Burkholderia pseudomallei and Burkholderia thailandensis are related pathogens that invade a variety of cell types, replicate in the cytoplasm, and spread to nearby cells. We have investigated temporal and spatial requirements for virulence determinants in the intracellular life cycle, using genetic dissection and photothermal nanoblade delivery, which allows efficient placement of bacterium-sized cargo into the cytoplasm of mammalian cells. The conserved Bsa type III secretion system (T3SS Bsa ) is dispensable for invasion, but is essential for escape from primary endosomes. By nanoblade delivery of B. thailandensis we demonstrate that all subsequent events in intercellular spread occur independently of T3SS Bsa activity. Although intracellular movement was essential for cell-cell spread by B. pseudomallei and B. thailandensis, neither BimA-mediated actin polymerization nor the formation of membrane protrusions containing bacteria was required for B. thailandensis. Surprisingly, the cryptic (fla2) flagellar system encoded on chromosome 2 of B. thailandensis supported rapid intracellular motility and efficient cell-cell spread. Plaque formation by both pathogens was dependent on the activity of a type VI secretion system (T6SS-1) that functions downstream from T3SS Bsa -mediated endosome escape. A remarkable feature of Burkholderia is their ability to induce the formation of multinucleate giant cells (MNGCs) in multiple cell types. By infection and nanoblade delivery, we observed complete correspondence between mutant phenotypes in assays for cell fusion and plaque formation, and time-course studies showed that plaque formation represents MNGC death. Our data suggest that the primary means for intercellular spread involves cell fusion, as opposed to pseudopod engulfment and bacterial escape from double-membrane vacuoles.

Objectives: To use the ethanol-lock technique (in conjunction with systemic antibiotics) to salvage central lines from removal and to prevent persistence of catheterrelated infections among pediatric patients with longterm intravascular devices. Patients: Forty children with diverse underlying disorders were treated for 51 catheter-related infections using the Childrens Hospital Los Angeles ethanol-lock technique.Interventions: Eligible infected central lines were instilled with a dose volume of 0.8 to 1.4 mL of 70% ethanol into the catheter lumen during 12 to 24 hours and then withdrawn. The volume of ethanol used was based on the type of intravascular device. Main Outcome Measures:Clearance of infection and incidence of recurrence.Results: Of the 51 ethanol-lock treatments in 40 children, no catheters were removed because of persistent infection. Eighty-eight percent (45/51) of the treated episodes cleared without recurrence (defined as a relapse within 30 days with the same pathogen). Twelve (75%) of 16 polymicrobial isolates and 33 (94%) of 35 monomicrobial isolates were successfully treated. There were no adverse reactions or adverse effects reported. Conclusion:This retrospective study supports the use of the ethanol-lock technique in conjunction with systemic antibiotics as an effective and safe method to retain the use of a previously infected central venous catheter, decrease the need for line removal, and eradicate persistent pathogens in catheter-related infections.

Sickle cell anemia (SCA) results in chronic volume overload of the heart due to hemodilution. Previous echocardiographic studies of cardiac function in children with SCA have not accounted for these abnormal loading conditions. The objectives of this study were to (1) determine how the degree of anemia and transfusion status relate to cardiac findings and (2) evaluate cardiac function using load-independent parameters of function. We evaluated 77 patients with SCA, ages 2 to 22 years (mean ± SD = 11.7 ± 4.7), using physical examination, electrocardiography, and echocardiography. We compared two groups of patients. Group 1 consisted of 57 non-transfused patients, and Group 2 consisted of 20 patients on a chronic transfusion protocol. Group 1 patients exhibited a significantly lower hemoglobin, higher cardiac output, and larger left ventricular (LV) end-diastolic dimension and LV mass than groups 2 (P < 0.05). However, the velocity of circumferential fiber shortening-wall stress index (a load-independent measure of systolic function) was normal and not statistically different between the two groups. Conversely, the LV myocardial performance index (a measure of combined systolic and diastolic function) was significantly higher in Group 2 (P < 0.001), possibly indicating impaired myocardial diastolic function. SCA in children results in a volume-overloaded heart with a significant increase in LV dimensions and mass, both proportional to the degree of anemia. Despite these abnormal loading conditions, systolic function is preserved. Patients on a chronic transfusion protocol may develop diastolic dysfunction despite iron chelation therapy. Am.