Intensified tuberculosis case-finding in HIV-positive adults managed at Ethiopian health centers: diagnostic yield of Xpert MTB/RIF compared with smear microscopy and liquid culture.
BACKGROUND
Detection of active tuberculosis (TB) before antiretroviral therapy (ART) initiation is important, but optimal diagnostic methods for use in resource-limited settings are lacking. We assessed the prevalence of TB, evaluated the diagnostic yield of Xpert MTB/RIF in comparison with smear microscopy and culture, and the impact of Xpert results on clinical management in HIV-positive adults eligible for ART at health centers in a region of Ethiopia.


METHODS
Participants were prospectively recruited and followed up at 5 health centers. Trained nurses collected data on socio-demographic characteristics, medical history and symptoms, and performed physical examination. Two paired morning sputum samples were obtained, and lymph node aspirates in case of lymphadenopathy. Diagnostic yield of Xpert MTB/RIF in sputum was compared with smear microscopy and liquid culture.


RESULTS
TB was diagnosed in 145/812 participants (17.9%), with bacteriological confirmation in 137 (16.9%). Among bacteriologically confirmed cases, 31 were smear-positive (22.6%), 96 were Xpert-positive (70.1%), and 123 were culture-positive (89.8%). Xpert MTB/RIF increased the TB detection rate by 64 cases (47.4%) compared with smear microscopy. The overall sensitivity of Xpert MTB/RIF was 66.4%, and was not significantly lower when testing one compared with two samples. While Xpert MTB/RIF was 46.7% sensitive among patients with CD4 cell counts >200 cells/mm(3), this increased to 82.9% in those with CD4 cell counts ≤100 cells/mm(3). Compared with Xpert-positive TB patients, Xpert-negative cases had less advanced HIV and TB disease characteristics.


CONCLUSIONS
Previously undiagnosed TB is common among HIV-positive individuals managed in Ethiopian health centers. Xpert MTB/RIF increased TB case detection, especially in patients with advanced immunosuppression. An algorithm based on the use of a single morning sputum sample for individuals with negative sputum smear microscopy could be considered for intensified case finding in patients eligible for ART. However, technical and cost-effectiveness issues relevant for low-income countries warrant further study.
Infectious Disease Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden ; Ministry of Health, Addis Ababa, Ethiopia.
Taye T
TT
Balcha
Clinical Microbiology, Regional and University Laboratories, Region Skåne, Sweden.
Erik
E
Sturegård
Infectious Disease Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden ; Regional Department of Infectious Disease Control and Prevention, Malmö, Sweden.
Niclas
N
Winqvist
Infectious Disease Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
Sten
S
Skogmar
Infectious Disease Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
Anton
A
Reepalu
Oromia Health Bureau, Addis Ababa, Ethiopia.
Zelalem Habtamu
ZH
Jemal
Columbia University Mailman School of Public Health, International Center for AIDS Care and Treatment Programs- Ethiopia, Addis Ababa, Ethiopia.
Gudeta
G
Tibesso
Department of Medical Microbiology, Faculty of Health Sciences, Linköping University, Sweden ; Department of Clinical Microbiology and Infectious diseases, Kalmar County Hospital, Sweden.
Thomas
T
Schön
Infectious Disease Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
Per
P
Björkman
D000328:Adult; D000904:Antibiotics, Antitubercular / Q000494:pharmacology; D001431:Bacteriological Techniques / Q000379:methods; D024881:Drug Resistance, Bacterial; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008853:Microscopy / Q000379:methods; D025202:Molecular Diagnostic Techniques / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics; D021141:Nucleic Acid Amplification Techniques / Q000379:methods; D015995:Prevalence; D011446:Prospective Studies; D015203:Reproducibility of Results; D012293:Rifampin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology*
D000904:Antibiotics, Antitubercular; D012293:Rifampin