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.

Beyond a vestigial organ: effects of the appendix on gut microbiome and colorectal cancer

The role of appendectomy in the pathogenesis of colorectal cancer (CRC) is a recent topic of contention. Given that appendectomy remains one of the most commonly performed operations and a first-line management strategy of acute appendicitis, it is inherently crucial to elucidate the association between prior appendectomy and subsequent development of CRC, as there may be long-term health repercussions. In this review, we summarize the data behind the relationship of CRC in post-appendectomy patients, discuss the role of the microbiome in relation to appendectomy and CRC pathogenesis, and provide an appraisal of our current understanding of the function of the appendix. We seek to piece together the current landscape surrounding the microbiome and immunological changes in the colon post-appendectomy and suggest a direction for future research involving molecular, transcriptomic, and immunologic analysis to complement our current understanding of the alterations in gut microbiome.

B cell immune profiles in dysbiotic vermiform appendixes of pancreatic cancer patients

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest solid tumors and is resistant to immunotherapy. B cells play an essential role in PDAC progression and immune responses, both locally and systemically. Moreover, increasing evidence suggests that microbial compositions inside the tumor, as well as in the oral cavity and the gut, are important factors in shaping the PDAC immune landscape. However, the gut-associated lymphoid tissue (GALT) has not previously been explored in PDAC patients. In this study, we analyzed healthy vermiform appendix (VA) from 20 patients with PDAC and 32 patients with colon diseases by gene expression immune profiling, flow cytometry analysis, and microbiome sequencing. We show that the VA GALT of PDAC patients exhibits markers of increased inflammation and cytotoxic cell activity. In contrast, B cell function is decreased in PDAC VA GALT based on gene expression profiling; B cells express significantly fewer MHC class II surface receptors, whereas plasma cells express the immune checkpoint molecule HLA-G. Additionally, the vermiform appendix microbiome of PDAC patients is enriched with Klebsiella pneumoniae, Bifidobacterium animalis, and Adlercreutzia equolifaciens, while certain commensals are depleted. Our findings may suggest impaired B cell function within the GALT of PDAC patients, which could potentially be linked to microbial dysbiosis. Additional investigations are imperative to validate our observations and explore these potential targets of future therapies.

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.

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 Effects of Deoxynivalenol on the Ultrastructure of the Sacculus Rotundus and Vermiform Appendix, as Well as the Intestinal Microbiota of Weaned Rabbits

Deoxynivalenol (DON) is a mycotoxin found in grains that poses a potential threat to human and animal health, and the gastrointestinal tract is the primary target organ. There are few studies focused on the toxicology of DON to rabbits, especially on the relation among DON, microbiota, and the gut-associated lymphoid tissue. A total of 30 weaned rabbits (35 d) were evenly divided into the control group and DON group (1.5 mg/kg bodyweight (BW)) based on their body weight. After a 24-day trial, the ultrastructures of the sacculus rotundus and vermiform appendix were observed using a scanning electron microscope and transmission electron microscopy. The morphology and microflora in the ileum, caecum, and colon were also examined. The results proved that the ultrastructure of the sacculus rotundus and vermiform appendix, as well as the integrity of the intestinal barrier (especially for the ileum), were impaired after DON was administrated to the rabbits. Compared to the control group, the relative abundance and diversity of the microflora decreased in all three intestinal segments in the DON group, particularly in the ileum and caecum. In conclusion, the toxic effect of DON on weaned rabbits may be performed by destroying the structure of the sacculus rotundus and vermiform appendix, as well as affecting the structure and diversity of the intestinal flora.

Escherichia coli as a carrier of tetracyclines and penicillins resistance in wild pheasant (Phasianus colchicus)

Wild animals like pheasant seem to be a good source of information about human activities. Therefore, the wild pheasants and relative stable appendix microcenosis were selected for antibiotic resistance testing. Penicillin resistance by MALDI-TOF Mass Spectrometry and tetracyclines resistance by genetic methods using specific primers were tested. Differences between tetracycline and penicillin resistance were detected. Results showed high prevalence of resistant Escherichia coli isolated from wild pheasant appendix. E. coli isolated from wild pheasant appendix carried plasmids for penicillins and tetracyclines resistance where they were responsible for enzymatic degradation of penicillin and carried genes for regulating efflux pumps for tetracyclines. Results showed that tetracyclines and penicillins resistance is widespread between wild pheasants with a carrier as Escherichia coli isolated from relative stable microcenosis of appendix.

No appendix necessary: Fecal transplants and antibiotics can resolve Clostridium difficile infection

The appendix has been hypothesized to protect the colon against Clostridium difficile infection (CDI) by providing a continuous source of commensal bacteria that crowd out the potentially unhealthy bacteria and/or by contributing to defensive immune dynamics. Here, a series of deterministic systems comprised of ordinary differential equations, which treat the system as an ecological community of microorganisms, model the dynamics of colon microbiome. The first model includes migration of commensal bacteria from the appendix to the gut, while the second model expands this to also include immune dynamics. Simulations and simple analytic techniques are used to explore dynamics under biologically relevant parameters values. Both models exhibited bistability with steady states of a healthy state and of fulminant CDI. However, we find that the appendix size was much too small for migration to affect the stability of the system. Both models affirm the use of fecal transplants in conjunction with antibiotic use for CDI treatment, while the second model also suggests that anti-inflammatory drugs may protect against CDI. Ultimately, in general neither the appendiceal migration rate of commensal microbiota nor the boost to antibody production could exert an appreciable impact on the stability of the system, thus failing to support the proposed protective role of the appendix against CDI.

