4 research outputs found
The role of virulence factors in the outcome of staphylococcal peritonitis in CAPD patients
<p>Abstract</p> <p>Background</p> <p>Peritonitis continues to be the most frequent cause of peritoneal dialysis (PD) failure, with an important impact on patient mortality. Gram-positive cocci such as <it>Staphylococcus epidermidis</it>, other coagulase-negative staphylococci (CoNS), and <it>Staphylococcus aureus </it>are the most frequent etiological agents of PD-associated peritonitis worldwide. The objective of the present study was to compare peritonitis caused by <it>S. aureus </it>and CoNS and to evaluate the factors influencing outcome.</p> <p>Methods</p> <p>Records of 86 new episodes of staphylococcal peritonitis that occurred between 1996 and 2000 in the Dialysis unit of a single university hospital were studied (35 due to <it>S. aureus</it>, 24 to <it>S. epidermidis </it>and 27 to other CoNS). The production of slime, lipase, lecithinase, nuclease (DNAse), thermonuclease (TNAse), α- and ÎČ-hemolysin, enterotoxins (SEA, SEB, SEC, SED) and toxic shock syndrome toxin-1 (TSST-1) was studied in <it>S. aureus </it>and CoNS. Antimicrobial susceptibility was evaluated based on the minimal inhibitory concentration determined by the E-test. Outcome predictors were evaluated by two logistic regression models.</p> <p>Results</p> <p>The oxacillin susceptibility rate was 85.7% for <it>S. aureus</it>, 41.6% for <it>S. epidermidis</it>, and 51.8% for other CoNS (p = 0.001). Production of toxins and enzymes, except for enterotoxin A and α-hemolysin, was associated with <it>S. aureus </it>episodes (p < 0.001), whereas slime production was positive in 23.5% of CoNS and 8.6% of <it>S. aureus </it>strains (p = 0.0047). The first model did not include enzymes and toxins due to their association with <it>S. aureus</it>. The odds of resolution were 9.5 times higher for <it>S. epidermidis </it>than for <it>S. aureus </it>(p = 0.02) episodes, and were similar for <it>S. epidermidis </it>and other CoNS (p = 0.8). The resolution odds were 68 times higher for non-slime producers (p = 0.001) and were not influenced by oxacillin resistance among vancomycin-treated cases (p = 0.89). In the second model, the resolution rate was similar for <it>S. aureus </it>and <it>S. epidermidis </it>(p = 0.70), and slime (p = 0.001) and α-hemolysin (p = 0.04) production were independent predictors of non-resolution.</p> <p>Conclusion</p> <p>Bacterial species and virulence factors rather than antibiotic resistance influence the outcome of staphylococcal peritonitis.</p
Comparison between qualitative and semiquantitative catheter-tip cultures: laboratory diagnosis of catheter-related infection in newborns
Comparison between qualitative and semiquantitative catheter-tip cultures: laboratory diagnosis of catheter-related infection in newborns
Este estudo prospectivo avaliou os mĂ©todos semiquantitativo e qualitativo de cultura de cateter para o diagnĂłstico de infecção relacionada a cateter (IRC) em recĂ©m-nascidos (RN). Foram incluĂdas pontas de cateteres provenientes de recĂ©m-nascidos internados na Unidade Neonatal do Hospital das ClĂnicas da Faculdade de Medicina de Botucatu, UNESP. Foram utilizadas as tĂ©cnicas semiquantitativa e qualitativa de cultura de cateter. Para o diagnĂłstico de IRC, os microrganismos isolados das culturas de cateteres e de hemoculturas perifĂ©ricas foram identificados e submetidos ao teste de sensibilidade a antimicrobianos. O padrĂŁo ouro correspondeu ao diagnĂłstico de certeza de IRC, com o isolamento do mesmo microrganismo (espĂ©cie e perfil de sensibilidade a antimicrobianos) isolado em hemocultura perifĂ©rica. Foram estudados 85 cateteres provenientes de 63 RN. A cultura semiquantitativa, embora tenha apresentado menor sensibilidade (90%), apresentou uma maior especificidade (71%) em comparação Ă sensibilidade de 100% e especificidade de 60% encontradas na cultura qualitativa. AtravĂ©s da identificação dos microrganismos obtidos nas culturas de cateteres, observou-se uma predominĂąncia de espĂ©cies de Estafilococos coagulase-negativa (ECN). A espĂ©cie Staphylococcus epidermidis foi a prevalente (77,5%) nos cateteres com culturas semiquantitativas positivas. Dos 11 episĂłdios de IRC diagnosticados, 8 (72,7%) foram associados a espĂ©cies de ECN, dos quais 6 eram da espĂ©cie S. epidermidis. TambĂ©m foram detectados dois casos de IRC por S. aureus e um caso por Candida parapsilosis. O mĂ©todo de cultura semiquantitativo cateter apresentou vantagens para o diagnĂłstico de IRC em RN quando comparado com o mĂ©todo qualitativo tradicional.This prospective study evaluated semiquantitative and qualitative catheter-culture methods for diagnosis of catheter-related infection (CRI) in newborns. Catheter tips from newborns admitted to the Neonatal Unit of the University Hospital of the Botucatu Medical School, UNESP were included in the study. Catheter cultures were performed with both semiquantitative and qualitative techniques. For CRI diagnosis, microorganisms isolated from catheter cultures and from peripheral blood cultures were identified and submitted to agent susceptibility test. The gold standard was the certain CRI diagnosis when same microorganism (specie and profile of susceptibility to agents) was isolated from both catheter tips and peripheral blood culture. A total of 85 catheters from 63 newborns were included in the study. The semiquantitative culture method, despite presenting lower sensitivity (90%), showed higher specificity (71%) when compared to 100% of sensitivity and 60% of specificity in the qualitative method. The identification of the microorganisms obtained from the catheter cultures showed a prevalence of coagulase-negative staphylococci(CNS) species. The specie Staphylococcus epidermidis (77.5%) was the prevalent in the catheters with positive semiquantitative cultures. Among 11 episodes with CRI diagnosis, 8 (72.7%) were associated with CNS species, of which 6 were S. epidermidis. Two episodes of CRI by S. aureus and one by Candida parapsilosis were also detected. The semiquantitative catheter-culture method showed advantages for CRI diagnosis in newborns when compared to the conservative qualitative method
Measurement of the mass difference between top and anti-top quarks in pp collisions at âs = 7 TeV using the ATLAS detector
A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb1 data sample of proton-proton collisions atâs = 7 TeV recorded with the ATLAS detector at the LHC, events consistent with tt production and decay into a single charged lepton final state are reconstructed. For each event, the mass difference between the top and anti-top quark candidate is calculated. A two b-tag requirement is used in order to reduce the background contribution. A maximum likelihood fit to these per-event mass differences yields ÎŽm = mt - mt = 0.67 ± 0.61 (stat) ± 0.41 (syst) GeV, consistent with CPT invarianc