Drug susceptibility in Mycobacterium tuberculosis of a sample of patients in Guinea Bissau

Prevalence and Drug Resistance Patterns of Mycobacterium tuberculosis among New Smear Positive Pulmonary Tuberculosis Patients in Eastern Ethiopia

The study aimed at determining the prevalence and drug resistance patterns of Mycobacterium tuberculosis among new smear positive pulmonary tuberculosis patients visiting TB diagnosis and treatment facilities at selected health facilities in eastern Ethiopia. A cross-sectional study was conducted between October 2011 and May 2013. A total of 408 new adult pulmonary TB patients (≥ 18 years) were enrolled in this study. Three consecutive sputum samples (spot, morning, and spot) were collected from each patient and transported to the Armauer Hansen Research Institute TB laboratory located in Addis Ababa for culture on Lowenstein Jensen slant media. DST was performed on 357 (87.5%) of the patient samples for isoniazid (H), rifampicin (R), ethambutol (E), and streptomycin (S) using the standard proportion method. The rate of resistance to any one drug was 23%. Any resistance to H, S, R, and E was 14%, 11.5%, 2.8%, and 0.3%, respectively. The highest proportion of monoresistance was observed against H (9.5%). MDRTB was detected in 1.1% of the patients. Any drug resistance was associated with HIV infection (COR = 3.7, 95% CI 1.905-7.222) (P = 0.000). Although the prevalence of MDRTB is relatively low in the study area, high prevalence of H resistance is a serious concern demanding close monitoring. Expanding diagnostic capacity for mycobacterial culture and DST is a vital step in this regard.

The Guinea-Bissau family of Mycobacterium tuberculosis complex revisited

The Guinea-Bissau family of strains is a unique group of the Mycobacterium tuberculosis complex that, although genotypically closely related, phenotypically demonstrates considerable heterogeneity. We have investigated 414 M. tuberculosis complex strains collected in Guinea-Bissau between 1989 and 2008 in order to further characterize the Guinea-Bissau family of strains. To determine the strain lineages present in the study sample, binary outcomes of spoligotyping were compared with spoligotypes existing in the international database SITVIT2. The major circulating M. tuberculosis clades ranked in the following order: AFRI (n = 195, 47.10%), Latin-American-Mediterranean (LAM) (n = 75, 18.12%), ill-defined T clade (n = 53, 12.8%), Haarlem (n = 37, 8.85%), East-African-Indian (EAI) (n = 25, 6.04%), Unknown (n = 12, 2.87%), Beijing (n = 7, 1.68%), X clade (n = 4, 0.96%), Manu (n = 4, 0.97%), CAS (n = 2, 0.48%). Two strains of the LAM clade isolated in 2007 belonged to the Cameroon family (SIT61). All AFRI isolates except one belonged to the Guinea-Bissau family, i.e. they have an AFRI_1 spoligotype pattern, they have a distinct RFLP pattern with low numbers of IS6110 insertions, and they lack the regions of difference RD7, RD8, RD9 and RD10, RD701 and RD702. This profile classifies the Guinea-Bissau family, irrespective of phenotypic biovar, as part of the M. africanum West African 2 lineage, or the AFRI_1 sublineage according to the spoligtyping nomenclature. Guinea-Bissau family strains display a variation of biochemical traits classically used to differentiate M. tuberculosis from M. bovis. Yet, the differential expression of these biochemical traits was not related to any genes so far investigated (narGHJI and pncA). Guinea-Bissau has the highest prevalence of M. africanum recorded in the African continent, and the Guinea-Bissau family shows a high phylogeographical specificity for Western Africa, with Guinea-Bissau being the epicenter. Trends over time however indicate that this family of strains is waning in most parts of Western Africa, including Guinea-Bissau (p = 0.048).

