Viridans streptococci

Background Methods for assigning strains to bacterial species are cumbersome and no longer fit for purpose. The concatenated sequences of multiple house-keeping genes have been shown to be able to define and circumscribe bacterial species as sequence clusters. The advantage of this approach (multilocus sequence analysis; MLSA) is that, for any group of related species, a strain database can be produced and combined with software that allows query strains to be assigned to species via the internet. As an exemplar of this approach, we have studied a group of species, the viridans streptococci, which are very difficult to assign to species using standard taxonomic procedures, and have developed a website that allows species assignment via the internet. Results Seven house-keeping gene sequences were obtained from 420 streptococcal strains to produce a viridans group database. The reference tree produced using the concatenated sequences identified sequence clusters which, by examining t...

We evaluated the in vitro microbiological efficacy of a generic ceftriaxone product against several clinically significant organisms collected from sterile sites. The minimum inhibitory concentration (MIC) of each was determined simultaneously with the reference and the generic ceftriaxone product. Comparative analysis of MICs between the two products for each isolate was performed using both categorical (interpretive) agreement and essential (actual MIC value) agreement. A total of 260 isolates were tested. Overall, there was categorical agreement of 98.9% and essential agreement of 95.8%. The categorical agreement for all isolates (96.7 - 100%) accorded with international standards, as no very major errors were seen and the major error rate was less than 3%. Of the 90 isolates of E. coli (40), Klebsiella spp. (40) and Salmonella spp. (10), 87.6% had an MIC less than or equal to 0.12mg/l. The generic ceftriaxone product showed equivalent efficacy by MIC determination to the referen...

Identification of viridans group streptococci (VGS) to the species level by genotypic and phenotypic methods is challenging since biologic or biochemical profiles may be ambiguous because of natural competence, ie, the ability of streptococci to take up free DNA from the ...

Identification of viridans group streptococci (VGS) to the species level is difficult because VGS exchange genetic material. We performed multilocus DNA target sequencing to assess phylogenetic concordance of VGS for a well-defined clinical syndrome. The hierarchy of sequence data was often discordant, underscoring the importance of establishing biological relevance for finer phylogenetic distinctions.

We evaluated the in vitro microbiological efficacy of a generic ceftriaxone product against several clinically significant organisms collected from sterile sites. The minimum inhibitory concentration (MIC) of each was determined simultaneously with the reference and the generic ceftriaxone product. Comparative analysis of MICs between the two products for each isolate was performed using both categorical (interpretive) agreement and essential (actual MIC value) agreement. A total of 260 isolates were tested. Overall, there was categorical agreement of 98.9% and essential agreement of 95.8%. The categorical agreement for all isolates (96.7 - 100%) accorded with international standards, as no very major errors were seen and the major error rate was less than 3%. Of the 90 isolates of E. coli (40), Klebsiella spp. (40) and Salmonella spp. (10), 87.6% had an MIC less than or equal to 0.12mg/l. The generic ceftriaxone product showed equivalent efficacy by MIC determination to the referen...

The viridans group Streptococci (VGS) are most abundant in the mouth; in some instances they might emerge as pathogens particularly in infective endocarditis (IE). In this study, we aimed to define and determine the susceptibility against antibiotics of VGS that are members of the oral microbiota of patients exhibiting a risk of developing IE. Forty-nine patients at risk of infective endocarditis were included in the study. Identification of the bacteria was performed using API STREP (bioMérieux, France). Gradient test strips (E-Test, France) were used to determine MIC of the bacteria against penicillin, ampicillin, and vancomycin. The distribution of the isolated VGS groups was determined as follows: Streptococcus mitis 32.6% and anginosus group - 32.6%, S. sanguinis group - 16.3%, S. mutans group - 12.2%, and S. salivarius group - 6.1%. The rates of resistance and reduced sensitivity of the isolates for penicillin and ampicillin were determined at 61.2% and 55.1%, respectively. Ho...

The aim of the study was to evaluate the species distribution, antimicrobial susceptibility and erythromycin-penicillin resistance mechanisms of viridans streptococci (VGS) isolates from blood cultures of adult patients with underlying diseases. Fifty VGS blood culture isolates were screened for their antibiotic susceptibilities against penicillin G, erythromycin and tetracycline by E-test. Clindamycin, cefotaxime, chloramphenicol, levofloxacin, linezolid and vancomycin susceptibility were performed by broth microdilution method. Erythromycin and penicillin resistance genotypes, ermB and mefA/E, pbp1a, pbp2b and pbp2x are amplified using PCR method. The clinical isolates included Streptococcus mitis (n. 19), S.oralis (n. 13), S.sanguinis, S.parasanguinis (n. 6, each), S.salivarius, S.vestibularis (n. 2, each), S.constellatus, S.sobrinus (n. 1, each). The percentage resistance against erythromycin and penicillin was 36% and 30%, respectively. The genotypic carriage rate of erythromyc...

Endophthalmitis is a potentially blinding intraocular infection that requires urgent intervention. Self-inflicted endophthalmitis is rare, difficult to diagnose, and requires a multidisciplinary approach for management. The purpose is to present a rare case of sequential self-inflicted acute endophthalmitis as a feature of Munchausen syndrome. This is a case report reviewing imaging and laboratory studies. A 42-year-old female patient developed culture-proven acute endophthalmitis sequentially in both eyes with different bacterial strains. There was clear evidence of self-inflicted corneal puncture tracks in the right eye, and during the course of inpatient psychiatric evaluation, the patient admitted to self-inflicted ocular perforations. Patients with Munchausen syndrome often injure themselves as a method of drawing attention, sympathy, or reassurance. Although ocular injuries due to psychiatric disease are known to occur, intraocular injection as a mode of self-injury is extremely rare. A high index of suspicion must be maintained when the reported history and clinical course are inconsistent.

A total of 100 patients of acute pharyngitis were evaluated clinically and investigated microbiologically. Eighty patients proved culture positive acute pharyngitis, among them 17 patients proved positive for beta-haemolytic streptococci, 14 patients for Staphylococcus aureus, 24 for pneumococci, 13 patients for Streptococcus viridans, 3 for Brahmanella catarrhalis, 4 for coagulase negative staphylococci, 5 had mixed infection. Further streptococcal grouping was carried out on these isolates. Out of 17 isolates of beta-haemolytic streptococci 13 (76.47%) belonged to group A and 2 each (11.76%) belonged to group C and group G.