Streptococcus gordonii is a primary coloniser of the tooth surface where it efficiently ferments carbohydrates at pH levels above 6.0. By not being able to maintain the pH of dental plaque to a level required for enamel dissolution, the dominance of S. gordonii in dental plaque is considered a sign of a healthy oral cavity. However, upon entering the bloodstream and encountering a rise in pH, S. gordonii may become pathogenic, being one of the major causative organisms associated with infective endocarditis. Proteome analyses of S. gordonii grown at steady state in a chemostat allowed the phenotypic changes associated with alterations in pH levels characteristic of these two environments to be determined. As an initial starting point to this study, a two-dimensional electrophoresis (2- DE) reference map of S. gordonii grown at pH 7.0 was produced. Although only 50% of the S gordonii genome was available in an annotated form during the course of this study, the closely related Streptococcus pneumoniae genome (with which S. gordonii shares 97.24% DNA sequence homology) had been completed in 2001. The use of both of these databases allowed many of the S. gordonii proteins to be identified by mass spectrometry. Four hundred and seventy six protein spots, corresponding to 250 different proteins, or 12.5% of the S. gordonii proteome, were identified, giving rise to the first comprehensive proteome reference map of this oral bacterium. Of the 250 different proteins, 196 were of cellular origin while 68 were identified from the extracellular milieu. Only 14 proteins were common to both compartments. Of particular interest among the 54 uniquely identified extracellular proteins was a homologue of a peptidoglycan hydrolase that has been associated with virulence in S. pneumoniae. Among the other proteins identified were ones involved in transport and binding, energy metabolism, translation, transformation, stress response and virulence. Twelve cell envelope proteins were identified as well as 25 others that were predicted to have a membrane association based on the presence of at least one transmembrane domain. The study also confirmed the existence of 38 proteins previously designated as �hypothetical� or with no known function. Mass spectral data for over 1000 protein spots were accumulated and archived for future analysis when sequencing of the S. gordonii genome is finally completed. Following the mapping of the proteome of S. gordonii, alterations in protein spots associated with growth of the bacterium at pH intervals of 0.5 units in the pH range 5.5 - 7.5 were determined. Only 16 protein spots were shown to be significantly altered in their level of expression despite the range of pH studied. Among the differentially expressed proteins was a manganese-dependent inorganic pyrophosphatase (PpaC), which regulates expression of adhesins required for coaggregation. The expression of PpaC was highest at pH 6.5 - 7.0, the pH of a healthy oral cavity, indicating that PpaC may play an important part in dental plaque formation. Another differentially expressed protein was the heat-inducible transcription repressor (HrcA). Alterations in HrcA were consistent with its role as a negative repressor in regulating heat-shock proteins at low pH, even though no changes in the level of heat-shock proteins were observed as the pH declined. This result gave rise to the hypothesis that the possible reason cariogenic bacteria, such as Streptococcus mutans, can out compete S. gordonii at low pH might simply be due to their ability to manipulate their proteome in a complex manner for survival and persistence at low pH, unlike S. gordonii. This may imply some prevailing level of genetic regulation that is missing in S. gordonii.

Manganese-deficient Streptococcus sanguinis mutants exhibit a dramatic decrease in virulence for infective endocarditis and in aerobic growth in manganese-limited media. Loss of activity of a manganese-dependent, oxygen-dependent ribonucleotide reductase (RNR) could explain the decrease in virulence. When the genes encoding this RNR are deleted, there is no growth of the mutant in aerobic broth culture or in an animal model. Testing the contribution of the aerobic RNR to the phenotype of a manganese transporter mutant, a heterologous class II RNR from Lactobacillus leichmannii called NrdJ that requires B12 rather than manganese as a cofactor was previously introduced into an RNR mutant of S. sanguinis. Aerobic growth was only partially restored. Currently, we sought to improve NrdJ-dependent growth by (i) amending the medium to increase cellular levels of B12; (ii) characterizing a spontaneous mutant of the NrdJ-complemented strain with improved aerobic growth; and (iii) altering this strain through further genetic manipulation.

