Clinicomicrobiological risk factors for infective endocarditis in viridans group streptococci bacteraemia.

BACKGROUND: When to perform echocardiography to rule out infective endocarditis (IE) in patients with viridans group streptococci (VGS) bloodstream infections (BSIs) is unclear. OBJECTIVES: We aimed to identify independent risk factors for IE in patients with VGS BSI. METHODS: This retrospective study conducted at Seoul National University Hospital from January 2013 to December 2022 involved patients with VGS and nutritionally variant streptococcal BSI, excluding single positive blood cultures and polymicrobial BSI cases. Independent risk factors were identified by multivariate logistic regression and sensitivity analyses according to echocardiography results, VGS species or the inclusion of possible IE cases. RESULTS: Of 845 VGS BSI cases, 349 were analysed and 86 IE cases were identified (24.6%). In the multivariate analysis, heart valve disease [adjusted odds ratio (aOR), 14.14, 95% CI, 6.14-32.58; P < 0.001], persistent bacteraemia (aOR, 5.12, 95% CI, 2.03-12.94; P = 0.001), age (per year, aOR, 0.98; 95% CI, 0.96-1.00; P = 0.015), solid cancer (aOR, 0.26; 95% CI, 0.13-0.53; P < 0.001) and haematologic malignancy (aOR, 0.04; 95% CI, 0.01-0.41; P = 0.006) were independently associated with IE. Sensitivity analyses yielded consistent results; also, infection by a member of the mitis group was independent risk factor for IE (aOR, 6.50; 95% CI, 2.87-14.68; P < 0.001). CONCLUSIONS: Younger age, heart valve disease, persistent bacteraemia, absence of underlying malignancy and BSI by a member of the mitis group were independent risk factors for IE in patients with VGS BSI. Echocardiographic evaluation could be prudently considered based on these clinicomicrobiological risk factors.

Low rates of complications and ß-lactam resistance in viridans group streptococci bloodstream infection among cancer patients receiving chemotherapy.

BACKGROUND: Viridans group streptococci (VGS) bloodstream infection (BSI) frequently occurs in cancer patients receiving chemotherapy, and is associated with infective endocarditis (IE) in up to 20% of cases in the general population. OBJECTIVES: In cancer patients receiving chemotherapy with VGS BSI, we aimed to: (i) determine the incidence of infective complications including IE, (ii) assess the utility of echocardiography in this patient population, (iii) determine the duration and type of antimicrobial therapy received for monomicrobial infections, and (iv) determine the evolution of antimicrobial resistance. METHODS: VGS BSIs (excluding Streptococcus pneumoniae and Streptococcus pseudopneumoniae) in cancer patients receiving chemotherapy were identified from a statewide public pathology database between 2013 and 2022 at our tertiary centre. Medical records were accessed for clinical, microbiological and radiological data. RESULTS: Of 581 patient episodes screened, 183 episodes involving 171 patients met inclusion criteria. Of these, 51% were bone marrow transplantation (BMT) patients, 40% were non-BMT haematology patients, and 8% were solid organ malignancy patients. The median age was 55 years, and 96% were neutropenic at the time of blood culture collection. A transthoracic echocardiogram was performed for 71% of episodes, and one patient met modified Duke's criteria for definite IE, although this diagnosis was not suspected on clinical grounds. Other complications were uncommon. Benzylpenicillin resistance was rare (2.9%) and did not change over time. Most episodes (75%) were treated with piperacillin/tazobactam. For monomicrobial BSIs, the median antibiotic duration was 5 days (IQR 2-7) post-neutropenia resolution. CONCLUSIONS: Infective complications and antimicrobial resistance are rare in cancer patients with VGS BSI. This may provide a safe opportunity to limit both investigations (e.g. echocardiogram) and prolonged exposure to broad-spectrum antimicrobials.

Antimicrobial susceptibility of Viridians Group of Streptococci isolated from infective endocarditis patients from 2018 to 2023.