[BACTERIOLOGICAL ASPECTS OF AN ACUTE APPENDICITIS]

Peculiarities of microflora in the appendix mucosa and abdominal exudate in different morphological forms of an acute appendicitis (AA) were studied up. In accordance to the bacteriological investigations data, anaerobic, and aerobic microorganisms in AA were revealed in a monoculture and in association, more frequently--obligate anaer- obes (bacteroids) with E. coli--in 82 (80.39%) observations, staphylococcus--in 52 (50.98%), fecal streptococcus--in 19 (18.63%). With progression of inflammatory process and destructive changes in the appendix wall the quantity of bacteroids and enterobacteria have had enhanced, while the quantity of lacto- and bifidumflora-- reduced.

Intestinal stem cells and intestinal homeostasis in health and in inflammation: A review

BACKGROUND

The human intestine is a complex group of organs, highly specialized in processing food and providing nutrients to the body. It is under constant threat from microbials and toxins and has therefore developed a number of protective mechanisms. One important mechanism is the constant shedding of epithelial cells into the lumen; another is the production and maintenance of a double-layered mucous boundary in which there is continuous sampling of the luminal microbiota and a persistent presence of antimicrobial enzymes. However, the gut needs commensal bacteria to effectively break down food into absorbable nutrients, which necessitates constant communication between the luminal bacteria and the intestinal immune cells in homeostasis. Disruption of homeostasis, for whatever reason, will give rise to (chronic) inflammation.

DISCUSSION

Both medical and surgical management of this disruption is discussed.

[DYNAMICS OF INDICES OF A LOCAL IMMUNITY IN AN ACUTE APPENDICITIS]

Abstract The results of investigation on dynamics of a local immunity indices in an acute appendicitis, depending on the pathological process stage as well as on bacteriological investigation of parietal microflora of processus vermicularis, were adduced. The sIgA and lisocymal dynamics have witnessed that while a destructive process progressing their concentration was enhanced, and in a gangrenous acute appendicitis they practically disappeared. Due to affection of a barrier function of the processus vermicularis wall a favorable conditions were created for the microorganisms intramural translocation as well as to abdominal cavity.

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

PURPOSE

The function of the appendix is largely unknown, but its microbiota likely contributes to function. Alterations in microbiota may contribute to appendicitis, but conventional culture studies have not yielded conclusive information. We conducted a pilot, culture-independent 16S rRNA-based microbiota study of paired appendix and rectal samples.

METHODS

We collected appendix and rectal swabs from 21 children undergoing appendectomy, six with normal appendices and fifteen with appendicitis (nine perforated). After DNA extraction, we amplified and sequenced 16S rRNA genes and analyzed sequences using CLoVR. We identified organisms differing in relative abundance using ANOVA (p<0.05) by location (appendix vs. rectum), disease (appendicitis vs. normal), and disease severity (perforated vs. non-perforated).

RESULTS

We identified 290 taxa in the study's samples. Three taxa were significantly increased in normal appendices vs. normal rectal samples: Fusibacter (p = 0.009), Selenomonas (p = 0.026), and Peptostreptococcus (p = 0.049). Five taxa were increased in abundance in normal vs. diseased appendices: Paenibacillaceae (p = 0.005), Acidobacteriaceae GP4 (p = 0.019), Pseudonocardinae (p = 0.019), Bergeyella (p = 0.019) and Rhizobium (p = 0.045). Twelve taxa were increased in the appendices of appendicitis patients vs. normal appendix: Peptostreptococcus (p = 0.0003), Bilophila (p = 0.0004), Bulleidia (p = 0.012), Fusobacterium (p = 0.018), Parvimonas (p = 0.003), Mogibacterium (p = 0.012), Aminobacterium (p = 0.019), Proteus (p = 0.028), Actinomycineae (p = 0.028), Anaerovorax (p = 0.041), Anaerofilum (p = 0.045), Porphyromonas (p = 0.010). Five taxa were increased in appendices in patients with perforated vs. nonperforated appendicitis: Bulleidia (p = 0.004), Fusibacter (p = 0.005), Prevotella (p = 0.021), Porphyromonas (p = 0.030), Dialister (p = 0.035). Three taxa were increased in rectum samples of patients with appendicitis compared to the normal patients: Bulleidia (p = 0.034), Dialister (p = 0.003), and Porphyromonas (p = 0.026).

CONCLUSION

Specific taxa are more abundant in normal appendices compared to the rectum, suggesting that a distinctive appendix microbiota exists. Taxa with altered abundance in diseased and severely diseased (perforated) samples may contribute to appendicitis pathogenesis, and may provide microbial signatures in the rectum useful for guiding both treatment and diagnosis of appendicitis.

Appendectomy and Clostridium difficile colitis: Relationships revealed by clinical observations and immunology

Advances in understanding the interaction between the human immune system and the microbiome have led to an improved understanding of the function of the vermiform appendix as a safe-house for beneficial bacteria in the colon. These advances have been made despite long standing clinical observations that the appendectomy is a safe and effective procedure. However, more recent clinical data show that an appendectomy puts patients at increased risk for recurrent Clostridium difficile (C. difficile)-associated colitis, and probably other diseases associated with an altered microbiome. At the same time, appendectomy does not apparently put patients at risk for an initial onset of C. difficile-associated colitis. These clinical observations point toward the idea that the vermiform appendix might not effectively protect the microbiome in the face of broad spectrum antibiotics, the use of which precedes the initial onset of C. difficile-associated colitis. Further, these observations point to the idea that historically important threats to the microbiome such as infectious gastrointestinal pathogens have been supplanted by other threats, particularly the use of broad spectrum antibiotics.

