Performance of indirect immunofluorescence assay, immunochromatography assay and reverse transcription-polymerase chain reaction for detecting human respiratory syncytial virus in nasopharyngeal aspirate samples

Comparison of the use of indirect immunofluorescence assay (IFA), immunochromatography assay (ICA-BD) and reverse transcription-polymerase chain reaction (RT-PCR) for detecting human respiratory syncytial virus (HRSV) in 306 nasopharyngeal aspirates samples (NPA) was performed in order to assess their analytical performance. By comparing the results obtained using ICA-BD with those using IFA, we found relative indices of 85.0 percent for sensitivity and 91.2 percent for specificity, and the positive (PPV) and negative (NPV) predictive values were 85.0 percent and 91.2 percent, respectively. The relative indices for sensitivity and specificity as well as the PPV and NPV for RT-PCR were 98.0 percent, 89.0 percent, 84.0 percent and 99.0 percent, respectively, when compared to the results of IFA. In addition, comparison of the results of ICA-BD and those of RT-PCR yielded relative indices of 79.5 percent for sensitivity and 95.4 percent for specificity, as well as PPV and NPV of 92.9 percent and 86.0 percent, respectively. Although RT-PCR has shown the best performance, the substantial agreement between the ICA-BD and IFA results suggests that ICA-BD, also in addition to being a rapid and facile assay, could be suitable as an alternative diagnostic screening for HRSV infection in children.

Detection of methicillin resistance in Staphylococcus aureus isolated from pediatric patients: is the cefoxitin disk diffusion test accurate enough?

We evaluated the performance of several methods for the detection of methicillin resistance in Staphylococcus aureus using 101 clinical S. aureus isolates from pediatric patients in a tertiary hospital in Brazil; 50 isolates were mecA-positive and 51 were mecA-negative. The Etest and oxacillin agar screening plates were 100 percent sensitive and specific for mecA presence. Oxacillin and cefoxitin disks gave sensitivities of 96 and 92 percent, respectively, and 98 percent specificity. Alterations of CLSI cefoxitin breakpoints increased sensitivity to 98 percent, without decreasing specificity. Our results highlight the importance of a continuing evaluation of the recommended microbiological methods by different laboratories and in different settings. If necessary, laboratories should use a second test before reporting a strain as susceptible, especially when testing strains isolated from invasive or serious infections. With the new (2007) CLSI breakpoints, the cefoxitin-disk test appears to be a good option for the detection of methicillin resistance in S. aureus.

Ceftriaxona: farmacocinética e farmacodinâmica; aplicações no tratamento da otite média aguda na criança / Ceftriaxone: pharmacokinetic and pharmacodinamic: aplications in the treatment of acute otitis media in child

Objetivos: A frequência das otites médias agudas na criança (OMA) e os riscos de fracassos terapêuticos relacionados com a resistência das bactérias responsáveis aos ß-lactamatos, principalmente o S. pneumoniae, determinaram a pesquisa de tratamentos alternativos. A escolha de uma antibioticoterapia adequada repousa na atividade antimicrobiana, bem como nas características farmacocinéticas gerais e locais do antibiótico de escolha; neste estudo säo analisadas as propriedades da ceftriaxona. Farmacocinética: Deve-se ter em mente a cinética plasmática, muito especial, desta cefalosporina de 3ª geraçäo: meia-vida muito prolongada, fixaçäo às proteínas plasmáticas de forma dose-dependente, liberando o antibiótico de forma progressiva e subsequente distribuiçäo extravascular importante. Cinética da ceftriaxona no ouvido médio: Desde o modelo experimental no gerbo(*) até o estudo em Pediatria e no adulto, encontram-se na criança as mesmas características de difusäo no ouvido médio: concentraçöes elevadas (até 35mg/l) e persistentes (19mg/l até a 48ª hora). Interpretaçäo destes dados em termos de farmacodinâmica: Ela é fundamentada em dois parâmetros principais: o tempo acima da CIM(T>CIM), que é, em todos os casos, >24 horas e, portanto, de 100 porcento entre duas doses; os quocientes inibidores (QI) que säo estabelecidos, mesmo para as taxas tardias em 24h na criança, em QI=35 ou QI=8,75, conforme a CIM90 da ceftriaxona como sendo de 1mg/l para os pneumococos. Conclusäo: Entre os ß-lactamatos, a ceftriaxona ocupa um lugar privilegiado, poeque oferece um tempo de 100 porcento acima da CIM para os agentes bacterianos da OMA. Estes dados conferem a esta molécula aplicaçäo terapêutica no tratamento da OMA, uma indicaçäo atualmente aprovada