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)

Viridans group streptococci bloodstream infections in neutropenic adult patients with hematologic malignancy: Single center experience.

Viridans group streptococci bloodstream infections (VGS BSI) remain a significant cause of mortality and morbidity in patients with severe neutropenia. The goal of our study was to evaluate clinical course and microbiological susceptibility of VGS BSI at our center. Retrospective analysis of all microbiologically documented bloodstream infections caused by VGS during the 9-year time period (from January 2006 until December 2014) was carried out. Only patients with severe neutropenia (< 500/µL) were included in the study. Clinical outcome and microbiological susceptibility pattern of isolates were recorded. Fifty-one individual patients with episode of VGS BSI were identified. The most frequent agent was Streptococcus mitis (23/51 cases, 45.1%). 88.2% (45/51) of patients were on recommended ciprofloxacin prophylaxis. 20/51 (39.2%) of patients suffered from mucositis at the time of diagnosis (10 patients had oral mucositis, 2 patients had bowel mucositis, and 8 patients both). Twenty-six patients (51.0%) had clinically relevant lung damage caused by VGS BSI (i.e., acute lung injury or acute respiratory distress syndrome). Twenty-four (47.0%) patients presented with bilateral lung infiltrated upon chest imaging, and two (4.0%) patients had unilateral lung infiltrates. Three patients (5.9%) died due to VGS BSI until day 28 of observation. No difference in signs of shock syndrome was observed in the patients during transplantation procedures compared to patients without transplantation as well as in a group received previous high-dose chemotherapy with cytosinarabinoside or in patients with mucositis. Only 3/51 of isolates (5.9%) were resistant to penicillin. All isolates were susceptible to empirical treatment. While the penicillin resistance of VGS remains low in middle Europe, initial antibiotic therapy of febrile neutropenia are still effective in most cases. The mortality and complication rates of VGS BSI were comparable to other studies, and no specific risk factor of shock presence could be identified.

Molecular Characterization of Group B Streptococcus Serotypes By Multiplex Polymerase Chain Reaction / Caracterização molecular dos sorotipos de estreptococos do grupo b por reação multiplex pcr

OBJECTIVE: Group B Streptococcus (GBS) serotypes (Ia, Ib and II to IX) are classified based on variations in their capsular polysaccharide; their prevalence differs between different geographic areas. We examined the prevalence of all GBS serotypes in rectal and vaginal swab samples obtained from 363 pregnant women followed at a Brazilian referral center (Hospital da Mulher Professor Doutor José Aristodemo Pinotti); bacterial susceptibility to antibiotics was further determined. METHOD: Prevalence of positive GBS was evaluated by latex agglutination and by multiplex PCR analysis; bacterial susceptibility to antibiotics, such as clindamycin, erythromycin, levofloxacin, linezolid, penicillin and tetracycline was determined by the disk diffusion method. RESULTS: (a) standard GBS culture and the multiplex PCR analysis tested positive for 83 swabs, collected from 72 women (prevalence of GBS colonization: 72/363; 20%); the most prevalent Serotype was Ia (n=43/83; 52%), followed by serotype V (n=14/83; 17%); according to anatomical origin, serotype Ia accounted for 27/59 (46%) and 16/24 (67%) of the vaginal and rectal samples, respectively; PCR also identified serotypes Ib, II, III and VI. Serotype VI is rarely described and had not been previously reported in Brazil or in Latin America. (b) The latex agglutination test only identified 44 positive samples, all of which were serotyped: 34 of these samples (77%) had serotypes matching those identified by multiplex PCR. (c) Only one sample (serotype Ia) showed resistance to erythromycin and clindamycin. CONCLUSION: Regional studies on GBS serotypes prevalence are essential to guide immunoprophylactic interventions (vaccines) and the implementation of adequate antibiotic prophylaxis or treatment. In this study, the incidence of the serotype VI, a new and rare serotype of GBS was described for the first time in a Brazilian population.

