Streptococcus bovis bacteraemia revisited: Clinical and microbiological correlates in a contemporary series of 59 patients

Comparative Evaluation of Current Biochemical-, Sequencing-, and Proteomic-Based Identification Methods for the Streptococcus bovis Group

The Streptococcus bovis group (previously group D streptococci) consists of seven distinct species and subspecies. Definitive identification within the group is important, as certain organisms have been associated with gastrointestinal carcinoma, bacteremia, infective endocarditis, meningitis, biliary tract disease, and carcinoma, among others. Definitive identification, however, remains elusive due to limitations and inconsistencies across commonly used identification platforms in the United States. Here, we compared the performance of standard biochemical (Trek Gram-positive identification [GPID] plate, Vitek 2 GPID), sequencing (16S rDNA, sodA) databases (NCBI, RDP, CDC MicrobeNet), and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) platforms (Vitek MS, Bruker Biotyper MS) using a set of eight type strains representing all seven strains within the S. bovis group. Despite the evaluation of contemporary methods, no single platform was able to definitively identify all type strains within the S. bovis group. Vitek MS (85.7%, 7/8) provided the most accurate definitive identifications, followed by sodA sequencing (75%, 6/8). Vitek 2 and Bruker Biotyper RUO platforms performed the next best (62.5%, 5/8). All remaining platforms failed to adequately differentiate type strains within the S. bovis group (range, 0 to 37.5%). Laboratorians and clinicians should be aware of the identification limitations of routine testing algorithms and incorporate reflex testing, when appropriate, to platforms such as Vitek MS and/or sodA sequencing that are more able to definitively identify S. bovis group organisms. Further clinical evaluation was conducted using 65 clinical isolates from three geographically distinct U.S. institutions. Future improvements in identification platforms may reveal new clinical and epidemiological trends for members of the S. bovis group.

Bacterial and Parasitic Pathogens as Risk Factors for Cancers in the Gastrointestinal Tract: A Review of Current Epidemiological Knowledge

The oncogenic potential of viral infections is well established and documented for many years already. However, the contribution of (commensal) bacteria and parasites to the development and progression of cancers has only recently gained momentum, resulting in a rapid growth of publications on the topic. Indeed, various bacteria and parasites have been suggested to play a role in the development of gastrointestinal cancer in particular. Therefore, an overview of the current epidemiological knowledge on the association between infections with bacteria and parasites and cancers of the gastrointestinal tract is needed. In this review, we summarized the methodological characteristics and main results of epidemiological studies investigating the association of 10 different bacteria (Bacteroides fragilis, Campylobacter spp., Clostridium spp., Enterococcus faecalis, Escherichia coli, Fusobacterium nucleatum, Porphyromonas gingivalis, non-typhoidal Salmonella, Salmonella Typhi, and Streptococcus spp.) and three parasites (Cryptosporidium spp., Schistosoma spp., and Strongyloides stercoralis) with gastrointestinal cancer. While the large body of studies based on microbiome sequencing provides valuable insights into the relative abundance of different bacterial taxa in cancer patients as compared to individuals with pre-malignant conditions or healthy controls, more research is needed to fulfill Koch's postulates, possibly making use of follow-up data, to assess the complex role of bacterial and parasitic infections in cancer epidemiology. Studies incorporating follow-up time between detection of the bacterium or parasite and cancer diagnosis remain valuable as these allow for estimation of cause-effect relationships.

The Effect of Nomenclature Revision of Streptococcus bovis to Streptococcus gallolyticus on Subsequent Colon Cancer Screening

Background

Lack of awareness of the taxonomic revision from the familiar Streptococcus bovis to the less familiar Streptococcus gallolyticus may be associated with a decrease in recommended colon cancer screening in patients with bacteremia from this organism. This could subsequently lead to a delay in diagnosis or underdiagnosis of colon cancer and other serious underlying gastrointestinal diseases. The aim of this study was to determine whether the nomenclature change of S. bovis to S. gallolyticus resulted in decreased colon cancer screening.

Methods

This study was a retrospective, observational, nationwide analysis of patients who had positive blood cultures for S. bovis/S. gallolyticus from any Veterans Affairs Medical Center (VAMC) between January 1, 2002, and December 31, 2017.

Results

There was no difference in the primary end point of intent for colonoscopy between the S. gallolyticus and S. bovis groups (66.5% [117/176] vs 62.1% [624/1005], respectively; P = .26). The overall mortality rate was 33.8% among 1181 patients included in the study, with a significantly lower mortality in patients with evidence of intent for colonoscopy (29.6% vs 42.5%; P ≤ .001), gastroenterology (GI) consultation (29.8% vs 41.4%; P < .001), infectious diseases (ID) consultation (29.4% vs 39.0%; P = .001), or either consultation (31.9% vs 40.7%; P = .013), compared to those that did not.