[Antibacterial therapy in surgery of patients with acute destructive appendicitis]

Character of microflora of exsudate of abdominals and mucosis microflora of vermicular appendix is studied for patients with the destructive forms of appendicitis with the purpose of development of variants of antibacterial therapy at surgical treatment of patients with acute appendicitis. The patients with the destructive forms of appendicitis, which were on treatment in a municipal clinical hospital N 4 Kyiv for period 2004-2010. An Inflammatory-destructive process in an appendix is conditioned by both aerobic (Escherichia coli - 46,6 %, Enterobacter - 4,2 %, Citrobacter - 4,2 %, Klebsiella - 3,3 %, Pseudomonas aeruginosa - 5,8 %, Staphylococcus - 4,2 %) and anaerobic microorganisms (Bacteroides - 100 %) and increase Candida - 17,5 %. Antibacterial therapy is effective at 46,7 % patients with acute appendicitis. At 49,6 % patients acute appendicitis develops on a background dysbiotic intestinal disturbances. Clinically the effective charts of empiric antibacterial monotherapy 6 days it is been: Moxifloxacini intravenously 400 mgs one time in twenty-four hours during, Ertapenemi for a 1 g one time in twenty-four hours intravenously and combined - Aztreonami for a 1 g twice in twenty-four hours and of Clindamycini for 600 mgs twice in twenty-four hours, intramuscular during; Cefepimumi for a 1 g twice in twenty-four hours and of Clindamycini for 600 mgs twice in twenty-four hours, intramuscular.

Splenic rupture in a patient with pelvic abscess and sepsis

A 49-year-old man underwent appendicectomy through a Lanz incision for necrotic appendicitis. He subsequently developed pelvic abscess in the postoperative period, which was drained under computed tomography (CT) guidance. The bacteriology of pus swabs taken during appendicectomy and abscess drainage revealed coliforms. Six days after appendicectomy, the patient had an acute collapse due to rupture of the spleen, which was treated by splenectomy. CT of the abdomen at the time of abscess drainage had confirmed a normal spleen. Histopathological examination of the spleen revealed nonspecific acute splenitis--red pulp congested and infiltrated with neutrophils complicated by rupture. We postulate the abdominal source of sepsis and associated inflammatory response as the cause for the splenic pathology and rupture.

Isolation of Aggregatibacter aphrophilus from a patient with acute appendicitis

OBJECTIVES

Acute appendicitis is a common surgical emergency. The etiology and pathophysiology of appendicitis have been well investigated. Aggregatibacter aphrophilus is a fastidious gram-negative coccobacilli. Detection of this organism in clinical samples and its differentiation from Haemophilus aphrophilus or from Aggregatibacter actinomycetemcomitans in routine microbiology settings could be difficult.

METHODS

In this rare case, we report the isolation of Aggregatibacter aphrophilus from the appendix of a 14-year-old boy presented with acute appendicitis. The genotypic method using 16S rRNA sequencing was used for identification of the organism at species level.

CONCLUSION

This case highlights the importance of detecting fastidious and rare microorganisms such as Aggregatibacter aphrophilus that could be associated with acute appendicitis.

Tuberculous appendix: a review of clinical presentations and outcomes

INTRODUCTION

Tuberculous appendix is surprisingly rare, even in countries where this infection is common. We report our experience with tuberculous appendix over a 15-year period.

METHODS

A search for cases of tuberculous appendix was conducted from January 1995 to December 2009 on the databases of the National Tuberculosis Centre and the Departments of Pathology and Surgery of Raja Isteri Pengiran Anak Saleha Hospital.

RESULTS

There were five cases of tuberculous appendix, giving a cumulative incidence of 0.08 percent of all appendectomies (n is 6,593), 0.2 percent of tuberculosis (TB) cases (n is 2,876) and 8.6 percent of abdominal TB (n is 58). Three patients were male and two were female, with a median age of 27 (range 25-48) years. Four patients presented with symptoms of acute appendicitis and one with an appendiceal mass following treatment for acute gastroenteritis. Only one patient had constitutional symptoms. Four patients had appendectomies (one laparoscopic and three open) within the same admission and one had interval appendectomy. Operative findings included perforated appendix (n is 1), appendiceal mass (n is 1) and acute appendicitis (n is 3). In all cases, the diagnoses were made only after review of the histology. None of the patients had pulmonary TB. Delay in initiating anti-TB treatment in one patient resulted in the development of an ileocutaneous fistula following appendectomy. This was resolved by excision, followed by anti-TB treatment.

CONCLUSION

Tuberculous appendix can present as acute appendicitis, and the diagnosis is often made after surgery. Any delay in treatment can lead to significant complications.

Isolated appendicular tuberculosis (TB) presented as peritonitis

Tuberculosis is very common entity in both developing and under developed countries. Each year 3 million people worldwide died of the disease. Among extra pulmonary TB, alimentary system accounts for about 3.0% cases. The Commonest presentation of alimentary tuberculosis is Ileo-caecal disease, but isolated appendicular involvement is very rarely seen. Although some cases have been reported from our neighboring countries, there is still no such report from Bangladesh. We are here for the first time reporting a case of isolated appendicular tuberculosis which presented to us with peritonitis.

