No abstract

Pseudomonas aeruginosa uses a complex type III secretion system to inject the toxins ExoS, ExoT, ExoU, and ExoY into the cytosol of target eukaryotic cells. This system is regulated by the exoenzyme S regulon and includes the transcriptional activator ExsA. Of the four toxins, ExoU is characterized as the major virulence factor responsible for alveolar epithelial injury in patients with P. aeruginosa pneumonia. Virulent strains of P. aeruginosa possess the exoU gene, whereas non-virulent strains lack this particular gene. The mechanism of virulence for the exoU+ genotype relies on the presence of a pathogenic gene cluster (PAPI-2) encoding exoU and its chaperone, spcU. The ExoU toxin has a patatin-like phospholipase domain in its N-terminal, exhibits phospholipase A2 activity, and requires a eukaryotic cell factor for activation. The C-terminal of ExoU has a ubiquitinylation mechanism of activation. This probably induces a structural change in enzymatic active sites required for phospholipase A2 activity. In P. aeruginosa clinical isolates, the exoU+ genotype correlates with a fluoroquinolone resistance phenotype. Additionally, poor clinical outcomes have been observed in patients with pneumonia caused by exoU+-fluoroquinolone-resistant isolates. Therefore, the potential exists to improve clinical outcomes in patients with P. aeruginosa pneumonia by identifying virulent and antimicrobial drug-resistant strains through exoU genotyping or ExoU protein phenotyping or both.

In 236 patients with fulminant viral hepatitis (FVH), type B (FBH) was most common (47.5%), followed by non-A non-B hepatitis (FNANB, 44.9%) and hepatitis type A (FAH, 7.6%). The survival rate was significantly higher in the FAH group than in the FBH and FNANB groups (61.1, 36.6 and 18.9% respectively), and was significantly higher in the FBH group than in the FNANB group. In spite of screening for hepatitis B virus (HBV), FBH was prevalent (27 of 41) in post-transfusion cases; this phenomenon is discussed in relation to a recently revealed mutation of HBV. Within a month after the onset of hepatitis symptoms all cases in the FAH, 93% in the FBH and 79% in the FNANB group, developed encephalopathy. When the duration of illness before the onset of encephalopathy was more than 10 days (a subacute form), the survival rate was significantly lower than when encephalopathy developed in less than 11 days (an acute form). This difference could be accounted for by the difference in the relative frequency of aetiological viruses in the two forms and the higher survival rate in the acute, than the subacute, form in the FNANB group.

Our data suggests that the use of FFP derived from male donors may be advantageous for posttransfusion pulmonary function, although PD is also determined by background characteristics.