The Limulus in vitro endotoxin assay was evaluated as a possible method for the prompt detection of significant gram-negative bacteriuria in children. This assay is capable of detecting endotoxin associated with intact cell walls of viable gram-negative bacteria as well as free endotoxin. Quantitative results are obtained following a 1-h incubation of Limulus lysate and 10-fold dilutions of otherwise untreated urine. A standard curve of Limulus activity and viable cell counts of Escherichia coli and Klebsiella pneumoniae in urine demonstrated that a positive Limulus reaction at a dilution of 1:100 or 1:1,000 indicated a colony count of at least 100,000 bacteria/ml. A positive Limulus reaction only from undiluted urine or at a dilution of 1: 10 indicated less than 100,000 cells/ml. These experimental observations were confirmed by comparing the Limulus test with quantitative plate counts on 209 urine specimens from a mixed pediatric population. These results indicate that the Limulus assay is a simple, accurate method for rapid presumptive detection of gram-negative bacteriuria in patients where an immediate diagnosis is needed. This test would also seem promising for screening large patient populations for bacteriuria or for monitoring the effectiveness of treatment of urinary tract infections.

The objectives of fluid therapy in the burned child can be simply stated and defined, and they should represent the basis for the resuscitation process. During the first 24 h after the burn, the ultimate goal is restoration of the patient's volume and electrolyte homeostasis. All efforts should be directed at monitoring or restoring organ function while simultaneously minimizing edema formation. Only the minimum amount of fluids and other nutrients needed to restore cell function should be provided. Electrolyte deficits and lactic acidosis must be promptly corrected and every attempt should be made to prevent further derangement in body homeostasis by replacing concurrent losses and anticipating maintenance fluid and electrolyte requirements. Restoration and maintenance of perfusion pressures should lead to maximal oxygenation of injured and noninjured tissues, which promotes spontaneous healing, minimizes wound conversion, decreases bacterial colonization and prepares the injured areas for early excision and grafting. It must be emphasized, however, that restoration of fluid and electrolyte balance and organ function does not necessarily imply a return to normal of all physiological variables. The cardiac output, for example, may not return to preburn levels for 24-48 h post injury, even when the intravascular volume has been completely replenished. Likewise, oliguria may persist for 48-72 h, or even longer, after the burn, as a result of excessive secretion of antidiuretic hormone stimulated by the stress of the injury rather than its effect on fluid balance. Thus, while the objectives can be easily enumerated and defined, they are difficult to meet.

Urinary lactic dehydrogenase (U-LDH) isoenzyme assays were performed on ch2) as well as normal controls (N = 24). Docuemntation of bladder and kidney infection was accomplished by means of the bladder washout test, culture of ureteric urine (in patients with urinary diversion), kidney function studies including the maximal urine concentration test, clinical symptomatology and radiologic appearance of the urinary tract. Total U-LDH in normal children (10.8 +/- 1 mU/ml) was lower than in patients with bladder (27.0 +/- 3.9 mU/ml) or kidney (226 +/- 67.3 mU/ml) infections (P less than 0.005). In normal children isoenzymes 1 and 2 predominated (LDH-1 migrates fastest to anode -- fast zone pattern). In patients with bladder infections, the isoenzyme patterns varied but the concentration of isoenzyme 5 (3.1 +/- 0.8 mU/ml) was lower (P less than 0.005) than in patients with kidney infections (120 +/- 39 mU/ml). In the latter, isoenzymes 4 and 5 predominated (slow zone pattern). Since overlap between kidney and bladder infections regarding isoenzyme 5 concentrations (at 3 SD) occurred in only one individual (patient 37), a correct differential diagnosis using U-LDH-5 alone would have been possible in 94% of the children with pyelonephritis or 97% of the total patient population (kidney + bladder).

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