Efficacy of antimicrobial coating suture coated polyglactin 910 with tricosan (Vicryl plus) compared with polyglactin 910 (Vicryl) in reduced surgical site infection of appendicitis, double blind randomized control trial, preliminary safety report

OBJECTIVE

To evaluate the efficacy and safety of new antibacterial suture (Vicryl Plus) compared with a traditional braided suture (Vicryl) in a clinical study. The primary goal was to study effectiveness on reduced surgical site infection in an appendectomy operation. The authors' secondary goal was to analyze the safety and physical properties of Vicryl plus.

MATERIAL AND METHOD

This was a prospective, randomized, controlled, double blind, comparative, single-center study. After appendectomy was done, the patients were randomized in two groups: Vicryl Plus and Vicryl to selected suture for suturing the abdominal sheath. The surgical site infection was evaluated for 30 days, 6 months, and 1 year. The surgeons and attending doctor were blind to the type of suture. This is the primary report of the first 100 patients.

RESULTS

There was no difference in demographic and preoperative clinical in both groups. Although there was no statistical difference in the surgical site infection of Vicryl and Vicryl Plus (8 and 10%, p = 0.05), one case of deep surgical site infection was detected in the Vicryl group. No complications and no difference in related suture materials were detected.

CONCLUSION

Coated polyglactin 910 with tricosan (Vicryl Plus) is safe and satisfactory in surgical practice. Surgical site infection of appendectomy seemed too to be comparable between coated polyglactin 910 with tricosan (Vicryl Plus) and traditional polyglactin 910 (Vicryl) group.

[A case of isolated tuberculosis of the appendix at the University Hospital Center in Brazzaville, Congo]

Since the outbreak of human immunodeficiency virus (HIV) infection, extrapulmonary tuberculosis has become increasingly frequent in developing countries. The purpose of this report is to describe a case of isolated tuberculosis of the appendix diagnosed following generalized peritonitis in a 53-year-old man. The appendix is the least frequent gastrointestinal location of isolated tuberculosis. Diagnosis was achieved by histopathological examination of the appendix immersed in formalin 10% after appendectomy. Paraffin-embedded histological sections stained with hematoxylin-eosin (HE) displayed caseofollicular lesions characteristic of infection by Koch bacillus. Outcome was favourable with a 9-month regimen of antituberculosis treatment according to the protocol of the World Health Organization (WHO).

Microbial induction of B and T cell areas in rabbit appendix

Gut-associated lymphoid tissue (GALT) development requires interaction with the intestinal microbiota. Because murine secondary lymphoid tissue development is driven by positive feedback interactions between B cells and stromal cells, we used in situ hybridization to determine whether intestinal commensals influence such interactions during rabbit appendix development. The features of positive feedback interactions we examined (CXCL13 mRNA expression, B cell accumulation and FDC differentiation) increased during early follicle development, but stalled in the absence of intestinal commensals. These features were reinitiated by commensals that stimulated follicle development and intrafollicular B cell proliferation. Our results suggest that rabbit appendix follicles develop in two phases: an initial phase of B cell recruitment to nascent follicles, possibly through positive feedback interactions, and a subsequent phase of intrafollicular B cell proliferation stimulated by intestinal commensals. In addition, we found that intestinal commensals stimulate appendix CCL21 mRNA expression and T cell area formation.

Comparative study of the intestinal mucus barrier in normal and inflamed colon

AIM

To study the role of mucus in the spatial separation of intestinal bacteria from mucosa.

PATIENTS AND METHODS

Mucus barrier characteristics were evaluated using histological material obtained by biopsy from purged colon, colon prepared with enema and material from untreated appendices fixed with non-aqueous Carnoy solution. Bacteria were evaluated using fluorescence in situ hybridization, with bacterial 16S RNA probes and related to the periodic acid Schiff alcian blue stain. Biopsies from controls (n = 20), patients with self-limiting colitis (SLC; n = 20), ulcerative colitis (n = 20) and 60 randomly selected appendices were investigated.

RESULTS

The mucosal surface beneath the mucus layer was free of bacteria in > or =80% of the normal appendices and biopsies from controls. The thickness of the mucus layer and its spread decreased with increasing severity of the inflammation; the epithelial surface showed bacterial adherence, epithelial tissue defects and deep mucosal infiltration with bacteria and leucocytes. Bacteria and leucocytes were found within mucus in all biopsy specimens from patients with ulcerative colitis, SLC, and acute appendicitis. The concentration of bacteria within mucus was inversely correlated to the numbers of leucocytes.

CONCLUSIONS

The large bowel mucus layer effectively prevents contact between the highly concentrated luminal bacteria and the epithelial cells in all parts of the normal colon. Colonic inflammation is always accompanied by breaks in the mucus barrier. Although the inflammatory response gradually reduces the number of bacteria in mucus and faeces, the inflammation itself is not capable of preventing bacterial migration, adherence to and invasion of the mucosa.

Primary Aortoappendicular Fistula Arising from an Infected, Chronic, Contained, Ruptured Abdominal Aortic Aneurysm

Gastrointestinal bleeding can be caused by a variety of pathologies. Primary aortoappendicular fistula is rare and, in our case, arose in addition to a chronic contained rupture sac of an abdominal aortic aneurysm. Clinical diagnosis is difficult. Aortic aneurysmorrhaphy along with extensive debridement and emphasis on antibiotic therapy is curative.

