Use of the Xpert(®) MTB/RIF assay for diagnosing pulmonary tuberculosis comorbidity and multidrug-resistant TB in obstetrics and gynaecology inpatient wards at the University Teaching Hospital, Lusaka, Zambia

Trop Med Int Health. 2013 Sep;18(9):1134-1140. doi: 10.1111/tmi.12145. Epub 2013 Jul 3.

Abstract

Objectives: In high-tuberculosis (TB)-endemic countries, comorbidity of pulmonary TB in hospitalised patients with non-communicable diseases is well documented. In this study, we evaluated the use of the Xpert(®) MTB/RIF assay for the detection of concomitant pulmonary TB in patients admitted to the University Teaching Hospital, Lusaka, Zambia, with a primary obstetric or gynaecological condition.

Methods: The Study population were inpatients admitted with a primary obstetric or gynaecological problem who had a concomitant cough and were able to expectorate a sputum sample. Sputum samples from 94 patients were analysed for the presence of Mycobacterium tuberculosis (M.tb) by standard smear microscopy, MGIT culture, MGIT drug-susceptibility testing (DST) and the Xpert(®) MTB/RIF assay. The sensitivity and specificity of the Xpert(®) MTB/RIF assay were evaluated against the culture gold standard.

Results: Twenty-six of 94 (27.7%) patients had culture-confirmed pulmonary TB. The Xpert(®) MTB/RIF assay had a sensitivity of 80.8% [95% CI: 60.0-92.7%]) compared against MGIT culture. The Xpert(®) MTB/RIF assay was more sensitive than sputum smear microscopy (21/26 (80.8%) vs. 13/26 (50.0%), P = 0.02) and detected an additional eight culture-confirmed cases. Culture DST analysis identified two monoresistant M.tb strains: one resistant to rifampicin (rifampicin sensitive by the Xpert(®) MTB/RIF assay) and one to ethambutol. HIV infection was linked with a 3-fold increase in risk of TB, accounting for 87.5% (21/24) of TB cases. 50% of cases presented as comorbidities with other communicable diseases (CDs) and non-communicable diseases (NCDs).

Conclusions: As an alternative to sputum microscopy, the Xpert(®) MTB/RIF assay provides a sensitive, specific and rapid method for the diagnosis of pulmonary TB in obstetric or gynaecological inpatients. Pulmonary TB is an important cause of concomitant comorbidity to the obstetric or gynaecological condition necessitating admission. TB and HIV comorbidities with other communicable and non-communicable diseases were also common. More proactive screening for TB comorbidity is required in obstetric and gynaecological wards.

Keywords: MDR-TB; Xpert® MTB/RIF assay; gynaecology; maternal; multidrug-resistant TB; obstetric; sensitivity; specificity; sub-Saharan Africa; tuberculosis; women.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bacteriological Techniques / instrumentation
  • Bacteriological Techniques / methods
  • Comorbidity
  • Female
  • Genital Diseases, Female / diagnosis
  • Genital Diseases, Female / epidemiology
  • HIV Infections / diagnosis
  • HIV Infections / epidemiology
  • Humans
  • Inpatients / statistics & numerical data
  • Microbial Sensitivity Tests / instrumentation
  • Microbial Sensitivity Tests / methods*
  • Mycobacterium tuberculosis / isolation & purification
  • Obstetrics and Gynecology Department, Hospital / statistics & numerical data*
  • Pregnancy
  • Pregnancy Complications, Infectious / diagnosis
  • Pregnancy Complications, Infectious / epidemiology
  • Prospective Studies
  • Sensitivity and Specificity
  • Sputum / microbiology
  • Tuberculosis, Multidrug-Resistant / diagnosis*
  • Tuberculosis, Multidrug-Resistant / epidemiology
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / epidemiology
  • Young Adult
  • Zambia / epidemiology