Clinical isolates of Streptococcus mitis/oralis-related species with reduced carbapenem susceptibility, harboring amino acid substitutions in penicillin-binding proteins in Japan.

Streptococcus mitis/oralis group isolates with reduced carbapenem susceptibility have been reported, but its isolation rate in Japan is unknown. We collected 356 clinical α-hemolytic streptococcal isolates and identified 142 of them as S. mitis/oralis using partial sodA sequencing. The rate of meropenem non-susceptibility was 17.6% (25/142). All 25 carbapenem-non-susceptible isolates harbored amino acid substitutions in/near the conserved motifs in PBP1A, PBP2B, and PBP2X. Carbapenem non-susceptibility is common among S. mitis/oralis group isolates in Japan.

Performance assessment of the Bruker Biotyper MALDI-TOF MS for the identification of difficult-to-identify viridans group streptococci.

Differentiating Streptococcus pneumoniae among nonpneumococcal viridans group streptococci (VGS) is challenging in conventional laboratories. Therefore, we aimed to evaluate the performance of the latest Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system in identifying VGS by comparing the results to those of the specific gene sequencing approach. Clinical isolates were initially identified using the BD Phoenix system to identify Streptococcus species. The optochin test was used to distinguish nonpneumococcal VGS from S. pneumoniae. The species of individual reference strains and clinical isolates were determined by comparing the sequences of the 16S rDNA, gyrB, sodA, groESL, or coaE genes with those in the GenBank sequence databases. We evaluated the performance of the Bruker Biotyper MALDI-TOF MS in VGS identification using two different machines with three databases. We collected a total of 103 nonpneumococcal VGS and 29 S. pneumoniae blood isolates at a medical center in northern Taiwan. Among these isolates, only seven could not be identified at the species level by the specific gene sequencing approach. We found that none of the nonpneumococcal VGS isolates were misidentified as pneumococci by the latest Biotyper system, and vice versa. However, certain strains, especially those in the mitis and bovis groups, could still not be correctly identified. The latest Bruker Biotyper 4.1 (DB_10833) showed significant improvement in identifying VGS strains. However, a specific gene sequencing test is still needed to precisely differentiate the species of strains in the mitis and bovis groups.

Emerging Resistance Trends in Viridans Group Streptococci Bloodstream Infections Among Immunocompromised Children Receiving Levofloxacin Prophylaxis.

BACKGROUND: Levofloxacin prophylaxis (LVXp) is often used for patients with underlying leukemia and severe neutropenia to reduce the risk of fever and bacteremia. This study evaluated trends in viridans group streptococci (VGS) antibiotic susceptibilities over time and clinical outcomes of children with VGS bloodstream infections (BSIs) during institutional adoption of LVXp. METHODS: VGS blood culture isolates between 1/1/2010 and 12/31/2021 with susceptibility testing reported were included. Available isolates were re-identified to the species level and additional susceptibility testing was performed. Demographic and clinical data were abstracted from medical records. RESULTS: A total of 264 VGS BSI isolates were identified in immunocompromised (IC, n = 125) and non-immunocompromised subjects, (non-IC, n = 139). IC subjects had lower rates of VGS isolates susceptible (S) to LVX and higher minimum inhibitory concentration (MICs) to LVX (p = 0.004) and ciprofloxacin (p = 0.0005) compared with non-IC subjects. No other evaluated antibiotic had increased MICs in either group. Fifteen of 19 (74%) LVX not susceptible (NS) isolates occurred in IC subjects, 13 represented breakthrough infections. IC subjects had higher rates of VGS-related shock (p = 0.012), need for pressor support (p = 0.039), and longer duration of hospitalization than non-IC subjects (p < 0.001). Clinical outcomes were comparable between subjects with LVX S and NS VGS BSI isolates. CONCLUSIONS: VGS with reduced susceptibility to LVX emerged during institutional adoption of LVXp in high-risk children with immunocompromising conditions, but did not result in significant differences in clinical outcomes. Ongoing surveillance and susceptibility testing are critical in weighing the utility of LVXp against emerging antimicrobial resistance in this high-risk population.

