A prospective controlled study of the association of Streptococcus bovis with colorectal carcinoma

Association of the Streptococcus bovis/Streptococcus equinus Complex With Colorectal Neoplasia: A Systematic Review and Meta-analysis

Background

Invasive infection with Streptococcus bovis/Streptococcus equinus complex (SBSEC) bacteria is associated with underlying colorectal neoplasia. However, the link between intestinal or fecal colonization with SBSEC isolates or antibody responses to SBSEC members and colorectal cancer is not thoroughly investigated in the literature.

Methods

We searched the PubMed, EMBASE, and Web of Science databases for case-control studies as well as retrospective or prospective cohort studies reporting an association between SBSEC bacteria and colorectal neoplasia.

Results

We identified 22 studies (15 case-control and 7 cohort) that met our inclusion criteria. Among the cohort studies, patients with SBSEC bacteremia were 3.73 times more likely to have underlying colorectal cancer compared with individuals with no bacteremia (relative risk [RR], 3.73; 95% CI, 2.79-5.01), whereas the risk of underlying colorectal adenoma in patients with SBSEC bacteremia was not significantly increased (RR, 5.00; 95% CI, 0.83-30.03). In case-control studies, patients with colorectal cancer were 2.27 times more likely to have evidence of intestinal or fecal colonization with SBSEC isolates (odds ratio [OR], 2.27; 95% CI, 1.11-4.62) and immunoglobulin G (IgG) antibody responses to SBSEC antigens (OR, 2.27; 95% CI, 1.06-4.86) compared with controls. Patients with colorectal adenoma were not more likely to be colonized with SBSEC isolates compared with controls (OR, 1.12; 95% CI, 0.55-2.25).

Conclusions

Apart from the well-established association of SBSEC bacteremia and underlying colorectal cancer, intestinal or fecal colonization with SBSEC isolates and IgG antibody responses to SBSEC antigens were higher in patients with colorectal cancer compared with controls. Neither bacteremia from SBSEC isolates nor colonization with SBSEC bacteria was associated with underlying colorectal adenoma.

Microbiota's role in health and diseases

The microbiome is a term that usually refers to the community of various microorganisms that inhabit/live inside human/animal bodies or on their skin. It forms a complex ecosystem that includes trillions of commensals, symbiotics, and even pathogenic microorganisms. The external environment, diet, and lifestyle are the major determinants influencing the microbiome's composition and vitality. Recent studies have indicated the tremendous influence of the microbiome on health and disease. Their number, constitution, variation, and viability are dynamic. All these elements are responsible for the induction, development, and treatment of many health disorders. Serious diseases such as cancer, metabolic disorders, cardiovascular diseases, and even psychological disorders such as schizophrenia are influenced directly or indirectly by microbiota. In addition, in the last few weeks, accumulating data about the link between COVID-19 and the microbiota were published. In the present work, the role of the microbiome in health and disease is discussed. A deep understanding of the exact role of microbiota in disease induction enables the prevention of diseases and the development of new therapeutic concepts for most diseases through the correction of diet and lifestyle. The present review brings together evidence from the most recent works and discusses suggested nutraceutical approaches for the management of COVID-19 pandemic.

The Road to Infection: Host-Microbe Interactions Defining the Pathogenicity of Streptococcus bovis/Streptococcus equinus Complex Members

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises several species inhabiting the animal and human gastrointestinal tract (GIT). They match the pathobiont description, are potential zoonotic agents and technological organisms in fermented foods. SBSEC members are associated with multiple diseases in humans and animals including ruminal acidosis, infective endocarditis (IE) and colorectal cancer (CRC). Therefore, this review aims to re-evaluate adhesion and colonization abilities of SBSEC members of animal, human and food origin paired with genomic and functional host-microbe interaction data on their road from colonization to infection. SBSEC seem to be a marginal population during GIT symbiosis that can proliferate as opportunistic pathogens. Risk factors for human colonization are considered living in rural areas and animal-feces contact. Niche adaptation plays a pivotal role where Streptococcus gallolyticus subsp. gallolyticus (SGG) retained the ability to proliferate in various environments. Other SBSEC members have undergone genome reduction and niche-specific gene gain to yield important commensal, pathobiont and technological species. Selective colonization of CRC tissue is suggested for SGG, possibly related to increased adhesion to cancerous cell types featuring enhanced collagen IV accessibility. SGG can colonize, proliferate and may shape the tumor microenvironment to their benefit by tumor promotion upon initial neoplasia development. Bacteria cell surface structures including lipotheichoic acids, capsular polysaccharides and pilus loci (pil1, pil2, and pil3) govern adhesion. Only human blood-derived SGG contain complete pilus loci and other disease-associated surface proteins. Rumen or feces-derived SGG and other SBSEC members lack or harbor mutated pili. Pili also contribute to binding to fibrinogen upon invasion and translocation of cells from the GIT into the blood system, subsequent immune evasion, human contact system activation and collagen-I-binding on damaged heart valves. Only SGG carrying complete pilus loci seem to have highest IE potential in humans with significant links between SGG bacteremia/IE and underlying diseases including CRC. Other SBSEC host-microbe combinations might rely on currently unknown mechanisms. Comparative genome data of blood, commensal and food isolates are limited but required to elucidate the role of pili and other virulence factors, understand pathogenicity mechanisms, host specificity and estimate health risks for animals, humans and food alike.