Conclusions

There was no difference in colon cancer screening rates between patients with episodes of bacteremia reported as S. bovis and those reported as S. gallolyticus. Overall mortality was lower in patients who had ID consultation, GI consultation, or evidence of colonoscopy.

Disseminated Streptococcus bovis infection after consumption of manatee meat: A case report and review of the literature

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Disseminated S. bovis group infections are unusual in adults.

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S. bovis infections are usually related to colorectal neoplasia o biliary tract disease.

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S. bovis group zoonotic transmission could be biologically plausible, as infection in marine animals has been documented.

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No cases of S. bovis group have been published in relation to manatee ingestion.

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Wild animal consumption increases the risk of serious infections that could represent a hazard for public health.

Streptococcus bovis bacteremia (currently called S. gallolyticus) represents an infrequent condition, but associated with a high rate of morbidity and mortality Amado et al. (2015). The clinical presentation is characterized by symptoms associated with disseminated infection and with a higher frequency of endocarditis and gastrointestinal neoplasms, often occult Amado et al. (2015), Olmos et al. (2016). Probable sources of infection and zoonotic transmission have not been explored in the literature. We present a case of disseminated infection after ingestion of a marine mammal.

Risk factors for the carriage of Streptococcus infantarius subspecies infantarius isolated from African fermented dairy products

Streptococcus infantarius subsp. infantarius (Sii) has been identified as predominant lactic acid bacteria in spontaneously fermented dairy products (FDPs) in sub-Saharan Africa including Côte d'Ivoire. However, Sii belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC). Most SBSEC members are assumed to be involved as opportunistic pathogens in serious diseases in both humans and animals. A population-based cross-sectional survey, including 385 participants was conducted in Korhogo, northern Côte d'Ivoire, to identify risk factors for Sii fecal carriage, including consumption of local FDPs. A structured questionnaire was used to gather participant's socio-demographic and economic characteristics, their relation to livestock and dietary habits. In addition, fresh stool and milk samples were collected. The identification of Sii was done using a SBSEC-specific PCR assay targeting 16S rRNA and groEL genes. The overall prevalence of SBSEC and Sii carriage was 23.2% (confidence interval CI 95% = 18.9-27.5) and 12.0% (CI 95% = 8.4-15.5) for stool, respectively. Prevalence of Sii was significantly higher in consumers of artisanal butter compared with non-consumers (57.1% vs 10.1%, odds ratio OR: 11.9, 95% CI: 3.9-36.6), as well as in persons handling livestock (OR = 3.9; 95% CI = 1.6-9.3) and livestock primary products (OR = 5.7; 95% CI = 2.3-14.3). The closer contact with livestock was a risk factor for Sii fecal carriage. Sii strains were isolated from fresh and fermented milk products with a prevalence of 30.4% and 45.4%, respectively. Analysis of Sii population structure through the SBSEC multi locus sequence typing assay revealed a close relationship across human and dairy isolates, possibly linked to a Kenyan human isolate. All these outcomes underline the interest of in-depth investigations on the ecology, potential reservoirs and pathways of contamination by Sii at the human-animal-environment interface in comparison to yet to be collected data from Europe, Asia and the Americas to further elucidate the various roles of Sii.

An Overview on Streptococcus bovis/Streptococcus equinus Complex Isolates: Identification to the Species/Subspecies Level and Antibiotic Resistance

Streptococcus bovis/Streptococcus equinus complex (SBSEC), a non-enterococcal group D Streptococcus spp. complex, has been described as commensal bacteria in humans and animals, with a fecal carriage rate in humans varying from 5% to over 60%. Among streptococci, SBSEC isolates represent the most antibiotic-resistant species—with variable resistance rates reported for clindamycin, erythromycin, tetracycline, and levofloxacin—and might act as a reservoir of multiple acquired genes. Moreover, reduced susceptibility to penicillin and vancomycin associated with mobile genetic elements have also been detected, although rarely. Since the association of SBSEC bacteremia and colon lesions, infective endocarditis and hepatobiliary diseases has been established, particularly in elderly individuals, an accurate identification of SBSEC isolates to the species and subspecies level, as well as the evaluation of antibiotic resistance, are needed. In this paper, we reviewed the major methods used to identify SBSEC isolates and the antimicrobial resistance rates reported in the scientific literature among SBSEC species.