L’endocardite infectieuse (EI) est une maladie rare, de diagnostic difficile et de pronostic réservé. Staphylococcus aureus (SA) et les streptocoques oraux en sont les principaux microorganismes responsables. L’évaluation du risque de survenue de l’EI et l’amélioration des connaissances justifiant la stratégie de prévention nécessitent la mise en place de grandes cohortes cliniques et l’utilisation de bases médico-administratives. Chez les 2 008 patients (pts) présentant une bactériémie à SA de la cohorte multicentrique nationale VIRSTA, nous avons développé et validé un score prédictif d’EI comportant les caractéristiques initiales des pts et celles initiales et évolutives de la bactériémie. Les pts dont le score était ≤ 2 avaient un très faible risque d’EI (1% ; valeur prédictive négative [IC95%] = 99% [98;99]) comparés à ceux dont le score était ≥ 3, à risque d’EI élevé (17%) pour lesquels une échocardiographie devrait être effectuée. Utilisant la base médico-administrative du SNIIRAM, nous avons évalué la relation entre la pratique de gestes buccodentaires invasifs (GBDI) et la survenue d’EI à streptocoques oraux à partir d’une cohorte de 138 876 porteurs de prothèses valvulaires cardiaques ainsi que d’un plan expérimental de type case-crossover incluant 648 EI à streptocoques oraux. L’incidence d’EI à streptocoques oraux [IC95%] était de 93,7 pour 100 000 PA [82,4;104,9] sans augmentation significative du risque dans les 3 mois suivant un GBDI (RR= 1,25 [0,82;1,82]). Dans l’analyse case-crossover, la fréquence d’exposition à un GBDI dans les 3 mois précédent l’EI était faible mais plus élevée que lors de périodes contrôles antérieures (5,1% vs 3,2% ; OR : 1,66 [1,05;2,63]). Les GBDI pourraient contribuer au développement des EI à streptocoques oraux dans la population de pts porteurs de prothèses valvulaires cardiaques.La qualité des données de VIRSTA associée à la puissance du SNIIRAM ont permis l’identification des pts à risque d’EI à SA et la clarification de la contribution des GBDI dans les EI à streptocoques oraux. / Infective endocarditis (IE) is a rare disease, difficult to diagnose, with high morbidity and mortality rates. Main involved microorganisms are Staphylococcus aureus and oral streptococci. Clinical research to improve IE risk assessment and IE prevention strategy requires the establishment of large clinical cohort studies and the use of medico-administrative databases. Using data from the multicenter French prospective VIRSTA cohort study on 2 008 adult patients (pts) with Staphylococcus aureus bloodstream infection (SAB), we have developed and validated an IE prediction score taking into account pts’ background and initial SAB characteristics. Pts with a score ≤ 2 had a very low risk of IE (1%, negative predictive value [95% CI] = 99% [98;99]) compared to those with a score ≥ 3, at higher risk of IE (17%) for whom an echocardiography is needed. Using the medico-administrative SNIIRAM database, we assessed the relation between invasive dental procedures (IDP) and oral streptococcal IE in a population-based cohort study of 138 876 pts with prosthetic heart valves and a case-crossover study including 648 pts with oral streptococcal IE. Incidence rate of oral streptococcal IE [95% CI] was 93.7 per 100 000 PA [82.4;104.9] without significant increase within the 3 months following IDP (RR = 1.25 [0.82;1.82]). In the case-crossover analysis, exposure to IDP was more frequent in the 3 months preceding IE than during previous control periods (5.1% vs. 3.2%, OR: 1.66 [1.05;2.63]). IDP may contribute to the development of oral streptococcal IE in pts with prosthetic heart valves.The quality of data from VIRSTA study combined with the power of SNIIRAM database made possible the identification of IE at-risk SAB pts and the evaluation of the IDP contribution in oral streptococcal IE.