Streptococcus bovis prosthetic valve endocarditis associated with silent colonic carcinoma

A 75-year-old woman was admitted to our hospital with a 3-month history of fever. Of note, she had a bioprosthetic mitral valve replacement 1 year prior to admission. Streptococcus bovis was isolated from three sets of blood cultures. An echocardiogram showed a flickering mass attached to the bioprosthesis. Her blood culture became sterile by the fourth day of ceftriaxone therapy. In spite of the absence of gastrointestinal symptoms, screening colonoscopy revealed an invasive colonic adenocarcinoma. The association linking S. bovis endocarditis and colonic tumours is well recognised. However, despite early reports of this association by Klein et al in 1979, a large number of practising physicians remain unaware of this phenomenon. This lack of awareness results in lost opportunities for early diagnosis and, consequently, improved outcome in such patients. Our report emphasises this association in an area with a low incidence of S. bovis endocarditis.

Gut microbiota, inflammation and colorectal cancer

Although genes contribute to colorectal cancer, the gut microbiota are an important player. Accumulating evidence suggests that chronic infection and the ensuing inflammation contributes to tumor initiation and tumor progression. A variety of bacterial species and tumor-promoting virulence mechanisms have been investigated. Significant advances have been made in understanding the composition and functional capabilities of the gut microbiota and its roles in cancer. In the current review, we discuss the novel roles of microbiota in the progression of colon cancer. Although microbiota technically include organisms other than bacteria e.g., viruses and fungi, this review will primarily focus on bacteria. We summarize epidemiological studies of human microbiome and colon cancer. We discuss the progress in the scientific understanding of the interplay between the gut microbiota, barrier function, and host responses in experimental models. Further, we discuss the potential application in prevention, diagnosis, and therapy of colon cancer by targeting microbiota. We discuss the challenges lie ahead and the future direction in studying gut microbiome in colon cancer to close the gap between the basic sciences and clinical application.

Gut microbiota imbalance and colorectal cancer

The gut microbiota acts as a real organ. The symbiotic interactions between resident micro-organisms and the digestive tract highly contribute to maintain the gut homeostasis. However, alterations to the microbiome caused by environmental changes (e.g., infection, diet and/or lifestyle) can disturb this symbiotic relationship and promote disease, such as inflammatory bowel diseases and cancer. Colorectal cancer is a complex association of tumoral cells, non-neoplastic cells and a large amount of micro-organisms, and the involvement of the microbiota in colorectal carcinogenesis is becoming increasingly clear. Indeed, many changes in the bacterial composition of the gut microbiota have been reported in colorectal cancer, suggesting a major role of dysbiosis in colorectal carcinogenesis. Some bacterial species have been identified and suspected to play a role in colorectal carcinogenesis, such as Streptococcus bovis, Helicobacter pylori, Bacteroides fragilis, Enterococcus faecalis, Clostridium septicum, Fusobacterium spp. and Escherichia coli. The potential pro-carcinogenic effects of these bacteria are now better understood. In this review, we discuss the possible links between the bacterial microbiota and colorectal carcinogenesis, focusing on dysbiosis and the potential pro-carcinogenic properties of bacteria, such as genotoxicity and other virulence factors, inflammation, host defenses modulation, bacterial-derived metabolism, oxidative stress and anti-oxidative defenses modulation. We lastly describe how bacterial microbiota modifications could represent novel prognosis markers and/or targets for innovative therapeutic strategies.

Colonic carriage of Streptococcus bovis and colorectal neoplasia: a prospective 17-year longitudinal case-control study

BACKGROUND

Patients with Streptococcus bovis infective endocarditis have an increased prevalence of advanced colonic neoplasia; however, an association with fecal carriage of the organism is unclear. S. bovis has been shown to promote colonic neoplasia in preclinical studies. The aim of this study was to examine the effect of S. bovis fecal carriage on the long-term risk of colonic neoplasia.

PATIENTS AND METHODS

Patients were prospectively recruited before colonoscopy. S. bovis was detected by culture in stool, colonic fluid aspirates, and biopsies. Patients continued colonoscopic surveillance at intervals according to accepted guidelines. The National Cancer Registry was checked for diagnoses of colorectal cancer on 31 December 2014.

RESULTS

A total of 118 patients were recruited [75 (72.8%) men, aged 64.5±9.3 years] including 15 with S. bovis. The mean duration of follow-up was 190.7±123.5 months. Colonic neoplasia was detected at colonoscopy in six (40.0%) and 49 (47%) patients with and without S. bovis, respectively (P=0.78). At the end of follow-up, colorectal cancer had developed in one (6.7%) S. bovis-positive and six (5.8%) S. bovis-negative patients (P=1.00).

CONCLUSION

Fecal carriage of S. bovis at baseline is not associated with an increased long-term risk of developing colonic neoplasia in this longitudinal study.

