Potential Transmission Pathways of Streptococcus gallolyticus subsp. gallolyticus

Geese as reservoirs of human colon cancer-associated Streptococcus gallolyticus

Recently, an increased number of reports have described pathogens of animal origin that cause a variety of infections and a rise in their transmission to humans. Streptococcus gallolyticus, a member of the Streptococcus bovis/Streptococcus equinus complex (SBSEC), is one of these pathogens and infects a wide range of hosts from mammals to poultry and has a broad functionality ranging from pathogenicity to food fermentation. As S. gallolyticus causes complications including bacteremia, infective endocarditis, and colorectal malignancy in humans, it is important to investigate its occurrence in various hosts, including geese, to prevent potential zoonotic transmissions. This study aimed to investigate the presence of S. gallolyticus in the droppings of clinically healthy and diarrheic geese, which were raised intensively and semi-intensively, by the in vitro culture method, characterize the isolates recovered by PCR and sequence-based molecular methods and determine their antibiotic susceptibility by the disk diffusion and gradient test methods. For this purpose, 150 samples of fresh goose droppings were used. Culture positivity for S. gallolyticus was determined as 8% (12/150). PCR analysis identified 54.55% (n = 6) of the isolates as S. gallolyticus subsp. gallolyticus and 45.45% (n = 5) as S. gallolyticus subsp. pasteurianus. Following the 16S rRNA sequence and ERIC-PCR analyses, S. gallolyticus subspecies exhibited identical cluster and band profiles that could be easily distinguished from each other and were clonally identified. High rates of susceptibility to florfenicol, penicillin, rifampicin, and vancomycin were detected among the isolates, regardless of the subspecies diversity. Both subspecies showed high levels of resistance to bacitracin, clindamycin, doxycycline, tetracycline, trimethoprim-sulfamethoxazole, and erythromycin and multiple MDR profiles, indicating their potential to become superbugs. This first report from Türkiye demonstrates the occurrence of the S. gallolyticus subspecies in geese. In view of the recent increase of geese production and the consumption of goose meat in Türkiye, the occurrence of S. gallolyticus in geese should not be ignored to prevent zoonotic transmission.

Sciatica caused by spinal epidural abscess as the initial clinical presentation of colon cancer: a rare case report and review of literature

BACKGROUND

Colorectal cancer is one of the most frequently diagnosed forms of cancer, and it is associated with several common symptoms and signs such as rectal bleeding, altered bowel habits, abdominal pain, anemia, and unintentional weight loss. Sciatica, a debilitating condition in which the patient experiences paresthesia and pain in the dermatome of associated lumbosacral nerve roots or sciatic nerve distribution, is not considered one of these. Here we present a case of colorectal cancer manifesting symptoms of sciatica alone.

CASE PRESENTATION

A 68-year-old male presented with progressive lower back pain radiating to his left thigh and calf over L5/S1 dermatome. Sciatica was suspected and initially underwent conservative treatment with analgesics. However, the symptoms progressed and MRI revealed an epidural abscess surprisingly. Surgical debridement was performed and pus culture isolated Streptococcus gallolyticus. Based on the strong association of S. gallolyticus with colorectal cancer, the presence of this pathogen prompted further tumor evaluation, even in the absence of the typical symptoms and signs. This investigation ultimately leads to the diagnosis of sigmoid adenocarcinoma.

CONCLUSIONS

Although rare, sciatica caused by S. gallolyticus infection of the spinal epidural space may serve as the initial presentation of colorectal cancer. Physicians should be aware of the strong association between S. gallolyticus and colorectal cancer. Based on what we currently know about the condition; a thorough systematic assessment of occult neoplasia for patients with S. gallolyticus infection is recommended.

