Influència dels serotips dels Streptococcus pneumoniae en l’evolució clínica de les pneumònies.

Estudi retrospectiu en el que es descriuen les característiques clíniques de pacients adults amb pneumònia causada per Streptococcus pneumoniae aïllats en mostres invasives i la influència dels serotips amb elevada capacitat de causar malaltia invasiva en l'evolució clínica d’aquestes. Es divideixen en 2 grups: en el grup E s’inclouen pacients infectats amb serotips amb elevada capacitat invasiva i en el grup X s’engloba a la resta. Els pacients del grup E són més joves i la mortalitat d’aquest grup és significativament més baixa (p = 0,022). No es troben diferències entre els grups en relació a comorbiditats i evolució clínica.

New Diagnostic Real-Time PCR for Specific Detection of Mycoplasma hominis DNA.

Mycoplasma hominis is a fastidious micro-organism causing genital and extragenital infections. We developed a specific real-time PCR that exhibits high sensitivity and low intrarun and interrun variabilities. When applied to clinical samples, this quantitative PCR allowed to confirm the role of M. hominis in three patients with severe extragenital infections.

Digestion of Streptococcus pneumoniae cell walls with its major peptidoglycan hydrolase releases branched stem peptides carrying proinflammatory activity.

The peptidoglycan of Gram-positive bacteria is known to trigger cytokine release from peripheral blood mononuclear cells (PBMCs). However, it requires 100-1000 times more Gram-positive peptidoglycan than Gram-negative lipopolysaccharide to release the same amounts of cytokines from target cells. Thus, either peptidoglycan is poorly active or only part of it is required for PBMC activation. To test this hypothesis, purified Streptococcus pneumoniae walls were digested with their major autolysin N-acetylmuramoyl-L-alanine amidase, and/or muramidase. Solubilized walls were separated by reverse phase high pressure chromatography. Individual fractions were tested for their PBMC-stimulating activity, and their composition was determined. Soluble components had a Mr between 600 and 1500. These primarily comprised stem peptides cross-linked to various extents. Simple stem peptides (Mr <750) were 10-fold less active than undigested peptidoglycan. In contrast, tripeptides (Mr >1000) were >/=100-fold more potent than the native material. One dipeptide (inactive) and two tripeptides (active) were confirmed by post-source decay analysis. Complex branched peptides represented </=2% of the total material, but their activity (w/w) was almost equal to that of LPS. This is the first observation suggesting that peptidoglycan stem peptides carry high tumor necrosis factor-stimulating activity. These types of structures are conserved among Gram-positive bacteria and will provide new material to help elucidate the mechanism of peptidoglycan-induced inflammation.

Teichoic acids are not required for Streptococcus pneumoniae and Staphylococcus aureus cell walls to trigger the release of tumor necrosis factor by peripheral blood monocytes.

In gram-negative bacteria, the outer membrane lipopolysaccharide is the main component triggering cytokine release from peripheral blood mononuclear cells (PBMCs). In gram-positive bacteria, purified walls also induce cytokine release, but stimulation requires 100 times more material. Gram-positive walls are complex megamolecules reassembling distinct structures. Only some of them might be inflammatory, whereas others are not. Teichoic acids (TA) are an important portion (> or =50%) of gram-positive walls. TA directly interact with C3b of complement and the cellular receptor for platelet-activating factor. However, their contribution to wall-induced cytokine-release by PBMCs has not been studied in much detail. In contrast, their membrane-bound lipoteichoic acids (LTA) counterparts were shown to trigger inflammation and synergize with peptidoglycan (PGN) for releasing nitric oxide (NO). This raised the question as to whether TA are also inflammatory. We determined the release of tumor necrosis factor (TNF) by PBMCs exposed to a variety of TA-rich and TA-free wall fragments from Streptococcus pneumoniae and Staphylococcus aureus. TA-rich walls from both organisms induced measurable TNF release at concentrations of 1 microg/ml. Removal of wall-attached TA did not alter this activity. Moreover, purified pneumococcal and staphylococcal TA did not trigger TNF release at concentrations as high as > or =100 microg/ml. In contrast, purified LTA triggered TNF release at 1 microg/ml. PGN-stem peptide oligomers lacking TA or amino-sugars were highly active and triggered TNF release at concentrations as low as 0.01 microg/ml (P. A. Majcherczyk, H. Langen, et al., J. Biol. Chem. 274:12537-12543,1999). Thus, although TA is an important part of gram-positive walls, it did not participate to the TNF-releasing activity of PGN.

Therapeutic effects of bacteriophage Cpl-1 lysin against Streptococcus pneumoniae endocarditis in rats.

Cpl-1, a pneumococcal phage lytic enzyme, was tested in rats with experimental endocarditis due to Streptococcus pneumoniae WB4. High-dose regimen Cpl-1 eliminated pneumococci from blood within 30 min and decreased bacterial titers in vegetations (>4 log10 CFU/g) within 2 h. Rapid bacterial lysis induced by Cpl-1 treatment increased cytokine secretion noticeably.