Association of Streptococcus gallolyticus subspecies gallolyticus with colorectal cancer: Serological evidence

The colonic opportunist Streptococcus gallolyticus subspecies gallolyticus (SGG) is potentially associated with colorectal cancer (CRC). Large-scale seroepidemiological data for SGG antibodies and their possible association with CRC is currently missing. Associations between CRC and antibody responses to SGG were examined in 576 CRC cases and 576 controls matched by sex, age and province from a population-based multicase-control project (MCC-Spain). MCC-Spain was conducted between 2008 and 2013 in 12 Spanish provinces. Antibody responses to recombinant affinity-purified SGG pilus proteins Gallo1569, 2039, 2178 and 2179 were analysed by multiplex serology. Polyomavirus (PyV) JC VP1 and PyV 6 VP1 proteins served as disease-specificity controls. In the control population, antibody responses to pilus proteins were mostly weak. Antibody responses to individual pilus proteins Gallo2039 (OR: 1.58, 95% CI: 1.09-2.28), Gallo2178 (OR: 1.58, 95% CI: 1.09-2.30) and Gallo2179 (OR: 1.45, 95% CI: 1.00-2.11) were significantly associated with CRC risk. The association was stronger for positivity to two or more pilus proteins of Gallo1569, Gallo2178 and Gallo2179 (OR:1.93, 95% CI: 1.04-3.56) and for double-positivity to Gallo2178 and Gallo2179 (OR: 3.54, 95% CI: 1.49-8.44). The association between SGG infection and CRC risk was stronger among individuals younger than 65 years. For the first time we demonstrated a statistically significant association of exposure to SGG antigens and CRC in a large seroepidemiological study. These results should stimulate further studies on the role of SGG in CRC pathogenesis.

The potential for fungal biopesticides to reduce malaria transmission under diverse environmental conditions

The effectiveness of conventional malaria vector control is being threatened by the spread of insecticide resistance. One promising alternative to chemicals is the use of naturally-occurring insect-killing fungi. Numerous laboratory studies have shown that isolates of fungal pathogens such as Beauveria bassiana can infect and kill adult mosquitoes, including those resistant to chemical insecticides.Unlike chemical insecticides, fungi may take up to a week or more to kill mosquitoes following exposure. This slow kill speed can still reduce malaria transmission because the malaria parasite itself takes at least eight days to complete its development within the mosquito. However, both fungal virulence and parasite development rate are strongly temperature-dependent, so it is possible that biopesticide efficacy could vary across different transmission environments.We examined the virulence of a candidate fungal isolate against two key malaria vectors at temperatures from 10-34 °C. Regardless of temperature, the fungus killed more than 90% of exposed mosquitoes within the predicted duration of the malarial extrinsic incubation period, a result that was robust to realistic diurnal temperature variation.We then incorporated temperature sensitivities of a suite of mosquito, parasite and fungus life-history traits that are important determinants of malaria transmission into a stage-structured malaria transmission model. The model predicted that, at achievable daily fungal infection rates, fungal biopesticides have the potential to deliver substantial reductions in the density of malaria-infectious mosquitoes across all temperatures representative of malaria transmission environments.Synthesis and applications. Our study combines empirical data and theoretical modelling to prospectively evaluate the potential of fungal biopesticides to control adult malaria vectors. Our results suggest that Beauveria bassiana could be a potent tool for malaria control and support further development of fungal biopesticides to manage infectious disease vectors.

Invasive streptococcal disease: a review for clinicians

INTRODUCTION

Streptococci are a genus of Gram-positive bacteria which cause diverse human diseases. Many of these species have the potential to cause invasive infection resulting from the presence of bacteria in a normally sterile site.

SOURCES OF DATA

Original articles, reviews and guidelines.

AREAS OF AGREEMENT

Invasive infection by a streptococcus species usually causes life-threatening illness. When measured in terms of deaths, disability and cost, these infections remain an important threat to health in the UK. Overall they are becoming more frequent among the elderly and those with underlying chronic illness. New observational evidence has become available to support the use of clindamycin and intravenous immunoglobulin in invasive Group A streptococcal disease.

AREAS OF CONTROVERSY

Few interventions for the treatment and prevention of these infections have undergone rigorous evaluation in clinical trials. For example, the role of preventative strategies such as screening of pregnant women to prevent neonatal invasive Group B streptococcal disease needs to be clarified.

FUTURE PROSPECTS

Studies of invasive streptococcal disease are challenging to undertake, not least because individual hospitals treat relatively few confirmed cases. Instead clinicians and scientists must work together to build national and international networks with the aim of developing a more complete evidence base for the treatment and prevention of these devastating infections.

Association of Streptococcus bovis presence in colonic content with advanced colonic lesion

AIM: To prospectively examine the association between presence of Streptococcus bovis (S. bovis) in colonic suction fluid and the endoscopic findings on colonoscopy.