The "3M" Approach to Cardiovascular Infections: Multimodality, Multitracers, and Multidisciplinary

Cardiovascular infections are associated with high morbidity and mortality. Early diagnosis is crucial for adequate patient management, as early treatment improves the prognosis. The diagnosis cannot be made on the basis of a single symptom, sign, or diagnostic test. Rather, the diagnosis requires a multidisciplinary discussion in addition to the integration of clinical signs, microbiology data, and imaging data. The application of multimodality imaging, including molecular imaging techniques, has improved the sensitivity to detect infections involving heart valves and vessels and implanted cardiovascular devices while also allowing for early detection of septic emboli and metastatic infections before these become clinically apparent. In this review, we describe data supporting the use of a Multimodality, Multitracer, and Multidisciplinary approach (the 3M approach) to cardiovascular infections. In particular, the role of white blood cell SPECT/CT and [¹⁸F]FDG PET/CT in most prevalent and clinically relevant cardiovascular infections will be discussed. In addition, the needs of advanced hybrid equipment, dedicated imaging acquisition protocols, specific expertise for image reading, and interpretation in this field are discussed, emphasizing the need for a specific reference framework within a Cardiovascular Multidisciplinary Team Approach to select the best test or combination of tests for each specific clinical situation.

Identification, antimicrobial resistance and molecular characterization of the human emerging pathogen Streptococcus gallolyticus subsp. pasteurianus

This study aimed to retrospectively identify 22Streptococcus bovis clinical strains based on the new taxonomy, as well as to investigate their antibiotic-resistance and clonality. Strains were identified by Phoenix100 system, 16S rRNA sequencing, and two MALDI-TOF MS platforms (Bruker Biotyper, Vitek MS). Antibiotic resistance was determined both phenotypically and genotypically, and clonality was assessed by PFGE. Most of strains (63.6%) were isolated from urine, and diabetes was the most common underlying disease (31.8%). Phoenix100 system revealed all strains belonged to biotype II, and 16S rRNA sequencing identified all strains as S. gallolyticus subsp pasteurianus (SGSP). Although both MALDI-TOF MS systems correctly identified isolates to the species level, only Bruker Biotyper accurately identified to the subspecies level. Erythromycin-resistant strains (31.8%) were also clindamycin-resistant and positive for erm(B). Strains resistant to tetracycline (68.2%) were also resistant to erythromycin. PFGE showed high genetic variability identifying 17 different pulsotypes, most of which single.

Bacteremia with the bovis group streptococci: species identification and association with infective endocarditis and with gastrointestinal disease

DNA sequencing of the intergenic spacer (ITS) region was used to identify 53 blood culture isolates that had previously been designated to the bovis group streptococci and clinical data was collected retrospectively from patients' records using a standardized protocol. ITS sequencing identified 19 (35.8%) isolates as Streptococcus gallolyticus subsp. gallolyticus, 12 (22.6%) as S. gallolyticus subsp. pasteurianus, two (3.8%) as S. gallolyticus subsp. macedonicus, seven (13.2%) as S. infantarius subsp. infantarius, 12 (22.6%) as S. lutetiensis and one (1.9%) as S. equinus. The association of S. gallolyticus subsp. gallolyticus with colorectal neoplasia and with infective endocarditis and the association between S. gallolyticus subsp. pasteurianus and pancreatic cancer were found to be clinically important. Also, a very high 1-year mortality rate with S. lutetiensis (66.7%) and S. gallolyticus subsp. pasteurianus (58.7%) bacteremia calls for intensive investigation for underlying disease focusing on the pancreas and the hepatobiliary system.

Streptococcus bovis septic arthritis and osteomyelitis: A report of 21 cases and a literature review

BACKGROUND

The Streptococcus bovis group (SBG) is a well-known cause of endocarditis, but its role in osteoarticular infections (OAIs) has not been well described.

METHODS

We analyzed all patients with OAIs by SBG diagnosed in our hospital (1988-2014). We selected those cases with septic arthritis and osteomyelitis, as defined according to clinical, microbiological, and imaging studies. Identification of the strains was performed by using the API 20 Strep and the GP card of the Vitek 2 system, and confirmed the identification by molecular methods. In addition, we reviewed the literature to select all cases of OAI by SBG during the period 1980-2015.

RESULTS

From the 83 cases of OAI included in the analysis (21 from our center and 62 from the literature review), 59 were osteomyelitis (57 of them spondylodiscitis) and 24 were arthritis (2 with associated spondylodiscitis). The mean age was 66.9 years, and 79.2% of the patients were men. Endocarditis (IE) was associated with 59% of the cases and this association was greater for osteomyelitis than for arthritis (78.9% vs. 13.6%; P = 0.001). OAI was a presenting symptom in 63% of the cases of IE. Colonoscopy was performed in 64 cases, which detected colorectal neoplasm (CRN) in 46 patients (71.8%), almost all asymptomatic. Some 69.5% of these neoplasm were carcinomas or advanced adenomas. The blood cultures were positive in 78.3% cases. In 45 cases, the S. bovis species was identified; in 82.2% of the cases the cause was Streptococcus gallolyticus subsp. gallolyticus. The mortality was 7.2%, which in no case was attributable to the OAI.