OCORRÊNCIA E DIVERSIDADE DE GENES pspA ENTRE AMOSTRAS DE Streptococcus pneumoniae PERTENCENTES A COMPLEXOS CLONAIS CIRCULANTES NO BRASIL

De PINA, Sandrine Ester da Cruz Monteiro. Ocorrência e diversidade de genes pspA entre amostras de Streptococcus pneumoniae pertencentes a complexos clonais circulantes no Brasil. Rio de Janeiro, 2015. Dissertação (Mestrado em Ciências Biológicas - Microbiologia), Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 2015. Streptococcus pneumoniae é um importante patógeno associado a infecções invasivas, sendo também geralmente encontrado na nasofaringe de portadores assintomáticos. A cápsula polissacarídica é o principal fator de virulência e constitui a base das vacinas atualmente licenciadas. Devido às limitações inerentes às vacinas existentes, proteínas desse microrganismo, como a proteína de superfície pneumocócica A (PspA), são consideradas alvos de grande interesse para a formulação de novas estratégias de prevenção. No entanto, devido à natureza polimórfica dos genes pspA, torna-se essencial o levantamento de dados sobre a distribuição desses genes entre as amostras de pneumococos circulantes em diferentes regiões geográficas. Desta forma, o presente estudo teve como objetivo analisar a ocorrência e a diversidade de genes pspA entre 413 amostras de S. pneumoniae isoladas no Brasil entre 1988 e 2014, além de avaliar a ocorrência desses genes em amostras clínicas de espécies relacionadas (Streptococcus mitis e Streptococcus pseudopneumoniae), investigar a ocorrência de eventos de recombinação nesses genes e avaliar a distribuição de biomarcadores por MALDI-TOF MS em cada tipo de gene pspA. Todas as amostras de S. pneumoniae e apenas uma amostra de S. mitis albergavam genes pspA. Genes da família 2 (com destaque para a clade 3) foram os mais comuns (59,6%) com índices de ocorrência crescentes ao longo do tempo, seguidos dos genes da família 1 (39%; com destaque para a clade 1) e da família 3 (1,4%; todas clade 6). Dentro de uma mesma clade, as amostras compartilharam >80% de similaridade em fragmentos do gene pspA, sendo as clades pertencentes a uma mesma família mais próximas entre si evolutivamente. Os tipos de genes pspA foram conservados dentro de cada complexo clonal, independente de qualquer outra característica da amostra (como sorotipo, origem clínica e perfil de susceptibilidade à penicilina). Sinais de eventos de recombinação foram detectados, entre amostras de S. pneumoniae e S. mitis, em fragmentos do gene pspA que representam os alvos mais prováveis para inclusão em uma nova vacina baseada em PspA. MALDI-TOF MS apresentou potencial para ser utilizada como alternativa na caracterização dos diferentes tipos de genes pspA, distribuindo as amostras de S. pneumoniae em subgrupos que se correlacionaram com a família de genes pspA, e permitindo a determinação de perfis de biomarcadores de interesse representativos de cada clade. Este estudo adiciona dados ao conhecimento da distribuição das famílias e clades de genes pspA entre as amostras de pneumococos circulantes em nosso meio, sendo este aspecto de extrema importância para a elucidação da epidemiologia desta espécie bacteriana, assim como representa um passo essencial no desenvolvimento de novas estratégias vacinais.

Mycoplasma hominis necrotizing pleuropneumonia in a previously healthy adolescent.

BACKGROUND: Mycoplasma hominis is a fastidious micro-organism causing systemic infections in the neonate and genital infections in the adult. It can also be the cause of serious extra-genital infections, mainly in immunosuppressed or predisposed subjects. CASE PRESENTATION: We describe a case of severe pneumonia and pericarditis due to Mycoplasma hominis in a previously healthy adolescent who did not respond to initial therapy. CONCLUSIONS: Mycoplasma hominis could be an underestimated cause of severe pneumonia in immunocompetent patients and should be particularly suspected in those not responding to standard therapy.

Global phylogenomic analysis of nonencapsulated Streptococcus pneumoniae reveals a deep-branching classic lineage that is distinct from multiple sporadic lineages.