Elizabethkingia Meningoseptica (E. Meningoseptica) an oxidase-positive gram-negative aerobic rod.1-2 Although ubiquitous in nature and widely distributed in soil and water, it is not a part of normal human flora. Cases of outbreaks of meningitis in premature neonates or infants have been reported, however, very few cases have been reported in adults.3 Infection is primarily nosocomial, or hospital acquired and has been implicated in bacteremia, meningitis, pneumonia, endocarditis especially in immunocompromised individuals.2-4 We report a 29-year-old male with past medical history significant for intravenous drug abuse, hepatitis C, oxymorphone induced hemolytic uremic syndrome, who presented to hospital with altered mental status. On admission, patient was unresponsive to vocal commands, febrile (102.3 F), tachycardic and tachypneic. He had pinpoint pupils and diffuse petechiae. In addition, he had erythematous flat macular lesions on his palms and dorsum of hands as well as injection marks in left cubital fossa. Cardiac examination was significant for a grade III systolic murmur at apical region and diastolic murmur at left second intercostal space. Laboratory studies revealed thrombocytopenia (43,000m/microL), lactic acidosis (4.9mmol/L), serum creatinine (Cr) of 6.6 mg/dL, glomerular filtration rate (GFR) of 10 ml/min. Transthoracic echocardiogram (TTE) revealed large mobile vegetation on aortic valve measuring 3.6 x 0.72 cm. Patient’s presentation was consistent with infective endocarditis with the vegetation seen on TTE and patient’s physical findings. Magnetic Resonance Imaging of the brain showed numerous small hemorrhagic infarcts, likely secondary to emboli from aortic valve vegetation. Patient required intubation for airway protection and started on hemodialysis. He was initially started on Meropenem and Vancomycin for infective endocarditis and later switched to Ciprofloxacin based on blood cultures and sensitivities which revealed methicillin sensitive staphylococcus aureus and multi-drug resistant E. Meningoseptica. Patient was transferred to long term care facility after acute care at the hospital. The increasing incidence of polymicrobial infective endocarditis and increasing resistance to antibiotic therapy pose challenges to the rapid assessment and treatment to mitigate the multi-organ involvement with septic emboli. Reports of pathogenicity associated with native valve endocarditis with this organism is scarce and exist primarily in a very few case reports and is resistant to many traditional antibiotics.5,6 E. Meningoseptica has shown antimicrobial susceptibility to the newer quinolones, rifampin, trimethoprim/sulfamethoxazole and ciprofloxacin with reasonable activity.7 Due to the unusual pattern of antibiotic resistance, early switching to appropriate antibiotics based on sensitivities is crucial for survival in patients with E. Meningoseptica. References 1..Kim KK, Kim MK, Lim JH, Park HY, Lee ST. Transfer of Chryseobacterium meningosepticum and Chryseobacterium miricola to Elizabethkingia gen. nov. as Elizabethkingia meningoseptica comb. nov. and Elizabethkingia miricola comb. nov. Int J Syst Evol Microbiol.2005 May;55(Pt 3):1287-93. 2:Shinha T, Ahuja R. Bacteremia due to Elizabethkingia meningoseptica. IDCases. 2015 Jan 17;2(1):13-5. doi: 10.1016/j.idcr.2015.01.002. eCollection 2015. 3..Jung SH, Lee B, Mirrakhimov AE, Hussain N. Septic shock caused by Elizabethkingia meningoseptica: a case report and review of literature. BMJ Case Rep. 2013 Apr 3;2013. pii: bcr2013009066. doi: 10.1136/bcr-2013-009066. 4.Ratnamani MS, Rao R. Elizabethkingia meningoseptica: Emerging nosocomial pathogen in bedside hemodialysis patients. Indian J Crit Care Med. 2013 Sep;17(5):304-7. 5.Bomb K, Arora A, Trehan N. Endocarditis due to Chryseobacterium meningosepticum. Indian J Med Microbiol. 2007 Apr;25(2):161-2. 6.Yang J, Xue W, Yu X. Elizabethkingia meningosepticum endocarditis: A rare case and special therapy. Anatol J Cardiol. 2015 May;15(5):427-8. 7. Hsu MS, Liao CH, Huang YT, Liu CY, Yang CJ, Kao KL, Hsueh PR. Clinical features, antimicrobial susceptibilities, and outcomes of Elizabethkingia meningoseptica (Chryseobacterium meningosepticum) bacteremia at a medical center in Taiwan,1999-2006. Eur J Clin Microbiol Infect Dis. 2011 Oct;30(10):1271-8.

No description available.

No description available.

No description available.

No description available.

No description available.

Background: Infective endocarditis is a rare but severe condition associated with a high mortality rate in small animal patients. This condition is caused by a microbial (most often bacterial) infection of the valvular portion of the endocardium, from which proliferative and/or erosive lesions on the cardiac valves or immediately adjacent structures develop. The two most commonly affected cardiac valves are the aortic and mitral valves. Case presentation: We report the clinical case of a 4-year old male neutered Bull terrier, 27.6 kg, body condition score 4/9, that presented with a 3-months history of pyrexia and general weakness. The patient history also revealed a transient left hind limb lameness (grade 2/4), which coincided with the onset of clinical signs about 3 months before presentation. On physical examination, a left-sided systolic heart murmur (grade 3/6) with the same intensity at the left heart base and apex, and an irregularly irregular heart rhythm were noted. Electrocardiography showed ventricular premature complexes, and echocardiography revealed lesions consistent with endocarditis involving the aortic and mitral valve. Bacterial culture of blood yielded a positive result, and the organism isolated was identified as Erysipelothrix rhusiopathiae. The extended patient history revealed that the dog lived close to a farm housing pigs and other livestock. Conclusion: We report a rare case of the premortal diagnosis of infective bacterial endocarditis in a dog due to E. rhusiopathiae infection. Most reports about this condition are from necropsy series. This clinical case report emphasizes that E. rhusiopathiae infection and bacteremia should be considered as a differential diagnosis in dogs with suspected infective endocarditis, especially in dogs living in rural areas with access to livestock and particularly farm pigs. Also, particular emphasis should be placed on the zoonotic potential of this infectious disease.