[Pneumatosis cystoides intestini caeci--a pseudotumor presented at autopsy]

A large focus of cystic intestinal pneumatosis appeared as an accidental finding in a 59-year-old man suffering from obstructive lung disease, with cor pulmonale as the cause of death. The gas pseudocysts were found in the submucosa, muscularis propria and in the subserosal space. The pseudocysts were lined by flattened cells of connective tissue origin with presence of occasional macrophages. We believe that the lesion started by focal damage of the mucosal membrane, which was followed by penetration of stool particles with microbes into the submucosa. E. coli and Morganella morgani are the probable producers of the gas bullets.

Molecular detection of Campylobacter jejuni in archival cases of acute appendicitis

The role of enteric bacteria in the pathogenesis of acute appendicitis is a controversial subject. Campylobacter jejuni has been previously demonstrated in a minority of cases of acute appendicitis using microbiological or immunohistochemical methods, notably in cases where inflammation was limited to the mucosa/submucosa. Our goal was to evaluate cases of acute appendicitis for C. jejuni DNA using molecular methods, and to compare our findings to the histologic features. In total, 50 archival cases of acute appendicitis were selected, and PCR was performed using primers targeting a 286-bp fragment of the mapA gene specific to C. jejuni. Twenty histologically unremarkable appendectomy specimens served as negative controls. Cases were reviewed with attention to particular histological features including mucosal ulceration, cryptitis, depth of inflammatory infiltrate, and the presence of mural necrosis. Of acute appendicitis cases, 22% (11/50) were positive for C. jejuni DNA by PCR analysis. Control cases were negative for C. jejuni DNA. All patients presented with signs and symptoms typical of acute appendicitis. Of the C. jejuni positive cases, only 27% contained acute inflammation limited to the mucosa/submucosa, whereas the remainder had mural or transmural inflammation; therefore, the histological features of C. jejuni-positive acute appendicitis cases were indistinguishable from C. jejuni-negative cases. In summary, C. jejuni DNA was detected in a significant percentage (22%) of acute appendicitis cases, a much higher percentage than previous studies using other methodologies. As C. jejuni is an enteric pathogen that does not exist as a commensal or nonpathogenic organism, the presence of C. jejuni DNA implies current or recent infection. Further study is needed to determine whether the presence of C. jejuni DNA in acute appendicitis indicates appendiceal involvement by C. jejuni enteritis, or if there is a true causative role for C. jejuni in acute appendicitis.

Acute isolated tuberculous appendicitis

Non-pulmonary tuberculosis is found with different frequencies in different countries of the world. It is said to constitute about 4% of all tuberculosis cases in Poland, about 25% in England and Wales and about 17% in the USA. It seems that these differences are the result of differences in rates of diagnosis and registration of new tuberculosis cases. This in turn is influenced by public health funding in the individual countries. In this work, we present a case of acute, isolated, tuberculous inflammation of the appendix. We call attention to the fact that pre-operative diagnosis is practically impossible. Clinical symptoms do not point to inflammatory changes. Only surgical evaluation, and especially the result of histopathological examination make it to possible to establish the final diagnosis to initiation of anti-tuberculous treatment.

Bacterial-induced inflammation in germ-free rabbit appendix

The intestinal ecosystem is defined by a series of interactions between the microbiota, the mucosal epithelium, and the gut-associated lymphoid tissue (GALT). Perturbations in the fine balance of the interactions between these components can result in gastrointestinal diseases such as inflammatory bowel disease (IBD). The pathophysiology of IBD is thought to develop as a result of dysregulated mucosal immune responses to normal luminal microflora. Several animal models for IBD have been developed and underscore the role of the immune system in development of disease. Most of the existing animal models studying IBD are based on the use of chemically induced IBD or of genetically modified and germ-free animals. It is, however, important to study inflammatory responses that can develop from interactions between bacteria, the mucosal epithelium, and GALT in animals that are not genetically modified or immunocompromised. In this report, we document the use of a germ-free ligated rabbit appendix model to induce inflammatory changes in response to specific bacteria. With the introduction of a Bacteroides vulgatus isolate from humans into the germ-free ligated appendix, we found chronic inflammatory changes, including glandular distortion, gland drop-out, decreased goblet cells, and crypt abscess formation. However, with the introduction of other experimental luminal contents, we observed no inflammation. These results show that specific microbial composition can induce inflammation. We suggest that this model may be useful to study the mechanism by which specific bacteria establish inflammatory responses in the gut.

Bacterial translocation in the normal human appendix parallels the development of the local immune system

Experimental modes and pathological conditions may result in bacterial translocation (BT), that is, the passage of indigenous bacteria colonizing the intestine through the intestinal mucosa to mesenteric lymph nodes. Yet no data are available on BT in the normal human gut. We determined the occurrence of BT and its extent in histologically normal, incidentally removed human vermiform appendices (VA) from individuals of different ages and correlated the findings with the development with age of associated lymphatic tissue. BT appears to pertain to normal antigen-sampling processes of the GALT in the VA. It also parallels the development of the GALT and its maintenance during adulthood. In the first two weeks after birth, when bacterial colonization of the gut evolves and when the VA lacks the protection of secretory IgA, BT was not detected. Thereafter, BT occurs along with development of the local GALT, which is fully built up after the first year. A physiological uptake of, or invasion by, bacteria may be instrumental (1) for tolerance induction against the indigenous flora and (2) for the stimulation and normal development of the GALT.