Isolation, characterization, and experimental infection of Streptococcus gallolyticus subspecies pasteurianus from commercial turkeys with acute septicemia: a pilot study

Streptococcus gallolyticus (SG) is a Gram-positive cocci found as commensal gut flora in animals and humans. SG has emerged as a cause of disease in young poults between 1 and 3 wk of age. SG is associated with septicemia resulting in acute mortality with no premonitory signs in turkeys. Three SG isolates were obtained from clinical field cases of acute septicemia of commercial turkeys and used in three independent experiments. In Experiment 1, embryos were inoculated 25 d of embryogenesis with varying concentrations of SG1, SG2, or SG3. In Experiment 2, day of hatch, poults were inoculated with varying concentrations using different routes of administration of SG1, SG2, or SG3. In Experiment 3, day of hatch, poults were inoculated with only isolate SG1 using different paths. Poults were randomly selected for necropsy on d 8 and d 15 and sampled to collect spleen, heart, and liver for SG on d 21, the remaining poults were necropsied and cultured. Samples were plated on Columbia nalidixic acid and colistin agar (CNA) (40°C, 18-24 h). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) confirmed suspect colonies. Data were analyzed using the chi-square test of independence, testing all possible combinations to determine significance (P < 0.05). Weight data were subjected to ANOVA using JMP with significance (P < 0.05). No differences were found in BW or BWG on d 0, 8, 15, or 22. Splenomegaly, focal heart necrosis, and pericarditis were observed in all groups in experiments 1 through 3. In Experiment 3, only airsacculitis was observed in a negative control in separate isolation (P > 0.05). On d 21 of Experiment 3, increased (P < 0.05) recovery of SG from spleens were observed in co-housed negative controls, as well as poults challenged by oral gavage (P > 0.05 for d 7 and d 14). These results confirm numerous previous studies indicating that SG subsp. pasteurianus is a primary infectious microorganism that causes septicemia in young poults.

Species and biotypes of Streptococcus bovis causing infective endocarditis

INTRODUCTION

Streptococcus bovis/equinus complex (SBEC) is a major cause of infective endocarditis (IE), although its incidence varies greatly depending on the geographical area. The characteristics of IE caused by Streptococcus gallolyticus susp. gallolyticus are well known; there are hardly any descriptions of IE caused by other species or biotypes.

METHODS

Retrospective cohort study, from 1990 to 2019, of all SBEC IE in adults in three Spanish hospitals, Lugo (LH), Barcelona (BH) and Ferrol (FH) where the population is mainly rural, urban and mixed, respectively. The incidence of IE was analyzed in 3 areas. Clinical characteristics of IE (277 cases, 258 biotyped) were compared according to SBEC species and biotypes.

RESULTS

There are significant differences between the incidence of SBEC IE in HL (27.9/10⁶) vs. HF and HB (8.8 and 7,1, respectively, p<0.001). We found significant differences (SbI vs. SbII) in mean age (68.5 vs. 73 years; p<0.01), duration of symptoms before diagnosis (46.9±46.5 vs. 30.4±40.9 days; p<0.01), presence of comorbidities: 39.1% (78) vs. 54.2% (32; p<0.04), predisposing heart illness:62.3% (124) vs. 81.3% (48; p<0.006), particularly, prosthetic or intravascular devices IE: 24.6% (49) vs. 52.4% (31; p<0.001), bi-valve involvement:23.6% (47) vs. 11.8% (7; p<0.05) and heart failure: 24.6% (49) vs. 38.9% (23; p<0.03). There were no significant differences in embolic events, need for surgery or mortality. The association with CRC was high in both groups: 77.7% vs. 66.6%.

CONCLUSIONS

IE due to SBEC has geographical variations in incidence and different clinical characteristics among biotypes. The association with CRC was high.

Suppurative meningoencephalitis and perineuritis caused by Streptococcus gallolyticus in a Japanese Black calf

A 179-day-old calf, which was weak and stunted, showed neurological signs and was euthanized. Postmortem examination revealed extensive and severe cloudy area in the meninges, and pleural pneumonia. Gram-positive cocci were isolated from systemic organs. Biochemical and 16S rRNA gene sequence analyses identified the isolate as Streptococcus gallolyticus, and its subspecies was suggested to be gallolyticus (SGG). The isolate was classified as a novel sequence type (ST115) by the multilocus sequence typing scheme for SGG and showed susceptibility to penicillin, ampicillin, amoxicillin, florfenicol, sulfamethoxazole-trimethoprim, and chloramphenicol. Histopathologically, suppurative meningoencephalitis and perineuritis were detected. As SGG has been isolated solely from a cow with mastitis in Japan, this is the first SGG infection in a calf with suppurative meningoencephalitis and perineuritis in this country.