Molecular characterization and drug resistance testing of Mycobacterium tuberculosis isolates from Chad

The molecular characterizations of the first 40 Mycobacterium tuberculosis isolates from Chad revealed a high proportion of isolates of the Cameroon family (33%), of which one isolate showed a monodrug resistance. In total, 9/33 (27%) isolates were resistant to isoniazid. The implications of these findings are discussed.

Genetic diversity in clinical isolates of Mycobacterium avium complex from Guinea-Bissau, West Africa

Isolates of Mycobacterium avium complex (MAC) were cultured from sputum samples obtained from patients in Guinea-Bissau, West Africa. Twenty-eight isolates hybridising with MAC probe (AccuProbe) were further characterised by different molecular techniques: hybridisation with species-specific probes (AccuProbe) for M. avium and M. intracellulare, partial sequencing of 16S rRNA gene and PCR detection of the DT1-DT6 sequences and the macrophage-induced gene (mig). Only one of the 28 isolates reacted with the M. avium probe and four with the M. intracellulare probe. Two isolates expressed the DT1 sequence, and three the DT6. The mig was detected in 18 (64%) of the isolates. Sequencing of 16S rRNA had the greatest discriminative power of the typing methods applied, without strong correlation with any other technique. Clinical MAC isolates from Guinea-Bissau demonstrated a wide genetic diversity among the members of M. avium complex that might reflect on biotope variation.

Sensitivity to anti-tuberculosis drugs in HIV-positive and -negative patients in Addis Ababa

A cross-sectional survey was conducted between 1 August and 31 December, 1998 in Addis Ababa, Ethiopia to determine the rate of primary drug resistance to anti-tuberculosis drugs and to investigate its possible association with HIV infection. Sputum culture, sensitivity to first-line anti-tuberculosis drugs and HIV testing were done for 236 sputum smear-positive pulmonary tuberculosis patients. Primary drug resistance level (single or multidrug resistance) had not changed significantly since 1994. Primary resistance occurred more often among HIV-positive than among HIV-negative patients. The association between drug resistance and HIV will have a serious impact in the control of tuberculosis because in recent years the prevalence of HIV has increased dramatically in Ethiopia. Therefore, further studies on drug resistance and HIV infection and the establishment of drug resistance surveillance are recommended.

High mortality and severe immunosuppression in hospitalized patients with pulmonary tuberculosis and HIV-2 infection in Guinea-Bissau

The aim of this study was to prospectively compare the clinical outcomes in HIV-2-infected and HIV-negative patients with culture-confirmed pulmonary tuberculosis, evaluate immunological changes and investigate risk factors for decreased survival in HIV-2-positive subjects. From 1994 to 1997, 127 consecutive patients with pulmonary tuberculosis were included at the Raoul Follereau Hospital in Bissau, the capital of Guinea-Bissau. All subjects were initially hospitalized, and then followed to the end of the 8-month treatment period. CD4 T-lymphocyte counts were determined by flow cytometry before, during and at the end of the treatment period. The prevalences of HIV-1, HIV-2 and HIV-1/HIV-2 dual reactivity were 8.7%, 23.6% and 9.4%, respectively (95% confidence intervals 3.8-13.6, 16.2-31.0 and 4.4-14.5, respectively). The mortality rate during the study period was significantly higher in HIV-2-positive (p < 0.01) and HIV-1/HIV-2 dually reactive (p < 0.01) patients than in HIV-negative individuals (52.9, 83.3 and 8.7 per 100 person-years, respectively). In HIV-1-positive patients the mortality rate was 30.8/100 person-years (p = NS). Baseline total CD4 cell counts were 213, 104, 235 and 624 x 10(6)/l (% CD4 = 17, 15, 20 and 40) among HIV-1-, HIV-2- and HIV-1/HIV-2-positive and HIV-negative subjects, respectively. The median rates of change per year of total CD4 cell counts in HIV-2-positive and HIV-negative subjects were 66 and 340 x 10(6)/l, respectively (interquartile ranges -78-249 and 21-624). In conclusion, we found a significantly higher mortality rate in HIV-2-positive compared to HIV-negative individuals. Baseline CD4 cell counts were markedly suppressed and similar in all 3 HIV-positive groups, and in a multivariate logistic regression analysis a value of CD4 percentage of < 10 was shown to be an independent predictor of decreased survival in HIV-2-infected subjects.