Impact of Intermediate Susceptibility to Penicillin on Antimicrobial Treatment and Outcomes of Endocarditis Caused by Viridans and Gallolyticus Group Streptococci.

BACKGROUND: Evidence supporting combination treatment with a beta-lactam plus an aminoglycoside (C-BA) for endocarditis caused by viridans and gallolyticus group streptococci (VGS-GGS) with intermediate susceptibility to penicillin (PENI-I) is lacking. We assessed the clinical characteristics and outcomes of PEN-I VGS-GGS endocarditis and compared the effectiveness and safety of C-BA with third-generation cephalosporin monotherapy. METHODS: Retrospective analysis of prospectively collected data of a cohort of definite endocarditis caused by penicillin-susceptible and PENI-I VGS-GGS (penicillin minimum inhibitory concentration ranging from 0.25 to 2 mg/L) between 2008 and 2018 in 40 Spanish hospitals. We compared cases treated with monotherapy or with C-BA and performed multivariable analyses of risk factors for in-hospital and 1-year mortality. RESULTS: A total of 914 consecutive cases of definite endocarditis caused by VGS-GGS with complete or intermediate susceptibility to penicillin were included. A total of 688 (75.3%) were susceptible to penicillin and 226 (24.7%) were PENI-I. Monotherapy was used in 415 (45.4%) cases (cephalosporin in 331 cases) and 499 (54.6%) cases received C-BA. In-hospital mortality was 11.9%, and 190 (20.9%) patients developed acute kidney injury. Heart failure (odds ratio [OR]: 6.06; 95% confidence interval [CI]: 1.37-26.87; P = .018), central nervous system emboli (OR: 9.83; 95% CI: 2.17-44.49; P = .003) and intracardiac abscess (OR: 13.47; 95% CI: 2.24-81.08; P = .004) were independently associated with in-hospital mortality among PEN-I VGS-GGS cases, while monotherapy was not (OR: 1.01; 95% CI: .26-3.96; P = .982). CONCLUSIONS: Our findings support the use of cephalosporin monotherapy in PEN-I VGS-GGS endocarditis in order to avoid nephrotoxicity without adversely affecting patient outcomes.

Species designation of streptococci causing infective endocarditis in patients with mitral valve prolapse.

OBJECTIVES: Viridans group streptococci (VGS) have been previously linked to infective endocarditis (IE) in patients with mitral valve prolapse (MVP). The species identification of VGS is now available in clinical laboratories; however, it has not been examined in MVP IE. Therefore, we detailed the clinical profile, species designations, and antibiotic susceptibility of VGS isolates from patients with MVP IE. METHODS: We retrospectively queried all adults with MVP and a definite or possible IE diagnosis seen at medical centers of the Mayo Clinic Enterprise from January 2009 to December 2021. Data, including clinical characteristics, comorbidities, microbiology, and outcomes, were extracted from electronic health records. VGS isolates from patients with MVP and IE were subclassified into mutans, salivarius, anginosus, sanguinis, and mitis groups. RESULTS: A total of 38 patients with MVP with IE due to streptococcal species were included. Overall, median age was 62.4 years and 32% of patients were females. The most prevalent comorbidities were diabetes mellitus (26%), hypertension (21%), heart failure (16%), and malignancy (16%). A total of (37%) patients presented with an embolic event at the time of their IE diagnosis, 27 (66%) required valve surgery, and no patient died within the hospital stay. The Streptococcus mitis group was the predominant (n = 17, 45%) species designation; S. anginosus and S. sanguinis were identified in three (8%) each; S. mutans in two (5%); and S. salivarius in one (3%). Non-VGS streptococcal pathogens included S. agalactiae in three patients (8%), S. equi in two (5%), and S. dysgalactiae and S. bovis in one each (3%). VGS were identified in five (13%) patients, but species designation was not done. No penicillin resistance was identified among the isolates. CONCLUSION: The S. mitis group was the predominant species in our investigation. Continued evaluation of VGS species should be considered to profile the IE risk based on species identification.