Dietary sophorolipid accelerates growth by modulation of gut microbiota population and intestinal environments in broiler chickens

BACKGROUND

Gut is a crucial organ for the host's defense system due to its filtering action of the intestinal membrane from hazardous foreign substances. One strategy to strengthen the gut epithelial barrier function is to upregulate beneficial microflora populations and their metabolites. Sophorolipid (SPL), which is a glycolipid bio-surfactant, could increase beneficial microflora and decrease pathogenic bacteria in the gastrointestinal tract. Therefore, herein, we conducted an experiment with broiler chickens to investigate the fortifying effects of SPL on the host's gut defense system by modulating the microbiota population.

METHODS

A total of 540 1-day-old chicks (Ross 308) were used, and they were immediately allotted into three treatment groups (6 replications with 30 chicks/pen) according to their initial body weight. The dietary treatments consisted of CON (basal diet), BAM (10 mg/kg bambermycin), and SPL (10 mg/kg SPL). During the experiment, birds freely accessed feed and water, and body weight and feed intake were measured at the end of each phase. On d 35, birds (one bird/pen) were sacrificed to collect jejunum and cecum samples.

RESULTS

Dietary SPL and BAM supplementation significantly accelerated birds' growth and also significantly improved feed efficiency compared to CON. Intestinal microbial community was significantly separated by dietary SPL supplementation from that of CON, and dietary SPL supplementation significantly increased Lactobacillus spp. and Akkermansia muciniphila. Moreover, birds fed with dietary SPL also showed the highest concentration of cecal butyrate among all treatment groups. Gut morphological analysis showed that dietary SPL significantly increased villus height, ratio of villus height to crypt depth, goblet cell numbers, and the gene expression levels of claudin-1 and mucin 2. Additionally, dietary SPL significantly decreased the mRNA expression level of pro-inflammatory cytokine, interleukin-6, and increased that of anti-inflammatory cytokine, interleukin-10, compared to other treatments.

CONCLUSIONS

Dietary SPL increases the beneficial bacterial population and butyrate concentration, which leads to a strengthened gut barrier function. In addition, the intestinal inflammation was also downregulated by dietary SPL supplementation.

Secretion, Maturation, and Activity of a Quorum Sensing Peptide (GSP) Inducing Bacteriocin Transcription in Streptococcus gallolyticus