CONCLUSIONS

OAIs are frequently the initial manifestation of IE caused by SBG. S. gallolyticus causes most of these infections. Echocardiogram and colonoscopy are therefore mandatory, given the species' close association with IE and CRN.

The clinical epidemiology and malignancies associated with Streptococcus bovis biotypes in 506 cases of bloodstream infections

OBJECTIVES

To determine the incidence of Streptococcus bovis (Sb) biotypes causing bacteraemia and associated malignancies.

METHODS

This is a retrospective analysis of patients with Sb bacteraemia, pulled out from a prospective surveillance protocol of bacteraemia cases, in three areas of Spain (1990-2013): a cattle area (Lugo), a fishing area (Ferrol) and an urban area (Barcelona). Colonoscopy and Sb biotypes (Sb-I and Sb-II) were determined in most cases.

RESULTS

506 patients with Sb bacteraemia; mean age 68.1 (±14.1) years, and 66.2% were males. The cattle area, compared with the fishing and urban areas, had higher incidence of bacteraemia by SbI (40.29 vs 9.38 vs 6.15 cases/10(6) person-years, P < 0.001) and bacteraemia by Sb-II (29.07 vs 9.84 vs 13.37 cases/10(6) person-years, P < 0.001). The Sb-I cases (n = 224), compared with Sb-II cases (n = 270), had greater rates of endocarditis (77.6% vs 9.6%, P < 0.001) and colorectal neoplasm (CRN) (50.9% vs 16.6%, P < 0.001), and smaller rates of biliary tract infection (2.2% vs 29.6%, P < 0.001) and non-colorectal malignancy (8.9% vs 31.4%, P < 0.001).

CONCLUSION

There was a link between the cattle area and higher incidence of Sb bacteraemia. Sb-I differed from Sb-II cases in clinical findings and associated malignancies. Colonoscopy is mandatory in cases of endocarditis or bacteraemia caused by Sb-I.

Streptococcus bovis endocarditis: analysis of cases between 2005 and 2014

Background

Streptococcus bovis is a classical etiology of endocarditis and is associated with colonic lesions. No series of cases from Brazil has been described.

Objectives

To describe aspects of S. bovis endocarditis.

Methods

This is a case series of patients admitted to a cardiac surgery referral center, during the years 2005–2014. Clinical, laboratory, echochardiographic, colonoscopic, treatment, surgical and outcome variables were studied.

Results

Nine patients with S. bovis endocarditis were included; all cases fulfilled the modified Duke criteria. Incidence was 8/220 (4%) in years 2006–2014. There were seven male and two female patients; mean age was 56.7 years, standard deviation 13.4. All patients had native aortic valve involvement. Presentation was subacute in 7/9 (71%). Fever was present in 7/9 (77.7%), embolic lesions to solid organs occurred in three, and perivalvular abscess in two patients. All echocardiograms showed moderate to severe valvular regurgitation and vegetations. Microcytic anemia was seen in 7/7 patients. Colonoscopy showed abnormal findings in 7/9 (77.7%). Surgery was indicated for 6/9 patients due to acute aortic regurgitation and left ventricular failure. All patients were discharged home.

Conclusions

S. bovis most frequently affected the aortic valve of male patients. Colon disease was frequent. Surgery was indicated frequently due to hemodynamic compromise.

Streptococcus bovis Bacteremia in Neonates in a Predominantly Hispanic Population

BACKGROUND

Streptococcus bovis bacteremia has been associated with gastrointestinal diseases, especially colon cancer, neoplastic colon polyps, and other malignancies of the GI tract in adults. Sporadic cases of S. bovis disease have also been reported in neonates and young infants. Although uncommon, S. bovis infection can cause fulminant neonatal sepsis and meningitis.

OBJECTIVES

We report a series of pediatric patients with S. bovis bacteremia in a county hospital in a United States-Mexico border city in order to examine the demographic and clinical associations.

METHODS

We characterized the demographic and clinical features in all pediatric patients with blood cultures positive for S. bovis at University Medical Center in El Paso, TX, USA between January 2000 and December 2010. Hospital records were systematically reviewed by using a standardized protocol.

RESULTS

A total of seven episodes of S. bovis bacteremia were documented in seven pediatric patients (four female and three male). Mean age was 1.2 days (range 1-3 days), all were Hispanic, average birth weight (3.25 kg). Mode of delivery was spontaneous vaginal delivery (five) and Caesarian section (two). All of our patients developed early (<1 week) onset disease and presented with signs of respiratory distress. Five out of seven babies presented with abdominal distention and diarrhea. Six had clinical evidence of sepsis at presentation. Respiratory distress was the most common manifestation of sepsis (seven). Aspiration pneumonia was diagnosed in two of them. Most patients were treated with a combination of antibiotics (six), either ampicillin and gentamicin or ampicillin and cefotaxime, and one with ampicillin alone. None of the pediatric patients had endoscopy and none of them died.

