Stepwise implementation of a new diagnostic algorithm for multidrug-resistant tuberculosis in Haiti.

SETTING: The uptake of tests endorsed by the World Health Organization to detect and appropriately confirm multidrug-resistant tuberculosis (MDR-TB) in low-income countries remains insufficient. OBJECTIVE: To validate the implementation of line-probe assays (LPA) and liquid culture to develop an algorithm to detect MDR-TB in the challenging setting of Haiti. METHODS: Through an EXPAND-TB (Expanding Access to New Diagnostics for TB) partnership, proficiency testing and validation of 221 acid-fast bacilli positive specimens were performed. Sensitivity, cost and processing time were analysed. RESULTS: Using liquid vs. solid culture shortened the turnaround time from 54 to 19 days, with a sensitivity of 100% vs. 98.6% and a total cost reduction of 13%. LPA detected all TB and MDR-TB cases at a lower cost than culture, in a mean time of 7.5 days. CONCLUSION: The combined use of molecular and liquid culture techniques accelerates the accurate diagnosis of TB and susceptibility testing against first-line drugs in a significantly shorter time, and is less expensive. The implementation of this new algorithm could significantly and accurately improve the screening and treatment follow-up of patients affected with TB and MDR-TB.

Bleach treatment of sputum samples aids pulmonary tuberculosis screening among HIV-infected patients in Laos.

BACKGROUND: Laos has a high prevalence of tuberculosis (TB) and a slowly increasing prevalence of human immunodeficiency virus/acquired immunedeficiency syndrome (HIV/AIDS). Sputum smear microscopy is the only method currently available for routine screening of pulmonary TB, although it only detects one in three cases among persons living with HIV (PLWH). Bleach treatment of sputum samples (bleach method) has been shown to significantly improve the sensitivity of the test; however, its effectiveness in PLWH remains to be determined in Laos. OBJECTIVES: To determine the performance of the bleach method as a diagnostic tool for pulmonary TB in PLWH and to assess its cost-effectiveness in Laos. RESULTS: Of 174 sputum samples collected from 92 patients, 29 were culture-positive for Mycobacterium tuberculosis in 17 patients. The sensitivity of the direct method and the bleach method was respectively 59% and 93%, and specificity was 100% for both methods. The incremental cost-effectiveness ratio for screening an additional case was US$17.40. CONCLUSION: The bleach method is simple, cheap, easy to perform and cost-effective in PLWH. Its implementation in laboratories involved in routine screening of pulmonary TB among PLWH would allow practitioners to start the treatment of this life-threatening co-infection earlier.

Characterization of low- and very-low-density hepatitis C virus RNA-containing particles.

The presence of hepatitis C virus (HCV) RNA-containing particles in the low-density fractions of plasma has been associated with high infectivity. However, the nature of circulating HCV particles and their association with immunoglobulins or lipoproteins as well as the characterization of cell entry have all been subject to conflicting reports. For a better analysis of HCV RNA-containing particles, we quantified HCV RNA in the low-density fractions of plasma corresponding to the very-low-density lipoprotein (VLDL), intermediate-density lipoprotein, and low-density lipoprotein (LDL) fractions from untreated chronically HCV-infected patients. HCV RNA was always found in at least one of these fractions and represented 8 to 95% of the total plasma HCV RNA. Surprisingly, immunoglobulins G and M were also found in the low-density fractions and could be used to purify the HCV RNA-containing particles (lipo-viro-particles [LVP]). Purified LVP were rich in triglycerides; contained at least apolipoprotein B, HCV RNA, and core protein; and appeared as large spherical particles with a diameter of more than 100 nm and with internal structures. Delipidation of these particles resulted in capsid-like structures recognized by anti-HCV core protein antibody. Purified LVP efficiently bind and enter hepatocyte cell lines, while serum or whole-density fractions do not. Binding of these particles was competed out by VLDL and LDL from noninfected donors and was blocked by anti-apolipoprotein B and E antibodies, whereas upregulation of the LDL receptor increased their internalization. These results suggest that the infectivity of LVP is mediated by endogenous proteins rather than by viral components providing a mechanism of escape from the humoral immune response.