Evolution and clonal traits of Mycobacterium tuberculosis complex in Guinea-Bissau

Two hundred twenty-nine consecutive isolates of Mycobacterium tuberculosis complex from patients with pulmonary tuberculosis in Guinea-Bissau, which is located in West Africa, were analyzed for clonal origin by biochemical typing and DNA fingerprinting. By using four biochemical tests (resistance to thiophene-2-carboxylic acid hydrazide, niacin production, nitrate reductase test, and pyrazinamidase test), the isolates could be assigned to five different biovars. The characteristics of four strains conformed fully with the biochemical criteria for M. bovis, while those of 85 isolates agreed with the biochemical criteria for M. tuberculosis. The remaining 140 isolates could be allocated into one of three biovars (biovars 2 to 4) representing a spectrum between the classical bovine (biovar 1) and human (biovar 5) tubercle bacilli. By using two genotyping methods, restriction fragment length polymorphism analysis with IS6110 (IS6110 RFLP analysis) and spoligotyping, the isolates could be separated into three groups (groups A to C) of the M. tuberculosis complex. Group A (n = 95), which contained the majority of classical human M. tuberculosis isolates, had large numbers of copies of IS6110 elements (mean number of copies, 9) and a distinctive spoligotyping pattern that lacked spacers 33 to 36. Isolates of the major group, group B (n = 119), had fewer IS6110 copies (mean copy number, 5) and a spoligotyping pattern that lacked spacers 7 to 9 and 39 and mainly comprised isolates of biovars 1 to 4. Group C isolates (n = 15) had one to three IS6110 copies, had a spoligotyping pattern that lacked spacers 29 to 34, and represented biovar 3 to 5 isolates. Four isolates whose biochemical characteristics conformed with those of M. bovis clustered with the group B isolates and had spoligotype patterns that differed from those previously reported for M. bovis, in that they possessed spacers 40 to 43. Interestingly, isolates of group B and, to a certain extent, also isolates of group C showed a high degree of variability in biochemical traits, despite genotypic identity in terms of IS6110 RFLP and spoligotype patterns. We hypothesize that isolates of groups B and C have their evolutionary origin in West Africa, while group A isolates are of European descent.

Pulmonary tuberculosis in Guinea-Bissau: clinical and bacteriological findings, human immunodeficiency virus status and short term survival of hospitalized patients

OBJECTIVE

To study tuberculosis patients in Guinea-Bissau with regard to clinical findings, bacteriologically verified diagnosis, human immunodeficiency virus (HIV) status and short term survival.

DESIGN

763 consecutive patients referred to the tuberculosis clinic with pulmonary symptoms underwent clinical examination and Ziehl-Neelsen sputum microscopy. Sputum for culture of mycobacteria on Löwenstein-Jensen medium was collected from all hospitalized patients, who were also screened by enzyme linked immunosorbent assay for the presence of HIV-1 and HIV-2 antibodies. HIV-positivity was confirmed by Western blot.

RESULTS

350 patients were diagnosed with tuberculosis and hospitalized. Adequate sputum samples were obtained from 301 patients, of whom 184 (61%) were positive on direct microscopy and the remaining 116 patients were diagnosed from clinical findings. Mycobacterium tuberculosis was cultured from 184 patients and M. avium in 16 patients, whereas in 101 patients the culture was negative. HIV-1 antibodies were found in 3.0%, HIV-2 antibodies in 16.4%, and dual infections in 2.0%. These figures, however, did not differ significantly from those of randomly selected age and sex matched controls. The prevalence of HIV-antibodies was statistically as common in patients with culture verified tuberculosis as in patients with clinically defined tuberculosis. Clinical acquired immunodeficiency syndrome was commonly diagnosed (80/301 patients) but significantly more often in HIV-positive, culture-positive tuberculosis patients, as were weight loss and lymphadenopathy. There was no statistical difference in short-time survival rate between the various patient groups.