CONCLUSION

Streptococcus bovis is considered as an uncommon pathogen in the newborn, but can be associated with substantial morbidity and mortality if not identified and treated early. Physicians should be alert to the less common presentation of neonatal bacteremia due to S. bovis.

Is Streptococcus bovis a urinary pathogen?

The Streptococcus bovis group (SBG) comprises several microorganisms associated with human infections. They have been associated with bacteremia, endocarditis, biliary tract infection, meningitis, and colorectal cancer, but their role as urinary pathogens is not well known. The objective of this investigation was to discover the incidence and clinical significance of the bacteriuria associated with this complex. A retrospective analysis of all adult patients with bacteriuria caused by SBG during the period 1995-2012 was carried out. During the study period, SBG was isolated in 153 adult patients, who had a mean age of 67 years, most of them being women (80%). Most of our patients (65%) had some underlying disease, with urologic disease being the most common (37%), followed by diabetes mellitus (27%) and neurologic disease (25%). Among the 88 patients in whom we were able to correctly assess symptoms, 45% had asymptomatic bacteriuria, 35% had lower urinary tract infection, and 20% had upper urinary tract infection. In 14 cases (9%), SBG was also isolated in blood cultures. Most of the isolates of SBG (72%) were S. gallolyticus subsp. pasteurianus. All isolates were susceptible to penicillin, 98% to nitrofurantoin, and 77% to fosfomycin. Although SBG bacteriuria is uncommon, it should not always be taken as a contaminant, mainly when S. pasteurianus is isolated, because it may cause urinary tract infections and, occasionally, sepsis, whereas when S. gallolyticus is isolated from urine, it may be a marker of underlying endocarditis and colorectal cancer.

Genomics, evolution, and molecular epidemiology of the Streptococcus bovis/Streptococcus equinus complex (SBSEC)

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) is a group of human and animal derived streptococci that are commensals (rumen and gastrointestinal tract), opportunistic pathogens or food fermentation associates. The classification of SBSEC has undergone massive changes and currently comprises 7 (sub)species grouped into four branches based on sequences identities: the Streptococcus gallolyticus, the Streptococcus equinus, the Streptococcus infantarius and the Streptococcus alactolyticus branch. In animals, SBSEC are causative agents for ruminal acidosis, potentially laminitis and infective endocarditis (IE). In humans, a strong association was established between bacteraemia, IE and colorectal cancer. Especially the SBSEC-species S. gallolyticus subsp. gallolyticus is an emerging pathogen for IE and prosthetic joint infections. S. gallolyticus subsp. pasteurianus and the S. infantarius branch are further associated with biliary and urinary tract infections. Knowledge on pathogenic mechanisms is so far limited to colonization factors such as pili and biofilm formation. Certain strain variants of S. gallolyticus subsp. macedonicus and S. infantarius subsp. infantarius are associated with traditional dairy and plant-based food fermentations and display traits suggesting safety. However, due to their close relationship to virulent strains, their use in food fermentation has to be critically assessed. Additionally, implementing accurate and up-to-date taxonomy is critical to enable appropriate treatment of patients and risk assessment of species and strains via recently developed multilocus sequence typing schemes to enable comparative global epidemiology. Comparative genomics revealed that SBSEC strains harbour genomics islands (GI) that seem acquired from other streptococci by horizontal gene transfer. In case of virulent strains these GI frequently encode putative virulence factors, in strains from food fermentation the GI encode functions that are pivotal for strain performance during fermentation. Comparative genomics is a powerful tool to identify acquired pathogenic functions, but there is still an urgent need for more physiological and epidemiological data to understand SBSEC-specific traits.

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.

[Streptococcus gallolyticus subsp. pasteurianus isolated from cerebrospinal fluid in a pediatric patient]

Streptococcus gallolyticus subsp. pasteurianus is known to cause bacterial meningitis in adults, and most of the few pediatric cases observed occurred in neonates. We report the case of a 9-month old boy with a history of repeated hospitalizations due to respiratory diseases, who presented meningitis and bacteremia by Streptococcus gallolyticus subsp. pasterianus. To our knowledge, this is the first reported case in Santa Fe to this date.

Streptococcus bovis bacteraemia: an evaluation of the long-term effect on cardiac outcomes

INTRODUCTION

Streptococcus bovis can lead to bacteraemia, septicaemia, and ultimately endocarditis. The objective of this study was to evaluate the long-term implications of S. bovis endocarditis on cardiac morbidity and mortality.