METHODS: From May 2012 to March 2013, 203 consecutive patients who underwent colonoscopy for any reason were enrolled in the study. Exclusion criteria included: antibiotic use in the previous month, age younger than 18 years, and inadequate preparation for colonoscopy. The colonoscopy was performed for the total length of the colon or to the occluding tumor. The endoscopic findings were registered. Samples were obtained proximal to the colonoscopic part of the suction tube from each patient and sent to the clinical microbiology laboratory for isolation and identification of S. bovis. Samples were incubated in enrichment media with addition of antibiotic disks for inhibition of growth of Gram-negative rods. The samples were seeded on differential growth media; suspected positive colonies were isolated and identified with Gram staining, catalase, and pyrrolidonyl arylamidase tests, and further identified using a VITEK2 system. Statistical analyses were performed using the Student’s t and χ² tests.

RESULTS: Of the 203 patients recruited, 49 (24%) patients were found to be S. bovis carriers; of them, the endoscopic findings included: 17 (34.7%) cases with malignant tumors, 11 (22.4%) with large polyps, 5 (10.2%) with medium-sized polyps, 6 (12.2%) with small polyps, 4 (8.1%) with colitis, and 6 (12.2%) normal colonoscopies. Of 154 patients found negative for S. bovis, the endoscopic findings included: none with malignant tumors, 9 (5.8%) cases with large polyps, 11 (7.1%) with medium-sized polyps, 26 (16.9%) with small polyps, 7 (4.5%) with colitis, and 101 (65.6%) normal colonoscopies. S. bovis (Gram-positive coccus) is considered part of the normal intestinal flora. There is an association between S. bovis bacteremia and colonic neoplasia. It is not well understood whether the bacterium has a pathogenetic role in the development of neoplasia or constitutes an epiphenomenon of colorectal neoplasms. There was a clear relationship between positivity for S. bovis in colonic suction fluid and findings of malignant tumors and large polyps in the colon.

CONCLUSION: There is an association between S. bovis bacteremia and malignant colonic lesions; this should prompt for development of a reliable screening method for advanced colonic lesions.

Streptococcus bovis infection and colorectal neoplasia: a meta-analysis

AIM

A meta-analysis was conducted to determine the risk associated with Streptococcus bovis infection and the occurrence of colorectal neoplasia (CRN). The level of risk remains unknown.

METHOD

We conducted a search of MEDLINE, PubMed and EMBASE up to January 2014. We used a random-effects model to analyse the data.

RESULTS

We identified 48 studies concerning three main topics: S. bovis septicaemia, S. bovis endocarditis and S. bovis faecal carriage. The total sample sizes were 1729, 807 and 1145, respectively; the 48 studies included 9 case-control studies and 39 case series. Overall, the presence of S. bovis infection was found to be significantly associated with the presence of CRN. Streptococcus bovis endocarditis showed the strongest association in analyses of case-control studies and case series (OR 14.54, 95% CI 5.66-37.35, test for heterogeneity I2 = 43.53; event rate of 0.53, 95% CI 0.45-0.61, test for heterogeneity I2 = 53.50). Similarly, S. bovis septicaemia was also associated with a high level of concurrence with CRN (OR 7.48, 95% CI 3.10-18.06, test for heterogeneity I(2) = 43.32; event rate 0.49, 95% CI 0.42-0.56, test for heterogeneity I2 = 69.97). Patients with CRN were found to have a higher incidence of S. bovis in faeces upon stool culture (OR 2.52, 95% CI 1.14-5.58, test for heterogeneity I2 = 69.17).

CONCLUSION

The meta-analysis showed a statistically significant association between the presence of S. bovis endocarditis or S. bovis septicaemia and CRN. Furthermore, there is a statistically significant increase in likelihood of finding S. bovis in the stool of individuals with CRN.

Streptococcus gallolyticus bacteraemia in hepatobiliary-pancreatic and colonic pathologies

BACKGROUND

Streptococcus gallolyticus bacteraemia has been associated with several pathologies, including bacterial endocarditis and colorectal cancer.

AIMS

In this study, we have analysed whether Streptococcus gallolyticus bacteraemia is associated with an increased risk of hepatobiliary and colonic pathology. The association with other pathologies and the antibiotic sensitivities of Streptococcus gallolyticus were also analysed.

DESIGN

Observational retrospective study.

METHODS

The case notes of patients with documented Streptococcus gallolyticus bacteraemia between 2007 and 2012 at Mater Dei hospital (Malta) were reviewed. Demographic and clinical data, including co-morbidities, clinical investigations, antibiotic sensitivities and mortality were analysed.

RESULTS

A total of 42 patients (33 males, 9 females) were recruited. Two patients were pre-term infants and were therefore excluded from the study. Mean age of the cohort population studied was 72 years (SD ± 14). One-year survival rate was 62%. Gastrointestinal (colonic and hepatobiliary-pancreatic) pathologies were present in 59.5% of patients with 16% of this group having more than one gastrointestinal pathology. High incidence rates of underlying diabetes mellitus (28.6%), valvular heart disease (21.4%) and malignancies (21.4%) were noted in this study. Furthermore, we observed that 14.3% of patients had an underlying respiratory pathology. Streptococcus gallolyticus was 100% sensitive to cefotaxime and vancomycin but was highly resistant to clindamycin, erythromycin and tetracycline.

CONCLUSION

Streptococcus gallolyticus bacteraemia is commoner in the elderly and in those with multiple underlying co-morbidities. The high incidence of gastrointestinal pathologies among patients with Streptococcus gallolyticus bacteraemia (59.5%) suggests that a thorough work-up for colonic and hepatobiliary/pancreatic pathology should be carried out in these patients.