INTRODUCTION: Viridans Group of Streptococci (VGS) are heterogeneous alpha hemolytic Streptococci that form commensal flora in the oral cavity, upper respiratory tract, gastrointestinal tract and female genital tract and are potential pathogens that can cause serious infections like infective endocarditis and bacteremia. Penicillin or Ceftriaxone is the recommended first line agent for definitive therapy of VGS endocarditis. Alteration in penicillin binding proteins can decrease the susceptibility of VGS to penicillin and other beta-lactam agents and complicate antimicrobial therapy for serious VGS infections like Infective endocarditis. The aim of our study was to determine the antimicrobial susceptibility pattern of viridians group Streptococci isolated from blood samples of infective endocarditis patients from April 2018 to September 2023 against betalactam and other agents. MATERIAL AND METHODS: Three sets of blood cultures with 8-10 ml per bottle were collected from suspected infective endocarditis and incubated in automated blood culture system (BACTEC from BD diagnostics). The broth from positive bottles was streaked on Blood agar, Chocolate agar and MacConkey agar plates and incubated at 37°C. Alpha hemolytic Streptococci that grew after 24-48 h were further identified and antimicrobial susceptibility determined by Vitek 2 system. RESULTS: A total of 100 VGS was isolated from blood samples of Infective endocarditis patients. The species most commonly isolated in our study was S. sanguinis (25%) and S.mitis/oralis group (23%) followed by Non speciated Viridans Streptococci (17%). The lowest penicillin susceptibility ie. PEN MIC <0.12 µg/ml of 40% was observed in S. alactolyticus group, followed by S. mitis (52%) and S. gallolyticus (56%). S. mitis/oralis group showed the lowest susceptibilities to betalactam antibiotics among all speciated and non speciated VGS. CONCLUSION: Infective endocarditis carries a very high mortality and morbidity and the emergence of resistance to betalactam agents like penicillin will only narrow available therapeutic options and further challenge the treatment.

High frequency of viridians group streptococci bacteremia in pediatric neuroblastoma high-risk patients during induction chemotherapy.

Existing literature on febrile neutropenia (FN) has categorized patients with acute leukemia or those undergoing allogeneic stem cell transplantation (SCT) as being high risk for severe infection, bacteremia, and poor outcomes. Comprehensive studies of infection risk in pediatric high-risk neuroblastoma (NB-HR) during induction chemotherapy are limited, and mostly merged within the solid tumor (ST) group. Therefore, it is unclear whether infectious complications and outcomes for NB-HR are the same as in other ST groups. We conducted a retrospective medical record review of pediatric FN patients in a single center from March 2009 to December 2016. FN episodes were categorized into five groups based on underlying diagnosis (acute myelogenous leukemia (AML), acute lymphocytic leukemia (ALL), NB-HR during induction chemotherapy, other solid tumors, and SCT). Comparative analyses of infectious complications between patients with NB-HR and those with other types of cancer diagnoses were performed. A total of 667 FN episodes (FNEs) were identified in 230 patients. FNEs occurred in 82 episodes with NB-HR. Bloodstream infection (BSI) occurred in 145 (21.7%) of total FN episodes. The most isolated organisms were the viridians group streptococci (VGS) (25%). NB-HR patients have higher rates of VGS bacteremia (OR 0.15, 95% [CI 0.04, 0.56]) and are more likely to be admitted to the Pediatric Intensive Care Unit (PICU) compared to patients with other solid tumors (OR 0.36, 95% [CI 0.15, 0.84]). Interestingly, there is no difference in VGS rates between patients with NB-HR and those with AML despite the fact that NB-HR patients do not receive a cytosine arabinoside (AraC)-based regimen. This large neuroblastoma cohort showed that patients with NB-HR during induction chemotherapy are at higher risk for VGS bacteremia and PICU admissions compared with patients with other solid tumors. Further prospective studies are needed to investigate infection-related complications in this high-risk group and to improve morbidity and mortality.

Findings of prosthetic valve endocarditis in the balloon-expandable trans-catheter aortic valve: review of the literature and tips of management.

Prosthetic valve endocarditis after transcatheter aortic valve implantation (TAVI) is a rare complication associated with a high mortality rate. Nonetheless, the rapid expansion of TAVI in recent years has proportionally increased the number of patients exposed to the risk of developing transcatheter valve infection. A 71-year-old female with recent history of TAVI was diagnosed with prosthetic valve obstruction secondary to endocarditis. The characteristics of clinical presentation of endocarditis in the balloon-expandable transcatheter valve and the intra-operative findings are discussed with a review of the literature and tips of management.

Multicenter Study of Endocarditis After Transcatheter Pulmonary Valve Replacement.