METHODS

A retrospective cohort study was performed between January 2000 and March 2009 to assess all patients diagnosed with S. bovis bacteraemia from the Belfast Health and Social Care Trust. The primary end-point for cardiac investigations was the presence of endocarditis. Secondary end-points included referral for cardiac surgery and overall mortality.

RESULTS

Sixty-one positive S. bovis blood cultures from 43 patients were included. Following echocardiography, seven patients were diagnosed with infective endocarditis (16.3 % of total patients); four patients (9.3 %) had native valve involvement while three (7.0 %) had prosthetic valve infection. Five of these seven patients had more than one positive S. bovis culture (71.4 %). Three had significant valve dysfunction that warranted surgical repair/replacement, one of whom was unfit for surgery. There was a 100 % recurrence rate amongst the valve replacement patients (n = 2) and six patients with endocarditis had colorectal pathology. Patients with endocarditis had similar long-term survival as those with non-endocarditic bacteraemia (57.1 % alive vs. 50 % of non-endocarditis patients, p = 0.73).

CONCLUSION

Streptococcus bovis endocarditis patients tended to have pre-existing valvular heart disease and those with prosthetic heart valves had higher surgical intervention and relapse rates. These patients experienced a higher rate of co-existing colorectal pathology but currently have reasonable long-term outcomes. This may suggest that they represent a patient population that merits consideration for an early surgical strategy to maximise long-term results, however, further evaluation is warranted.

Streptococcus bovis group and biliary tract infections: an analysis of 51 cases

Streptococcus bovis is a well-known cause of endocarditis, but its role in other infections has not been well described. We analysed prospectively all patients with biliary tract infections caused by S. bovis group during the period 1988-2011. We selected those cases associated with cholangitis and cholecystitis, defined according to Tokyo guidelines. Identification of the strains was performed using the API 20 Strep and the GP card of the Vitek 2 system, and was confirmed by molecular methods. Our series included 51 cases (30 cholangitis and 21 cholecystitis). The associated microorganisms were: Streptococcus infantarius (biotype II/1) 29 cases (57%), Streptococcus gallolyticus subsp. pasteurianus (biotype II/2) 20 cases (39%) and Streptococcus gallolyticus subsp. gallolyticus (biotype I) two cases (4%). The only difference found between S. infantarius and S. gallolyticus subsp. pasteurianus was a greater association of the first with malignant strictures of the bile ducts: 48% (14/29) versus 5% (1/20), p <0.001. Thirty-seven of the cases also had bacteraemia, causing 20% (37/185) of all S. bovis bacteraemia, with differences between S. gallolyticus subsp. gallolyticus (2/112; 2%) and the other two microorganisms: S. infantarius and S. gallolyticus subsp. pasteurianus (35/73; 48%; p <0.001). The vast majority of biliary tract infections due to S. bovis group are caused by S. infantarius and S. gallolyticus subsp. pasteurianus (S. bovis biotype II), and nearly half of the bacteraemia due to these two species has a biliary source (43% of the S. infantarius and 56% of S. gallolyticus subsp. pasteurianus).

Association of Streptococcus bovis endocarditis and advanced colorectal neoplasia: a case-control study

OBJECTIVE

To study the association between Streptococcus bovis (S. bovis) endocarditis and advanced colorectal neoplasia.

METHODS

This was a case-control study of patients with S. bovis endocarditis undergoing colonoscopic evaluation. Patients were matched 1:20 with controls by gender and age (±2 years) from a large screening colonoscopy database. The baseline, colonoscopic and clinicopathological characteristics of patients with S. bovis endocarditis were analyzed.

RESULTS

From 1996 to 2010, 18 adult patients with S. bovis bacteremia were identified, of whom 10 with infective endocarditis (IE) underwent colonoscopic evaluation. Endocarditis involved a native or prosthetic valve in six and four of those patients, respectively. All 10 patients recovered without recurrence of IE (mean follow-up duration 49.6 months). None had a concurrent or preceding history of colon disease and only one had subclinical chronic liver disease. Advanced neoplasia, defined as the presence of polyps ≥1 cm (n = 6), villous histology (n = 3), high-grade focal dysplasia (n = 1) or cancer (n = 1), was found under colonoscopy in 6 of the 10 cases (60.0%) compared with 13/200 (6.5%) matched controls (OR 21.6, 95% CI 5.4-86.1, P < 0.0001).

CONCLUSIONS

S. bovis endocarditis is strongly associated with the presence of advanced colorectal neoplasia. In the absence of any contraindication, colonoscopic examination is strongly recommended in patients with endocarditis. The exact pathophysiological mechanisms underlying this association and the predilection for S. bovis bacteremia in patients with advanced colonic neoplasia remain unclear.

