Genetic diversity and drug resistance pattern of Mycobacterium tuberculosis strains isolated from pulmonary tuberculosis patients in the Benishangul Gumuz region and its surroundings, Northwest Ethiopia.

INTRODUCTION: Tuberculosis (TB) remains a major global public health problem and is the leading cause of death from a single bacterium, Mycobacterium tuberculosis (MTB) complex. The emergence and spread of drug-resistant strains aggravate the problem, especially in tuberculosis high burden countries such as Ethiopia. The supposedly high initial cost of laboratory diagnosis coupled with scarce financial resources has limited collection of information about drug resistance patterns and circulating strains in peripheral and emerging regions of Ethiopia. Here, we investigated drug susceptibility and genetic diversity of mycobacterial isolates among pulmonary tuberculosis patients in the Benishangul Gumuz region and its surroundings in northwest Ethiopia. METHODS AND MATERIAL: In a cross-sectional study, 107 consecutive sputum smear-positive pulmonary tuberculosis (PTB) patients diagnosed at two hospitals and seven health centers were enrolled between October 2013 and June 2014. Sputum samples were cultured at Armauer Hansen Research Institute (AHRI) TB laboratory, and drug susceptibility testing (DST) was performed against Isoniazid, Rifampicin, Ethambutol, and Streptomycin using the indirect proportion method. Isolates were characterized using polymerase chain reaction (PCR)based Region of Difference 9 (RD9) testing and spoligotyping. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) for Windows version 24.0. RESULTS: Of 107 acid-fast-bacilli (AFB) smear-positive sputum samples collected, 81.3% (87/107) were culture positive. A PCR based RD9 testing revealed that all the 87 isolates were M. tuberculosis. Of these isolates, 16.1% (14/87) resistance to one or more drugs was observed. Isoniazid monoresistance occurred in 6.9% (6/87). Multidrug resistance (MDR) was observed in two isolates (2.3%), one of which was resistant to all the four drugs tested. Spoligotyping revealed that the majority, 61.3% (46/75) of strains could be grouped into ten spoligotype patterns containing two to 11 isolates each while the remaining 38.7% (29/75) were unique. SIT289 (11 isolates) and SIT53 (nine isolates) constituted 43.5% (20/46) among clustered isolates while 29.3% (22/75) were ''New" to the database. The dominant families were T, 37% (28/75), CAS, 16.0% (12/75), and H, 8% (6/75), adding up to 51.3% (46/75) of all isolates identified. CONCLUSION AND RECOMMENDATIONS: The current study indicates a moderate prevalence of MDR TB. However, the observed high monoresistance to Isoniazid, one of the two proxy drugs for MDR-TB, reveals the hidden potential threat fora sudden increase in MDR-TB if resistance to Rifampicin would increase. Clustered spoligotype patterns suggest ongoing active tuberculosis transmission in the area. The results underscore the need for enhanced monitoring of TB drug resistance and epidemiological studies in this and other peripheral regions of the country using robust molecular tools with high discriminatory power such as the Mycobacterial Interspersed Repetitive Units -Variable Number of Tandem Repeats (MIRU-VNTR) typing and whole-genome sequencing (WGS).

A Breast Lump in an Elderly Lady - Carcinoma or else ?.

Breast tuberculosis (TB) is rare form of extra-pulmonary TB. It is most commonly seen in women of reproductive age group, especially in young, multiparous women who are breast feeding. In geriatric women, breast TB in some cases simulates with breast carcinoma due to common signs which include hard breast lump with nodular surface, ulceration, fixity to skin, discharging sinus, retraction of nipple, axillary lymphadenopathy etc. Hence, it is very difficult to differentiate breast TB from breast cancer, especially in elderly women on clinical ground only, and therefore, histopathological diagnosis is mandatory. Fine needle aspiration cytology is frequently inconclusive due to very small amount of tissue material, and open biopsy or lumpectomy followed by histopathological examination is necessary to confirm the diagnosis of breast TB. Six-month course of anti-tuberculous therapy - ATT (rifampicin, isoniazid, pyrazinamide and ethambutol) is adequate for complete resolution. Here, we report a case of breast TB in an elderly women presenting with left sided breast lump with ulceration of overlying skin and ipsilateral axillary lymphadenopathy. This case of tuberculous mastitis was suspected to be carcinoma due to presence of hard, tender, breast lump with irregular margin, nodular surface, ulceration, purulent discharge and ipsilateral axillary lymphadenopathy in absence of any constitutional symptoms of TB, and heterogenous, hypoechoic mass on USG, which was confirmed by histopathological examination of resected breast lump and responded fully to ATT.