Interaction of pathogenic bacteria with rabbit appendix M cells: bacterial motility is a key feature in vivo

Rabbit appendix consists mainly of lymphoid follicles (LF) covered by M cells, the specialized antigen-sampling cells of the mucosal immune system, and surrounded by glandular epithelium. Until now, these M cells have been characterized morphologically and histologically by using cellular markers. Here, the adhesion and transport of pathogenic bacteria were investigated to assess the function of M cells of the appendix. We used the enteroinvasive motile Salmonella typhimurium and the rabbit enteropathogenic non-motile Escherichia coli RDEC-1, which are known to target specifically rabbit M cells of Peyer's patches (PPs). We found that S. typhimurium efficiently attached and was transported through appendix M cells in vivo. In contrast to S. typhimurium, RDEC-1 targeted M cells only ex vivo, when bacteria were allowed to have direct contact with the surface of the follicle. The difference in interaction of the two bacteria with appendix M cells led us to investigate whether this could be correlated with the lack of motility of RDEC-1. We used an aflagellate mutant of S. typhimurium and found that it had the same infection phenotype as RDEC-1. Gene complementation restored the efficiency of infection to that of S. typhimurium wild-type strain. In conclusion, we show that M cells of the appendix display features of the canonical M cells of PP, since they efficiently sample luminal pathogenic bacteria. However, due to the morphology of the appendix, motile bacteria appear to be more potent in their interactions with appendix M cells.

[The role of enteropathogenic infection, local immunity, and autosensibilisation in pathogenesis of acute surgical diseases of peritoneal cavity by the example of acute appendicitis]

The complex of interrelated pathogenic factors in development of postoperative suppurative inflammatory complication with abdominal cavity organs lesion was studied on the example of an acute appendicitis. It includes enteropathogenic microorganisms, insufficiency of local immunity, deficiency of immunoglobulins, lysozym. Findings show the possibility in seeking the measures of prevention of emergent state, in particular, an acute appendicitis.

Role of commensal bacteria in development of gut-associated lymphoid tissues and preimmune antibody repertoire

Intestinal bacteria are required for development of gut-associated lymphoid tissues (GALT), which mediate a variety of host immune functions, such as mucosal immunity and oral tolerance. In rabbits, the intestinal microflora are also required for developing the preimmune Ab repertoire by promoting somatic diversification of Ig genes in B cells that have migrated to GALT. We studied the mechanism of bacteria-induced GALT development. Bacteria were introduced into rabbits in which the appendix had been rendered germfree by microsurgery (we refer to these rabbits as germfree-appendix rabbits). We then identified specific members of the intestinal flora that promote GALT development. The combination of Bacteroides fragilis and Bacillus subtilis consistently promoted GALT development and led to development of the preimmune Ab repertoire, as shown by an increase in somatic diversification of VDJ-C micro genes in appendix B cells. Neither species alone consistently induced GALT development, nor did Clostridium subterminale, Escherichia coli, or Staphylococcus epidermidis. B. fragilis, which by itself is immunogenic, did not promote GALT development; hence, GALT development in rabbits does not appear to be the result of an Ag-specific immune response. To identify bacterial pathways required for GALT development, we introduced B. fragilis along with stress-response mutants of B. subtilis into germfree-appendix rabbits. We identified two Spo0A-controlled stress responses, sporulation and secretion of the protein YqxM, which are required for GALT development. We conclude that specific members of the commensal, intestinal flora drive GALT development through a specific subset of stress responses.

[Actinomycosis of the appendix. Report of two cases]

INTRODUCTION

We report two patients with actinomycosis of the appendix extending to the caecum and the ileum, and diagnosed postoperatively on histological analysis, the authors reviewed the literature.

EXEGESIS

Actinomycosis of the appendix can be acute or chronic. Diagnosis may be obtained preoperatively on the analysis of aspiration or biopsy material under CT scan control. It is frequently done postoperatively on the analysis of surgical specimen. Actinomycosis can be treated with antibiotics only during six months if the diagnosis is made preoperative, by surgery followed by antibiotics during 6-12 months, according to the extension of the actinomycosis, if the diagnosis is made after surgery, and by a combination of a surgery and antibiotics in complex forms.

CONCLUSION

Actinomycosis of the appendix is an infrequent pathology that merits to be known. With antibiotic therapy, we can avoid surgery or wide resections.

Helicobacter pylori infection in patients undergoing appendectomy

AIMS

Helicobacter pylori has been found in the upper gastrointestinal tract; it is incriminated as aetiological factor in various pathological conditions. This prospective study assesses the presence of this microorganism in the appendix flora and the possible role of its infection in the pathogenesis of acute appendicitis.

METHODS

H. pylori was investigated in 46 consecutive patients undergoing emergent appendectomy for presumed acute appendicitis. Blood sample for serological test of H. pylori infection was drawn before operation. The removed appendix specimen was stained for H. pylori; confirmation was made by PCR (Polymerase Chain Reaction) analysis. The intensity of inflammation was determined pathologically grading from no inflammation to gangrenous appendicitis. Statistical analysis was made using the chi-square test.

RESULTS

Seropositivity for H. pylori infection was found in 18 patients (39%), but the microbe was detected in just two appendix specimens (4%). In all seropositive patients acute appendicitis was confirmed by the pathology study; serous (33%) and purulent or gangrenous (67%). The latter incidence in the seronegative patients was 50%. There were found eight specimens (17%) negative for inflammation dealing all with seronegative patients.

CONCLUSIONS

It seems that H. pylori colonizes the appendix in small proportion and is unlikely to be associated in direct correlation with acute appendicitis. However, seropositive patients with acute inflammation are likely to suffer from purulent or gangrenous form.

Initial nonoperative management for periappendiceal abscess

PURPOSE

Our goal was to compare initial operative and nonoperative management for periappendiceal abscess complicating appendicitis.