Gut bacteria in health and disease: a survey on the interface between intestinal microbiology and colorectal cancer

A healthy human body contains at least tenfold more bacterial cells than human cells and the most abundant and diverse microbial community resides in the intestinal tract. Intestinal health is not only maintained by the human intestine itself and by dietary factors, but is also largely supported by this resident microbial community. Conversely, however, a large body of evidence supports a relationship between bacteria, bacterial activities and human colorectal cancer. Symbiosis in this multifaceted organ is thus crucial to maintain a healthy balance within the host-diet-microbiota triangle and accordingly, changes in any of these three factors may drive a healthy situation into a state of disease. In this review, the factors that sustain health or drive this complex intestinal system into dysbiosis are discussed. Emphasis is on the role of the intestinal microbiota and related mechanisms that can drive the initiation and progression of sporadic colorectal cancer (CRC). These mechanisms comprise the induction of pro-inflammatory and pro-carcinogenic pathways in epithelial cells as well as the production of (geno)toxins and the conversion of pro-carcinogenic dietary factors into carcinogens. A thorough understanding of these processes will provide leads for future research and may ultimately aid in development of new strategies for CRC diagnosis and prevention.

Significant Association of Streptococcus bovis with Malignant Gastrointestinal Diseases

Streptococcus bovis is a Gram-positive bacterium causing serious human infections, including endocarditis and bacteremia, and is usually associated with underlying disease. The aims of the current study were to compare prevalence of the bacterium associated with malignant and nonmalignant gastrointestinal diseases and to determine the susceptibility of the isolated strains to different antimicrobial agents. The result showed that the prevalence of S. bovis in stool specimens from patients with malignant or with nonmalignant gastrointestinal diseases was statistically significant. This result may support the idea that there is correlation between S. bovis and the malignant gastrointestinal diseases.

Streptococcus bovis peritonitis complicating peritoneal dialysis--a review of 10 years' experience

OBJECTIVE

An association of Streptococcus bovis bacteremia with carcinoma of colon has been reported, but data regarding peritoneal dialysis (PD) peritonitis caused by S. bovis is scarce. In this study, we examined the clinical characteristics, associations, and outcomes of this disease entity.

METHODS

The case records of patients with S. bovis PD peritonitis presenting to 2 renal centers between January 2000 and September 2010 were reviewed. Clinical features and outcomes were identified and analyzed.

RESULTS

Of cultures from 23 episodes of S. bovis peritonitis in 20 patients (1.28% of all peritonitis episodes at our center), 19 (82.6%) showed S. bovis alone, and 4 (17.4%) showed mixed growth. In 7 episodes, the S. bovis was moderately resistant to penicillin G. Rates of resistance to clindamycin and erythromycin were 43.5% and 47.8% respectively. In 18 episodes (78.3%), a primary response was achieved with a first-generation cephalosporin and an aminoglycoside. In 4 episodes, a secondary response was achieved after a switch from cephalosporin to vancomycin, and in 1 episode with mixed growth, the Tenckhoff catheter had to be removed. Repeat peritonitis occurred in 3 patients at a mean of 50.0 months (range: 24.2 - 83.1 months). Of the 20 patients of S. bovis peritonitis, 10 (50%) underwent either a barium enema or a colonoscopy. One patient had history of colonic carcinoma 2 years before the peritonitis, and a subsequent work-up revealed no recurrence. Three patients had diverticulosis, and one had a concomitant sigmoid polyp. Findings in the other 6 patients were normal. No colorectal malignancy had developed in the remaining 10 patients after a mean follow-up of 76.6 months (range: 0.8 - 125.1 months).

CONCLUSIONS

Outcomes in S. bovis PD peritonitis were favorable, and an association with colorectal cancer was not found in our patients. Routine colonoscopy in these patients remains controversial and should be individualized.

The association of Streptococcus bovis/gallolyticus with colorectal tumors: the nature and the underlying mechanisms of its etiological role

Streptococcus bovis (S. bovis) bacteria are associated with colorectal cancer and adenoma. S. bovis is currently named S. gallolyticus. 25 to 80% of patients with S. bovis/gallolyticus bacteremia have concomitant colorectal tumors. Colonic neoplasia may arise years after the presentation of bacteremia or infectious endocarditis of S. bovis/gallolyticus. The presence of S. bovis/gallolyticus bacteremia and/or endocarditis is also related to the presence of villous or tubular-villous adenomas in the large intestine. In addition, serological relationship of S. gallolyticus with colorectal tumors and direct colonization of S. gallolyticus in tissues of colorectal tumors were found. However, this association is still under controversy and has long been underestimated. Moreover, the etiological versus non-etiological nature of this associationis not settled yet. Therefore, by covering the most of up to date studies, this review attempts to clarify the nature and the core of S. bovis/gallolyicus association with colorectal tumors and analyze the possible underlying mechanisms.

