A new highly sensitive point of care screen for spontaneous bacterial peritonitis using the leukocyte esterase method.

BACKGROUND & AIMS: Urine reagent strips measuring leukocyte esterase activity have been studied to screen spontaneous bacterial peritonitis (SBP) but are insensitive. We calibrated a strip specifically for ascitic fluid to achieve high sensitivity in this diagnosis. METHODS: Experiments were conducted on ascitic fluid from patients with cirrhosis. Samples with SBP were diluted with native acellular ascitic fluid to achieve PMN counts below, above, and close to the diagnostic threshold of 250 PMN/microl. A model of SBP was created by spiking negative ascitic fluid samples (<250 PMN/microl) with activated PMN from blood of patients with sepsis, and diluted to achieve a range of PMN. Aliquots were tested at 2, 3, 4, and 10 min with the Periscreen leukocyte esterase strip. PMN/microl was correlated to timings and color scales: white defined negative (PMN <250/microl); and shades of brown, purple, and pink defined positive. Ascitic fluid samples were obtained from 58 patients. Negative ascitic fluid was used from 32 to generate the model SBP. RESULTS: One thousand three hundred and four experiments were performed with a median PMN count of 492/microl (0-7510). After exclusion of uninterpretable colorimetric results, 1089 experiments were analyzed [PMN of 444/microl (0-7510)]. The best result was obtained at 3 min (n=299), with Se: 100%, Sp: 57.9%; NPV: 100%, PPV: 76.5%. The test was not interpretable in bloody, chylous or bilious ascitic fluid, or concurrent imipenem treatment. CONCLUSIONS: This new leukocyte esterase strip calibrated to an ascitic fluid PMN count 250/microl is a robust screening tool when the strip turns any hue of tan/brown at 3 min.

The impact of intercurrent EBV infection on ATP levels in CD4+ T cells of pediatric kidney transplant recipients.

ImmuKnow measures ATP (ng/mL) in PHA-activated CD4+ T cells from patient's whole blood. According to published reports, median ImmuKnow is 258 ng/mL in stable pediatric kidney transplant (PKT) recipients > or =12 yr, and 165 ng/mL in those <12 yr. However, data on the effect of infection or AR on ImmuKnow are scarce. We studied the effect of Epstein-Barr virus (EBV) viremia on ImmuKnow in PKT with GD. Twenty-eight PKT with GD were reviewed. Group 1 has 19 PKT > or =12 yr, and group 2 has nine PKT <12 yr. Mean follow-up was 19.4 +/- 12 months. All ImmuKnow values discussed in this study were measured during GD +/- fever. None had ImmuKnow pretransplant. EBV DNA was isolated from patient blood by real-time PCR. Group 1 has eight boys and 11 girls (mean age = 16.6 +/- 2.4 yr). Group 2 has two boys and seven girls (mean age = 6 +/- 3.1 yr). Median ImmuKnow was 292 ng/mL in group 1, and 370 ng/mL in group 2. Nine children developed EBV viremia: two in group 1 (median ImmuKnow = 273 ng/mL), and seven in group 2 (median ImmuKnow = 475 ng/mL). Overall mean ImmuKnow in the nine EBV viremic patients was higher than that in the 19 non-viremic ones (422 +/- 176 ng/mL, and 302 +/- 113 ng/mL, respectively, unequal variance t-test, p = 0.08). Eight children developed AR (all in G1, median ImmuKnow = 272 ng/mL). In group 1, one patient developed concurrent EBV viremia and rejection, while another patient developed EBV viremia six months following a rejection episode. In group 2, none developed simultaneous AR, CMV, or BK virus infection with EBV viremia. None developed post-transplant lymphoproliferative disease. In summary, EBV viremia was paradoxically associated with high ImmuKnow in PKT <12 yr. This suggests strong co-stimulation of PHA-activated CD4+ T cells by EBV-transformed B cells.