Outcomes of neutropenic hemato-oncological patients with viridans group streptococci (VGS) bloodstream infection based on penicillin susceptibility.

Viridans group streptococci (VGS) bloodstream infection (BSI) in neutropenic patients can be a severe complication. A higher prevalence of vancomycin use has been reported due to reduced susceptibility to penicillin. We aimed to assess the impact on mortality of both penicillin minimal inhibitory concentration (MIC) and the use of vancomycin. We conducted a retrospective multicenter study including consecutive neutropenic patients with VGS BSI between 2007 and 2019. Univariable and multivariable analyses were conducted to evaluate risk factors for mortality, including penicillin susceptibility as an independent variable. Non-susceptibility to penicillin was defined as MIC ≥ 0.25. We included 125 neutropenic patients with VGS BSI. Mean age was 53 years and ~ 50% were women. Overall, 30-day mortality rate was 25/125 (20%), and 41 patients (33%) had a VGS isolate non-susceptible to penicillin. In univariable analysis, no significant association was demonstrated between penicillin non-susceptibility and mortality (9/25, 26% vs. 32/100, 32%, p = 0.81). Among patients with a non-susceptible strain, the use of vancomycin was not significantly associated with mortality (empirical, p = 0.103, or definitive therapy, p = 0.491). Factors significantly associated with increased mortality in multivariable analysis included functional status (ECOG > 1, adjusted odds ratio [aOR] 12.53, 95% CI 3.64-43.14; p < 0.0001); allogeneic transplantation (aOR 6.33, 95% CI 1.96-20.46; p = 0.002); and co-pathogen in blood cultures (aOR 3.99, 95% CI 1.34-11.89; p = 0.013). Among neutropenic hemato-oncological patients with VGS BSI, penicillin non-susceptibility and the use of vancomycin were not associated with mortality. Thus, vancomycin should not be used routinely as empirical therapy in neutropenic patients with suspected VGS BSI.

Comparative Genomics of Streptococcus oralis Identifies Large Scale Homologous Recombination and a Genetic Variant Associated with Infection.

The viridans group streptococci (VGS) are a large consortium of commensal streptococci that colonize the human body. Many species within this group are opportunistic pathogens causing bacteremia and infective endocarditis (IE), yet little is known about why some strains cause invasive disease. Identification of virulence determinants is complicated by the difficulty of distinguishing between the closely related species of this group. Here, we analyzed genomic data from VGS that were isolated from blood cultures in patients with invasive infections and oral swabs of healthy volunteers and then determined the best-performing methods for species identification. Using whole-genome sequence data, we characterized the population structure of a diverse sample of Streptococcus oralis isolates and found evidence of frequent recombination. We used multiple genome-wide association study tools to identify candidate determinants of invasiveness. These tools gave consistent results, leading to the discovery of a single synonymous single nucleotide polymorphism (SNP) that was significantly associated with invasiveness. This SNP was within a previously undescribed gene that was conserved across the majority of VGS species. Using the growth in the presence of human serum and a simulated infective endocarditis vegetation model, we were unable to identify a phenotype for the enriched allele in laboratory assays, suggesting a phenotype may be specific to natural infection. These data highlighted the power of analyzing natural populations for gaining insight into pathogenicity, particularly for organisms with complex population structures like the VGS. IMPORTANCE The viridians group streptococci (VGS) are a large collection of closely related commensal streptococci, with many being opportunistic pathogens causing invasive diseases, such as bacteremia and infective endocarditis. Little is known about virulence determinants in these species, and there is a distinct lack of genomic information available for the VGS. In this study, we collected VGS isolates from invasive infections and healthy volunteers and performed whole-genome sequencing for a suite of downstream analyses. We focused on a diverse sample of Streptococcus oralis genomes and identified high rates of recombination in the population as well as a single genome variant highly enriched in invasive isolates. The variant lies within a previously uncharacterized gene, nrdM, which shared homology with the anaerobic ribonucleoside triphosphate reductase, nrdD, and was highly conserved among VGS. This work increased our knowledge of VGS genomics and indicated that differences in virulence potential among S. oralis isolates were, at least in part, genetically determined.