The surrounding capsule of Streptococcus pneumoniae has been identified as a major virulence factor and is targeted by pneumococcal conjugate vaccines (PCV). However, nonencapsulated S. pneumoniae (non-Ec-Sp) have also been isolated globally, mainly in carriage studies. It is unknown if non-Ec-Sp evolve sporadically, if they have high antibiotic nonsusceptiblity rates and a unique, specific gene content. Here, whole-genome sequencing of 131 non-Ec-Sp isolates sourced from 17 different locations around the world was performed. Results revealed a deep-branching classic lineage that is distinct from multiple sporadic lineages. The sporadic lineages clustered with a previously sequenced, global collection of encapsulated S. pneumoniae (Ec-Sp) isolates while the classic lineage is comprised mainly of the frequently identified multilocus sequences types (STs) ST344 (n = 39) and ST448 (n = 40). All ST344 and nine ST448 isolates had high nonsusceptiblity rates to β-lactams and other antimicrobials. Analysis of the accessory genome reveals that the classic non-Ec-Sp contained an increased number of mobile elements, than Ec-Sp and sporadic non-Ec-Sp. Performing adherence assays to human epithelial cells for selected classic and sporadic non-Ec-Sp revealed that the presence of a integrative conjugative element (ICE) results in increased adherence to human epithelial cells (P = 0.005). In contrast, sporadic non-Ec-Sp lacking the ICE had greater growth in vitro possibly resulting in improved fitness. In conclusion, non-Ec-Sp isolates from the classic lineage have evolved separately. They have spread globally, are well adapted to nasopharyngeal carriage and are able to coexist with Ec-Sp. Due to continued use of PCV, non-Ec-Sp may become more prevalent.

Sub-inhibitory concentrations of vancomycin prevent quinolone-resistance in a penicillin-resistant isolate of Streptococcus pneumoniae.

BACKGROUND: The continuous spread of penicillin-resistant pneumococci represents a permanent threat in the treatment of pneumococcal infections, especially when strains show additional resistance to quinolones. The main objective of this study was to determine a treatment modality impeding the emergence of quinolone resistance. RESULTS: Exposure of a penicillin-resistant pneumococcus to increasing concentrations of trovafloxacin or ciprofloxacin selected for mutants resistant to these drugs. In the presence of sub-inhibitory concentrations of vancomycin, development of trovafloxacin-resistance and high-level ciprofloxacin-resistance were prevented. CONCLUSIONS: Considering the risk of quinolone-resistance in pneumococci, the observation might be of clinical importance.

Ureaplasma urealyticum, Mycoplasma hominis and adverse pregnancy outcomes.

PURPOSE OF REVIEW: Mycoplasma hominis and Ureaplasma urealyticum may colonize the human genital tract and have been associated with adverse pregnancy outcomes. Chorioamnionitis, spontaneous preterm labour and preterm premature rupture of membranes are significant contributors to neonatal morbidity and mortality. However, as these bacteria can reside in the normal vaginal flora, there are controversies regarding their true role during pregnancy and thus the need to treat these organisms. RECENT FINDINGS: We review here the recent data on the epidemiology of mycoplasmas and their clinical role during pregnancy. The association of these organisms with preterm labour has been suggested by many observational studies, but proof of causality remains limited. PCR is an excellent alternative to culture to detect the presence of these organisms, but culture allows antibiotic susceptibility testing. Whether antimicrobial treatment of mycoplasma-colonized pregnant patients can effectively reduce the incidence of adverse pregnancy outcomes warrants further investigations. SUMMARY: The role of Mycoplasma spp. and U. urealyticum in adverse pregnancy outcomes is increasingly accepted. However, sole presence of these microorganisms in the vaginal flora might be insufficient to cause pathological issues, but their combination with other factors such as bacterial vaginosis or cervical incompetence may be additionally needed to induce preterm birth.

Treatment of genital mycoplasma in colonized pregnant women in late pregnancy is associated with a lower rate of premature labour and neonatal complications.

Mycoplasma hominis and Ureaplasma spp. may colonize the human genital tract and have been associated with adverse pregnancy outcomes such as preterm labour and preterm premature rupture of membranes. However, as these bacteria can reside in the normal vaginal flora, there are controversies regarding their true role during pregnancy and so the need to treat these organisms. We therefore conducted a retrospective analysis to evaluate the treatment of genital mycoplasma in 5377 pregnant patients showing symptoms of potential obstetric complications at 25-37 weeks of gestation. Women presenting with symptoms were routinely screened by culture for the presence of these bacteria and treated with clindamycin when positive. Compared with uninfected untreated patients, women treated for genital mycoplasma demonstrated lower rates of premature labour. Indeed preterm birth rates were, respectively, 40.9% and 37.7% in women colonized with Ureaplasma spp. and M. hominis, compared with 44.1% in uncolonized women (Ureaplasma spp., p 0.024; M. hominis, p 0.001). Moreover, a reduction of neonatal complications rates was observed, with 10.9% of newborns developing respiratory diseases in case of Ureaplasma spp. colonization and 5.9% in the presence of M. hominis, compared with 12.8% in the absence of those bacteria (Ureaplasma spp., p 0.050; M. hominis, p <0.001). Microbiological screening of Ureaplasma spp. and/or M. hominis and pre-emptive antibiotic therapy of symptomatic pregnant women in late pregnancy might represent a beneficial strategy to reduce premature labour and neonatal complications.

Ureaplasma diversum- ja Mycoplasma bovigenitalium -sukuelintartunnat suomalaisissa lypsykarjoissa ja sonneissa

Summary: Ureaplasma diversum and Mycoplasma bovigenitalium genital tract infections in Finnish dairy herds and bulls