Streptococcus gallolyticus subsp. gallolyticus is an emerging opportunistic pathogen responsible for septicemia and endocarditis in the elderly. Invasive infections by S. gallolyticus subsp. gallolyticus are strongly linked to the occurrence of colorectal cancer (CRC). It was previously shown that increased secondary bile salts under CRC conditions enhance the bactericidal activity of gallocin, a bacteriocin produced by S. gallolyticus subsp. gallolyticus, enabling it to colonize the mouse colon by outcompeting resident enterococci (L. Aymeric, F. Donnadieu, C. Mulet, L. du Merle, et al., Proc Natl Acad Sci U S A 115:E283-E291, 2018, https://doi.org/10.1073/pnas.1715112115). In a separate study, we showed that S. gallolyticus subsp. gallolyticus produces and secretes a 21-mer peptide that activates bacteriocin production (A. Proutière, L. du Merle, B. Périchon, H. Varet, et al., mBio 11:e03187-20, 2020, https://doi.org/10.1128/mBio.03187-20). This peptide was named CSP because of its sequence similarity with competence-stimulating peptides found in other streptococci. Here, we demonstrate that CSP is a bona fide quorum sensing peptide involved in activation of gallocin gene transcription. We therefore refer to CSP as GSP (gallocin-stimulating peptide). GSP displays some unique features, since its N-terminal amino acid lies three residues after the double glycine leader sequence. Here, we set out to investigate the processing and export pathway that leads to mature GSP. Heterologous expression in Lactococcus lactis of the genes encoding GSP and the BlpAB transporter is sufficient to produce the 21-mer form of GSP in the supernatant, indicating that S. gallolyticus subsp. gallolyticus BlpAB displays an atypical cleavage site. We also conducted the first comprehensive structure-activity relationship (SAR) analysis of S. gallolyticus subsp. gallolyticus GSP to identify its key structural features and found that unlike many other similar streptococci signaling peptides (such as CSPs), nearly half of the mature GSP sequence can be removed (residues 1 to 9) without significantly impacting the peptide activity.IMPORTANCE Streptococcus gallolyticus subsp. gallolyticus is an opportunistic pathogen associated with colorectal cancer (CRC) and endocarditis. S. gallolyticus subsp. gallolyticus utilizes quorum sensing (QS) to regulate the production of a bacteriocin (gallocin) and gain a selective advantage in colonizing the colon. In this article, we report (i) the first structure-activity relationship study of the S. gallolyticus subsp. gallolyticus QS pheromone that regulates gallocin production, (ii) evidence that the active QS pheromone is processed to its mature form by a unique ABC transporter and not processed by an extracellular protease, and (iii) supporting evidence of interspecies interactions between streptococcal pheromones. Our results revealed the minimal pheromone scaffold needed for gallocin activation and uncovered unique interactions between two streptococcal QS signals that warrant further study.

The Influence of Essential Oils on Gut Microbial Profiles in Pigs

Simple Summary

In recent years, the intake of ultra-processed foods has increased dramatically worldwide. Missing natural foods in the diet raise the need of biologically active food components that could compensate for this deficiency and help maintain proper immune status. In this study, the microbial changes in pigs as experimental animals were assessed as influenced by consumption of oregano extract combination with peppermint and thyme essential oils. The results demonstrated that the combination of plant extracts had a positive effect on the gastrointestinal tract of animals by increasing the number of probiotic bacteria. Based on the results obtained it may be outlined that the combination of oregano extract and peppermint and thyme essential oils can be promising ingredient as a functional component for the development of the new nutraceutical preparation.

Abstract

In recent years, the intake of ultra-processed foods has increased dramatically worldwide. Missing natural foods in the diet raise the need of biologically active food components that could compensate for this deficiency and help maintain proper immune status. This study used pigs as an animal model for the assessment of the impact of consumption of Origanum vulgare plant extract combined with Mentha piperita and Thymus vulgaris essential oils on microbial profile in intestines. A single group of weaned pigs received basal diet, while the other group basal diet supplemented with plant extract and two essential oils in the form of bilayer tablets prepared using “liquid/solid” phase technology. Metagenomic sequencing was performed with the aim to investigate changes of microbial communities in ileum, caecum, and colon. The results demonstrated that the combination of essential oils was non cytotoxic, and had a positive effect on the microbial composition in the large intestine of pigs due to significant increase in the number of probiotic bacteria. The amount of Lactobacillus was 2.5 times and Bifidobacterium 1.9 times higher in the animal group fed with supplement. The combination, however, had some negative impact on the variety of minor species in the distal part of the ileum. Additional studies need to be performed to obtain knowledge on how combinations of essential oils can change bacterial variety in the proximal part of the gastrointestinal tract.

Characterization of Bacteriophage Peptides of Pathogenic Streptococcus by LC-ESI-MS/MS: Bacteriophage Phylogenomics and Their Relationship to Their Host