CONCLUSION

The diagnostic criteria applied, which are generally used in developing countries, identified most patients with pulmonary tuberculosis; however, a substantial number of patients are treated for tuberculosis without definite diagnostic criteria. The prevalence of HIV-infection was high but statistically no significant difference was demonstrated between the patient groups, controls and patients hospitalized for diseases other than tuberculosis.

Direct detection of Mycobacterium tuberculosis in sputum samples from Guinea Bissau by an rRNA target-amplified test system

SETTING

There is a need for more sensitive and rapid methods for laboratory confirmation in the diagnosis of tuberculosis.

OBJECTIVE

To investigate the applicability of a target rRNA amplified test system (AMTDT, Gen-Probe, CA) for rapid detection of Mycobacterium tuberculosis.

DESIGN

The rRNA amplified test system was compared to standard methods for acid fast microscopy and mycobacterial culture for the demonstration of M. tuberculosis in sputum samples from 247 patients in Guinea Bissau with suspected tuberculosis.

RESULTS

The highest incidence of positive samples was obtained with the AMTDT test. Out of 274 sputum samples 96 (35%) were positive by the AMTDT test, 82 (30%) were positive by culture and 38 (14%) by direct microscopy. Using culture as reference method the sensitivity of the test was 85% (after discrepancy analysis 87%), and the specificity was 86% (after discrepancy analysis 93%).

CONCLUSION

The sensitivity and specificity of the AMTDT test used in this setting indicates that it may be a valuable complement for improving the laboratory diagnosis of tuberculosis.

High proportion of multi-drug resistant Mycobacterium tuberculosis in Saudi Arabia

289 patients with TB, presented to a single tertiary care unit in Saudi Arabia between 1989 and 1994. The isolate from each patient was tested for in vitro susceptibility to rifampicin, isoniazid, ethambutol, pyrazinamide and streptomycin. 25 patients (8.7%) had isolates resistant to at least 1 anti-tuberculous drug. Single drug resistance (SDR)-mainly isoniazid-occurred in 14, and resistance to at least 2 drugs (multi-drug resistance-MDR) in 11, of which 8 were due to both isoniazid and rifampicin. Previous drug treatment occurred significantly more often in patients with MDR (8/11), than SDR (1/14) (p = 0.0021). A literature review of another 5571 patients from Saudi Arabia with TB revealed an incidence of resistance of M. tuberculosis isolates to at least 1 anti-tuberculous drug tested, of between 5.9% and 44%. The overall percentage of patients with resistant tuberculosis (including our own patients) was 14.9%. Resistance to streptomycin (8.9%), isoniazid (6.6%), and rifampicin (6.1%) were the commonest reported. There were as many patients with MDR as there were SDR. A history of previous anti-tuberculous treatment was found in over 40%. The high rate of anti-tuberculous resistance in Saudi Arabia may be due to poor supervision of anti-TB treatment, the embryonic healthcare system, over-the-counter antibiotic availability, treatment of endemic diseases such as brucella with rifampicin etc., a large migrant work force, and possibly increased toxicity of anti-tuberculous drugs secondary to the high incidence of chronic liver disease in the country.

Biochemical heterogeneity of Mycobacterium tuberculosis complex isolates in Guinea-Bissau

Fifty-six strains of the Mycobacterium tuberculosis complex from patients in Guinea-Bissau were examined by using four biochemical tests (niacin production, nitrate reductase, pyrazinamidase, and resistance to thiophen-2-carboxylic acid hydrazide). The isolates were divided into five different biovars within a spectrum ranging from classical human M. tuberculosis to classical M. bovis.