Molecular characterization of a novel mosaic tet(S/M) gene encoding tetracycline resistance in foodborne strains of Streptococcus bovis

The presence of antibiotic-resistance (AR) genes in foodborne bacteria of enteric origin represents a relevant threat to human health in the case of opportunistic pathogens, which can reach the human gut through the food chain. Streptococcus bovis is a human opportunistic pathogen often associated with infections in immune-compromised or cancer patients, and it can also be detected in the environment, including fermented foods. We have focused on the molecular characterization of a tetracycline (Tet)-resistance gene present in 39 foodborne isolates of S. bovis phenotypically resistant to this drug. The gene was identified as a novel tet(S/M) fusion, encoding a mosaic protein composed of the N-terminal 33 amino acids of Tet(S), in-frame with the Tet(M) coding sequence. Heterologous expression of the mosaic gene was found to confer Tet resistance upon Escherichia coli recipients. Moreover, the tet(S/M) gene was found to be transcriptionally inducible by Tet under the endogenous tet(S) promoter in both S. bovis and E. coli. Nucleotide sequencing of the surrounding genomic region of 16.2 kb revealed large blocks of homology with the genomes of Streptococcus infantarius and Lactococcus lactis. A subregion of about 4 kb containing mosaic tet(S/M) was flanked by two copies of the IS1216 mobile element. PCR amplification with primers directed outwards from the tet(S/M) gene identified the presence of a 4.3 kb circular form corresponding to the intervening chromosomal region between the two IS1216 elements, but lacking a replication origin. The circular element shared extensive overall homology with a region of the multidrug-resistance plasmid pK214 from Lc. lactis, containing tet(S), as well as the IS1216 transposase-containing element and intervening non-coding sequences. Linear reconstruction of the insertion events likely to have occurred within this genomic region, inferred from sequence homology, provides further evidence of the chromosomal rearrangements that drive genomic evolution in complex bacterial communities such as the gut and food microbiota.

Association between bacteremia due to Streptococcus gallolyticus subsp. gallolyticus (Streptococcus bovis I) and colorectal neoplasia: a case-control study

BACKGROUND

The association between bacteremia by Streptococcus gallolyticus subsp. gallolyticus (SGG) and colorectal neoplasia (CRN) is well established but the frequency of the association varies widely in different studies. We conducted a case-control study to assess the association between SGG bacteremia and CRN.

METHODS

An analysis of all SGG bacteremias was performed during the period 1988-2011. The frequency of CRN in patients with SGG bacteremia was compared with the frequency of CRN in a symptomatic control group of patients matched at a 1:2 ratio for gender and age (±3 years) without S. bovis bacteremia and personal history of CRN and with increased risk of CRN (by the presence of symptoms, signs, or test suspicious of colonic pathology or by family history of CRN).

RESULTS

One hundred nine cases of SGG bacteremia were detected (mean age, 66 years; 87% male). Colonoscopy was performed in 98 cases, diagnosing 69 cases of CRN: 57 adenomas (39 advanced adenomas) and 12 invasive carcinomas. Only 4 cases had suspected CRN before the blood culture. The prevalence of CRN was higher in patients with SGG bacteremia than in the 196 control patients (70% vs 32%; odds ratio [OR], 5.1; 95% confidence interval [CI], 3.0-8.6). This difference was not significant when comparing nonadvanced adenomas (19% vs 12%), but we found significant differences in advanced adenomas (40% vs 16%; OR, 3.5; 95% CI, 2.0-6.1) and invasive carcinomas (12% vs 5%; OR, 2.9; 95% CI, 1.2-6.9).

CONCLUSIONS

The frequency of CRN among SGG infected patients is significantly increased compared with symptomatic age-matched controls, indicating that SGG infection is a strong indicator for underlying occult malignancy.

Clinical Importance of Streptococcus gallolyticus infection among colorectal cancer patients: systematic review and meta-analysis

BACKGROUND

Streptococcus bovis has long been associated with colorectal cancer (CRC). However, not all genospecies are as closely related to CRC. With this systematic review, we aim to increase the awareness of the association between S. bovis biotype I (Streptococcus gallolyticus) and CRC and urge for uniform molecular microbiological classification.

METHODS

In January 2011, the PubMed database was searched for all studies that investigated the association between S. bovis, infective endocarditis (IE), and CRC. A total of 191 studies were screened for eligibility and yielded 52 case reports and 31 case series, of which 11 were used for meta-analysis on the association between S. bovis biotype, IE, and adenomas/carcinomas (CRC).

