Mycobacterium africanum, an emerging disease in high-income countries?

BACKGROUND: Mycobacterium africanum is a cause of tuberculosis (TB) that has mainly been described in Africa, but immigration and travel patterns have contributed to the spread of the disease to other countries. METHODS: We retrospectively reviewed TB cases due to M. africanum during 2000-2010 in seven Spanish hospitals. Selected clinical charts were reviewed using a predefined protocol that included demographical, clinical and microbiological data and outcome. RESULTS: Although 57 cases were diagnosed, only 36 clinical charts were available for review: 82.8% were men and the mean age was 31.6 years (range 12-81). Forty-four cases were from Africa, 1 from the Philippines, 1 from India, and 4 from Spain, while the country of origin was unknown in 7 cases. The most frequent site of infection was the lung (58.3%). Four cases (6.9%) were resistant to at least one first-line anti-tuberculosis drug. CONCLUSIONS: Disease due to M. africanum in industrialised countries is mainly associated with immigration from endemic areas, although some cases also occur among native-born populations.

Rifampicin-resistant Mycobacterium tuberculosis: susceptibility to isoniazid and other anti-tuberculosis drugs.

Based on data from 14 Supranational Tuberculosis (TB) Reference Laboratories worldwide, the proportion of rifampicin (RMP) resistant isolates that were isoniazid (INH) susceptible by phenotypic drug susceptibility testing varied widely (0.5-11.6%). RMP-resistant isolates that were INH-susceptible had significantly lower rates of resistance to other first- and second-line anti-tuberculosis drugs (except rifabutin) compared to multidrug-resistant isolates. RMP resistance is not always a good proxy for a presumptive diagnosis of multidrug-resistant TB, which has implications for use of molecular assays that identify only RMP resistance-associated DNA mutations.

Evaluation of the VersaTREK system compared to the Bactec MGIT 960 system for first-line drug susceptibility testing of Mycobacterium tuberculosis.

The aim of this study was to evaluate the reliability of the VersaTREK system for Mycobacterium tuberculosis drug susceptibility testing compared with results obtained with the Bactec MGIT 960 system. A total of 67 strains were evaluated. Overall agreement was at 98.5%. Kappa indexes were 1.0 for isoniazid, rifampin, and ethambutol, 0.937 for pyrazinamide, and 0.907 for streptomycin. The VersaTREK system is validated for M. tuberculosis drug susceptibility testing.

Resistance to anti-tuberculosis medications in the Horn of Africa.

We performed drug susceptibility testing among chronic patients hospitalised in the tuberculosis (TB) referral centre of the capital of Djibouti. Among 36 patients tested, 27 had multidrug-resistant TB and four had extensively drug-resistant TB. National guidelines must be revised urgently and the administration of second-line TB medications strictly controlled.

Tuberculosis transmission patterns among Spanish-born and foreign-born populations in the city of Barcelona.

During a 2-year period (2003-2004), tuberculosis (TB) transmission in Barcelona and the factors related to transmission among the Spanish- and foreign-born populations were studied by molecular epidemiology. Data were obtained from TB cases and Conventional Contact Tracing registries and genotyping was performed using restriction fragment length polymorphism (RFLP)-IS6110 and MIRU12 as a secondary typing method. Of the 892 TB cases reported, 583 (65.3%) corresponded to Spanish-born and 309 (34.6%) to foreign-born. Six hundred and eighty-seven cases (77%) were confirmed by culture. RFLP typing of 463/687 (67.4%) isolates was performed, revealing 280 (60.5%) unique and 183 (39.5%) shared patterns, which were grouped into 65 clusters. Spanish-born individuals were significantly more clustered than foreign-born individuals (44.6% vs. 28.8%; p 0.016). Clustering in foreign-born individuals was associated with HIV (p 0.051, odds ratio = 3.1, 95% confidence interval 1-10.9) and alcohol abuse (p 0.022), whereas, in the Spanish-born individuals, clustering was associated with age in the range 21-50 years, (p 0.024). Of the total clusters, 36/65 (55.3%) included only Spanish-born patients, whereas 22/65 (33.8%) included individuals from both populations. In mixed clusters, the index case was Spanish-born in 53% and foreign-born in 47%. Among the foreign-born, 2.8% were ill on arrival, 30% developed TB within the first year and 50.3% developed TB within the first 2 years; 58.3% were from South America. In conclusion, half of the foreign-born TB patients developed the disease during the first 2 years after arrival, which, in most cases, was the result of endogenous reactivation. Recent TB transmission among Spanish-born and foreign-born populations, as well as bidirectional transmission between communities, contributed significantly to the burden of TB in Barcelona, suggesting the need to improve Public Health interventions in both populations.