BACKGROUND: Endocarditis has emerged as one of the most impactful adverse events after transcatheter pulmonary valve replacement (TPVR), but there is limited information about risk factors for and outcomes of this complication. OBJECTIVES: The purpose of this study was to evaluate risk factors for and outcomes of endocarditis in a large multicenter cohort. METHODS: The authors established an international registry focused on characterizing endocarditis after TPVR, including the incidence, risk factors, characteristics, and outcomes. RESULTS: Investigators submitted data for 2,476 patients who underwent TPVR between July 2005 and March 2020 and were followed for 8,475 patient-years. In total, 182 patients were diagnosed with endocarditis a median of 2.7 years after TPVR, for a cumulative incidence of 9.5% (95% CI: 7.9%-11.1%) at 5 years and 16.9% (95% CI: 14.2%-19.8%) at 8 years (accounting for competing risks: death, heart transplant, and explant) and an annualized incidence of 2.2 per 100 patient-years. Staphylococcus aureus and Viridans group Streptococcus species together accounted for 56% of cases. Multivariable analysis confirmed that younger age, a previous history of endocarditis, and a higher residual gradient were risk factors for endocarditis, but transcatheter pulmonary valve type was not. Overall, right ventricular outflow tract (RVOT) reintervention was less often to treat endocarditis than for other reasons, but valve explant was more often caused by endocarditis. Endocarditis was severe in 44% of patients, and 12 patients (6.6%) died, nearly all of whom were infected with Staphylococcus aureus. CONCLUSIONS: The incidence of endocarditis in this multicenter registry was constant over time and consistent with prior smaller studies. The findings of this study, along with ongoing efforts to understand and mitigate risk, will be critical to improve the lifetime management of patients with heart disease involving the RVOT. Although endocarditis can be a serious adverse outcome, TPVR remains an important tool in the management of RVOT dysfunction.

Identification of Streptococcus pseudopneumoniae and other mitis group streptococci using matrix assisted laser desorption/ionization - time of flight mass spectrometry.

This study evaluated the ability of the MALDI-ToF MS from Bruker Daltonics to identify clinical Mitis-Group-Streptococcus isolates with a focus on Streptococcus pseudopneumoniae. The results were analyzed using the standard log(score) and the previously published list(score). Importantly, using the log(score) no misidentifications occurred and 27 of 29 (93%) S. pneumoniae and 27 of 30 (90%) S. oralis strains were identified, but only 1 of 31 (3%) S. pseudopneumoniae and 1 of 13 (8%) S. mitis strains were identified. However, our results show that 30 of 31 S. pseudopneumoniae strains had a S. pseudopneumoniae Main Spectral Profiles within the 3 best matches. Using the list(score) all S. oralis and S. pneumoniae strains were identified correctly, but list(score) misidentified 10 S. pseudopneumoniae and 5 S. mitis. We propose to use the log(score) for identification of S. pneumoniae, S. pseudopneumoniae, S. mitis and S. oralis, but for some strains additional testing may be needed.

Diagnosing odontogenic sinusitis of endodontic origin: A multidisciplinary literature review.

PURPOSE: Endodontic disease is one of the most common causes of bacterial odontogenic sinusitis (ODS). Diagnosing ODS of endodontic origin involves otolaryngologists confirming sinusitis, and dental specialists confirming endodontic sources. The purpose of this study was to conduct a multidisciplinary literature review to highlight clinical and microbiological features of ODS, and the most optimal diagnostic modalities to confirm endodontic disease. METHODS: An extensive review of both medical and dental literature was performed by rhinologists, endodontists, and an infectious disease specialist. Frequencies of various clinical and microbiological features from ODS studies were collected, and averages were calculated. Different endodontic testing and imaging modalities were also evaluated on their abilities to confirm endodontic disease. RESULTS: ODS patients most often present with unilateral sinonasal symptoms for over 3 months, purulence on nasal endoscopy, and overt dental pathology on computed tomography (CT). Subjective foul smell, and maxillary sinus cultures demonstrating anaerobes and α-streptococci (viridans group) may be more specific to ODS. For endodontic evaluations, cold pulp testing and cone-beam CT imaging are most optimal for confirming pulpal and periapical disease. CONCLUSION: Diagnosing ODS requires collaboration between otolaryngologists and dental specialists. Clinicians should suspect ODS when patients present with unilateral sinonasal symptoms, especially foul smell. Patients will generally have purulent drainage on nasal endoscopy, and both sinus opacification and overt dental pathology on CT. However, some patients will have subtle or absent dental pathology on CT. For suspected endodontic disease, endodontists should be consulted for at least cold pulp testing, and ideally cone-beam CT.