RESULTS

Among the S. bovis-infected patients who underwent colonic evaluation, the median percentage of patients who had concomitant adenomas/carcinomas was 60% (interquartile range, 22%), which largely exceeds the disease rate reported in the general asymptomatic population. Meta-analysis showed that patients with S. bovis biotype I infection had a strongly increased risk of having CRC (pooled odds ratio [OR], 7.26; 95% confidence interval [CI], 3.94-13.36) and IE (pooled OR, 16.61; 95% CI, 8.85-31.16), compared with S. bovis biotype II-infected patients. Notably, CRC occurred more often among patients with S. bovis IE than among patients with S. bovis infection at other sites (pooled OR, 3.72; 95% CI, 2.03-6.81).

CONCLUSIONS

Our meta-analysis clearly indicates that S. bovis should no longer be regarded as a single species in clinical practice, because S. gallolyticus (S. bovis biotype I) infection, in particular, has an unambiguous association with CRC.

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.

Reidentification of Streptococcus bovis isolates causing bacteremia according to the new taxonomy criteria: still an issue?

All Streptococcus bovis blood culture isolates recovered from January 2003 to January 2010 (n = 52) at the Hospital Universitario Ramón y Cajal were reidentified on the basis of their genetic traits using new taxonomic criteria. Initial identification was performed by the semiautomatic Wider system (Fco. Soria-Melguizo, Spain) and the API 20 Strep system (bioMérieux, France). All isolates were reidentified by PCR amplification and sequencing of both the 16S rRNA and sodA genes and by mass spectrometry using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; Bruker, Germany). Results of 16S rRNA/sodA gene sequencing were as follows: Streptococcus gallolyticus subsp. gallolyticus, 14/14 (number of isolates identified by 16S rRNA/number of isolates identified by sodA gene sequencing); Streptococcus gallolyticus subsp. pasteurianus, 24/24; Streptococcus spp., 7/0; Streptococcus infantarius subsp. infantarius, 0/2; Streptococcus lutetiensis, 0/5; Leuconostoc mesenteroides, 4/0; and Lactococcus lactis, 3/3. MALDI-TOF MS identified 27 S. gallolyticus isolates but not at the subspecies level, 4 L. mesenteroides isolates, 3 L. lactis isolates, and 6 S. lutetiensis isolates, whereas 12 isolates rendered a nonreliable identification result. Pulsed-field gel electrophoresis grouped all S. gallolyticus subsp. gallolyticus isolates into 3 major clusters clearly different from those of the S. gallolyticus subsp. pasteurianus isolates, which, in turn, exhibited no clonal relationship. The percentages of resistance to the tested antimicrobials were 38% for erythromycin, 23% for fosfomycin, 10% for levofloxacin, 6% for tetracycline, and 4% for co-trimoxazole. The most frequent underlying diseases were hepatobiliary disorders (53%), endocarditis (17%), and malignancies (12%). We conclude that sequencing of the sodA gene was the most discriminatory method and that S. gallolyticus subsp. pasteurianus appears to have a higher genetic diversity than S. gallolyticus subsp. gallolyticus.

[Descriptive analysis of diseases associated with Streptococcus bovis bacteremia]

BACKGROUND AND OBJECTIVE

It is well-known the relationship between Streptococcus bovis (S. bovis) bacteremia and colon cancer, liver cirrhosis and others neoplasms. However, a study protocol to rule out these underlying diseases has not been carried out yet. Our objective was to describe S. bovis bacteremia and associated diseases.

PATIENTS AND METHOD

Multicenter, retrospective cohort study. S. bovis bacteremias episodes between 2001 and 2009 were included. Mean variables: colon neoplasm, non-colonic neoplasm or liver cirrhosis. Epidemiologist aspects, bacteremia related variables, personal and familiar history and clinical and analytical data were collected.

RESULTS

Ninety three patients were included. One out of four individuals had a colon neoplasm. Fifty seven per cent were concomitant cases with bacteremia and six cases were diagnosed after bacteremia (time bacteremia-diagnosis of neoplasm [months], median [Q1-Q3], 2.6 [1-11]). Fourteen (15%) patients were diagnosed with any non-colonic neoplasm (mainly biliary and pancreatic [6 cases] or esophagus-gastric [3 cases]). There were three patients (21%) with concomitant bacteremia non-colonic neoplasm and two after it (1.2 and 10.4 months). Twenty-one (23%) patients suffered from liver cirrhosis.

CONCLUSIONS

Patients with S. bovis bacteremia must undergo a study designed to rule out underlying diseases. We suggest that this study should include: a colonic evaluation, ideally by colonoscopy, a liver evaluation by serum chemistry, an abdominal ultrasound scan or a method of liver fibrosis assessment, a gastroscopy and an evaluation of biliary and pancreatic areas by magnetic resonance imaging.