The present work focuses on LC-ESI-MS/MS (liquid chromatography-electrospray ionization-tandem mass spectrometry) analysis of phage-origin tryptic digestion peptides from mastitis-causing Streptococcus spp. isolated from milk. A total of 2,546 non-redundant peptides belonging to 1,890 proteins were identified and analyzed. Among them, 65 phage-origin peptides were determined as specific Streptococcus spp. peptides. These peptides belong to proteins such as phage repressors, phage endopeptidases, structural phage proteins, and uncharacterized phage proteins. Studies involving bacteriophage phylogeny and the relationship between phages encoding the peptides determined and the bacteria they infect were also performed. The results show how specific peptides are present in closely related phages, and a link exists between bacteriophage phylogeny and the Streptococcus spp. they infect. Moreover, the phage peptide M∗ATNLGQAYVQIM∗PSAK is unique and specific for Streptococcus agalactiae. These results revealed that diagnostic peptides, among others, could be useful for the identification and characterization of mastitis-causing Streptococcus spp., particularly peptides that belong to specific functional proteins, such as phage-origin proteins, because of their specificity to bacterial hosts.

Proteomic Characterization of Antibiotic Resistance, and Production of Antimicrobial and Virulence Factors in Streptococcus Species Associated with Bovine Mastitis. Could Enzybiotics Represent Novel Therapeutic Agents Against These Pathogens?

Streptococcus spp. are major mastitis pathogens present in dairy products, which produce a variety of virulence factors that are involved in streptococcal pathogenicity. These include neuraminidase, pyrogenic exotoxin, and M protein, and in addition they might produce bacteriocins and antibiotic-resistance proteins. Unjustifiable misuse of antimicrobials has led to an increase in antibiotic-resistant bacteria present in foodstuffs. Identification of the mastitis-causing bacterial strain, as well as determining its antibiotic resistance and sensitivity is crucial for effective therapy. The present work focused on the LC–ESI–MS/MS (liquid chromatography–electrospray ionization tandem mass spectrometry) analysis of tryptic digestion peptides from mastitis-causing Streptococcus spp. isolated from milk. A total of 2706 non-redundant peptides belonging to 2510 proteins was identified and analyzed. Among them, 168 peptides were determined, representing proteins that act as virulence factors, toxins, anti-toxins, provide resistance to antibiotics that are associated with the production of lantibiotic-related compounds, or play a role in the resistance to toxic substances. Protein comparisons with the NCBI database allowed the identification of 134 peptides as specific to Streptococcus spp., while two peptides (EATGNQNISPNLTISNAQLNLEDKNK and DLWC*NM*IIAAK) were found to be species-specific to Streptococcus dysgalactiae. This proteomic repository might be useful for further studies and research work, as well as for the development of new therapeutics for the mastitis-causing Streptococcus strains.

Selectived and Reshaped Early Dominant Microbial Community in the Cecum With Similar Proportions and Better Homogenization and Species Diversity Due to Organic Acids as AGP Alternatives Mediate Their Effects on Broilers Growth

Understanding the differences in microbial communities shaped by different food selective forces, especially during early post-hatch period, is critical to gain insight into how to select, evaluate, and improve antibiotic growth promoters (AGPs) alternatives in food animals. As a model system, commercial diet-administered OAs (DOAs) and water-administered OAs (WOAs) were used separately or in combination as Virginiamycin alternatives for broiler feeding during two growth phases: 1–21 days and 22–42 days. Among these three OA-treated groups, the DOA group was most similar to the AGP group in the composition and the proportion of these dominant bacterial communities at the level of phylum, family, and genus in cecal chyme of broilers. Sub-therapeutic Virginiamycin decreased the richness, homogenization, and species diversity of gut microbiota, especially in the early growth stage from days 1 to 21. Among these three OA supplementation schemes, it was clear that DOA supplementation was more likely to increase or maintain the richness, homogenization, species diversity, and predicted gene functions of cecal microbiota in treated broilers than either no supplementation or AGP supplementation during two experimental stages. The interference of DOA treatment with early colonization of probiotics and pathogens in broiler cecum was the most similar to AGP treatment, and OAs did not cause the occurrence of Virginiamycin-resistant strains of Enterococcus at the end of this trial. In terms of the predicted gene functions of the microbiota, AGP and DOA treatments provided a similar selective force for microbial metabolism functions in the cecum of broiler chickens, especially in the early growth stage. Noticeably, the relative abundance of some microbiome that was modified by Virginiamycin or DOA supplementation was significantly correlated with body weight gain and KEGG pathway analysis-annotated gene functions such as replication and repair, translation, nucleotide metabolism, and so on. With the comprehensive analysis of these results and practical application, shortened DOA supplementation, after optimization of the amount of addition, would be a suitable alternative to sub-therapeutic Virginiamycin. It was suggested that the programed intestinal microecology under such early selection forces and the effective addition time may be the key elements to focus on the designed alternate strategies of AGPs in food animals.