High mortality associated with retreatment of tuberculosis in a clinic in Kampala, Uganda: a retrospective study.

The World Health Organization recommends for tuberculosis retreatment a regimen of isoniazid (H), rifampicin (R), ethambutol (E), pyrazinamide (Z), and streptomycin (S) for 2 months, followed by H, R, E, and Z for 1 month and H, R, and E for 5 months. Using data from the National Tuberculosis and Leprosy Program registry, this study determined the long-term outcome under programmatic conditions of patients who were prescribed the retreatment regimen in Kampala, Uganda, between 1997 and 2003. Patients were traced to determine their vital status; 62% (234/377) patients were found dead. Having ≤ 2 treatment courses and not completing retreatment were associated with mortality in adjusted analyses.

Truncated structural variants of lipoarabinomannan in Mycobacterium leprae and an ethambutol-resistant strain of Mycobacterium tuberculosis.

Current knowledge on the structure of lipoarabinomannan (LAM) has resulted primarily from detailed studies on a few selected laboratory strains of Mycobacterium tuberculosis, Mycobacterium bovis BCG, and Mycobacterium smegmatis. Our previous work was the first to report on the salient structural features of M. tuberculosis clinical isolates and demonstrated significant structural variations. A prime effort is to correlate a particular structural characteristic with observed differences in eliciting an immunobiological response, especially in the context of CD1-restricted presentation of LAM to T cells. T cell clones derived from the cutaneous lesions of leprosy patients have been shown to recognize specifically LAM from Mycobacterium leprae and not from M. tuberculosis Erdman or H37Rv. Herein we provide further fine structural data on LAM from M. leprae (LepLAM) and a tuberculosis clinical isolate, CSU20 (CSU20LAM), which was unexpectedly recognized by the supposedly LepLAM-specific CD1-restricted T cell clones. In comparison with the de facto laboratory LAM standard from M. tuberculosis H37Rv (RvLAM), LepLAM derived from in vivo grown M. leprae is apparently simpler in its arabinan architecture with a high degree of exposed, non-mannose-capped termini. On the other hand, CSU20, an ethambutol-resistant clinical isolate, makes a vastly heterogeneous population of LAM ranging from rather small and non-mannose-capped to full-length and fully capped variants. LepLAM and CSU20LAM contain a higher level of succinylation than RvLAM, which, in the context of truncated or less elaborated arabinan, may contribute to selective recognition by T cells. LAM from all species could be resolved into discrete forms by isoelectric focusing based apparently on their arabinan heterogeneity. In the light of our current and more recent findings, we reason that all immunobiological data should be cautiously interpreted and that the actual LAM variants that may be present in vivo during infection and pathogenesis need to be taken into consideration.

Evaluation of modified short course chemotherapy in active pulmonary tuberculosis patients with human immunodeficiency virus infection in University College Hospital, Ibadan, Nigeria--a preliminary report.

