Infective Endocarditis from Streptococcus viridans Associated with Colonic Carcinoma: A Case Report

Relevance of [18F]FDG-PET/CT in the detection of colon pathology, in patients studied by bacteriemia or infectious endocarditis caused by enteropathogenic microorganisms

PURPOSE

Association between S. gallolyticus infective endocarditis (IE) and malignant lesions of the gastrointestinal tract is well described. We hypothesize that other enteropathogenic microorganisms, such as S. viridans and E. faecalis are also related with colorectal pathology. Our aim is to determine the frequency of focal colorectal FDG deposits, suggestive of tumoral lesions and their correlation with colorectal pathology, in patients with infection caused by different commensal microorganisms of the gastrointestinal tract.

METHODS

We retrospectively examined 61 patients diagnosed with bacteremia (BSI) and IE (possible or definite) according to Duke's criteria, caused by enteropathogenic microorganisms, who underwent a full-body [¹⁸F]FDG-PET/CT in our institution. We looked for colorrectal FDG deposits and morphological lesions. All IE patients underwent a complete colonoscopy and the histological results were classified into four groups: malignant lesion, premalignant lesion, benign lesion and no lesion. We evaluated the correlation between the findings of the [¹⁸F]FDG-PET/CT with the histopathological diagnosis and the involved microorganism.

RESULTS

PET/CT detected 20 colorectal FDG deposits (32.79%-OR: 47.28), 2 within bacteriemic patients (16.7%) confirmed as malignant and premalignant lesions and 18 in IE group (36.6%), 17 of them corresponding to colorrectal pathology: 11 malignant, 5 premalignant and 1 benign lesions. In the IE subgroup, the colonoscopy detected colorectal lesions in 51.02% of the patients: 11malignant, 8premalignant and 6benign. We found a higher incidence of colorectal FDG deposits in Streptococcus spp. subgroup. Regarding the anatomopathological colonic findings there was a predominance of patients affected by S. viridans, followed by E. faecalis and S. gallolyticus.

CONCLUSION

Patients studied by PET/CT for systemic infection, especially IE, caused by S. viridans or E. faecalis, in addition to S. gallolyticus, show a greater probability of presenting incidental colorectal FDG deposits, mostly corresponding to malignant or pre-malignant lesions. Therefore, it is necessary to carry out an exhaustive search of possible colorectal foci in these exams.

The Clinical View on Streptococcus anginosus Group – Opportunistic Pathogens Coming Out of Hiding

Three distinct streptococcal species: Streptococcus anginosus, Streptococcus intermedius, and Streptococcus constellatus, belonging to the Streptococcus anginosus group (SAG), also known as Streptococcus milleri group, have been attracting clinicians and microbiologists, not only as oral commensals but also as opportunistic pathogens. For years they have been simply classified as so called viridans streptococci, and distinct species were not associated with particular clinical manifestations. Therefore, description of SAG members are clearly underrepresented in the literature, compared to other medically relevant streptococci. However, the increasing number of reports of life-threatening infections caused by SAG indicates their emerging pathogenicity. The improved clinical data generated with the application of modern molecular diagnostic techniques allow for precise identification of individual species belonging to SAG. This review summarizes clinical reports on SAG infections and systematizes data on the occurrence of individual species at the site of infection. We also discuss the issue of proper microbiological diagnostics, which is crucial for further clinical treatment.

A Case of Necrotizing Soft Tissue Infection Secondary to Perforated Colon Cancer

Necrotizing soft tissue infections are aggressive infections that cause necrosis of muscle, fascia, and tissue. They typically follow fascial planes that lack insufficient blood supply. Early drainage and debridement are essential for survival in these patients. This is a case of a patient who presented in diabetic ketoacidosis with a necrotizing soft tissue infection localized to the left flank and abdomen with underlying colon cancer pathology.