Brain Abscess in a Patient with Osteopetrosis: A Rare Complication

Brain abscess formation is extremely rare in patients with osteopetrosis. Herein, we report a case of viridans streptococci brain abscess in an immunocompromised child diagnosed with osteopetrosis. The patient presented with a sudden change in mental status and convulsions. Radiological evaluation revealed a temporal lobe brain abscess, and intravenous antibiotherapy was started immediately. The patient underwent abscess drainage, and laboratory investigation of pus material revealed viridans streptococci.

Antibiotic Resistance of Viridans Group Streptococci Isolated from Dental Plaques.

Viridans group streptococci (VGS) are a common cause of infective endocarditis, and dental plaque is the major source of these bacteria. The present study examined the antibiotic resistance of 635 VGS isolates obtained from dental plaques. Isolates from supragingival plaques were identified using the rapid ID 32 Strep and mini API reader (bioMérieux, France), and minimal inhibitory concentrations (MICs) were determined by a broth microdilution method. High rates of resistance to ampicillin and tetracycline were detected among the isolates. The most resistant species were Streptococcus sanguinis and Streptococcus salivarius. Among the 635 isolates, 9.1% were resistant to erythromycin, and 20.6% to tetracycline. All isolates were sensitive to vancomycin. Resistance to amoxicillin was observed in 0.2% of all isolates. In this study, we showed the incidence of antimicrobial resistance and the susceptibility patterns among 635 VGS isolates from dental plaque.

The epidemiological and clinical features of odontogenic infective endocarditis.

Antibiotic prophylaxis (AP) of infective endocarditis (IE) in dental practice is a controversial topic. We evaluated the characteristics of the odontogenic IE and assessed the practice and sources of information pertaining to the topic utilized by the Croatian dentists. We conducted a retrospective review of consecutive medical charts of adult patients with IE, admitted to the University Hospital for Infectious Diseases in Zagreb, Croatia, between January 2007 and December 2017. In addition, a cross-sectional, self-reporting questionnaire survey was conducted with participation of 348 Croatian dentists. Of the 811 admissions for suspected IE (40.3% of all Croatian and 92.1% of all Zagreb hospitals), 386 patients were confirmed as definite IE: 68 with odontogenic IE and 318 with IE of other origin. Their first hospital admissions were analyzed. Definite odontogenic IE was defined as a positive echocardiographic result in conjunction with two separate positive blood cultures showing exclusive oral cavity pathogen or Streptococcus viridans associated with current or recent (< 1 month) dental, periodontal, or oral cavity infection. The annual number of new odontogenic IE patients appeared constant over time. In 91.2% of the cases, odontogenic IE was not preceded by a dental procedure; poor oral health was found in 51.5% of patients, and 47.1% had no cardiac condition that increases the IE risk. In-hospital mortality was 5.1% with conservative treatment and 4.5% with cardiac surgery and was much lower for odontogenic IE than in non-odontogenic IE (14.6% and 34.4%, respectively). An increasing number of admissions for non-odontogenic IE were observed in parallel with an increasing number of staphylococcal IE. Surveyed dentists (500 invited, 69.6% responded) were aware of the AP recommendations, but were largely reluctant to treat patients at risk. In people with poor oral health, AP should be considered regardless of cardiac risk factors. Improvement of oral health should be the cornerstone of odontogenic IE prevention.

Differentiation between Streptococcus pneumoniae and other viridans group streptococci by matrix-assisted laser desorption/ionization time of flight mass spectrometry.

OBJECTIVES: Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is becoming the method of choice for bacterial identification. However, correct identification by MALDI-TOF of closely related microorganisms such as viridans streptococci is still cumbersome, especially in the identification of S. pneumoniae. By making use of additional spectra peaks for S. pneumoniae and other viridans group streptococci (VGS). We re-identified viridans streptococci that had been identified and characterized by molecular and phenotypic techniques by MALDI-TOF. METHODS: VGS isolates (n = 579), 496 S. pneumoniae and 83 non-S. pneumoniae were analysed using MALDI-TOF MS and the sensitivity and specificity of MALDI-TOF MS was assessed. Hereafter, mass spectra analysis was performed. Presumptive identification of proteins represented by discriminatory peaks was performed by molecular weight matching and the corresponding nucleotides sequences against different protein databases. RESULTS: Using the Bruker reference library, 495 of 496 S. pneumoniae isolates were identified as S. pneumoniae and one isolate was identified as non-S. pneumoniae. Of the 83 non-S. pneumoniae isolates, 37 were correctly identified as non-S. pneumoniae, and 46 isolates as S. pneumoniae. The sensitivity of the MALDI-TOF MS was 99.8% (95% confidence interval (CI) 98.9-100) and the specificity was 44.6% (95% CI 33.7-55.9). Eight spectra peaks were mostly present in one category (S. pneumoniae or other VGS) and absent in the other category and inversely. Two spectra peaks of these (m/z 3420 and 3436) were selected by logistic regression to generate three identification profiles. These profiles could differentiate between S. pneumoniae and other VGS with high sensitivity and specificity (99.4% and 98.8%, respectively). CONCLUSIONS: Spectral peaks analysis based identification is a powerful tool to differentiate S. pneumoniae from other VGS species with high specificity and sensitivity and is a useful method for pneumococcal identification in carriage studies. More research is needed to further confirm our findings. Extrapolation of these results to clinical strains need to be deeply investigated.