Over the period, 1st October 1999 to 30th April 2002 a clinical trial of the modified short-course chemotherapy (SCC) in newly diagnosed cases of pulmonary tuberculosis with human immunodeficiency virus (HIV) infection in Ibadan, Nigeria was carried out. The modified SCC used was adopted by World Health Organisation (WHO)/International Union against Tuberculosis and Lung Diseases (IUALTD) for developing countries and also by the Nigerian National Tuberculosis and Leprosy Control Programmed (NTLCP). The regimen used consisted of ethambutol (E), isoniazid (H), rifampicin (R) and pyrazinamide (Z) in the intensive phase of 2 months. The continuation phase was 6 months of ethambutol (E) and isoniazid(H), i.e. 2EHRZ/6EH. Sputum conversion was 90% at the second month of treatment and there was no bacteriological relapse after 18 months of follow-up. Side effects were few and consisted mainly of acne vulgaris in 20 (22.5%) of 89 patients during the continuation phase. It is concluded that this modified 8-month chemotherapy regimen adopted by NTLCP is efficacious in treatment of smear positive pulmonary tuberculosis (PTB) patients with background HIV infection.

Treatment of Mycobacterium avium-intracellulare complex lung disease with a macrolide, ethambutol, and clofazimine.

BACKGROUND: Mycobacterium avium-intracellulare (MAC) causes progressive lung disease. Recommended treatment regimens include a macrolide and a rifamycin, but drug intolerance and relapse after treatment is completed often limit successful therapy. METHODS: Consecutive individuals referred for treatment of MAC lung disease were treated with a regimen that included either clarithromycin, 500 mg bid, or azithromycin, 250 mg/d, on weekdays; ethambutol, 15 mg/kg/d; and clofazimine, 100 mg/d. The intention was to treat patients for a minimum of 12 months. The diagnosis of MAC lung disease was confirmed by multiple positive sputum culture findings in patients with typical symptoms and radiologic findings. RESULTS: Thirty patients (27 women and 3 men; mean age, 70 +/- 9.4 years [SD]) were treated. A total of 22 of the patients reported adverse effects from clarithromycin or azithromycin. Intolerance of clarithromycin resulted in the withdrawal of four patients before sputum conversion. The remaining patients continued treatment for an average of 10 months, and sputum findings converted to negative in all 26 patients (87%). One patient died of unrelated causes while still receiving therapy, and five patients (19%) relapsed an average of 17 months after treatment was completed. CONCLUSIONS: Treatment with a macrolide, ethambutol, and clofazimine was successful in 20 of 30 patients (67%) with MAC lung disease and is a reasonable alternative to rifamycin-containing regimens.

Modified short-course chemotherapy of pulmonary tuberculosis in Ibadan, Nigeria--a preliminary report.

Over a 3 year period 3rd of April 1995 and 6th of April 1998 a controlled clinical trial of the modified short-course chemotherapy (SSC) in newly diagnosed cases of pulmonary tuberculosis in Nigeria was carried out. Between The SCC used was the one adopted from World Health Organisation/International Union Against Tuberculosis and Lung Diseases for developing countries by the Nigerian National Tuberculosis and Leprosy Control Programme (NTLCP). The regimen used consisted of streptomycin (S), isoniazid (H), Rifampicin (R) and pyrazinamide (Z) in the initial or intensive phase of 2 months. Ethambutol (E) was sometimes substituted for streptomycin. The continuation phase was 6 months of thiacetazone, (T) and isoniazid (H), i.e., 2SHRZ/6TH or 2EHRZ/6TH. Sputum conversion was 90% at the second month of treatment and there was no bacteriological relapse after 18 months of follow-up. Side effects were few and consisted mainly of acne vulgaris which occurred in twenty (20.6%) of 97 patients during the continuation phase. It is concluded that the 8-month chemotherapy regimen adopted by NTLCP is efficacious in treatment of smearpositive pulmonary tuberculosis (PTB).

Role of embB in natural and acquired resistance to ethambutol in mycobacteria.