Oral mitis group streptococci reduce infectivity of influenza A virus via acidification and H2O2 production.

Members of the mitis group streptococci are the most abundant inhabitants of the oral cavity and dental plaque. Influenza A virus (IAV), the causative agent of influenza, infects the upper respiratory tract, and co-infection with Streptococcus pneumoniae is a major cause of morbidity during influenza epidemics. S. pneumoniae is a member of mitis group streptococci and shares many features with oral mitis group streptococci. In this study, we investigated the effect of viable Streptococcus oralis, a representative member of oral mitis group, on the infectivity of H1N1 IAV. The infectivity of IAV was measured by a plaque assay using Madin-Darby canine kidney cells. When IAV was incubated in growing culture of S. oralis, the IAV titer decreased in a time- and dose-dependent manner and became less than 100-fold, whereas heat-inactivated S. oralis had no effect. Other oral streptococci such as Streptococcus mutans and Streptococcus salivarius also reduced the viral infectivity to a lesser extent compared to S. oralis and Streptococcus gordonii, another member of the oral mitis group. S. oralis produces hydrogen peroxide (H2O2) at a concentration of 1-2 mM, and its mutant deficient in H2O2 production showed a weaker effect on the inactivation of IAV, suggesting that H2O2 contributes to viral inactivation. The contribution of H2O2 was confirmed by an inhibition assay using catalase, an H2O2-decomposing enzyme. These oral streptococci produce short chain fatty acids (SCFA) such as acetic acid as a by-product of sugar metabolism, and we also found that the inactivation of IAV was dependent on the mildly acidic pH (around pH 5.0) of these streptococcal cultures. Although inactivation of IAV in buffers of pH 5.0 was limited, incubation in the same buffer containing 2 mM H2O2 resulted in marked inactivation of IAV, which was similar to the effect of growing S. oralis culture. Taken together, these results reveal that viable S. oralis can inactivate IAV via the production of SCFAs and H2O2. This finding also suggests that the combination of mildly acidic pH and H2O2 at low concentrations could be an effective method to inactivate IAV.

Infective endocarditis: association between origin of causing bacteria and findings during oral infection screening.

BACKGROUND: Oral streptococci represent the causing microorganism for infective endocarditis (IE) in many patients. The impact of oral infections is questioned, and it has been suggested that bacteraemia due to daily routines may play a bigger part in the aetiology of IE. The aim of this study was to examine the association between oral health and infective endocarditis caused by oral bacteria in comparison with bacteria of other origin than the oral cavity. METHODS: A retrospective study was conducted at Haukeland University Hospital from 2006- 2015. All consecutive adult patients admitted to hospital for treatment of IE and subjected to an oral focus screening including orthopantomogram, were included. The clinical, radiological and laboratory characteristics of the patients, collected during oral infectious focus screening, were analysed. Patient survival was calculated using Kaplan-Meier and mortality rates were compared using Cox-regression. RESULTS: A total of 208 patients were included, 77% (n = 161) male patients and 23% (n = 47) female, mean age was 58 years. A total of 67 (32%) had IE caused by viridans streptococci. No statistically significant correlation could be found between signs of oral infection and IE caused by viridans streptococci. The overall mortality at 30 days was 4.3% (95% CI: 1.6-7.0). There was no statistical difference in mortality between IE caused by viridans streptococci or S. aureus (HRR = 1.16, 95% CI: 0.57-2.37, p = 0.680). CONCLUSION: The study indicates that the association between origin of the IE causing bacteria and findings during oral infection screening might be uncertain and may suggest that the benefit of screening and elimination of oral infections in patients admitted with IE might be overestimated. However, the results should be interpreted with caution and further studies are needed before any definite conclusions can be drawn.

Beta-lactam antibiotics and viridans group streptococci.

