Trichococcus shcherbakoviae subsp. psychrophilus subsp. nov., a psychrotolerant facultative anaerobe isolated from a cold spring

A psychrotolerant facultative anaerobe, strain SKBG^T, was isolated from the bottom sediments of the cold mineral spring Buxichen (Buryatia, Russia). Gram-positive non-motile cocci with a diameter of 1.75-2.5 µm were observed singly or in long chains. Cells grew in the temperature range from ̶ 5-35 °C. Growth was observed within the pH range of 7.0-9.5, with the optimum growth at pH 7.6 and at a NaCl concentration from 0-1.0 % (optimum 0.1 % (w/v)). Strain SKBG^T was a chemoorganoheterotroph that used sugars and some organic acids as substrates. The predominant fatty acids in cell walls were С_16:1ω9, С_18:1ω9, and С_16 : 0. The 16S rRNA gene sequence of strain SKBG^T shared high similarity (>99 %) with those of the type strains of the genus Trichococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain SKBG^T and Trichococcus shcherbakoviae Art^T (=DSM 107162^T=VKM B-3260^T) were 70.1 and 95.4 %, respectively. The genomic DNA G+C content of strain SKBG^T was 47.1 mol%. Compared with the type strain of T. shcherbakoviae, the new strain was characterized by a temperature optimum for growth (10 °C) significantly lower than that of T. shcherbakoviae DSM 107162^T (20-30 °C). Based on phenotypic and genomic characteristics, the isolate SKBG^T was classified as T. shcherbakoviae subsp. psychrophilus subsp. nov. The type strain is SKBG^T (=VKM B-3241^Т=JCM 33326^T).

Microbial population shift and metabolic characterization of silver diamine fluoride treatment failure on dental caries

The objective of this pilot study was to describe the microbial profiles present in the plaque and saliva of children who continued to develop new carious lesions following treatment with silver diamine fluoride ("nonresponders") compared to caries active, caries-free, and children immediately receiving SDF treatment for untreated caries in order to identify potential microbial differences that may relate to a re-incidence of caries. Saliva and plaque samples from infected and contralateral sites were obtained from twenty children who were either caries free, had active carious lesions, were caries active and received SDF treatment immediately before sampling, or had previously received SDF treatment and developed new caries. In total, 8,057,899 Illumina-generated sequence reads from 60 samples were obtained. Reads were processed using the Quantitative Insights Into Microbial Ecology pipeline. Group differences were assessed using Analysis of Variance Models and Tukey Honest Significant Differences. To identify significant taxa between treatment groups, Linear discriminant analysis Effect Size (LefSe) and Analysis of Differential Abundance Taking Sample Variation Into Account were used. Differential abundant analysis indicated that members of the Lachnospiraceae family were significantly enriched in non-responders and the genus Tannerella and species Granulicatella adiances were also highly abundant in this group. LefSe analysis between non-responders and SDF-treated groups revealed that genera Leptotrichia and Granulicatella were enriched in non-responders. We observed the highest abundance of phosphotransferase system and lowest abundance of lipopolysaccharide synthesis in non-responders. The microbiome in dental biofilms is responsible for initiation and progression of dental caries. SDF has been shown to be effective in arresting the progression carious lesions, in part due to its antimicrobial properties. Findings suggest that the differential abundance of select microbiota and specific pathway functioning in individuals that present with recurrent decay after SDF treatment may contribute to a potential failure of silver diamine fluoride to arrest dental caries. However, the short duration of sample collection following SDF application and the small sample size emphasize the need for further data and additional analysis.

Epidemiology, Clinical Features, and Outcome of Infective Endocarditis due to Abiotrophia Species and Granulicatella Species: Report of 76 Cases, 2000-2015

Background

Infective endocarditis (IE) caused by Abiotrophia (ABI) and Granulicatella (GRA) species is poorly studied. This work aims to describe and compare the main features of ABI and GRA IE.

Methods

We performed a retrospective study of 12 IE institutional cases of GRA or ABI and of 64 cases published in the literature (overall, 38 ABI and 38 GRA IE cases).

Results

ABI/GRA IE represented 1.51% of IE cases in our institution between 2000 and 2015, compared to 0.88% of HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)-related IE and 16.62% of Viridans group streptococci (VGS) IE. Institutional ABI/GRA IE case characteristics were comparable to that of VGS, but periannular complications were more frequent (P = .008). Congenital heart disease was reported in 4 (10.5%) ABI and in 11 (28.9%) GRA cases (P = .04). Mitral valve was more frequently involved in ABI than in GRA (P < .001). Patient sex, prosthetic IE, aortic involvement, penicillin susceptibility, and surgical treatment were comparable between the genera. New-onset heart failure was the most frequent complication without genera differences (P = .21). Five (13.2%) ABI patients and 2 (5.3%) GRA patients died (P = .23). Factors associated with higher mortality were age (P = .02) and new-onset heart failure (P = .02). The genus (GRA vs ABI) was not associated with higher mortality (P = .23).

Conclusions

GRA/ABI IE was more prevalent than HACEK IE and approximately one-tenth as prevalent as VGS; periannular complications were more frequent. GRA and ABI genera IE presented similar clinical features and outcomes. Overall mortality was low, and related to age and development of heart failure.