METHODS

This study is a retrospective review of 155 consecutive patients with appendicitis complicated by periappendiceal abscess treated between 1992 and 1998. Eighty-eight patients were treated initially nonoperatively, and 67 patients were treated operatively. All patients had localized abdominal tenderness and either computed tomography or intraoperative documentation of an abscess.

RESULTS

Our patient population consisted of 107 males and 48 females, with an average age of 33 (range, 16-75) years. Age, gender, comorbidity, white blood cell count, temperature, and heart rate did not differ significantly between groups. For the initial nonoperative management group, the failure rate was 5.8 percent and the appendicitis recurrence rate was 8 percent after a mean follow-up of 36 weeks. The response to treatment of the initial nonoperative group and the initial operative group was compared by length of stay (9 +/- 5 days vs. 9 +/- 3 days; P = not significant), days until white blood cell count normalized (3.8 +/- 4 days vs. 3.1 +/- 3 days; P = not significant), days until temperature normalized (3.2 +/- 3 days vs. 3.1 +/- 2 days; P = not significant), and days until a regular diet was tolerated (4.7 +/- 4 days vs. 4.6 +/- 3 days; P = not significant). Complication rate was significantly lower in the nonoperative group (17 vs. 36 percent; P = 0.008).

CONCLUSIONS

Initial nonoperative management of appendicitis complicated by periappendiceal abscess is safe and effective. Patients undergoing initial nonoperative management have a lower rate of complications, but they are at risk for recurrent appendicitis.

Mycobacterial spindle cell pseudotumor of the appendix vermiformis in a patient with aids

Mycobacterial pseudotumor (MP) is a rare pathologic presentation of both Mycobacterium tuberculosis and non-tuberculous mycobacterial disease, hitherto reported to occur only in immunosuppressed patients with or without human immunodeficiency virus infection. This lesion shares close pathologic resemblance to certain mesenchymal neoplasms, particularly Kaposi's sarcoma (KS), from which it must be properly differentiated due to distinct prognosis and therapy. We report a case of MP obliterating the lumen of the appendix vermiformis in a 34-year-old patient who died of complications of AIDS at our hospital in Rio de Janeiro. A total of 24 cases of MP (including our patient) have been described in the literature. MP has been found especially in lymph nodes, but extranodal lesions have been described in the skin, spleen, lung, bone marrow, brain and, in our patient, the appendix vermiformis. We offer a review of the other 23 published case reports of MP in both HIV-infected and uninfected patients and discuss the pathologic features that differentiate MP from KS.

The role of Yersinia enterocolitica and Yersinia pseudotuberculosis in granulomatous appendicitis: a histologic and molecular study

Granulomatous appendicitis is an enigmatic entity. Purported causes include Crohn's disease, foreign body reactions, sarcoidosis, and infectious agents; however, most cases remain idiopathic. Yersinia enterocolitica (YE) and Y. pseudotuberculosis (YP) have been implicated as causes of appendicitis, ileocolitis, and mesenteric adenitis. The authors examined the potential role of YE and YP in granulomatous appendicitis using histologic and molecular methods. Forty cases of granulomatous appendicitis were evaluated for histologic features including transmural inflammation, number and character of granulomas, and mucosal changes. Twort Gram, Grocott methenamine-silver (GMS), and Ziehl-Neelsen stains were evaluated, and polymerase chain reaction (PCR) analysis was performed to identify pathogenic YP and YE. Twenty-five percent (10 of 40) of the cases were positive for pathogenic Yersinia by PCR (four YE, four YP, and two with both species). Prominent histologic features included epithelioid granulomas with lymphoid cuffing, transmural inflammation with lymphoid aggregates, mucosal ulceration, and cryptitis. One Yersinia-positive case contained mural Gram-negative bacilli; fungal and acid-fast bacilli stains were all negative. Except for one culture-negative case, serologies and cultures were not done or results were unavailable. Two Yersinia-positive patients were diagnosed subsequently with Crohn's disease, suggesting a possible relationship between the two entities. No other patients developed significant sequelae. YE and YP are important causes of granulomatous appendicitis, and Yersinia infection may mimic Crohn's disease. No histologic features distinguish reliably between Yersinia species, or between Yersinia-positive and Yersinia-negative cases. Because special stains and cultures are often not diagnostic, PCR analysis is an excellent technique for the diagnosis of Yersinia.

In vitro antibiotic susceptibility of Bacteroides fragilis strains isolated from excised appendix of patients with phlegmonous or gangrenous appendicitis

Out of 34 studied after-appendectomy tissues of adult and child patients 86 different strains of anaerobes were isolated. The antibiotic susceptibility of 30 isolated B. fragilis strains was tested using E tests. All studied strains were sensitive to imipenem, clindamycin and penicillin/tazobactam. Sensitivity to penicillin and cefoxitin was variable among these strains. One strain resistant to metronidazole (MIC--256 mg/L) and 3 strains with increased MIC to metronidazole were detected. Most of isolated strains were beta-lactamase producers.