The aim of this review is to present an update on the susceptibility of viridans group streptococci (VGS) to ß-lactam antimicrobials, with emphasis on the Argentinean scenario. VGS are a heterogeneous group including five groups of species, each one exhibiting peculiar susceptibility patterns to penicillin (PEN). Species of the Streptococcus mitis group are frequently nonsusceptible to PEN. PEN resistance is associated with changes in PEN-binding proteins. In Argentina, one to two thirds of VGS are nonsusceptible to PEN. Third generation cephalosporins and carbapenems are currently more effective in vitro than PEN against VGS. Mortality was associated to nonsusceptibility to PEN in at least two studies involving patients with bacteremia caused by VGS. Treatment of endocarditis due to VGS should be adjusted/to the PEN susceptibility of the isolates. Vancomycin may be an alternative choice for treating endocarditis caused by PEN-resistant isolates (MIC≥4µg/ml).

Genetic variability of the helix 54 of the 23S rDNA and its use as a molecular target for identification of species within the viridans group streptococci (VGS).

The aim of the present study is to establish a method, based on sequence analysis of the helix 54 of 23S rRNA gene, to identify clinical relevant strains belonging to viridans group streptococci (VGS). A set of 25 randomly selected clinical isolates of alpha-hemolytic streptococci from upper respiratory tract were characterized by the routine phenotypic methods (API 20 Strep test). Molecular characterization was assessed by genotypic analysis of the nucleotide sequence of the helix 54 of 23S rRNA and Intergenic spacer region 16S23S. Partial sequencing of the gdh gene was used on 10 strains of mitis group. Sequence variations of the helix 54 allowed the identification of strains to group level and even to species level for certain strains within sanguinis and anginosus groups. Infact, species identification was ambiguous for some strains belonged to the salivarius group (of VGS16 to VGS20) and the mitis group (of VGS1 to VGS14). These results are almost similar to those obtained by sequencing the 16S23S intergenic region. Thus, we use the gdh gene sequencing for the identification of strains, not recognized, within the mitis group. The results generated herein indicate that no single methodology can be used to provide an accurate identification to the species level of all VGS, although nucleotide sequence analysis of the helix 54 of 23S rRNA gene proved to be a reliable method for the identification of VGS to the group level and even to the species level within sanguinis and anginosus groups.

Case Report: Use of Percutaneous Coronary Revascularization to Temporarily Stabilize a Patient With Streptococcus Viridans Bioprosthetic Aortic Valve Endocarditis Resulting in Non-Embolic Left Main Coronary Artery Obstruction.

A patient with a bio-prosthetic aortic valve streptococcus viridans bacterial endocarditis (SBE) presented with acute massive myocardial ischemia caused from a vegetation adherent to and extending from the valve and growing into the left main (LM) and left circumflex coronary (LCX) coronary arteries. Immediate salvage PCI of the LM and LCX was performed with initial stabilization of the patient.

Infecciones por estreptococos del grupo S. anginosus en pediatría / S. anginosus group streptococcal infections in children

Los estreptococos del grupo Streptococcus anginosus (EGA), también llamados "Streptococcus milleri", fueron reconocidos como parte de los estreptococos del grupo viridans (EGV) desde principios del siglo XX. Su rol como patógenos humanos, sin embargo comenzó a destacarse recién en la década de 1970. En esta actualización se describen aspectos microbiológicos y clínicos de los EGA. Los métodos fenotípicos de identificacón e incluso algunos genotípicos carecen de precisión para reconocer las tres especies del grupo (Streptococcus anginosus, Streptococcus constellatus y Streptococcus intermedius) e incluso pueden fallar en su clasificación a nivel de grupo. La mayoría de ellos son sensibles a los antibióticos beta-lactámicos pero son considerables los porcentajes de resistencia a macrólidos, lincosamidas y tetraciclinas. Los EGA son colonizantes habituales de las mucosas orofaríngea, intestinal y genitourinaria, pero, cada vez más frecuentemente, son reconocidos como patógenos humanos. Es ampliamente conocida su capacidad de formar abscesos en órganos sólidos, especialmente abscesos cerebrales, pulmonares y hepáticos. También producen sinusitis, empiemas y colecciones en piel y tejidos blandos, hueso, articulaciones, etc. Se han encontrado asociados con exacerbaciones pulmonares en pacientes con fibrosis quística y con enfermedad pulmonar obstructiva crónica. Producen también infecciones posteriores a mordeduras humanas, infecciones diseminadas, bacteriemia sin foco aparente y, en menor medida, endocarditis infecciosa (AU)

