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Table 1 AFB detection and grading in spot-morning-spot sputum specimens using Z-N method

From: Comparative evaluation of a two-reagent cold stain method with Ziehl-Nelseen method for pulmonary tuberculosis diagnosis

ZN; no. (%)/362
Sputum specimen Grade
3+ 2+ 1+ Scanty Negative Total
1st Spot 8(2.2) 8(2.2) 6(1.7) 2(0.6) 338(93.4) 362(100)
Moring 9(2.5) 7(1.9) 6(1.7) 2(0.6) 338(93.4) 362(100)
2nd Spot 7(1.9) 10(2.8) 5(1.4) 1(0.3) 339(93.6) 362(100)
  1. ZN Ziehl-Neelsen, AFB acid fast bacilli; 3+ = More than 10 AFB per oil immersion field in at least 20 fields; 2+ = 1–9 AFB per oil immersion field in at least 50 fields; 1+ = 10–99 AFB in 100 oil immersion fields; Scanty = 1–9 AFB in 100 oil immersion fields.