Trial-of-antibiotic algorithm for the diagnosis of tuberculosis in a district hospital in a developing country with high HIV prevalence

Int J Tuberc Lung Dis. 2000 Jun;4(6):513-8.


Objective: To evaluate a diagnostic algorithm for pulmonary tuberculosis based on smear microscopy and objective response to trial of antibiotics.

Setting: Adult medical wards, Hlabisa Hospital, South Africa, 1996-1997.

Methods: Adults with chronic chest symptoms and abnormal chest X-ray had sputum examined for Ziehl-Neelsen stained acid-fast bacilli by light microscopy. Those with negative smears were treated with amoxycillin for 5 days and assessed. Those who had not improved were treated with erythromycin for 5 days and reassessed. Response was compared with mycobacterial culture.

Results: Of 280 suspects who completed the diagnostic pathway, 160 (57%) had a positive smear, 46 (17%) responded to amoxycillin, 34 (12%) responded to erythromycin and 40 (14%) were treated as smear-negative tuberculosis. The sensitivity (89%) and specificity (84%) of the full algorithm for culture-positive tuberculosis were high. However, 11 patients (positive predictive value [PPV] 95%) were incorrectly diagnosed with tuberculosis, and 24 cases of tuberculosis (negative predictive value [NPV] 70%) were not identified. NPV improved to 75% when anaemia was included as a predictor. Algorithm performance was independent of human immunodeficiency virus status.

Conclusion: Sputum smear microscopy plus trial of antibiotic algorithm among a selected group of tuberculosis suspects may increase diagnostic accuracy in district hospitals in developing countries.

MeSH terms

  • AIDS-Related Opportunistic Infections / diagnosis
  • AIDS-Related Opportunistic Infections / drug therapy
  • Adult
  • Algorithms
  • Amoxicillin / therapeutic use*
  • Anti-Bacterial Agents / therapeutic use*
  • Erythromycin / therapeutic use*
  • Female
  • Hospitals, District
  • Humans
  • Male
  • Middle Aged
  • Penicillins / therapeutic use*
  • Prospective Studies
  • Sensitivity and Specificity
  • South Africa
  • Sputum / microbiology
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / drug therapy


  • Anti-Bacterial Agents
  • Penicillins
  • Erythromycin
  • Amoxicillin