Intestinal microflora and diversification of the rabbit antibody repertoire

The rabbit establishes its primary Ab repertoire by somatically diversifying an initial repertoire that is limited by restricted VH gene segment usage during VDJ gene rearrangement. Somatic diversification occurs in gut-associated lymphoid tissue (GALT), and by about 1-2 mo of age nearly all Ig VDJ genes are somatically diversified. In other species that are known to establish their primary Ab repertoire by somatic diversification, such as chicken, sheep, and cattle, diversification appears to be developmentally regulated: it begins before birth and occurs independent of exogenous factors. Because somatic diversification in rabbit occurs well after birth in GALT, the diversification process may not be developmentally regulated, but may require interaction with exogenous factors derived from the gut. To test this hypothesis, we examined Ab repertoire diversification in rabbits in which the appendix was ligated shortly after birth to prevent microbial colonization and all other organized GALT was surgically removed. We found that by 12 wk of age nearly 90% of the Ig VDJ genes in PBL were undiversified, indicating that intestinal microflora are required for somatically diversifying the Ab repertoire. We also examined repertoire diversification in sterilely derived remote colony rabbits that were hand raised away from contact with conventional rabbits and thereby acquired a different gut microflora. In these remote colony rabbits, GALT was underdeveloped, and 70% of the Ig VDJ genes in PBL were undiversified. We conclude that specific, currently unidentified intestinal microflora are required for Ab repertoire diversification.

Comparative in vitro activities of trovafloxacin (CP-99,219) against 221 aerobic and 217 anaerobic bacteria isolated from patients with intra-abdominal infections

Four hundred thirty-eight bacteria cultured from specimens of patients with serious intra-abdominal infections were tested by agar dilution against trovafloxacin and other quinolones and antimicrobial agents. Trovafloxacin inhibited 435 strains (99.3%) at < or =2 microg/ml. All the quinolones had similar activities against Enterobacteriaceae and Pseudomonas sp., but trovafloxacin showed superior activities against streptococci, enterococci, and anaerobic organisms. Because of its excellent in vitro activities against diverse bacteria, trovafloxacin has potential use as a single agent for polymicrobial infections.

Characteristics of an unusual anaerobic pigmented gram-negative rod isolated from normal and inflamed appendices

During our studies of the bacterial etiology of appendicitis, we often isolated a previously undescribed anaerobic gram-negative rod. This organism resembled the Bacteroides fragilis group because it was resistant to bile and because of its special-potency-disk pattern (resistant to vancomycin, kanamycin, and colistin), but unlike the B. fragilis group, this bacterium produced brown pigment on media containing hemolysed blood. The cellular fatty acid pattern, with iso-C15:0 being the predominant acid, was most closely related to the fatty acid profile of Porphyromonas species; however, this organism differed from Porphyromonas species by being bile-resistant and by not producing butyrate as a metabolic endproduct. Enzymatic activities of 31 isolates were determined with use of the API ZYM system and Rosco diagnostic tablets. These profiles were different from those of Prevotella, Porphyromonas, and related species. This organism was isolated from 40% of appendiceal tissue samples; no obvious qualitative or quantitative difference in rates of isolation from patients with inflamed or normal appendices was observed.

Efficacy of azithromycin and rifabutin in preventing infection by Mycobacterium avium complex in beige mice

We investigated the potential of the azalide, azithromycin, and rifabutin in preventing disseminated infection due to Mycobacterium avium complex (MAC) in beige mice. Azithromycin 200 mg/kg, rifabutin (30 mg/kg or 60 mg/kg) were administered by gavage 6 days before mice were challenged orally with 10(8) cfu MAC and daily for 10 days thereafter during which time the mice were again challenged with the same inoculum on alternate days (days +1, +3, +5, +7, and +9). Sixty-four days later, the presence of bacteria in the blood and the number of viable bacteria in liver, spleen and appendix were estimated. Treatment with azithromycin and 60 mg/kg/day rifabutin but not 30 mg/kg/day, significantly decreased the incidence of bacteraemia and the number of bacteria in the appendix. The administration of azithromycin resulted in significantly fewer MAC in the liver and spleen but not in the appendix whereas the converse was true of 60 mg/kg rifabutin. Our results indicate that both azithromycin and rifabutin can prevent MAC disseminated infection, but that the azalide is more effective than the rifamycin in reducing the burden of infection.

Eikenella corrodens as an intra-abdominal pathogen

Eikenella corrodens is a facultative anaerobe found as normal flora in the oral cavity, gastrointestinal system, and genitourinary tracts. It is most often associated with infections of the head and neck or those due to human bite wounds. However, the organism can be an important pathogen in intra-abdominal infections. Our case report and review of the literature revealed 19 cases of E. corrodens infections of the intra-abdominal cavity. The most common intra-abdominal site of infection was the appendix, noted in seven of the 19 reported cases. Abscess formation was noted in 15 of the 19 reports. The clinical course of the infection in most patients appeared to be indolent, evolving over several days. The majority (11 of 19) of patients described in these cases were less than 25 years old. E. corrodens is usually found concomitantly with other organisms. There appears to be a specific association between E. corrodens and streptococcal species. The drugs of choice for treatment of infections due to E. corrodens are ampicillin, penicillin, or a second generation cephalosporin. This organism is resistant to drugs traditionally active against anaerobic organisms, such as clindamycin and metronidazole.

Intestinal spirochetosis in children: report of two cases

Two cases of intestinal spirochetosis in two children are reported. The first patient, a 7 1/2-year-old boy, presented with diarrhea and rectal bleeding. After the diagnosis was made by a rectal biopsy, he was given metronidazole and neomycin. Symptoms persisted despite a further rectal biopsy that showed clearance of the organisms. Appendiceal spirochetosis was an incidental finding in our second patient, an 8-year-old girl who presented with acute abdominal pain and in whom mesenteric adenitis was diagnosed clinically at laparotomy. The possible pathogenic mechanisms causing clinical symptoms are discussed.