Antimicrobial Resistance in Streptococcus spp

The genus Streptococcus includes Gram-positive organisms shaped in cocci and organized in chains. They are commensals, pathogens, and opportunistic pathogens for humans and animals. Most Streptococcus species of veterinary relevance have a specific ecological niche, such as S. uberis, which is almost exclusively an environmental pathogen causing bovine mastitis. In contrast, S. suis can be considered as a true zoonotic pathogen, causing specific diseases in humans after contact with infected animals or derived food products. Finally, Streptococcus species such as S. agalactiae can be sporadically zoonotic, even though they are pathogens of both humans and animals independently. For clarification, a short taxonomical overview will be given here to highlight the diversity of streptococci that infect animals. Several families of antibiotics are used to treat animals for streptococcal infections. First-line treatments are penicillins (alone or in combination with aminoglycosides), macrolides and lincosamides, fluoroquinolones, and tetracyclines. Because of the selecting role of antibiotics, resistance phenotypes have been reported in streptococci isolated from animals worldwide. Globally, the dynamic of resistance acquisition in streptococci is slower than what is experienced in Enterobacteriaceae, probably due to the much more limited horizontal spread of resistance genes. Nonetheless, transposons or integrative and conjugative elements can disseminate resistance determinants among streptococci. Besides providing key elements on the prevalence of resistance in streptococci from animals, this article will also largely consider the mechanisms and molecular epidemiology of the major types of resistance to antimicrobials encountered in the most important streptococcal species in veterinary medicine.

Correlation between Streptococcus bovis bacteremia and density of cows in Galicia, northwest of Spain

BACKGROUND

There are few data on the epidemiology of infections caused by Streptococcus bovis (Sb). Some studies suggest that both residence in rural areas and contact with livestock could be potential risk factors.

METHODS

We performed a retrospective study for the period 2005-2016 of all cases of bacteremia caused by Sb in Galicia (a region in the northwest of Spain). The association between the incidence rate of Sb bacteremia and the number of cattle by province and district was analyzed.

RESULTS

677 cases were included with a median age of 76 years, 69.3% males. The most frequent infections were endocarditis (234 cases, 34.5%), primary bacteremia (213 cases, 31.5%) and biliary infection (119 cases, 17.5%). In 252 patients, colon neoplasms were detected (37.2%). S. gallolyticus subsp. gallolyticus was the predominant species (52.3%). Mortality was 15.5% (105 cases). The annual incidence rate was 20.2 cases/10⁶ inhabitants and was correlated with the density of cattle (p < 0.001), but not with rurality. When comparing the two provinces with a strong predominance of rural population, but with important differences in the number of cattle, such as Orense and Lugo, with 6% and 47.7% of Galician cattle, respectively, the rates were very different: 15.8 and 43.6 cases/10⁶, respectively, with an RR of 2.7 (95% CI, 2.08-3.71). Some districts of the province of Lugo had rates higher than 100 cases/10⁶ inhabitants.

CONCLUSIONS

Our study shows a significant correlation between the rates of Sb bacteremia and cattle density, suggesting a possible transmission of Sb from cows to people.

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.

