazole 1500 mg/24 h for 3 days). In the event of allergy to ceftriaxone, it will be replaced by levofloxacin (500 mg/24 h in one intravenous injection, for 3 days). The expected organ space SSI rate is 12% in the population of patients with CAA operated on by laparoscopy. With a non-inferiority margin of 5%, a two-sided alpha risk of 5%, a beta risk of 20%, and a loss-to-follow-up rate of 10%, the calculated sample size is 1476 included patients, i.e., 738 per group. Due to three interim analyses at 10%, 25%, and 50% of the planned sample size, the total sample size increases to 1494 patients (747 per arm).

TRIAL REGISTRATION

Ethical authorization by the Comité de Protection des Personnes and the Agence Nationale de Sécurité du Médicament: ID-RCB 2017-00334-59. Registered on ClinicalTrials.gov (NCT03688295) on 28 September 2018.

The gallbladder and vermiform appendix influence the assemblage of intestinal microorganisms

Surgical procedures for the symptomatic removal of the gallbladder and the vermiform appendix have been posited to adversely shift the assemblage of the intestinal microbiome increasing the risk of disease. The associated mechanisms have been linked with dysbiosis of the gut microbiota. Cholecystectomy causes changes of bile acid compositions and bile secretion patterns as bile acids interact with the intestinal microbiota in a bidirectional capacity. An appendectomy precludes the further recolonization of the proximal colon with a commensal biofilm that could maintain a stable intestinal microbiome. Epidemiological studies indicate that there is an increased risk of disease rather than causality following a cholecystectomy and appendectomy. This narrative review summarizes studies that report on the role that bile salts and the appendix, contribute to the assemblage of the intestinal microbiome in health and disease.

Comparing the rates of methane production in patients with and without appendectomy: results from a large-scale cohort

There is no clear study identifying the microbiome of the appendix. However, in other diverticular conditions, such as diverticulosis, methanogens appear important. We investigated whether patients who had undergone appendectomies had decreased levels of exhaled methane (CH₄). Consecutive patients who underwent breath testing (BT) from November 2005 to October 2013 were deterministically linked to electronic health records. The numbers of patients with CH₄ ≥ 1 ppm (detectable) and ≥ 3 and ≥ 10 ppm (excess) were compared between patients who did and did not undergo appendectomy using a multivariable model adjusted for age and sex. Of the 4977 included patients (48.0 ± 18.4 years, 30.1% male), 1303 (26.2%) had CH₄ ≥ 10 ppm, and 193 (3.9%) had undergone appendectomy. Appendectomy was associated with decreased odds of CH₄ ≥ 1, ≥ 3, and ≥ 10 ppm (ORs (95% CI) = 0.67 (0.47–0.93), p = 0.02; 0.65 (0.46–0.92), p = 0.01; and 0.66 (0.46–0.93), p = 0.02, respectively). Additionally, the percentage of CH₄ producers increased 4-fold from the first to ninth decade of life. This is the first study to report that appendectomy is associated with decreased exhaled CH₄. The appendix may play an active physiologic role as a reservoir of methanogens.

Medical Treatment: An Emerging Standard in Acute Appendicitis?

Appendicectomy has been accepted as the gold standard for the management of appendicitis over the years, but there has been an increasing evidence and trend toward the conservative approach to the management of appendicitis. The aim of this review is to search existing literature and to evaluate and compare the conservative and operative approaches to the management of appendicitis. An electronic search of published literature was conducted through Pubmed, Google Scholar, Embase, and Medline using a variety of search items to find relevant observational studies, randomized clinical trials, systematic reviews, and meta-analyses. Bibliographies of selected articles were also analyzed for publications of interest relevant to the scope of the topic. The articles that reported primary outcomes after the management of appendicitis, complications, economic implications, and duration of follow-up were reviewed in detail. The major primary outcomes show a high recurrence rate and failed treatment associated with the conservative management of appendicitis. The other outcomes obtained show that there is an increased incidence of complications associated with operative management. Economic implications and cost-effectiveness analysis show that conservative treatment may be preferred. The length of hospital stay was significantly higher in conservative approach to management; however, shorter time off activities was observed. In general, the conservative management of appendicitis is still regarded as safe, effective, and efficacious, and further research with well-constructed study design, and larger sample size is required.

