Dissemination of Yersinia pseudotuberculosis within mice after oral inoculation was analyzed. Y. pseudotuberculosis translocated to organs such as the liver and spleen shortly after oral inoculation, but was quickly cleared. In contrast, a second temporally distinct bacterial translocation event resulted in successful hepatosplenic replication of the bacteria. Replicating pools of bacteria could be established in these organs in mouse mutants that lacked Peyer's patches. These animals frequently had sterile mesenteric lymph nodes, a finding consistent with translocation taking place independently of regional lymph node colonization. In further contradiction to accepted models for dissemination of enteropathogens, clonal analysis revealed that bacteria causing disease in the spleen and liver of C57BL/6J mice were derived from populations located outside the intestinal lymph nodes. Replication of bacteria in the intestine before translocation appeared critical for dissemination, as transient selective suppression by streptomycin of bacterial growth in the intestine delayed dissemination of Y. pseudotuberculosis. These results collectively indicate that hepatosplenic colonization appears intimately connected with the ability of Y. pseudotuberculosis to successfully establish replication in the intestinal lumen and does not result from ordered spread leading from the intestine to regional lymph nodes before dissemination.

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SummaryInvasive fungal infections (IFIs) continue to cause considerable morbidity and mortality in haematopoietic stem cell transplant (HSCT) recipients. This review focuses on the risks for, and diagnosis of, IFIs (candidiasis, aspergillosis and other mould infections), and factors that affect current outcomes. Diagnosis of IFI is difficult, with the sensitivity of the gold standard tests (culture and histopathology) often <50%. Therefore, physicians rely on a constellation of clinical signs, radiography, culture, histopathology and adjunctive tests to establish diagnosis. HSCT recipients often have multiple co-morbidities, and understanding the current outcomes and prognostic variables is therefore important for overall management. This paper reviews historical trends and current data.