Streptococci from the Streptococcus anginosus group (SAG), also termed "Streptococcus milleri", were recognized as members of the viridans group streptococci (VGS) in the early 20th century. Nevertheless, their role as human pathogens only became evident in the 1970s. In this update, microbiological and clinical aspects of the SAG are described. Phenotypic and even some genotypic identification methods lack accuracy in recognizing the three species of the group (Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius) and may fail to classify them at the group level. Most of them are sensitive to beta-lactam antibiotics but rates of resistance to macrolides, lincosamides, and tetracyclines are significant. SAGs are common colonizers of the oropharyngeal, intestinal, and genitourinary mucosa, but are increasingly recognized as human pathogens. Their ability to form abscesses in solid organs, especially brain, lung and liver, is widely known. They may produce sinusitis, empyemas, and collections in skin and soft tissues, bone, joints, etc. They have also been associated with pulmonary exacerbations in patients with cystic fibrosis and chronic obstructive pulmonary disease. In addition, they may cause infections following human bites, disseminated infections, bacteremia without apparent focus, and, to a lesser extent, infective endocarditis (AU)

Clinical characteristics and outcome of infective endocarditis due to Abiotrophia and Granulicatella compared to Viridans group streptococci.

OBJECTIVE: To describe the clinical characteristics and outcome of Abiotrophia and Granulicatella infective endocarditis and compare them with Viridans group streptococci infective endocarditis. METHODS: All patients in the International Collaboration on Endocarditis (ICE) - prospective cohort study (PCS) and the ICE-PLUS cohort were included (n = 8112). Data from patients with definitive or possible IE due to Abiotrophia species, Granulicatella species and Viridans group streptococci was analyzed. A propensity score (PS) analysis comparing the ABI/GRA-IE and VGS-IE groups according to a 1:2 ratio was performed. RESULTS: Forty-eight (0.64%) cases of ABI/GRA-IE and 1,292 (17.2%) VGS-IE were included in the analysis. The median age of patients with ABI/GRA-IE was lower than VGS-IE (48.1 years vs. 57.9 years; p = 0.001). Clinical features and the rate of in-hospital surgery was similar between ABI/GRA-IE and VGS-IE (52.1% vs. 45.4%; p = 0.366). Unadjusted in-hospital death was lower in ABI/GRA-IE than VGS-IE (2.1% vs. 8.8%; p = 0.003), and cumulative six-month mortality was lower in ABI/GRA-IE than VGS-IE (2.1% vs. 11.9%; p<0.001). After PS analysis, in-hospital mortality was similar in both groups, but six-month mortality was lower in the ABI/GRA IE group (2.1% vs. 10.4%; p = 0.029). CONCLUSIONS: Patients with ABI/GRA-IE were younger, had similar clinical features and rates of surgery and better prognosis than VGS-IE.

Pediatric AML patients with acute-onset cardiomyopathy in the setting of Streptococcus viridans bacteremia after anthracyclines.

We reviewed three very similar cases of acute-onset heart failure in children with acute myeloid leukemia who received anthracyclines during their treatment. All three children were diagnosed with recent Streptococcus viridans bacteremia and had persistent tachycardia prior to acute-onset heart failure with near-complete resolution within weeks. We hypothesize their heart failure was secondary to sepsis-induced cardiomyopathy with anthracycline-induced cardiac myocyte damage as a predisposing factor. We suggest prophylaxis and methods of early detection to prevent and better treat acute heart failure in pediatric oncology patients receiving anthracyclines.

16S rRNA is a valuable tool in finding bacterial aetiology of community-acquired pleural empyema-a population-based observational study in South Sweden.