OBJETIVO: Os sorotipos (Ia, Ib e II ao IX) do estreptococo do grupo B (GBS) são classificados baseado nas variações em seus polissacarídeos capsulares; sua prevalência difere entre diferentes áreas geográficas. Nós examinamos a prevalência de todos os sorotipos do estreptococo do grupo B em amostras de swabs vaginal e retal obtidas de 363 mulheres seguidas em um centro de referência brasileiro, o Hospital da Mulher Professor Doutor José Aristodemo Pinotti; a susceptibilidade bacteriana a antibióticos foi também determinada. MÉTODO A prevalência de estreptococo do grupo B positivo foi avaliada por aglutinação em látex e através de análise por multiplex PCR; susceptibilidade bacteriana a antibióticos, tais como clindamicina, eritromicina, levofloxacin, linezolide, penicilina e tetraciclina foi determinada pelo método de disco difusão. RESULTADOS: (a) Tanto a cultura padrão para estreptococo do grupo B quanto a análise por multiplex PCR testaram positivos para 83 swabs. A prevalência para colonização por GBS foi 20%. O sorotipo Ia foi o mais prevalente (n= 43/83; 52%), seguido pelo sorotipo V (n= 14/83; 17%); De acordo com a origem anatômica, o sorotipo Ia positivou 27/59 (46%) e 16/24 (67%) das amostras vaginais e retais, respectivamente; o teste de PCR também identificou os sorotipos Ib, II, III, VI. O sorotipo VI é raramente descrito e não reportado no Brasil ou na América Latina até esta data. (b) O teste de aglutinação em látex somente identificou 44 amostras positivas, todas das quais foram sorotipadas: 34 destas amostras (77%) tiveram os sorotipos coincidindo com aqueles identificados pela multiplex PCR. (c) Somente uma amostra (sorotipo Ia) mostrou resistência a eritromicina e clindamicina. CONCLUSÃO: Estudos regionais sobre a prevalência dos sorotipos do estreptococo do grupo B são essenciais para guiar medidas imunoprofiláticas (vacinas) e a implementação de adequada antibiótico profilaxia. Neste estudo, a incidência do sorotipo VI foi descrita pela primeira vez na população Brasileira, um novo e raro sorotipo do estreptococo do grupo B.

Comparasion of five gene loci (rnpB, 16S rRNA, 16S-23S rRNA, sodA and dnaJ) to aid the molecular identification of viridans-group streptococci and pneumococci.

Viridans-group streptococci (VGS) consist of several taxa which historically have been highly diverse. However, at times it may become necessary to have a reliable scheme for the identification of these organisms to the species level. The aim of this study is to compare the ability of five gene loci, namely rnpB, 16S rRNA, 16S-23S rRNA, sodA and dnaJ, to speciate such organisms through a sequence typing-based approach. Reference organisms consisting of six VGS species were compared based on sequence typing, followed by comparison of 31 wild-type respiratory isolates, and showed that employment of sequence typing using the rnpB gene locus was the most specific and reliable. Therefore, the use of rnpB sequencing for the identification of VGS to species level is a reliable and feasible option, based on a single gene target.

Spondylodiscitis and endocarditis caused by S. vestibularis.

Streptococcus vestibularis is a recently described member of the viridans group that was first isolated from the vestibular mucosa of the human oral cavity and described as a new species in 1988. It has been rarely associated with human infections. In few papers, it has been reported as a causal agent of systemic infection in immunosupressed adults and in those with other severe underlying diseases, like coronary valve diseases. A 65-year-old woman was admitted to the hospital with complaints of fever for three months, general malaise, effort dyspnea, weight loss, back pain and myalgia. Both native aortic valve endocarditis and spondylodiscitis due to Streptococcus vestibularis were detected. The patient was successfully treated with intravenous potassium penicillin G and gentamicin for six weeks, followed by oral amoxicillin for three months, in addition to aortic valve replacement. In all patients with spondylodiscitis, infective endocarditis should be considered, particularly in patients with heart valve disease history, since spondylodiscitis may be the presenting sign of an infective endocarditis. Cardiac valve replacement surgery should be performed if the course of fever and inflammatory syndrome is unfavorable after appropriate antibiotic treatment. We report the first case with both native aortic valve endocarditis and spondylodiscitis due to Streptococcus vestibularis.

