Acquired rifampicin resistance during first TB treatment: magnitude, relative importance, risk factors and keys to control in low-income settings.

Background: The incidence of acquired rifampicin resistance (RIF-ADR; RR) during first-line treatment varies. Objectives: Compare clinically significant RIF-ADR versus primary and reinfection RR, between regimens (daily versus no rifampicin in the continuation phase; daily versus intermittent rifampicin in the continuation phase) and between rural Bangladesh and Kinshasa, Democratic Republic of Congo. Methods: From patients with treatment failure, relapse, or lost to follow-up, both the outcome and baseline sputum sample were prospectively collected for rpoB sequencing to determine whether RR was present in both samples (primary RR) or only at outcome (RIF-ADR or reinfection RR). Results: The most frequent cause of RR at outcome was primary RR (62.9%; 190/302). RIF-ADR was more frequent with the use of rifampicin throughout versus only in the intensive phase (difference: 3.1%; 95% CI: 0.2-6.0). The RIF-ADR rate was higher with intermittent versus daily rifampicin in the continuation phase (difference: 3.9%; 95% CI: 0.4-7.5). RIF-ADR after rifampicin-throughout treatment was higher when resistance to isoniazid was also found compared with isoniazid-susceptible TB. The estimated RIF-ADR rate was 0.5 per 1000 with daily rifampicin during the entire treatment. Reinfection RR was more frequent in Kinshasa than in Bangladesh (difference: 51.0%; 95% CI: 34.9-67.2). Conclusions: RR is less frequently created when rifampicin is used only during the intensive phase. Under control programme conditions, the RIF-ADR rate for the WHO 6 month rifampicin daily regimen was as low as in affluent settings. For RR-TB control, first-line regimens should be sturdy with optimal rifampicin protection. RIF-ADR prevention is most needed where isoniazid-polyresistance is high, (re)infection control where crowding is extreme.

Rifampin drug resistance tests for tuberculosis: challenging the gold standard.

The rapid diagnosis of rifampin resistance is hampered by a reported insufficient specificity of molecular techniques for detection of rpoB mutations. Our objective for this study was to document the prevalence and prognostic value of rpoB mutations with unclear phenotypic resistance. The study design entailed sequencing directly from sputum of first failure or relapse patients without phenotypic selection and comparison of the standard retreatment regimen outcome, according to the mutation present. We found that among all rpoB mutations, the best-documented "disputed" rifampin resistance mutations (511Pro, 516Tyr, 526Asn, 526Leu, 533Pro, and 572Phe) made up 13.1% and 10.6% of all mutations in strains from Bangladesh and Kinshasa, respectively. Except for the 511Pro and 526Asn mutations, most of these strains with disputed mutations tested rifampin resistant in routine Löwenstein-Jensen medium proportion method drug susceptibility testing (DST; 78.7%), but significantly less than those with common, undisputed mutations (96.3%). With 63% of patients experiencing failure or relapse in both groups, there was no difference in outcome of first-line retreatment between patients carrying a strain with disputed versus common mutations. We conclude that rifampin resistance that is difficult to detect by the gold standard, phenotypic DST, is clinically and epidemiologically highly relevant. Sensitivity rather than specificity is imperfect with any rifampin DST method. Even at a low prevalence of rifampin resistance, a rifampin-resistant result issued by a competent laboratory may not warrant confirmation, although the absence of a necessity for confirmation needs to be confirmed for molecular results among new cases. However, a result of rifampin susceptibility should be questioned when suspicion is very high, and further DST using a different system (i.e., genotypic after phenotypic testing) would be fully justified.

Baseline assessment of collaborative tuberculosis/HIV activities in Kinshasa, the Democratic Republic of Congo.

Ninety-two clinics were surveyed in 2005 as part of a baseline assessment of HIV activities in Tuberculosis (TB) clinics in Kinshasa, Democratic Republic of Congo. Some HIV activities were implemented in 58% of TB clinics. The majority of health had > or = 1 health care worker (HCW) trained in either HIV counseling or testing (71%). Fifty-three clinics offered counseling and testing to TB patients; twenty-two (42%) routinely offered HIV CT to all patients, while others used selective criteria. While most offered on-site counseling (92%) and testing (77%), not all 53 clinics had a HCW trained in counseling and only 31 had access to a counseling room. Cotrimoxazole prophylaxis was offered in 51% of clinics; antiretroviral treatment in 17%. Shortcomings in human resources, infrastructure and quality of services were revealed. Strengthening those clinics already implementing HIV activities could be prioritized to achieve the goals set forward by the Global Plan to Stop TB.