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 enduring effects of early-life stress on the microbiota-gut-brain axis are buffered by dietary supplementation with milk fat globule membrane and a prebiotic blend

Nutritional interventions targeting the microbiota-gut-brain axis are proposed to modulate stress-induced dysfunction of physiological processes and brain development. Maternal separation (MS) in rats induces long-term alterations to behaviour, pain responses, gut microbiome and brain neurochemistry. In this study, the effects of dietary interventions (milk fat globule membrane [MFGM] and a polydextrose/galacto-oligosaccharide prebiotic blend) were evaluated. Diets were provided from postnatal day 21 to both non-separated and MS offspring. Spatial memory, visceral sensitivity and stress reactivity were assessed in adulthood. Gene transcripts associated with cognition and stress and the caecal microbiota composition were analysed. MS-induced visceral hypersensitivity was ameliorated by MFGM and to greater extent with the combination of MFGM and prebiotic blend. Furthermore, spatial learning and memory were improved by prebiotics and MFGM alone and with the combination. The prebiotic blend and the combination of the prebiotics and MFGM appeared to facilitate return to baseline with regard to HPA axis response to the restraint stress, which can be beneficial in times where coping mechanisms to stressful events are required. Interestingly, the combination of MFGM and prebiotic reduced the long-term impact of MS on a marker of myelination in the prefrontal cortex. MS affected the microbiota at family level only, while MFGM, the prebiotic blend and the combination influenced abundance at family and genus level as well as influencing beta-diversity levels. In conclusion, intervention with MFGM and prebiotic blend significantly impacted the composition of the microbiota as well as ameliorating some of the long-term effects of early-life stress.

Preoperative assessment of complicated appendicitis through stress reaction and clinical manifestations

This study assessed the severity of the disease through the preoperative clinical manifestations and inflammatory reaction indicators of acute appendicitis, and established a score table to predict complicated appendicitis (CA).The clinical data of 238 patients with acute appendicitis in our hospital were retrospectively analyzed, which included 18 patients with acute simple appendicitis (7.6%), 170 patients with acute purulent appendicitis (72.0%), and 48 patients with acute gangrene and perforation (20.3%). The clinical manifestations and inflammatory reaction indicators were analyzed by univariate logistic regression. Multivariate logistic regression analysis was performed to screen out the independent risk factors of CA. The β coefficients of independent risk factors entering the multivariate model were assigned by rounding, and the total score was the sum of values of all factors. Finally, verification and analysis were performed for the predictive model, and the operating characteristic curve (ROC) curve was drawn. Then, the area under the curve (AUC) was compared with the THRIVE scale, and the Hosmer-Lemeshow method was used to evaluate whether the model fitted well.The multivariate logistic regression analysis of independent risk factors was performed, and the values were rounded to the variable assignment based on the β coefficient values. The plotted ROC and AUC was calculated as 0.857 (P < .001). Using the Hosmer-Lemeshow method, the X-value was 12.430, suggesting that the prediction model fitted well.The scoring system can quickly determine whether this is a CA, allowing for an earlier and correct diagnosis and treatment. Furthermore, the scoring system was convenient, economical, and affordable. Moreover, it is easy to popularized and promote.

Creek to Table: Tracking fecal indicator bacteria, bacterial pathogens, and total bacterial communities from irrigation water to kale and radish crops

The impact of microbially contaminated irrigation water on risks to produce safety and public health is a complex issue that is not well understood. This study tracked fecal indicators, pathogenic bacteria, and total bacterial communities from a creek water irrigation source to irrigated produce to assess the impact of irrigation events on soil and produce-associated microbiota. Kale and radishes were drip-irrigated using Mid-Atlantic creek water in October 2017. Plant and soil samples were collected immediately before and after irrigation, and for 3 consecutive days thereafter. All samples (n = 134), including irrigation water, were tested for generic Escherichia coli and total coliforms (TC) using standard membrane filtration or direct plating, and for Salmonella enterica and Listeria monocytogenes by selective enrichment. DNA extracted from all samples was PCR-amplified for the V3-V4 region of the 16S rRNA gene for bacterial community profiling. In soil, TC levels were significantly higher immediately and 3 days post-irrigation compared to pre-irrigation (p < 0.01). E. coli levels in soil increased after irrigation, but the difference was not significant (p = 0.31), and die-off was not observed. No E. coli were detected on kale leaves. TC increased over the study period on radish roots (p < 0.01) but not kale leaves (p = 0.43). Although target pathogens were detected in irrigation water, S. enterica was detected from only one post-irrigation kale sample and L. monocytogenes was not detected in the field. The 16S rRNA gene sequencing data revealed differences in bacterial community structure and composition across sample types and showed that radish soil and root surface bacterial communities were more strongly influenced by irrigation compared to kale samples. This study provides insights into the impact of irrigation water on fresh produce microbiota, revealing that, although irrigation did influence crop-associated microbiota (especially below ground) in the field, bacterial pathogens were not likely transferred to the crop.