Non-tuberculous mycobacteria in the sputum of HIV-infected patients: infection or colonization?

It can be difficult to establish the clinical significance of the isolation of non-tuberculous mycobacteria (NTM) from the sputum of HIV-infected patients. In this observational study, we have investigated factors associated with having NTM infection. During the period of the study, 10 patients had NTM infection and 14 had NTM colonization. Factors associated with having NTM infections were: CD4 lymphocyte count <50 cells/mL (odds ratio [OR] 10; 95% confidence interval [CI] 1.4-69.3), haemoglobin <11 g/dL (OR 7.2; 95% CI 1.08-47.9), weight loss (OR 9; 95% CI 1.3-63.9), duration of symptoms for more than a month (OR 54; 95% CI 4.2-692.5), the presence of acid fast bacilli (AFB) in sputum (OR 30.3; 95% CI 2.6-348.9) and repeated positive NTM cultures in other sputum samples (OR 4.3; 95% CI 1.6-11.7). In conclusion, we must suspect NTM infection in patients with long-standing symptoms, anaemia, low CD4 lymphocyte count, several positive sputum cultures and when AFB are seen.

Clinical patterns of cutaneous nontuberculous mycobacterial infections.

BACKGROUND: Cutaneous nontuberculous mycobacterial infections result from external inoculation, spread of a deeper infection, or haematogenous spread of a disseminated infection. There are two species-specific infections (fish-tank or swimming-pool granuloma, due to Mycobacterium marinum, and Buruli ulcer, caused by M. ulcerans). Most infections, however, produce a nonspecific clinical picture. OBJECTIVES: To define clinical patterns of cutaneous disease in nontuberculous mycobacterial infections. METHODS: Fifty-one patients with cutaneous nontuberculous mycobacterial infections were reviewed. Clinical and histopathological features of normal hosts and immunosuppressed patients were compared. Two subgroups of immunosuppressed patients were distinguished: patients with cutaneous infection and patients with a disseminated infection and cutaneous involvement. RESULTS: In immunosuppressed patients the number of lesions was significantly higher. Abscesses and ulceration were also more frequently observed. Different species were found in normal hosts and immunosuppressed patients. Several clinical patterns of cutaneous infection were defined: lymphocutaneous or sporotrichoid lesions; nonlymphocutaneous lesions at the site of trauma; folliculitis and furunculosis involving the lower extremities; disseminated lesions on the extremities in immunosuppressed patients. Two patterns were observed in patients with a disseminated infection: localized cutaneous lesions and disseminated cutaneous and mucosal lesions. CONCLUSIONS: Cutaneous manifestations of nontuberculous mycobacterial infections may be classified according to criteria such as cutaneous lesions and immune status.

Non-tuberculous mycobacteria: patterns of isolation. A multi-country retrospective survey.

OBJECTIVE: To collect data on non-tuberculous mycobacteria (NTM) isolated from clinical laboratories in different countries to establish: 1) whether the isolation of NTM was increasing, 2) which species were increasing, and 3) whether there was any pattern of geographical distribution. DESIGN: In 1996, the Working Group of the Bacteriology and Immunology Section of the International Union Against Tuberculosis and Lung Disease contacted 50 laboratories in different countries for the necessary information. RESULTS: The number of patients reported with NTM was 36099 from 14 countries. Mycobacterium avium complex, M. gordonae, M. xenopi, M. kansasii and M. fortuitum were the five species most frequently isolated. There was a significant upward trend for M. avium complex and M. xenopi. Pigmented mycobacteria predominated in Belgium, the Czech Republic and the Mediterranean coast of Spain. Non-chromogenic mycobacteria were found to be predominant in the area of the Atlantic coast of Brazil and in Turkey, the United Kingdom, Finland and Denmark. CONCLUSIONS: There was an increase in the number of NTM isolated from clinical samples of patients. Isolation of the most frequent species is constantly changing in most of the geographical areas, and newer species are emerging due to better diagnostic techniques to detect and identify NTM.

Determinants of drug-resistant tuberculosis: analysis of 11 countries.