Distribution of species and antimicrobial resistance among enterococci isolated from the fecal microbiota of captive blue-fronted parrot (Amazona aestiva) in Rio de Janeiro, Brazil

Enterococcal strains recovered from fecal samples of captive blue-fronted parrots (Amazona aestiva) assisted at two wild animal screening centers in Rio de Janeiro, Brazil, were identified as Enterococcus hirae (the predominant species; 75.3%), followed by Enterococcus faecalis (17.3%), Enterococcus casseliflavus (4.8%), Enterococcus gallinarum (1.7%), and Enterococcus hermanniensis (0.9%). All strains were susceptible to linezolid and teicoplanin. Rates of nonsusceptibility (including resistant and intermediate categories) to other 16 antimicrobials tested varied from 69.3% to 0.4%, A considerable proportion (48.0%) of the strains was multidrug-resistant and diverse genetic determinants associated with antimicrobial resistance were identified. Tetracycline-resistant strains carried the tet(M) and/or tet(L) genes. Macrolides resistance was associated with the erm(B), erm(A) and mefA genes, while 43.2% of the isolates were negative for the investigated genes. High-level resistance to gentamicin associated with the aac(6')-le-aph(2″)-la gene was detected in one E. faecalis strain. The two strains presenting high-level resistance to streptomycin were negative for the ant(6')-Ia, ant(3')-Ia, ant(9')-Ia and ant(9')-Ib genes. The vat(D) gene was found in all the 47 quinupristin/dalfopristin resistant strains identified as non-E. faecalis. Analysis of PFGE profiles of E. hirae strains after restriction with SmaI demonstrated the occurrence of five clonal groups. The predominant E. hirae clone was distributed among birds in the two institutions, suggesting that this clone was well adapted to the host and environments investigated. The four clonal groups identified among E. faecalis were composed by small numbers of strains and, generally, restricted to birds in the same sector. The occurrence of enterococcal strains exhibiting antimicrobial resistance traits and carrying genetic determinants that represent potential threats to the health of both humans and animals, in the intestinal microbiota of A. aestiva, highlights the need for additional monitoring studies to elucidate the population structure and the dynamics of transmission of these microorganisms among animals, humans and the environment.

Strain-dependent interactions of Streptococcus gallolyticus subsp. gallolyticus with human blood cells

BACKGROUND

Streptococcus gallolyticus subsp. gallolyticus (S. gallolyticus) is the causative pathogen in up to 20% of streptococcal-induced infective endocarditis (IE) cases. However, the underlying mechanisms of pathogenesis in S. gallolyticus have not yet been solved. Pathogens causing IE need to employ virulent strategies to initiate and establish infections, such as escape the bloodstream, invade the host-cell, and persist intracellularly. In this study, we examined the induction of inflammation by different S. gallolyticus strains in relation to their survival in whole blood and cell culture models as well as their ability to induce platelet aggregation. Phagocytosis of these bacteria by macrophages, followed by intracellular survival, was also quantified.

METHODS

In whole blood and THP-1 cell culture assays bacterial growth kinetics was determined by plating, followed by colony counting. Induction of interleukin (IL)-6 expression in whole blood of three healthy volunteers, caused by different strains, was quantified by ELISA. Gene expression of cytokines (IL1B, IL6 and IL8) was quantified by real-time PCR after stimulating THP-1 monocytes with bacteria. Induction of platelet aggregation was analyzed by light transmission aggregometry using the BORN method. A macrophage model was used to analyze phagocytosis of strains and their survival in macrophages within 48 h.

RESULTS

Strains promoted IL-6 secretion in a time-dependent fashion. For example, DSM16831 induced IL-6 secretion in whole blood earlier than other isolates, and was eliminated in the whole blood of one volunteer, whereas UCN34 could grow. Platelet aggregation depended on the different isolates used and on the individual platelet donor. Two strains (AC1181 and 010672/01) induced cytokine gene expression in THP-1 monocytes only marginally, compared to other strains. The phagocytosis rate of S. gallolyticus isolates differed significantly, and the isolates UCN34 and BAA-2069 could persist for a considerable time in the phagocytes.

CONCLUSION

The strain-dependent differences of S. gallolyticus isolates, observed during interaction with human blood cells, support the hypotheses that divergences in individual virulence factors determine a distinct pathogenicity of the isolates. These data constitute an additional step towards the elucidation of mechanisms in the complex, multifactorial pathogenesis of this IE pathogen.