Associations between echocardiographic manifestations and bacterial species in patients with infective endocarditis: a cohort study.

BACKGROUND: The diagnosis of infective endocarditis (IE) is based on microbiological analyses and diagnostic imaging of cardiac manifestations. Echocardiography (ECHO) is preferred for visualization of IE-induced cardiac manifestations. We investigated associations between bacterial infections and IE manifestations diagnosed by ECHO. METHODS: In this cohort study, data from patients aged 18 years or above, with definite IE admitted at the Karolinska University Hospital between 2008 and 2017 were obtained from Swedish National Registry of Endocarditis. Bacteria registered as pathogen were primarily selected from positive blood culture and for patients with negative blood culture, bacteria found in culture or PCR from postoperative material was registered as pathogen. Patients with negative results from culture or PCR, and patients who did not undergo ECHO during hospital stay, were excluded. IE manifestations diagnosed by ECHO were obtained from the registry. Chi-squared test and two-sided Fisher's exact test was used for comparisons between categorical variables, and student's t test was used for continuous numerical variables. Multivariable analyses were performed using logistic regression. Secular trend analyses were performed using linear regression. Associations and the strength between the variables were estimated using odds ratios (ORs) with 95% confidence intervals (CIs). P < 0.05 was considered significant. RESULTS: The most common bacteria were Staphylococcus aureus (n = 239, 49%) and viridans group streptococci (n = 102, 21%). The most common manifestations were vegetation in the mitral (n = 195, 40%), aortic (n = 190, 39%), and tricuspid valves (n = 108, 22%). Associations were seen between aortic valve vegetations and Enterococcus faecalis among patients with native aortic valves, between mitral valve vegetations and streptococci of group B or viridans group, between tricuspid valve vegetations and S. aureus among patients with intravenous drug abuse, and between perivalvular abscesses as well as cardiovascular implantable electronic device (CIED)-associated IE and coagulase negative staphylococci (all P < 0.05). CONCLUSIONS: Associations were found between certain bacterial species and specific ECHO manifestations. Our study contributes to a better understanding of IE manifestations and their underlying bacterial etiology, which pathogens can cause severe infections and might require close follow-up and surgical treatment.

Cumulative incidence and mortality of infective endocarditis in Siriraj hospital-Thailand: a 10-year retrospective study.

BACKGROUND: To investigate the cumulative incidence of and factors associated with mortality among patients with infective endocarditis (IE) at Thailand's largest national tertiary referral center. METHODS: Medical charts of adult patients diagnosed with IE by Duke criteria at Siriraj Hospital during January 2005 to May 2015 were retrospectively reviewed. RESULTS: Of 380 patients, 66.3% had definite IE, and 81.3% had native valve IE (NVE). Cumulative IE incidence was 5.67/1000 admissions. The most common pathogens were viridans group streptococci (VGS) (39.7%), methicillin-sensitive Staphylococcus aureus (MSSA) (13.1%), and beta-hemolytic streptococci (11.5%) in NVE; and, MSSA (20.3%), VGS (20.3%), and Enterococcus spp. (16.9%) in prosthetic valve (PVE) or device-related IE (DRIE). Overall in-hospital mortality was 18.4%. Mortality was significantly higher in PVE/DRIE than in NVE (26.8% vs. 16.5%, p = 0.047). End-stage renal disease (ESRD) (aOR: 9.43, 95% CI: 2.36-37.70), diabetes mellitus (DM) (aOR: 2.81, 95% CI: 1.06-7.49), neurological complication (aOR: 14.16, 95% CI: 5.11-39.22), congestive heart failure (aOR: 4.32, 95% CI: 1.91-9.75), hospital-acquired infection (aOR: 3.78, 95% CI: 1.66-8.57), renal complication (aOR: 3.12, 95%CI: 1.32-7.37), and other complication during admission (aOR: 3.28, 95% CI: 1.41-7.61) were independently associated with mortality. CONCLUSIONS: The incidence of IE, and the mortality rate among those diagnosed with IE are both increasing in Thailand - particularly among those with PVE or DRIE. End-stage renal disease, diabetes mellitus, and development of IE-related complications during admission were found to be independent predictors of mortality.