SETTING: Eleven countries/territories. OBJECTIVES: Global information on the determinants of drug-resistant tuberculosis (TB) based on representative data is not available. We therefore studied the relationship between demographic characteristics, prior TB treatment, and human immunodeficiency virus (HIV) infection with anti-tuberculosis drug resistance. METHODS: Population-based representative data on new and previously treated patients with TB collected within an international drug resistance surveillance network. RESULTS: Of 9,615 patients, 8,222 (85.5%) were new cases of TB and 1,393 (14.5%) were previously treated cases. Compared with new cases, previously treated cases were significantly more likely to have resistance to one (OR = 2.5,95% CI 2.1-3.0; P < 0.001), two (OR = 4.6, 95%CI 3.7-5.6; P < 0.001), three (OR = 11.5, 95%CI 8.6-15.3; P < 0.001), and four (OR = 18.5, 95% CI 12.0-28.5; P < 0.001) drugs. An approximately linear increase in the likelihood of having multidrug-resistant tuberculosis (MDR-TB) was observed as the total time (measured in months) of prior anti-tuberculosis treatment increased (P < 0.001, chi2 for trend). In multivariate analysis, prior TB treatment for 6-11 months (OR = 7.6, 95% CI 2.6, 22.4; P < 0.001) and > or = 12 months (OR 13.7, 95% CI 4.5-41.6; P < 0.001), but not HIV positivity, was associated with MDR-TB. CONCLUSION: This study shows that prior but ineffective treatment is a strong predictor of drug resistance, and that HIV is not an independent risk factor for MDR-TB. The association between length of treatment and drug resistance may reflect longer treatment as a result of treatment failure in patients with drug resistance; it may also reflect irregular prior treatment for TB, leading to drug resistance.

Isolation of mycobacteria from frozen fish destined for human consumption.

Mycobacteria were isolated from defrost water and tissue of sole (Solea solea), hake (Merluccius merluccius), cod (Gadus morhua), ling (Genypterus blacodes), and monkfish (Lophius piscatorius) on Löwenstein-Jensen medium after incubation at different temperatures. Samples of frozen fish were obtained under sterile conditions inside a refrigeration chamber (-18 to -22 degrees C) in a wholesale market from which these products are distributed to shops for retail sale and human consumption.

Cutaneous infections due to nontuberculous mycobacteria: histopathological review of 28 cases. Comparative study between lesions observed in immunosuppressed patients and normal hosts.

To evaluate the histopathological features observed in patients with cutaneous infections due to nontuberculous mycobacteria (NTM) and to compare the histopathological patterns observed in immunosuppressed patients and normal hosts. Twenty-eight biopsy specimens corresponding to 27 patients with cutaneous infections due to NTM were reviewed. Eighteen biopsies corresponded to normal hosts (14 Mycobacterium marinum, 2 Mycobacterium chelonae, 1 Mycobacterium terrae and 1 Mycobacterium gordonae) and 10 biopsy specimens were obtained from 9 immunosuppressed patients (3 Mycobacterium chelonae, one of which had two biopsies, 1 Mycobacterium abscessus, 2 Mycobacterium kansasii, 1 Mycobacterium marinum, 1 Mycobacterium avium complex and 1 Mycobacterium simiae). A panel of histopathological features was evaluated by two independent observers in each biopsy specimen. Epidermal changes (acanthosis, pseudoepitheliomatous hyperplasia, exocytosis) were mainly observed in M. marinum infections. In immunosuppressed patients the infiltrate tended to be deeper, involving the subcutaneous tissue (100%) with a more diffuse distribution and constant abscess formation. A marked granulomatous inflammatory reaction was observed in 83% of immunocompetent and in 60% of immunosuppressed patients. In immunosuppressed patients a relationship between the chronic evolution of the disease and granuloma formation was demonstrated. A diffuse infiltrate of histiocytes with occasionally foamy appearance was noted in three biopsy specimens from three patients with AIDS. Acute and chronic panniculitis was detected in 8 biopsy specimens. In one biopsy (M. chelonae) an acute suppurative folliculitis was observed. Different histopathological patterns can be noted in biopsy specimens from cutaneous nontuberculous mycobacterial infections. The evolution of the disease and the immunologic status of the host may explain this spectrum of morphological changes. Tuberculoid, palisading and sarcoid-like granulomas, a diffuse infiltrate of histiocytic foamy cells, acute and chronic panniculitis, non-specific chronic inflammation, cutaneous abscesses, suppurative granulomas and necrotizing folliculitis can be detected. Suppurative granulomas are the most characteristic feature in skin biopsy specimens from cutaneous NTM infections. Some histopathological patterns seem more prevalent in immunosuppressed patients.