Case-control study: Determination of potential risk factors for the colonization of healthy volunteers with Streptococcus gallolyticus subsp. gallolyticus

Streptococcus gallolyticus subsp. gallolyticus was identified in humans and animals as commensal of the gut and can act as a causative agent of endocarditis and septicemia. A case-control study was performed to identify yet unknown risk factors for the transmission of this facultative pathogen. The prevalence in the gut of 99 healthy volunteers was determined using real-time polymerase chain reaction resulting in 62.5% S. gallolyticus subsp. gallolyticus positive excrements. Subsequent cultivation offered three isolates and epidemiological analysis based on MLST revealed sequence type (ST) 3 and ST 7, previously detected from bovine and endocarditis patients. These results support the hypotheses of the zoonotic potential of this bacterium. Participant questionnaires were evaluated concerning personal characteristics, nutritional habits and animal contact. Specifically, closer contact between participants and animals influenced the colonization of the human gut significantly and was further affected if volunteers used excrement for the fertilization of plants.

New Insights into the Enterococcus faecium and Streptococcus gallolyticus subsp. gallolyticus Host Interaction Mechanisms

Enterococcus faecium and Streptococcus gallolyticus subsp. gallolyticus (S. gallolyticus) were classically clustered into the Lancefield Group D streptococci and despite their taxonomic reclassification still share a similar genetic content and environment. Both species are considered as opportunistic pathogens. E. faecium is often associated with nosocomial bacteraemia, and S. gallolyticus is sporadically found in endocarditis of colorectal cancer patients. In both cases, the source of infection is commonly endogenous with a translocation process that launches through the intestinal barrier. To get new insights into the pathological processes preceding infection development of both organisms, we used an in vitro model with Caco-2 cells to study and compare the adhesion, invasion and translocation inherent abilities of 6 E. faecium and 4 S. gallolyticus well-characterized isolates. Additionally, biofilm formation on polystyrene, collagen I and IV was also explored. Overall results showed that E. faecium translocated more efficiently than S. gallolyticus, inducing a destabilization of the intestinal monolayer. Isolates Efm106, Efm121 and Efm113 (p < .001 compared to Ef222) exhibited the higher translocation ability and were able to adhere 2–3 times higher than S. gallolyticus isolates. Both species preferred the collagen IV coated surfaces to form biofilm but the S. gallolyticus structures were more compact (p = .01). These results may support a relationship between biofilm formation and vegetation establishment in S. gallolyticus endocarditis, whereas the high translocation ability of E. faecium high-risk clones might partially explain the increasing number of bacteraemia.

Organic Turkey Flocks: A Reservoir of Streptococcus gallolyticus subspecies gallolyticus

Streptococcus gallolyticus subspecies gallolyticus (S. gallolyticus) can colonise the gastrointestinal tract of humans and animals and is known to cause similar infections in both humans and animals. Data about the spread or prevalence in farm animals are missing. In this study, Trypton Soya Agar was modified to a selective medium enabling the isolation and quantification of S. gallolyticus from faecal samples. The bacterium was observed in 82 out of 91 faecal samples obtained from 18 different organic turkey flocks. The prevalence of shedding birds was estimated by the number of positive fresh droppings and reached up to 100% on most farms. Furthermore, for the first time S. gallolyticus was quantified in faeces from poultry flocks. The median of colony forming units (CFU) per gramme faeces was 3.6 x 10⁵CFU/g. Typing of one isolate from each positive faecal sample by multilocus sequence typing delivered 24 sequence types (STs). Most of the isolates belonged to the clonal complex CC58. The same STs of this complex were detected in up to six different flocks. Partly, these flocks were located in various regions and stocked with varying breeding lines. Regarding the biochemical profiles of the same STs from different farms, the results did not contradict a spread of specific STs in the organic turkey production. Moreover, checking the pubMLST database revealed that STs found in this study were also found in other animal species and in humans. The high detection rate and the number of S. gallolyticus in turkey faeces indicate that this bacterium probably belongs to the common microbiota of the gastrointestinal tract of turkeys from organic flocks. Furthermore, the findings of this study support the suggestion of a possible interspecies transmission.