Successful treatment of an acute infective endocarditis secondary to fish bone penetrating into left atrium caused by Granulicatella adiacens and Candida albicans: A case report

RATIONAL

Infective endocarditis caused by a foreign body of the upper digestive tract is rare. We report a rare case of Granulicatella adiacens and Candida albicans coinfection acute endocarditis combined with systematic embolization caused by a fish bone from the esophagus penetrating into the left atrium.

PATIENT CONCERN

A 42-year-old woman was admitted to our hospital because of fever, abdominal pain, headache, and right limb weakness.

DIAGNOSES

Clinical examination indicated endocarditis and systemic embolisms secondary to a fish bone from the esophagus penetrating into the left atrium. The emergency surgery confirmed the diagnosis. Cultures of blood and vegetation show G adiacens and C albicans.

INTERVENTIONS

Antimicrobial therapy lasted 6 weeks after surgery.

OUTCOMES

The patient was discharged with excellent condition7 weeks after hospitalization and was well when followed 6 months later.

LESSONS

The successful treatment of this patient combines quick diagnosis, timely surgery, and effective antimicrobial regimen. This rare possibility should be kept up in mind in acute infective endocarditis cases.

Salivary microbiota and caries occurrence in Mutans Streptococci-positive school children

AIM

To compare the composition of the salivary microbiota in caries-affected vs. caries-free mutans streptococci (MS)- positive children with mixed dentition.

MATERIALS AND METHODS

Twenty eight healthy, 11-12-year-old schoolchildren with high MS counts (>10⊃5 CFU/mL) were included in this study. The children were screened with the Dentocult SM Strip Mutans test (Orion Diagnostica, Espoo, Finland) and examined using the International Caries Detection and Assessment System (ICDAS). The microbial composition of the saliva was assessed using the Human Oral Microbe Identification Microarray (HOMIM). Microbial differences between caries-affected (n=18) and caries-free children (n=10) were compared by Mann-Whitney analysis.

RESULTS

The microbiota of the caries-affected vs. caries-free children was rather similar. Abiotrophia defectiva and Actinomyces meyeri/A. odontolyticus were significantly higher in caries-affected than in caries-free children (p=0.006, 0.046, respectively). Shuttleworthia satelles was significantly higher in caries-free compared to caries-affected children (p=0.031). A. defectiva and A. meyeri/A. odontolyticus correlated positively with caries severity measured by ICDAS Caries Index (p = 0.494, 0.454, 0.400 respectively) while S. satelles was negatively correlated with caries severity (p= -0.489).

CONCLUSIONS

Salivary A. defectiva and A. meyeri/A. odontolyticus and are associated with caries occurrence in MS-positive children with mixed dentition.

Infective endocarditis due to Abiotrophia defectiva and Granulicatella spp. complicated by infectious intracranial cerebral aneurysms: a report of three cases and review of the literature

Nutritionally variant streptococci, now classified as Abiotrophia defectivaor Granulicatella spp., are thought to account for 2 % of all infective endocarditis cases but estimates of their frequency are complicated by changes in nomenclature and difficulties in obtaining positive microbiology cultures. Their growth characteristics and difficulty undertaking antibiotic susceptibility testing may impede optimal antibiotic treatment decisions. We describe three patients with definite infective endocarditis due to these organisms seen at our hospital between 2005 and 2010, all of whom presented with neurological symptoms due to infectious intracranial cerebral aneurysms. We recommend that, for patients with left-sided infective endocarditis due to A. defictiva and Granulicatella spp., clinicians should consider imaging the central nervous system.

Infective endocarditis caused by Granulicatella adiacens

Granulicatella adiacens, a recently nomenclatured bacterium, was considered as one of the nutritionally variant streptococci (NVS) and is a mouth commensal. It is redesignated as a streptococcus like bacterium since it differs from streptococci. We report a case of infective endocarditis (IE) caused by this fastidious and unusual bacteria in a 63-year-old man with rheumatic valvular heart disease. G. adiacens was isolated from four of his blood culture samples, which was sensitive to beta lactams, moderately sensitive to gentamicin and resistant to erythromycin and co-trimoxazole. Patient recovered completely on treatment with high dose of ampicillin and gentamicin for 28 days.

Endocarditis caused by nutritionally variant streptococci: a case report and literature review

Infective endocarditis (IE) due to Abiotrophia and Granulicatella species, previously referred to as nutritionally variant streptococci (NVS), occurs rarely and is often associated with negative blood cultures. Rates of treatment failure, infection relapse and mortality are higher than those of endocarditis caused by other viridans streptococci. We report a case of endocarditis caused by Granulicatella adiacens in a young man with no risk factors, who was successfully treated with surgery and combination antimicrobial chemotherapy, and provide a literature review of endocarditis attributable to these rare species of fastidious gram-positive cocci which have proven exceedingly difficult to treat, with high rates of relapse and therapeutic failure despite in vitro effective antibiotic treatment regimens. Analysis of literature revealed a high prevalence (61%) of valvular heart predisposing conditions associated with endocarditis caused by NVS, such as congenital valvular heart disease or heart valve prosthesis. On the other hand, 39% of cases showed no evidence of risk factors. Combination antimicrobial chemotherapy with penicillin and gentamicin represents the antimicrobial treatment of choice in the management of patients with IE attributable to NVS. Heart valve replacement surgery should be considered in cases of hemodynamic derangement due to significant valve destruction.