The mycobacterial embCAB operon encodes arabinosyl transferases, putative targets of the antimycobacterial agent ethambutol (EMB). Mutations in embB lead to resistance to EMB in Mycobacterium tuberculosis. The basis for natural, intrinsic resistance to EMB in nontuberculous mycobacteria (NTM) is not known; neither is the practical implication of resistance to EMB in the absence of embB mutations in M. tuberculosis well understood. The conserved embB resistance-determining region (ERDR) of a collection of 13 strains of NTM and 12 EMB-resistant strains of M. tuberculosis was investigated. Genotypes were correlated with drug susceptibility phenotypes. High-level natural resistance to EMB (MIC, . or =64 microg/ml) was associated with a variant amino acid motif in the ERDR of M. abscessus, M. chelonae, and M. leprae. Transfer of the M. abscessus emb allele to M. smegmatis resulted in a 500-fold increase in the MICs. In M. tuberculosis, embB mutations were associated with MICs of > or =20 microg/ml while resistance not associated with an ERDR mutation generally resulted in MICs of < or =10 microg/ml. These data further support the notion that the emb region determines intrinsic and acquired resistance to EMB and might help in the reassessment of the current recommendations for the screening and treatment of infections with EMB-resistant M. tuberculosis and NTM.

A single point mutation in the embB gene is responsible for resistance to ethambutol in Mycobacterium smegmatis.

Ethambutol [EMB; dextro-2,2'-(ethylenediimino)-di-1-butanol] is an effective drug when used in combination with isoniazid for the treatment of tuberculosis. It inhibits the polymerization of arabinan in the arabinogalactan and lipoarabinomannan of the mycobacterial cell wall. Recent studies have shown that arabinosyltransferases could be targets of EMB. These enzymes are encoded by the emb locus that was identified in Mycobacterium smegmatis, Mycobacterium leprae, Mycobacterium avium, and Mycobacterium tuberculosis. We demonstrate that a missense mutation in the M. smegmatis embB gene, one of the genes of the emb locus, confers resistance to EMB. The level of resistance is not dependent on the number of copies of the mutated embB gene, indicating that this is a true mechanism of resistance. The mutation is located in a region of the EmbB protein that is highly conserved among the different mycobacterial species. We also identified in this region two other independent mutations that confer EMB resistance. Furthermore, mutations have recently been described in the same region of the EmbB protein from clinical EMB-resistant M. tuberculosis isolates. Together, these data strongly suggest that one of the mechanisms of resistance to EMB consists of missense mutations in a particular region of the EmbB protein that could be directly involved in the interaction with the EMB molecule.

Pot shots.

AIDS: Certain HIV drugs have significant side effects. There have been reports from Europe that some hemophiliacs using protease inhibitors suffered from spontaneous bleeding. Clofazimine, sold as Lamprene, has been shown to cause harm when used with clarithromycin and ethambutol to treat MAC. Lamprene may cause internal bleeding, nausea, diarrhea, dizziness, drowsiness, and dry skin. Results of a Taiwanese trial of thymosin-alpha indicate that it did not help treat Hepatitis B in a statistically significant way. NAC, an antioxidant, may increase glutathione levels and indirectly increase survival.^ieng

Recognition of the lipid intermediate for arabinogalactan/arabinomannan biosynthesis and its relation to the mode of action of ethambutol on mycobacteria.

Despite major advances in our understanding of the structure of mycobacterial cell walls, little is known of their biogenesis, and yet they are the site of action of many anti-tuberculosis drugs and implicated in much of the pathology of tuberculosis and leprosy. A family of monoglycosyl polyprenylphosphates was isolated from Mycobacterium smegmatis, containing arabinose, ribose, and mannose. The isoprenoid nature of the lipid components was established by 1H NMR, and fast atom bombardment mass spectroscopy (FAB-MS) demonstrated the presence of C50 decaprenyl-P derivatives and smaller amounts of the C35 octahydroheptaprenyl-P products. The configuration of the mycobacterial decaprenol was established as mono-trans, octa-cis, pointing to carriers of unusual structure. Combined gas chromatography (GC)/MS, FAB-MS/MS, and 1H NMR allowed characterization of one of the primary components as beta-D-arabinofuranosyl-1-monophosphodecaprenol. Pulse-chase metabolic labeling of cells with D-[14C]glucose indicated that the decaprenyl-P-arabinose is an active intermediate in the biosynthesis of the arabinan of cell wall arabinogalactan and arabinomannan. The identification of polyprenyl-P-ribose suggests the existence of ribose-containing polysaccharides in the cell walls of M. smegmatis or/and of a novel epimerase in the D-arabinose biosynthetic pathway. Ethambutol, a powerful anti-tuberculosis drug known to inhibit arabinogalactan and arabinomannan biosynthesis, results in the rapid accumulation of decaprenyl-P-arabinose, indicating that the drug interferes with either the transfer of arabinose from the donor or, alternatively, the synthesis of the arabinose acceptor itself.

