Nitroblue tetrazolium test in bacterial and viral infections

The reduction of nitroblue tetrazolium (NBT) dye by neutrophils from 379 patients with infectious diseases and 268 controls has been examined. The mean NBT score was 29.8% (72.3% positive tests) in the 231 patients with non-tuberculous bacterial infections, 9.7% (28.1% positive tests) in the 135 patients with viral infections 5.3% (1.5% positive tests) in the controls. Positive tests were demonstrated in 1 of 7 patients with tuberculosis and in 4 of 6 with mycoplasma pneumonia. Patients with urinary tract infections or septicemia had the highest percentage of positive tests, particularly when the infections were caused by gram-negative bacteria. In acute bacterial infection, the 176 patients who had not received any antibacterial therapy prior to testing had a significantly higher mean NBT score and proportion (77.8%) of positive tests than the remaining 55 pretreated patients (54.5%). Recent antibiotic treatment seriously invalidates the NBT test results. In acute viral infection, 29 of the 38 positive tests were obtained from patients with acute hepatitis (mean score 20.0%) or infectious mononucleosis (mean score 9.3%). When evaluating the test results, special attention should be paid to patients with hepatitis. Endotoxin stimulated NBT tests disclosed normal enhancement of NBT reduction by neutrophils from the patients and the controls. Cautiously interpreted, the NBT reduction by neutrophils from the patients and the controls. Cautiously interpreted, the NBT test results may be useful as an adjunct in the differential diagnosis of major bacterial and viral infections.