The patient was a 54-year-old female who initially presented with acute dyspnea and left flank pain for two weeks. On admission, she was afebrile, tachycardic, tachypneic, and hypertensive. After being transferred to the ICU for diabetic ketoacidosis management, she began complaining of left abdominal pain and the CT showed concerns for a possible necrotizing soft tissue infection in the left flank region. She was taken to the operating room immediately for debridement and started on broad-spectrum antibiotics. The next day, an exploratory laparotomy was performed with a hemicolectomy and creation of an end colostomy due to concern for a perforated colonic malignancy. A final debridement was completed and a wound vacuum-assisted closure (VAC) was placed. Final pathology demonstrated well-differentiated colonic adenocarcinoma invading into the muscularis propria.

Overall, necrotizing soft tissue infections can be related to a perforated viscus especially a colonic malignancy and this case demonstrates the importance of proper surgical management and high clinical suspicion for possible underlying pathology in a soft tissue infection.

Viridans streptococcal infective endocarditis associated with fixed orthodontic appliance managed surgically by mitral valve plasty: A case report

RATIONALE

Streptococcus viridans, a heterogeneous group of alpha-hemolytic streptococci, is part of the normal flora of the mouth, usually responsible for dental caries (Streptococcus mutans, Streptococcus sanguinis), and pericoronitis, as well as for subacute infective endocarditis. They are responsible for 40-60% of the endocarditis cases occurring on the normal valves, especially in male patients and over 45 years of age. A change in the bacterial flora of the oral cavity is taking part after orthodontic fixed appliances are introduced into the oral cavity, change that is associated with an increased concentration of the acidogenic bacteria. Bacteraemia is the consequence of oral cavity infections, the association of infective endocarditis with fixed orthodontic appliance, as it has been described by us for the first time, caused by Abiotrophia defectiva.

PATIENT CONCERNS

We present the case of a female Caucasian patient, aged 22 years, who developed infective endocarditis with Streptococcus viridans associated with fixed orthodontic appliance, located on the mitral valve, without previous cardiac pathology, and the therapeutic difficulties associated with allergic reactions (to vancomycin, and spironolactone).

DIAGNOSES

Repetitive haemocultures were positive with Streptococcus viridans, while transthoracic echography revealed a severe mitral failure through anteromedial segment of the anterior mitral valve leaf prolapse with eccentric jet to the posterior wall.

INTERVENTIONS

During hospitalization, the decision to undergo surgical intervention was taken after obtaining negative haemocultures. The patient underwent surgically intervention, and a mitral valve plasty with insertion of neochords was performed.

OUTCOMES

Intraoperative and subsequently post-discharge transesophageal echography, highlighted normofunctional mitral plasty with a remaining regurgitation grade I-II of IV, with good openness, minor tricuspid regurgitation, and mild pulmonary hypertension.

LESSONS

Endocarditis with oral streptococci associated with fixed orthodontic appliance seems to be not so unlikely even in young or without previous cardiac pathology patients, requiring attention in identifying possible pre-existing cardiac conditions like mitral valve prolapse with clinical and echographic monitoring of such cases. Educating and motivating the patient to observe the oral hygiene represent key steps for an optimal oral health during orthodontic treatment. Mechanical tooth cleaning helps maintaining a good oral hygiene during fixed orthodontics and decreasing the oral health risks.

Human oral microbiota and its modulation for oral health

The oral microbiome is an important part of the human microbiome. The oral cavity contains several significantly different niches with distinct microbial communities. A wide range of microorganisms inhabit the human oral cavity, including bacteria, fungi, viruses, archaea and protozoa. These microorganisms form a complex ecological community that influences oral and systemic health. The most prevalent oral diseases, dental caries and periodontal diseases, are microbiota-associated diseases. Moreover, increasing evidences have supported that many systemic diseases are associated with disturbances in the oral ecosystem, such as diabetes, cardiovascular diseases and tumors. The current control of dental plaque-related diseases is nonspecific and is centered on the removal of plaque by mechanical means. Due to this realization about the oral microbiome, several new methods based on the modulation of the microbiome that aim at maintaining and reestablishing a healthy oral ecosystem have been developed.