Treating an intramuscular abscess following toothpick injury in a diabetic patient: A case report and literature review (CARE Complaint).

RATIONALE: Toothpick puncture (TPP) is a penetrating injury that can result in bringing pathogens to the deep space. Such penetrating wounds are typically of pinpoint size with initial symptoms appearing subtle. Consequently, the injury itself is often neglected by patients, or is not detected during physical examinations by medical doctors. Reported complications from such injuries include osteomyelitis and septic arthritis, mostly due to delayed treatment. PATIENT CONCERNS: A diabetic patient aged 83-year-old presented a 2-day history of skin redness, swelling, and tenderness over his forearm following a TPP a week earlier. Laboratory investigations showed leukocytosis with neutrophilic predominance and a high level of C-reactive protein. Before his operation, cultures of aspirated fluid from the injured site revealed the presence of Streptococcus anginosus, Streptococci viridans, Prevotella intermedia, and Pavimonas (Peptostreptococcus) micra. DIAGNOSIS: Intramuscular abscess associated with toothpick injury. INTERVENTIONS: Surgical irrigation with debridement and adjunctive antibiotics of ceftriaxone and clindamycin were given with a satisfactory response. Cultures of debrided tissue showed the presence of P intermedia and P (Peptostreptococcus) micra. OUTCOMES: A split-thickness skin graft was done. Patient was discharged on the 30th postoperative day. LESSONS: Toothpick injury, initial symptoms of which are subtle, can in some cases, lead to serious complications especially when managements are delayed. In such situations (including the present case), surgical irrigation and debridement are administrated for the eradication of infections, removal of potentially retained toothpick, and tissue cultures analyzed. Adjunctive antibiotics is recommended to combat both the aerobic and anaerobic microorganisms of the gastrointestinal tract, skin surface, and oral cavity.

Clinical Significance of Isolates Known to Be Blood Culture Contaminants in Pediatric Patients.

Background and objectives: The objective of this study was to investigate the clinical significance of isolates from blood stream infection known to be blood culture contaminants in pediatric patients. Materials and Methods: Microbiological reports and medical records of all blood culture tests issued from 2002 to 2012 (n = 76,331) were retrospectively reviewed. Evaluation for potential contaminants were done by reviewing medical records of patients with the following isolates: coagulase-negative Staphylococcus, viridans group Streptococcus, Bacillus, Corynebacterium, Micrococcus, Aerococcus, and Proprionibacterium species. Repeated cultures with same isolates were considered as a single case. Cases were evaluated for their status as a pathogen. Results: Coagulase-negative Staphylococcus had clinical significance in 23.8% of all cases. Its rate of being a true pathogen was particularly high in patients with malignancy (43.7%). Viridans group Streptococcus showed clinical significance in 46.2% of all cases. Its rate of being a true pathogen was similar regardless of the underlying morbidity of the patient. The rate of being a true pathogens for remaining isolates was 27.7% for Bacillus and 19.0% for Corynebacterium species. Conclusions: Coagulase-negative Staphylococcus and viridans group Streptococcus isolates showed high probability of being true pathogens in the pediatric population, especially in patients with underlying malignancy.

Variants of the bile: solubility test to differentiate Streptococcus pneumoniae from other viridans group streptococci.

Aim: Bile salts promote the specific autolysis of pneumococcal cells, allowing the differentiation between Streptococcus pneumoniae and other viridans group streptococci (VGS). Material & methods: One hundred clinical VGS isolates identified by amplification and sequencing of 16S rRNA, groEL and sodA genes were analyzed with different variants of bile-solubility tests: tube testing read by naked eye; tube testing where the lysis was measured as the decrease of turbidity with a densitometer; and direct testing on blood agar plate. Results: As expected, all S. pneumoniae isolates were fully lysed in the presence of bile salts except for one isolate that partially lysate in tube testing as well as on the blood agar plate. None of the VGS were lysed by bile salts. Conclusion: Bile-solubility testing is an accurate and technically nondemanding method to discriminate between S. pneumoniae and other VGS species.