Multiple cold abscesses in a borderline lepromatous patient on multidrug therapy.

A 25-year-old male patient was diagnosed as a case of borderline lepromatous (BL) type of leprosy in erythema nodosum leprosum type reaction. He was put on multidrug treatment. He took regular treatment. Approximately a year after the beginning of the treatment he developed multiple cold abscesses and later tuberculosis of the left hip joint. He was given antitubercular treatment with 4 drugs and the abscesses were treated surgically. He showed good response. This unusual case and the role of intermittent rifampicin is discussed.

Studies on the mechanisms of the synergistic effects of ethambutol and other antibacterial drugs on Mycobacterium avium complex.

Synergistic effects of combinations of anti-mycobacterial drugs on Mycobacterium avium complex (MAC) in vitro was studied by radiometric respirometry. Pronounced synergy was seen for several drug combinations where ethambutol was found to be the key drug in the synergistic potentiation. Microcalorimetric studies show that a very rapid physico-chemical interaction occurs between the cell-surface of MAC and ethambutol. When MAC cells were pretreated with ethambutol and then subjected to streptomycin the thermal response significantly differed from that seen with MAC cells which had not been pretreated. The typical thermal effects of the interaction of ethambutol with live and UV-killed MAC cells was not seen with heat-killed MAC cells. It is proposed that specific cell-surface protein(s) act as receptors in the initial interaction with ethambutol.

Synergistic effect of rifampin, streptomycin, ethionamide, and ethambutol on Mycobacterium intracellulare

A method of quantitative estimation to determine the interaction of antituberculosis drugs is suggested. The design of experiments, performed on 7H11 agar plates, is adjusted to the following statistical treatment by combined use of probit analysis and isobologram methods. By plotting the values reflecting the inhibition of 75% of the bacterial population (ED75) with their confidence limits on the isobologram, it was found that the clearest results proving synergism between the drugs could be obtained. Six 2-drug combinations and 6 3-drug combinations were tested against strains of Mycobacterium intracellulare (serovar 8), and a synergistic effect was demonstrated in most of them. These were various combinations of rifampin, streptomycin, ethambutol, and ethionamide. The application of probit analysis to the data derived from testing single drugs can provide a quantitative estimation of the actual drug resistance of the M. intracellulare strains.

Acción de los esquemas con isoniacida y rifampicina sobre el hígado de enfermos tuberculosos / Effect of isoniazid and rifampicin regimens on the liver of tuberculosis patients

Se estudió un grupo de 86 enfermos tuberculosos que recebieron esquemas terapèuticos con Isoniacida y Rifampicina y se evaluó la acción de esas drogas sobre el hígado. Para ello, antes de iniciar la quimioterapia, se praticó una biopsia hepática y se dosaron transaminasas, fosfatasa y bilirrubina séricas; al finalizar el tercer mes de tratamiento se repitió una biopsia hepática. Los tests funcionales se repitieron mensualmente durante todo el tratamiento. El grupo I (10 casos) recibió Isonacida, Ethambutol y Estreptomicina. En la biopsia inicial hubo 1 caso con transformación grasa y 1 con necrosis focal; al 3er. mes persistía la necrosis focal en 1 caso y apreció en otros 3. El grupo II (14 casos) recibió Rifampicina, Ethambutol y Capreomicina.