Colon Carcinoma Presenting as Streptococcus anginosus Bacteremia and Liver Abscess

A collection of dead white blood cells within the liver is called a liver abscess, and pyogenic liver abscess (PLA) is the most common type. PLA is commonly associated with biliary tract infections. However, in this case report, we present a rare cause of Streptococcus anginosus bacteremia and PLA which is associated with a carcinoma of the colon at the splenic flexure. The presentation mimicked a cholecystitis clinically, but the radio-imaging revealed a liver abscess. Blood cultures revealed an uncommon etiological agent, S. anginosus group which is otherwise a commensal in the human gut. In this case report, we aimed to summarize the microbiological aspects of S. anginosus group of organisms, the relevant clinicopathological considerations and the management.

Colorectal Cancer Associated with Streptococcus anginosus Bacteremia and Liver Abscesses

Streptococcus anginosus is part of the normal flora of the human gastrointestinal tract. Their ability to cause abscesses is very unique and sets them apart from the rest of the streptococci groups. While an association of group D streptococcus bacteremia and endocarditis with colorectal carcinoma is well established, S. anginosus infections are rarely implicated with colonic malignancy. We present a case of a 62-year-old male who presented to the hospital with fatigue and generalized abdominal pain. Computed tomography of the abdomen revealed multiple liver abscesses and rectal thickening. Blood cultures were found to grow S. anginosus bacteria. Colonoscopy revealed a rectal mass which was later confirmed to be rectal adenocarcinoma. This case presents an association between S. anginosus bacteremia and presence of colorectal cancer which has been highlighted in only a few case reports in literature. This should prompt clinicians to screen for colorectal cancer in patients with S. anginosus bacteremia.

Streptococcus viridians bacteraemia and colonic adenocarcinoma

Even though Streptococcus bacteraemia is an infrequent presentation of colonic malignancies, there is a well-established link between Streptococcus bovis bacteraemia and colonic malignancies. Most of the physicians are well aware of this correlation and further workup is pursued in most of the cases. However, many physicians may not be aware that other species of Streptococcus viridians, other than S. bovis, can be associated with colonic malignancies. In this case report, we present a case of Streptococcus viridians (anginosus) bacteraemia as a complication of an undiagnosed sigmoid adenocarcinoma. While further evidence is needed to warrant a gastrointestinal (GI) workup in a patient with other species of Streptococcus viridians bacteraemia, we would like to increase the awareness in the physicians' community regarding Streptococcus viridians, other than S. bovis bacteraemia. This would be especially relevant for patients who have no GI screening, as Streptococcus viridians bacteraemia can be an early sign of colonic neoplasm.

Oral microbiota and cancer

Inflammation caused by infections may be the most important preventable cause of cancer in general. However, in the oral cavity the role of microbiota in carcinogenesis is not known. Microbial populations on mouth mucosa differ between healthy and malignant sites and certain oral bacterial species have been linked with malignancies but the evidence is still weak in this respect. Nevertheless, oral microorganisms inevitably up-regulate cytokines and other inflammatory mediators that affect the complex metabolic pathways and may thus be involved in carcinogenesis. Poor oral health associates statistically with prevalence of many types of cancer, such as pancreatic and gastrointestinal cancer. Furthermore, several oral micro-organisms are capable of converting alcohol to carcinogenic acetaldehyde which also may partly explain the known association between heavy drinking, smoking, poor oral health and the prevalence of oral and upper gastrointestinal cancer. A different problem is the cancer treatment-caused alterations in oral microbiota which may lead to the emergence of potential pathogens and subsequent other systemic health problems to the patients. Hence clinical guidelines and recommendations have been presented to control oral microbiota in patients with malignant disease, but also in this area the scientific evidence is weak. More controlled studies are needed for further conclusion.

Streptococcus sanguis endocarditis associated with colonic carcinoma

Infective endocarditis caused by Streptococcus bovis is known to be associated with colorectal malignancy. Other less common streptococci, specifically Streptococcus sanguis, can be similarly associated with gastrointestinal carcinoma. We present a case of disseminated colorectal carcinoma occurring after a confirmed S sanguis endocarditis, that required mitral valve surgery. There may be a need for gastrointestinal surveillance in patients presenting with bacteraemia caused by less common streptococci.