Infectious causes of colorectal cancer

Colorectal cancer is a major cause of cancer-related morbidity and mortality in the United States and many other regions of the world. Our understanding of the pathogenesis of colorectal cancer, from the precursor adenomatous polyp to adenocarcinoma, has evolved rapidly. Colorectal carcinogenesis is a sequential process characterized by the accumulation of multiple genetic and molecular alterations in colonic epithelial cells. However, the development of colorectal cancer involves more then just a genetic predisposition. External or environmental factors presumably play a significant role, and inflammatory bowel diseases, obesity, alcohol consumption, and a diet high in fat and low in fiber have all been implicated as risk factors for the development of either colonic adenomas or carcinomas. We are becoming increasingly aware of microbes as causes of malignancies. This article reviews the various microbes that have been associated with the development of colorectal carcinomas.

Molecular detection, quantification, and isolation of Streptococcus gallolyticus bacteria colonizing colorectal tumors: inflammation-driven potential of carcinogenesis via IL-1, COX-2, and IL-8

Background

Colorectal cancer (CRC) has long been associated with bacteremia and/or endocarditis by Streptococcus gallolyticus member bacteria (SGMB) but the direct colonization of SGMB along with its molecular carcinogenic role, if any, has not been investigated. We assessed the colonization of SGMB in CRC patients with history of bacteremia (CRC-w/bac) and without history of bacteremia (CRC-wo/bac) by isolating SGMB from feces, mucosal surfaces of colorectum, and colorectal tissues and detecting SGMB DNA, via PCR and in situ hybridization (ISH) assays targeting SodA gene in colorectal tissues. Moreover, mRNA of IL1, IL-8, COX-2, IFN-γ, c-Myc, and Bcl-2 in colorectal tissues of studied groups was assessed via ISH and RT-PCR.

Results

SGMB were found to be remarkably isolated in tumorous (TU) and non-tumorous (NTU) tissues of CRC-w/bac, 20.5% and 17.3%, and CRC-wo/bac, 12.8% and 11.5%, respectively while only 2% of control tissues revealed SGMB (P < 0.05); such contrast was not found in mucosal and fecal isolation of SGMB. The positive detection of SGMB DNA in TU and NTU of CRC-w/bac and CRC-wo/bac via PCR, 48.7%, 35.9%, 32.7%, and 23%, respectively, and ISH, 46.1%, 30.7%, 28.8%, and 17.3%, respectively, was higher than in control tissues, 4 and 2%, respectively (P < 0.05). SGMB count measured via quantitative PCR of SGMB DNA in terms of copy number (CN), in TU and NTU of CRC-w/bac and CRC-wo/bac, 2.96-4.72, 1.29-2.81, 2.16-2.92, and 0.67-2.07 log₁₀ CN/g respectively, showed higher colonization in TU than in NTU and in CRC-w/bac than in CRC-wo/bac (P < 0.05). The PCR-based mRNA ratio and ISH-based percentage of positively stained cells of IL-1, 1.77 and 70.3%, COX-2, 1.63 and 44.8%, and IL-8, 1.73 and 70.3%, respectively, rather than IFN-γ, c-Myc, and Bcl-2, were higher in SGMB positive patients than in control or SGMB negative patients (P < 0.05).

Conclusions

The current study indicated that colorectal cancer is remarkably associated with SGMB; moreover, molecular detection of SGMB in CRC was superior to link SGMB with CRC tumors highlighting a possible direct and active role of SGMB in CRC development through most probably inflammation-based sequel of tumor development or propagation via, but not limited to, IL-1, COX-2, and IL-8.

Streptococcus bovis endocarditis, a silent sign for colonic tumour

AIM

An association between colonic carcinoma and Streptococcus bovis endocarditis/bacteraemia was first suggested in 1951. This knowledge has great clinical implications, yet we found scant awareness amongst general surgical trainees. The aim of this article was to review the evidence available in the literature and explore the pathophysiology behind this association.

METHOD

The literature was reviewed, between 1950 and 2008, using Pubmed, Embase and Ovid database searches. We utilized different combinations of the keywords: Streptococcus bovis, endocarditis, septicaemia and colon cancer/carcinoma. Quality assessment was determined using the Oxford Centre for Evidence-based Medicine Levels of Evidence (May 2001). Studies were selected based on their relevance to the aims to be addressed.

RESULTS

We included nine case reports and found 24 studies demonstrating an association between S. bovis bacteraemia/endocarditis and colon cancer; the reported incidence in studies was variable (6-67%). The majority of studies (20) were retrospective analysis of data; only four studies were prospective. A total of 12 of 24 studies also reported an association with extra-colonic malignancy (1-22%) and 12 with liver disease (3-57%). Eight studies relevant to the pathophysiology of this association were identified.

CONCLUSION

Streptococcus bovis endocarditis and/or bacteraemia is an early clue to the likely presence of colorectal cancer. Whilst further studies are required to determine the precise pathophysiology, clinicians should be aware of this association. It is advisable to investigate rigorously for colon cancer in all patients presenting with S. bovis endocarditis/bacteraemia; such patients may also present with liver disease or, occasionally, extra-colonic malignancy.

