Direct drug susceptibility testing of Mycobacterium tuberculosis for rapid detection of multidrug resistance using the Bactec MGIT 960 system: a multicenter study

Conventional indirect drug susceptibility testing of Mycobacterium tuberculosis with liquid medium is well established and offers time-saving and reliable results. This multicenter study was carried out to evaluate if drug susceptibility testing (DST) can be successfully carried out directly from processed smear-positive specimens (direct DST) and if this approach could offer substantial time savings. Sputum specimens were digested, decontaminated, and concentrated by the laboratory routine procedure and were inoculated in Bactec MGIT 960 as well as Lowenstein-Jensen (LJ) medium for primary isolation. All the processed specimens which were acid-fast bacterium (AFB) smear positive were used for setting up direct DST for isoniazid (INH) and rifampin (RIF). After the antimicrobial mixture of polymyxin B, amphotericin B, nalidixic acid, trimethoprim, and azlocillin (PANTA) was added, the tubes were entered in the MGIT 960 instrument using the 21-day protocol (Bactec 960 pyrazinamide [PZA] protocol). Results obtained by direct DST were compared with those obtained by indirect DST to establish accuracy and time savings by this approach. Of a total of 360 AFB smear-positive sputum specimens set up for direct DST at four sites in three different countries, 307 (85%) specimens yielded reportable results. Average reporting time for direct DST was 11 days (range, 10 to 12 days). The average time savings by direct DST compared to indirect DST, which included time to isolate a culture and perform DST, was 8 days (range, 6 to 9 days). When results of direct DST were compared with those of indirect DST, there was 95.1% concordance with INH and 96.1% with rifampin. These findings indicate that direct DST with the Bactec MGIT 960 system offers further time savings and is a quick method to reliably detect multidrug resistance (MDR) cases.     

Frequency of dual tuberculosis/human immunodeficiency virus infection in patients presenting at tertiary care centers at karachi

Objective: To determine the frequency of dual infection of Tuberculosis and Human Immunodeficiency Virus (HIV) and document the sexual practices of infected patients. Design: Cross-sectional study. Place and Duration of Study: Medical Unit-IV of Civil Hospital, Karachi, Pakistan, in collaboration with Sindh AIDS Control Program at Services Hospital, Karachi, from January 2003 to December 2004. Patients and Methods: Patients were recruited in the study at both centers and tested for both HIV and TB if any one disease was identified. Diagnosis of TB was based on positive sputum AFB smear / caseous granulomatous lesion on histopathology. Diagnosis of HIV was based on positive anti-HIV serology by LISA technique. A questionnaire was also administered to all the study participants regarding demographics, sexual practices, blood transfusion and intravenous drug abuse. Results: A total of 196 patients of HIV and TB were screened for the presence of dual infection (TB/HIV). Dual infection was present in 38 (19.39%) of patients. Out of 126 patients of HIV, evidence of TB was detected in 38 (30.16%). During the same duration, 70 patients of tuberculosis were screened for HIV and none was tested positive for HIV. History of illicit sexual relationship was found in 121 (96.03%) patients and 5 of these were homosexuals. Conclusion: Dual infection was present in patients of HIV with TB but vice versa was not documented in this study.     

Hepatitis C virus RNA elimination and development of resistance in replicon cells treated with BMS-790052

BMS-790052, a first-in-class hepatitis C virus (HCV) replication complex inhibitor, targeting nonstructural protein 5A (NS5A), displays picomolar to nanomolar potency against genotypes 1 to 5. This exceptional potency translated into robust anti-HCV activity in clinical studies with HCV genotype 1-infected subjects. To date, all BMS-790052-associated resistance mutations have mapped to the N-terminal region of NS5A. To further characterize the antiviral activity of BMS-790052, HCV replicon elimination and colony formation assays were performed. Replicon was cleared from genotype 1a and 1b replicon cells in a time- and dose-dependent manner. Elimination of the genotype 1a replicon required longer treatment durations and higher concentrations of BMS-790052 than those for the genotype1b replicon. Single amino acid substitutions that conferred relatively low levels of resistance were observed at early time points and at low doses. Higher doses and longer treatment durations yielded mutations that conferred greater levels of resistance, including linked amino acid substitutions. Replicon cells that survived inhibitor treatment remained fully sensitivity to pegylated alpha interferon (pegIFN-α) and other HCV inhibitors. Moreover, genotype 1a replicon elimination was markedly enhanced when pegIFN-α and BMS-790052 were combined. Resistant variants observed in this study were very similar to those observed in a multiple ascending dose (MAD) monotherapy trial of BMS-790052, validating replicon elimination studies as a model to predict clinical resistance. Insights gained from the in vitro anti-HCV activity and resistance profiles of BMS-790052 will be used to help guide the clinical development of this novel HCV inhibitor.     

Incidence of colorectal cancer in Kashmir valley, India

Background

There is wide variation in the incidence of colorectal cancer globally and also within the same country among different racial or ethnic groups. The present population-based study was undertaken to determine the incidence of colorectal cancer in Kashmiri population which is non-migratory and ethnically homogeneous having stable food habits.

Methods

Over a period of one year, all newly diagnosed and histological proved cases of colorectal cancer in all possible areas, where such patients are diagnosed and treated were prospectively registered.

Results

A total of 212 cases of colorectal cancers were registered; of them 113 (53.3%) originated in the colon and other 99 (46.7%) in rectum. Male to female ratio was 1.2:1. The crude incidence rate of colorectal cancer was 3.65/100,000; it was 3.78 in males, and 3.50/100,000 in females. The incidence rates for colorectal cancer in Muslims and Hindus were different. The crude incidence rate for colorectal carcinoma was highest for district Srinagar 6.19/100,000 (urban area) and lowest for district Kupwara (rural area) 1.59/100,000. The highest numbers of cases were detected in the age group 55–59 years (n?=?34). The age-specific rate for colorectal carcinoma was highest in the age group 55–59 years (17.21/100,000), followed by 65–69 years (14.86/100,000). The age standardized incidence rate was 4.52/100,000 per year. The truncated age adjusted incidence rates in age group 35–64 years was 8.31/100,000; while that for colorectal carcinoma was 8.77/100,000 in males and 7.66/100,000 in females.

Conclusion

We conclude that the incidence of colorectal cancer in Kashmir valley is similar to that reported in the rest of India.