BACKGROUND: The incidence of community-acquired pleural empyema is increasing. Knowledge of the bacterial aetiology is important in order to base recommendations on empirical antimicrobial treatment. The primary aim of the present study was to describe the bacterial aetiology of adult patients with culture proven and/or 16S rRNA-positive community-acquired pleural infection. METHODS: We performed a retrospective, population-based observational cohort study in Skåne County, south of Sweden. We included all patients with pleural samples obtained between 1st of January 2011 to 31st of December 2017 in Skåne, south of Sweden, with a positive culture and/or 16S rRNA result. Exclusion criteria were patients with culture-negative and/or 16S rRNA-negative pleural samples, age < 18 years, pleural empyema caused by trauma or iatrogenesis, pleural infection caused by tuberculosis or fungi, simultaneous lung- or abscess of the abdomen and bacterial species considered to be contaminants. RESULTS: A total of 291 patients were included in the study, of which 63% were men and the median age was 69 years. The dominating bacterial aetiology was viridans streptococci (36%), followed by Streptococcus pneumoniae (14%) and anaerobic bacteria (12%). 16S rRNA added information of bacterial aetiology in addition to standard culturing methods in 63% of the patients. CONCLUSION: We found that the aetiology of adult patients with culture proven and/or 16S rRNA-positive community-acquired pleural empyema is dominated by viridans streptococci, S. pneumoniae and anaerobic bacteria. Our study shows that 16S rRNA is a valuable tool in finding the bacterial aetiology of community-acquired pleural empyema.

Viridans Group Streptococcus Meningitis in an Immunocompetent Child: A Case Report.

BACKGROUND Viridans group streptococci (VGS) are commensal organisms in humans that are considered contaminants when isolated from culture specimens. However, VGS can be pathogenic when recovered multiple times from blood cultures or when in immunocompromised hosts. VGS are the leading cause of dental abscesses and infective endocarditis in children with underlying congenital heart diseases. They are not commonly involved in meningeal infections, but meningitis due to VGS can be fatal if not treated. The onset is usually preceded by an upper respiratory tract infection or in association with neurological surgical procedures. CASE REPORT Our patient was a 14-month-old girl with no significant past medical history who presented with fevers and irritability for 2 weeks. A full sepsis workup, including blood, urine, and cerebrospinal fluid (CSF) cultures, was obtained. Culture results were notable for the abundant growth of VGS in the CSF. However, brain imaging and echocardiogram were normal, with no evidence of brain abscesses or cardiac vegetations, respectively. The patient had shown marked clinical improvement after receiving 2 weeks of intravenous ceftriaxone, which was selected based on the VGS susceptibility profile. CONCLUSIONS Bacterial meningitis is one of the most burdensome infectious diseases worldwide, despite improvements in diagnostic methods, management, and national immunization programs. Clinicians should consider VGS in the differential diagnosis of potential infections that can cause meningitis.

Performance assessment of ASTA MicroIDSys, a new matrix assisted laser desorption ionization-time of flight mass spectrometry system, for identification of viridans group streptococci.

The performance of the ASTA MicroIDSys system (ASTA), a new matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) system, was evaluated for the identification of viridans group streptococci (VGS) and compared with the results obtained with the Bruker Biotyper system (Bruker Daltonics). A total of 106 Streptococcus reference strains belonging to 24 species from the bacterial strain bank was analyzed using the two MALDI-TOF MS systems. Of the 106 reference strains tested, ASTA MicroIDSys and Bruker Biotyper correctly identified 84.9% and 81.1% at the species level, 100% and 97.2% at the group level and 100% and 98.1% at the genus level, respectively. The difference between the two systems was not statistically significant (P = 0.289). Out of 24 species, 13 species were accurately identified to the species level with 100% accurate identification rates with both systems. The accurate identification rates at the species level of ASTA MicroIDSys and Bruker Biotyper were 100% and 87.5% for the S. anginosus group; 78.4% and 73.5% for the S. mitis group; 91.7% and 91.7% for the S. mutans group; and 100% and 100% for the S. salivarius group, respectively. The ASTA MicroIDSys showed an identification performance equivalent to that of the Bruker Biotyper for VGS. Therefore, it would be useful for the identification of VGS strains in clinical microbiology laboratories.