Streptococcus bovis bacteremia related to colon adenoma in a chronic hemodialysis patient

Abstract We report the case of a 54-year-old hemodialysis patient who presented with recurrent fever due to Streptococcus bovis bacteremia related to colonic tubulovillous adenoma. Following polypectomy and broad-spectrum antibiotic therapy, the patient totally recovered. In this paper, we discussed the relation between S. bovis bacteremia, colonic adenomas, and hemodialysis. Awareness of this association is critical for early diagnosis and management.

Infectious agents and colorectal cancer: a review of Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus

Based on the high volume of bacteria and viruses that the intestine is exposed to and the importance of infectious agents in some gastrointestinal and anogenital cancers, it is not surprising the many studies have evaluated the association between colorectal cancer and infectious agents. This review highlights investigations of four agents in relation to colorectal cancer. Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus have all been evaluated as possible etiologic agents for colorectal cancer. For each of these agents, a review of possible mechanisms for carcinogenesis and epidemiologic evidence is discussed, and future directions for research are proposed.

Ecology and pathogenicity of gastrointestinal Streptococcus bovis

Streptococcus bovis is an indigenous resident in the gastrointestinal tracts of both humans and animals. S. bovis is one of the major causes of bacterial endocarditis and has been implicated in the incidence of human colon cancer, possibly due to chronic inflammatory response at the site of intestinal colonization. Certain feeding regimens in ruminants can lead to overgrowth of S. bovis in the rumen, resulting in the over-production of lactate and capsular polysaccharide causing acute ruminal acidosis and bloat, respectively. There are multiple strategies in controlling acute lactic acidosis and bloat. The incidence of the two diseases may be controlled by strict dietary management. Gradual introduction of grain-based diets and the feeding of coarsely chopped roughage decrease the incidence of the two disease entities. Ionophores, which have been used to enhance feed conversion and growth rate in cattle, have been shown to inhibit the growth of lactic acid bacteria in the rumen. Other methods of controlling lactic acid bacteria in the ruminal environment (dietary supplementation of long-chain fatty acids, induction of passive and active immune responses to the bacteria, and the use of lytic bacteriophages) have also been investigated. It is anticipated that through continued in-depth ecological analysis of S. bovis the characteristics responsible for human and animal pathogenesis would be sufficiently identified to a point where more effective control strategies for the control of this bacteria can be developed.

Colonoscopy is mandatory after Streptococcus bovis endocarditis: a lesson still not learned. Case report

Background

Even though the relationship between certain bacterial infections and neoplastic lesions of the colon is well-recognized, this knowledge has not been sufficiently translated into routine practice yet.

Case presentation

We describe the case of a 51-year-old man who was admitted to our Surgical Department due to rectal bleeding and abdominal pain. Preoperative colonoscopy, staging exams and subsequent surgery demonstrated a stenotic adenocarcinoma of the sigmoid colon, invading the left urinary tract and the homolateral bladder wall, with regional lymph nodes involvement and massive bilobar liver metastases (T4N1M1). After Hartmann's rectosigmoidectomy and despite systemic chemotherapy, a rapid progression occurred and the patient survived for only 5 months after diagnosis. Five years before detecting this advanced colonic cancer, the patient underwent aortic valve replacement due to a severe Streptococcus bovis endocarditis. Subsequent to this infection he never underwent a colonoscopy until overt intestinal symptoms appeared.

Conclusion

As this case illustrates, in the unusual setting of a Streptococcus bovis infection, it is necessary to timely and carefully rule out occult colon cancer and other malignancies during hospitalization and, if a tumor is not found, to schedule endoscopic follow-up. Rigorous application of these recommendations in the case described would have likely led to an earlier diagnosis of cancer and maybe saved the patient's life.

Surveillance of patients at increased risk of colon cancer: inflammatory bowel disease and other conditions

Colorectal cancer (CRC) is the second most common cause of cancer-related mortality in the United States. Colonoscopic screening with removal of adenomatous polyps in individuals at average risk is known to decrease the incidence and associated mortality from colon cancer. Certain conditions, notably inflammatory bowel disease involving the colon, a family history of polyps or cancer, a personal history of colon cancer or polyps, and other conditions such as acromegaly, ureterosigmoidostomy, and Streptococcus bovis bacteremia are associated with an increased risk of colonic neoplasia. This article reviews the CRC risks associated with these conditions and the currently recommended surveillance strategies.

Streptococcus suis Endocarditis and Colon Carcinoma: A Case Report

Streptococcus bovis has classically been associated with colorectal carcinomas in literature. Curiously enough, no other Streptococcus species have hitherto been associated with such a malignancy or any other tumors. This report presents a case of early-stage colorectal carcinoma diagnosed in a patient with infection with the related Streptococcus species S suis. A discussion of possible pathogenetic implications follows.

Unusual bacterial infections and colorectal carcinoma--Streptococcus bovis and Clostridium septicum: report of three cases

Several types of unusual bacterial infections have been reported in association with colorectal malignancy. In the three cases described, uncommon infections resulted in further workup and subsequent resection for occult colonic malignancy. Awareness of this association is critical for early diagnosis and management.