[Drug resistance in Mycobacterium tuberculosis. A multicenter study of the Barcelona area. Grupo de Trabajo sobre Resistencias en Tuberculosis]. / Farmacorresistencia de Mycobacterium tuberculosis. Estudio multicéntrico en el area de Barcelona. Grupo de Trabajo sobre Resistencias en Tuberculosis.

BACKGROUND: The aims of this multicenter study was to establish the level of primary and acquired drug resistance of M. Tuberculosis strains isolated in Barcelona and to identify possible risk groups using clinical data. PATIENTS AND METHODS: All tuberculosis patients with isolation and identification of M. tuberculosis strains from October 1995 to September 1997 were included. Susceptibility tests isoniazid, rifampin, ethambutol, streptomycin and pyrazinamide were performed using the Bactec 460 system and the proportions method on solid medium. Logistic progression was used for statistical analysis. RESULTS: The total number of patients included was 1,749 (1,535 non-treated and 214 previously treated). Primary drug resistance was 5.7% (isoniazid 3.8%; rifampin 1.0%, streptomycin 2.1%, ethambutol 0.3% and pyrazinamide 1.0%). Acquired drug resistance was 20.5% (isoniazid 17.3%, rifampin 9.8%, ethambutol 1.9%, streptomycin 4.7% and pyrazinamide 6.5%). Primary drug resistance was associated with people over 60 years old and women. CONCLUSIONS: The low level of drug resistance enables antituberculosis treatment of non-treated patients to start with the standardised three-drug regimes except in the case of foreign people from countries with a high level of drug resistance. Susceptibility tests are recommended on all M. tuberculosis strains isolated, together with controlled studies of drug resistance surveillance.

In vitro susceptibility of Mycobacterium kansasii to the difluorinated quinolone sparfloxacin using a broth microdilution and macrodilution MIC system.

OBJECTIVES: To study the minimum inhibitory concentrations (MIC) of the difluorinated quinolone sparfloxacin against 32 clinical isolates of Mycobacterium kansasii from 23 patients, all of whom had clinically significant infections due to M. kansasii, and 11 the acquired immune-deficiency syndrome (AIDS). To study the correlation between the microdilution and macrodilution techniques in M7H9 broth. DESIGN: The MICs were determined by two methods: broth microdilution in microplates and broth macrodilution in tubes. The isolates were inoculated into two-fold drug dilutions (ranging from 0.063 to 8 microg/ml) in Middlebrook 7H9 broth and then incubated at 37 degrees C for 21 days. RESULTS: All 32 strains were susceptible, with identical MIC results in both methods, 96.9% of them showing an MIC of 0.25 microg/ml. CONCLUSION: These MIC studies suggest that sparfloxacin may be useful for drug treatment of slow-growing nontuberculous mycobacteria such as M. kansasii. The microdilution method appears to be a reliable method for routine susceptibility testing of M. kansasii, and is easy to interpret and to carry out.

Rapid method for testing susceptibility of Mycobacterium tuberculosis by using DNA probes.

The increasing number of multidrug-resistant Mycobacterium tuberculosis strains has stimulated the interest of investigators in finding a rapid method for susceptibility testing. We used commercially available rRNA DNA-bioluminescence-labelled probes (Accu-Probe, Gen Probe, Inc. San Diego, Calif.) for this purpose. The study was performed in three chronological steps. (i) We studied the correlation between the photometric light units (PLUs) given by the hybridization method, the numbers of CFU per milliliter, and turbidity as nephelometric units for six different inocula of an M. tuberculosis strain over 14 days. A good correlation (c > 0.9; P < 0.05) was found from the third day for all concentrations used. (ii) Over a period of 14 days we studied the evolution of the PLUs for 20 strains growing in medium with 0.2 microl of isoniazid (H) per ml and 18 strains in medium with 1 microl of rifampin (R) per ml to standardize the method. Susceptible and resistant strains were used according to the reference proportions method in Middlebrook 7H10, and the MICs were determined in solid and liquid media. The final inoculum of a 10(-2) dilution from a McFarland no. 1 standard and reading at 3 and 5 days provided the best results. A quotient was established to find a cutoff point between resistant and susceptible strains. (iii) We used the standardized parameters in 117 tests with H and R. On day 3, the sensitivity, specificity, positive predictive value, and negative predictive value for detecting resistant strains were 86.8, 100, 100, and 90.1%, respectively, and on day 5 they were 96.2, 100, 100, and 94%, respectively. We concluded that the method is readily available, is easy to perform, and could be useful for screening resistant M. tuberculosis strains.

