Advances in the laboratory diagnosis of Mycobacterium tuberculosis.

Mycobacterium tuberculosis (MTB), the agent of human tuberculosis remains a leading cause of mortality globally. Its resurgence during the last two decades is a reflection of its opportunistic relationship with HIV. The challenges associated with the disease are enormous and often debilitating. The role of clinical and research laboratories is central and significant in this regard as prompt and adequate diagnosis are key factors in the management and control of the disease.

Antimicrobial susceptibility test of Helicobacter pylori isolated from Jos, Nigeria.

Fifty-five strains of Helicobacter pylori isolated from November 1997 until October 1998 from 33 female and 22 male adults attending for endoscopy at the Evangel Hospital, Jos, Nigeria were assayed for antibiotic susceptibility to amoxycillin, clarithromycin, metronidazole and tetracycline by the E-test strip method. Minimum inhibitory concentration (MIC) within the attainable peak serum concentrations for each drug was used as the parameter to determine the susceptibility of H. pylori. The results showed 100% susceptibility for amoxycillin, 89.0% for tetracycline, 87.3% for clarithromycin and 60% for metronidazole. The MIC50 and MIC90 values were: 0.016 microgram/mL and 0.75 microgram/mL for amoxycillin, 0.016 microgram/mL and 2 micrograms/mL for clarithromycin, 0.094 microgram/mL and 12 micrograms/mL for tetracycline, and 2 micrograms/mL and > 48 micrograms/mL for metronidazole. The MIC90 values for metronidazole (> 48 micrograms/mL) and tetracycline (12 micrograms/mL) were in each case higher than the break-point value (peak serum concentrations) of 8 micrograms/mL for metronidazole and 3 micrograms/mL for tetracycline. This pattern of resistance to metronidazole and tetracycline has to be considered when therapeutic regimens against H. pylori contain either or both drugs.

Anti-CagA antibodies in Helicobacter pylori-positive patients and blood donors from Nigeria.

The prevalence of antibodies to CagA protein was evaluated in 174 Helicobacter pylori-positive. subjects: 110 patients submitted to upper gastrointestinal endoscopy and 64 male blood donors. The patients were from different regions of Nigeria: Jos, North, Benue,West and East and the blood donors were from Jos. Sera were assayed for anti-CagA antibodies using Helicobacter p120, CagA ELISA (Viva Diagnostika, Hürth, Germany). Anti-CagA antibodies were detected in 104 (94.5%) patients and in 61 (95.3%) blood donors (P=1.0). Patients from the Benue region presented a lower frequency of anti-CagA antibodies than patients from the other regions (P=0.0004). When the subjects were stratified by age, a significant increase in IgG concentration was observed among the men (P=0.03) but not among the women (P=0.57) or among the blood donors (P=0.83). In conclusion, similarly toAsian countries, CagA-positive H. pylori infection is highly frequent in Nigeria.

Drug resistance profile of Mycobacterium tuberculosis isolates from pulmonary tuberculosis patients in Jos, Nigeria.

The drug resistance profile of 100 Mycobacterium tuberculosis isolates from pulmonary tuberculosis (PTB) cases in Jos, Nigeria, was investigated between August 2006 and September 2007. Drug susceptibility testing for 50 new, 11 follow-up and 39 unclassified cases of PTB was performed on Löwenstein-Jensen medium by the proportion method, using isoniazid (0.2 microg/ml), rifampicin (40 microg/ml), ethambutol (2 microg/ml) and streptomycin (4 microg/ml). Susceptibility to all four drugs was found in 76, 62 and 55%, and multidrug resistance (combined resistance to isoniazid and rifampicin with or without resistance to any other drug) in 4, 31 and 18% of the new, unclassified and follow-up cases, respectively. Monoresistance was found in 15% of the cases. Nine of the 16 isolates (56%) showing multidrug resistance were resistant to all four drugs. These findings are critical and the risk to public health is high, particularly with an overall multidrug resistance of 16%. We suggest that TB management and control programs in Jos are revised to enhance patient's accessibility to treatment sites, promote patients' adherence to drugs, improve diagnostic practices, regularly assess drug resistance profiles, and undertake contact tracing for patients with multidrug-resistant TB.