Inflammatory bowel disease and Streptococcus bovis

Evidence suggests a trend for a higher fecal carriage rate of Streptococcus bovis in adult patients with inflammatory bowel disease (IBD). This study defines the fecal carriage rate of S. bovis among children with IBD compared to controls. Subjects with IBD were prospectively enrolled from the patient population of a pediatric gastroenterology practice. Stool samples from IBD patients as well as controls were analyzed within 24 hr for the presence of S. bovis. The study enrolled 47 patients with IBD and 34 controls. Among the 47 IBD patients, 3 had a positive stool culture for S. bovis (6%) and 1 had an equivocal result between S. bovis and S. salivarius. Including this equivocal result, 8.5% of IBD patients were S. bovis carriers. Among the 34 controls, 3 (9%) were found to be fecal carriers of S. bovis. Assuming that the equivocal stool was indeed S. bovis, these groups are not statistically different as determined by Fisher's exact test (P=0.6). We conclude that the fecal carriage rate of S. bovis is not increased among pediatric patients with IBD compared with controls.

[Streptococcus milleri. An early sign of cancer in otorhinolaryngologic patients?]

The Streptococcus milleri group, which also includes S. anginosus, S. intermedius and S. constellatus, is found in the oropharynx and gastrointestinal tract mucosa. Recent isolations of S. milleri DNA sequences have been made from both gastric and oesophageal carcinoma. There are only a few publications on the isolation of viable bacteria and S. milleri DNA, and their role in carcinogenesis, in otorhinolaryngologic malignoma. We present four patients with a cervical abscess and the isolation of S. milleri -group bacteria, without signs of malignancy or other risk factors. After a delay of several months, squamous cell carcinoma of the oropharynx was diagnosed in three patients and a neck metastasis without primary tumor in the fourth.

Continuous ambulatory peritoneal dialysis-related peritonitis caused by Streptococcus bovis

The first case of Streptococcus bovis peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD) in a 40-year-old Chinese woman suffering from systemic lupus erythematosus is reported. Streptococcus bovis is part of the normal flora in the human intestine and, less commonly, the female genital tract. Being a rare cause of peritonitis, the possible link between genital tract colonization by Streptococcus bovis and retrograde invasion of the peritoneal cavity is postulated to be the cause of continuous ambulatory peritoneal dialysis peritonitis in this patient. Since invasive Streptococcus bovis infection is associated with gastrointestinal pathology (Streptococcus bovis biotype I) and chronic liver diseases (Streptococcus bovis biotype II), identifying the biotype of Streptococcus bovis could guide treatment by indicating that further investigation of these underlying diseases is required.

Streptococcus bovis bacteremia from a venous access port in a patient with AIDS

We report the first case of S. bovis bacteremia related to endoluminal colonization of a venous access port in a setting of advanced HIV infection, neutropenia and co-infection with HBV. The patient had no bowel abnormalities. The clinical picture was mild and was resolved by removal of the device.

[Recurrent fever as presenting from of colon carcinoma]

Fever of unknown origin (FUO) has been rarely associated with colonic cancer. In less than 1% of cases of FUO a colonic cancer is found as the main cause of fever. The authors reviewed 4 cases of colonic cancer whose first manifestation was FUO. Recurrent episodes of brief, self-limited fever, without a characteristic pattern, may be the first symptom of colonic cancer. On occassions, E. coli bacteremia may be the herald of an occult colonic malignancy.

Promotion of intestinal carcinogenesis by Streptococcus bovis

The involvement of Streptococcus bovis, an member of the human gut flora, in colorectal neoplastic diseases is an object of controversy. The aim of this study was to determine the effects of S.bovis and of antigens extracted from the bacterial cell wall on early preneoplastic changes in the intestinal tract. Adult rats received i. p. injections of azoxymethane (15 mg/kg body weight) once per week for 2 weeks. Fifteen days (week 4) after the last injection of the carcinogen, the rats received, by gavage twice per week during 5 weeks, either S.bovis (10(10) bacteria) or wall-extracted antigens (100 microg). One week after the last gavage (week 10), we found that administration of either S.bovis or of antigens from this bacterium promoted the progression of preneoplastic lesions through the increased formation of hyperproliferative aberrant colonic crypts, enhanced the expression of proliferation markers and increased the production of IL-8 in the colonic mucosa. Our study suggests that S.bovis acts as a promoter of early preneoplastic lesions in the colon of rats. The fact that bacterial wall proteins are more potent inducers of neoplastic transformation than the intact bacteria may have important implications in colon cancer prevention.

[Comparative analysis of antibiotic sensitivity of Streptococcus pneumoniae strains isolated from patients and carriers]

The data on antibiotic sensitivity of 38 strains of S. pneumoniae isolated from children and 46 strains isolated from carriers are presented. The isolates from the carriers had significantly higher sensitivity to benzylpenicillin, ampicillin, methicillin, oxacillin, cefazolin, erythromycin, oleandomycin and lincomycin. Resistance to gentamicin was more frequent in the strains isolated from the carriers. Among the strains of S. pneumoniae isolated from the patients and carriers representatives of serovar K19 were more frequent. There were no statistically reliable difference in them by sensitivity to benzylpenicillin, ampicillin, cefazolin, lincomycin and rifampicin. Still, the isolates from the carriers were much more sensitive to methicillin, oxacillin, oleandomycin and erythromycin.