Comparison of two 2,3-diacyl trehalose antigens from Mycobacterium tuberculosis and Mycobacterium fortuitum for serology in tuberculosis patients.

Immunoglobulin G antibodies against two 2,3-diacyl trehalose (DAT) antigens from Mycobacterium tuberculosis (DATT) and Mycobacterium fortuitum (DATF) were studied by enzyme-linked immunosorbent assay of 356 serum samples. The sera were obtained from non-tuberculosis-infected individuals (282 serum samples) and tuberculosis patients (74 serum samples). Non-tuberculosis-infected individuals were healthy people (120 serum samples; positive purified-protein-derivative skin test, 60 patients; negative purified-protein-derivative skin test, 60 patients) patients with nontuberculosis lung disease (59 serum samples), contacts of sputum-smear-positive tuberculosis patients (57 serum samples), and human immunodeficiency virus-infected patients with nontuberculosis lung disease (46 serum samples). Of the 74 patients with tuberculosis, 14 were human immunodeficiency virus infected. The sensitivity of the method using DATT was 44.5%, and that with DATF was 48.6%. The specificities with both antigens were 99.1%. There were no significant differences between the mean values for both antigens (P = 0.2815). We therefore concluded that both antigens were interchangeable. As M. fortuitum, a fast-growing mycobacterium, could be a good source of antigen DAT, these results deserve consideration in the serology of tuberculosis.

[Isolation of mycobacteria in patients with cystic fibrosis: a prospective study]. / Aislamiento de micobacterias en pacientes con fibrosis quística: estudio prospectivo.

OBJECTIVE: A prospective study to assess the incidence of mycobacterial infection in patients with cystic fibrosis in our geographical area was performed. PATIENTS AND METHODS: A monitored follow-up was carried out in 91 patients over a period of 20 months, during which time 522 respiratory samples were obtained. These were processed by standard techniques of decontamination with sodiumlaurylsulphate, cultured on Löwenstein-Jensen medium and identified by biochemical and cultural characteristics and hybridization by specific probes. At the same time, the clinical reports of the patients with positive culture were reviewed. RESULTS: Positive cultures of mycobacteria were obtained from 4 patients. Environmental mycobacteria were isolated in three of them (M. xenopi, M. fortuitum and M. avium) and M. chelonei and later M. tuberculosis in the forth. None of the isolations of environmental mycobacteria were associated with deterioration of pulmonary function, while the isolation of M. tuberculosis in one of the patients coincided with an episode of decompensation in respiratory function. None of the patients presented sensitivity of the tuberculin skin test. CONCLUSIONS: It is advisable to investigate the mycobacteria in the presence of exacerbation of the respiratory process, above all taking into account the high incidence of tuberculosis in our geographical area. The isolation of environmental mycobacteria was not associated with pulmonary deterioration, but they represent a potential danger as opportunist pathogens, affecting patients of which many are candidates for lung transplants.

Incidence and significance of acid-fast bacilli in sputum smears at the end of antituberculous treatment.

OBJECTIVE: A group of patients with pulmonary tuberculosis (PT) who received and correctly completed antituberculous therapy were studied to determine the incidence and significance of positive acid-fast bacilli (AFB) in sputum smears at the end of this treatment. DESIGN: Retrospective chart review of persons with bacteriologically proved PT. PATIENTS: Of 1,052 patients diagnosed as having PT between 1988 and 1992, 453 who fulfilled the following criteria were included in the study: (1) diagnosis established by positive AFB and positive culture in sputum smears; (2) no previous antituberculous treatment had been received; (3) HIV serologic test results were negative; (4) treatment was correctly completed; (5) they were followed up throughout the period of treatment; and (6) expectoration was still present at the end of treatment and at least two spontaneous sputum samples could be obtained. RESULTS: Positive AFB of sputum smears were found at the end of treatment in 10 (2.2%) of the 453 patients studied. Five patients had only one positive smear, and the other five had more than one. Of these ten cases, sputum culture was negative in eight, which were considered to be unviable bacilli, and positive for nontuberculous mycobacteria in two. Clinical symptoms or worsening on chest radiograph were observed only in one patient with unviable bacilli, but they were caused by a concomitant nonspecific respiratory tract infection. CONCLUSIONS: Positive AFB smear results at the end of completed treatment regimens analyzed in this study have occurred because of unviable bacilli and nontuberculous mycobacteria colonization. The presence of more than one positive smear seems not to increase the probability of treatment failure and is more frequently due to nontuberculous mycobacteria. Results of culture can thus be awaited without the need to prolong or modify antituberculous therapy.