Spondylodiscitis and endocarditis caused by S. vestibularis

Streptococcus vestibularis is a recently described member of the viridans group that was first isolated from the vestibular mucosa of the human oral cavity and described as a new species in 1988. It has been rarely associated with human infections. In few papers, it has been reported as a causal agent of systemic infection in immunosupressed adults and in those with other severe underlying diseases, like coronary valve diseases. A 65-year-old woman was admitted to the hospital with complaints of fever for three months, general malaise, effort dyspnea, weight loss, back pain and myalgia. Both native aortic valve endocarditis and spondylodiscitis due to Streptococcus vestibularis were detected. The patient was successfully treated with intravenous potassium penicillin G and gentamicin for six weeks, followed by oral amoxicillin for three months, in addition to aortic valve replacement. In all patients with spondylodiscitis, infective endocarditis should be considered, particularly in patients with heart valve disease history, since spondylodiscitis may be the presenting sign of an infective endocarditis. Cardiac valve replacement surgery should be performed if the course of fever and inflammatory syndrome is unfavorable after appropriate antibiotic treatment. We report the first case with both native aortic valve endocarditis and spondylodiscitis due to Streptococcus vestibularis.

Acetaldehyde production from ethanol by oral streptococci.

Alcohol is a well documented risk factor for upper digestive tract cancers. It has been shown that acetaldehyde, the first metabolite of ethanol is carcinogenic. The role of microbes in the production of acetaldehyde to the oral cavity has previously been described in several studies. In the present study, the aim was to investigate the capability of viridans group streptococci of normal oral flora to produce acetaldehyde in vitro during ethanol incubation. Furthermore, the aim was to measure the alcohol dehydrogenase (ADH) activity of the bacteria. Eight clinical strains and eight American Type Culture Collection (ATCC) strains of viridans group streptococci were selected for the study. Bacterial suspensions were incubated in two different ethanol concentrations, 11 mM and 1100 mM and the acetaldehyde was measured by gas chromatography. ADH-activity was measured by using a sensitive spectroscopy. The results show significant differences between the bacterial strains regarding acetaldehyde production capability and the detected ADH-activity. In particular, clinical strain of Streptococcus salivarius, both clinical and culture collection strains of Streptococcus intermedius and culture collection strain of Streptococcus mitis produced high amounts of acetaldehyde in 11 mM and 1100 mM ethanol incubation. All these four bacterial strains also showed significant ADH-enzyme activity. Twelve other strains were found to be low acetaldehyde producers. Consequently, our study shows that viridans group streptococci may play a role in metabolizing ethanol to carcinogenic acetaldehyde in the mouth. The observation supports the concept of a novel mechanism in the pathogenesis of oral cancer.

Viridans streptococci isolated by culture from blood of cancer patients: clinical and microbiologic analysis of 50 cases.

Clinical and microbiologic studies of 50 cases of viridans streptococcal bacteremia in cancer patients were performed. The bacteria were identified to species level by sequencing analysis of the 16S rRNA gene. At least nine Streptococcus spp. were found, including S. mitis (25 strains, 50.0% of 50); currently unnamed Streptococcus spp. (11 strains); S. parasanguis (five strains); S. anginosus (three strains); S. salivarius (two strains); and one strain each of S. gordonii, S. sanguis, S. sobrinus, and S. vestibularis. There were no S. oralis strains. Among 11 antibiotics of nine classes tested, no resistance to vancomycin, linezolid, or quinupristin-dalfopristin was seen. Resistance to penicillin (MIC, 4 to 12 mug/ml) was noted only among S. mitis strains (28.0%, 7/25) and not non-S. mitis strains (0/25) (P = 0.004). Significantly more S. mitis strains than non-S. mitis strains were resistant to fluoroquinolones and to > or =3 classes of antibiotics. Isolation of quinolone-resistant organisms was associated with the prior usage of quinolones (P = 0.002). Quantitative blood cultures showed that the strains resistant to levofloxacin or gatifloxacin were associated with higher colony counts than were their corresponding nonresistant strains. The young and elderly patients also had higher levels of bacteremia caused predominantly by S. mitis. Septic shock was present in 17 (34.0% of 50) patients, and 13 of those cases were caused by S. mitis (P = 0.007). These results suggest that S. mitis is the most common cause of viridans streptococcal bacteremia in cancer patients and is more resistant to antibiotics than other species.

Viridans streptococci bacteremia in children with malignancy: relevance of species identification and penicillin susceptibility.

Our aim was to determine the significance of species identification and penicillin susceptibility of viridans streptococci in children with malignancies. Streptococcus mitis accounted for 58% of invasive viridans streptococcal infections of which 51% were penicillin-nonsusceptible. There was no significant association between species or penicillin susceptibility pattern and clinical presentation or outcome.