title: Comparison of rapid tests for detection of rifampicin-resistant Mycobacterium tuberculosis in Kampala, Uganda.
abstract: BACKGROUND
  Drug resistant tuberculosis (TB) is a growing concern worldwide. Rapid detection of resistance expedites appropriate intervention to control the disease. Several technologies have recently been reported to detect rifampicin resistant Mycobacterium tuberculosis directly in sputum samples. These include phenotypic culture based methods, tests for gene mutations and tests based on bacteriophage replication. The aim of the present study was to assess the feasibility of implementing technology for rapid detection of rifampicin resistance in a high disease burden setting in Africa.
  
  
  METHODS
  Sputum specimens from re-treatment TB patients presenting to the Mulago Hospital National TB Treatment Centre in Kampala, Uganda, were examined by conventional methods and simultaneously used in one of the four direct susceptibility tests, namely direct BACTEC 460, Etest, "in-house" phage test, and INNO- Rif.TB. The reference method was the BACTEC 460 indirect culture drug susceptibility testing. Test performance, cost and turn around times were assessed.
  
  
  RESULTS
  In comparison with indirect BACTEC 460, the respective sensitivities and specificities for detecting rifampicin resistance were 100% and 100% for direct BACTEC and the Etest, 94% and 95% for the phage test, and 87% and 87% for the Inno-LiPA assay. Turn around times ranged from an average of 3 days for the INNO-LiPA and phage tests, 8 days for the direct BACTEC 460 and 20 days for the Etest. All methods were faster than the indirect BACTEC 460 which had a mean turn around time of 24 days. The cost per test, including labour ranged from $18.60 to $41.92 (USD).
  
  
  CONCLUSIONS
  All four rapid technologies were shown capable of detecting rifampicin resistance directly from sputum. The LiPA proved rapid, but was the most expensive. It was noted, however, that the LiPA test allows sterilization of samples prior to testing thereby reducing the risk of accidental laboratory transmission. In contrast the Etest was low cost, but slow and would be of limited assistance when treating patients. The phage test was the least reproducible test studied with failure rate of 27%. The test preferred by the laboratory personnel, direct BACTEC 460, requires further study to determine its accuracy in real-time treatment decisions in Uganda.
authors.affiliation: Department of Medical Microbiology, Makerere University College of Health Sciences, Kampala, Uganda. ogwangsam@yahoo.com
authors.forename: Sam
authors.initials: S
authors.lastname: Ogwang
authors.forename: Benon B
authors.initials: BB
authors.lastname: Asiimwe
authors.forename: Hamidou
authors.initials: H
authors.lastname: Traore
authors.forename: Francis
authors.initials: F
authors.lastname: Mumbowa
authors.forename: Alphonse
authors.initials: A
authors.lastname: Okwera
authors.forename: Kathleen D
authors.initials: KD
authors.lastname: Eisenach
authors.forename: Susan
authors.initials: S
authors.lastname: Kayes
authors.forename: Edward C
authors.initials: EC
authors.lastname: Jones-López
authors.forename: Ruth
authors.initials: R
authors.lastname: McNerney
authors.forename: William
authors.initials: W
authors.lastname: Worodria
authors.forename: Irene
authors.initials: I
authors.lastname: Ayakaka
authors.forename: Roy D
authors.initials: RD
authors.lastname: Mugerwa
authors.forename: Peter G
authors.initials: PG
authors.lastname: Smith
authors.forename: Jerrold
authors.initials: J
authors.lastname: Ellner
authors.forename: Moses L
authors.initials: ML
authors.lastname: Joloba
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology; D005240:Feasibility Studies; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000191:economics / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011933:Reagent Kits, Diagnostic; D012293:Rifampin / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000382:microbiology; D014454:Uganda
chemical_list: D000904:Antibiotics, Antitubercular; D011933:Reagent Kits, Diagnostic; D012293:Rifampin