Extensive Mycobacterium tuberculosis circulation in a highly endemic prison and the need for urgent environmental interventions.

Aimed at assessing the circulation of Mycobacterium tuberculosis in a highly endemic prison, this 13-month prospective study was performed on strains isolated from tuberculosis (TB) cases detected passively and actively. We used X-ray screening of newly admitted inmates and mass screening at the beginning of the study and again 1 year later. Of the 94 strains genotyped by restriction fragment-length polymorphism, 79 (84·0%) belonged to one of the 12 identified clusters (2-21 strains each), including two main clusters (18 and 21 cases, respectively). A history of TB treatment was reported in 22/79 (27·8%) clustered cases. Time-space distribution of clustered cases was predominantly consistent with transmission, in micro-epidemics. Given the dominant pattern of exogenous infection and the extensive strain circulation, effective TB control should emphasize reduction of overcrowding and improvement of environmental measures as a complement to detection and treatment of cases.

Immunological diagnosis of tuberculosis based on recombinant antigens ESAT-6 and CFP-10 in children from an endemic area in northeast Brazil.

Diagnostic tests for tuberculosis (TB) using interferon gamma (IFN-γ) responses produced by T lymphocytes after stimulation by early secretory antigen target 6 (ESAT-6), culture filtrate protein 10 (CFP-10) or purified protein derivate (PPD) were carried out using ELISA (enzyme-linked immunosorbent assay) in whole blood culture supernatants from children with suspected TB disease (n=21), latent TB infection (LTBI; n=17) and negative controls (NC; n=21) from Recife, Pernambuco, Brazil. The results were analysed using the ROC (receiver operating characteristic) curves and the areas under the curve (AUC) generated varied from 0.5 to 1.0 with higher values indicating increased discriminatory ability. Comparisons of AUCs were made using non-parametric assumptions, and the differences were considered significant if P<0.05. The ROC curve showed a statistical difference (P = 0.015) between the LTBI and NC groups with an AUC of 0.731, TB disease and NC (AUC=0.780; P=0.002) and a group with TB (latent infection+disease, n=38) and NC (AUC=0.758; P = 0.001) when the antigen used was ESAT-6. No statistical difference was found between the groups when CFP-10 or PPD was used. In conclusion, the ESAT-6 test may be the most appropriate for diagnosis of childhood TB, both LTBI and TB disease, when associated with epidemiological and clinical data, especially in endemic areas such as Brazil.

Phenotypic and genotypic variant of MDR-Mycobacterium tuberculosis multiple isolates in the same tuberculosis episode, Rio de Janeiro, Brazil

Assuming that the IS6110-restriction fragment length polymorphism (RFLP) changes at a constant rate of 3.2 years, this methodology was applied to demonstrate, for the first time, variant patterns of Mycobacterium tuberculosis (MTB) in multiple isolates obtained at short time intervals from sputum and blood of an HIV+ patient with multiple admissions to the Emergency Room and to the multidrug-resistant tuberculosis (MDR-TB) Reference Center of a secondary-care hospital in Rio de Janeiro, Brazil. In sputum, the IS6110-RFLP appeared in isolates with two variant patterns with 10 and 13 IS6110 copies. However, blood presented only the pattern corresponding to 10 copies, suggesting compartmentalization. With regard to the exact match of 10 of 13 bands, this may be a subpopulation with the same clonal origin and this may be related to the IS6110 transposition. A susceptibility test demonstrated an MDR profile (INH R, RIF R, SM R, and EMB R), with the sputum isolate also exhibiting EMB S (R = resistant; S = sensitive). A gene mutation confirmed resistance only to streptomycin. There was agreement between the results of the phenotypic test and the clinical response to MDR-TB treatment, suggesting serious implications with regard to treatment administration based exclusively on molecular methods, and calling attention to the fact that more effective control strategies against the emergence of MDR strains must be implemented by the TB control program to prevent transmission of MDR-MTB strains at health facilities in areas highly endemic for TB.

Phenotypic and genotypic variant of MDR-Mycobacterium tuberculosis multiple isolates in the same tuberculosis episode, Rio de Janeiro, Brazil.

Assuming that the IS6110-restriction fragment length polymorphism (RFLP) changes at a constant rate of 3.2 years, this methodology was applied to demonstrate, for the first time, variant patterns of Mycobacterium tuberculosis (MTB) in multiple isolates obtained at short time intervals from sputum and blood of an HIV+ patient with multiple admissions to the Emergency Room and to the multidrug-resistant tuberculosis (MDR-TB) Reference Center of a secondary-care hospital in Rio de Janeiro, Brazil. In sputum, the IS6110-RFLP appeared in isolates with two variant patterns with 10 and 13 IS6110 copies. However, blood presented only the pattern corresponding to 10 copies, suggesting compartmentalization. With regard to the exact match of 10 of 13 bands, this may be a subpopulation with the same clonal origin and this may be related to the IS6110 transposition. A susceptibility test demonstrated an MDR profile (INH(R), RIF(R), SM(R), and EMB(R), with the sputum isolate also exhibiting EMB(S) (R = resistant; S = sensitive). A gene mutation confirmed resistance only to streptomycin. There was agreement between the results of the phenotypic test and the clinical response to MDR-TB treatment, suggesting serious implications with regard to treatment administration based exclusively on molecular methods, and calling attention to the fact that more effective control strategies against the emergence of MDR strains must be implemented by the TB control program to prevent transmission of MDR-MTB strains at health facilities in areas highly endemic for TB.

Pleural fluid ADA, IgA-ELISA and PCR sensitivities for the diagnosis of pleural tuberculosis.

The diagnosis of pleural tuberculosis (pTB) is difficult, and more sensitive and specific techniques are needed. In the period August 1998 to November 2002, we evaluated 132 patients with a pleural effusion submitted to a thoracentesis and pleural biopsy in a tertiary care hospital in Rio de Janeiro, Brazil. Three tests were performed and compared in the pleural fluid: ADA activity measurement, IgA-ELISA for two combined specific Mycobacterium tuberculosis antigens, and polymerase chain reaction (PCR) for detection of M. tuberculosis DNA. Ninety-five patients (72%) were given a final diagnosis of pTB. Overall histopathologic sensitivity was 77%. The sensitivities of pleural fluid culture and AFB smear were 42% and 1%, respectively. Twenty-one (22%) additional patients had a clinical diagnosis of pTB. Median follow-up time of all TB patients after the completion of antituberculous treatment was 13 months. Sensitivities of ADA, IgA-ELISA and PCR were 91%, 78% and 82%, while specificities were 93%, 96% and 85%, respectively. Only ADA sensitivity was significantly higher than the histopathologic examination (McNemar chi2 test; p = 0.002) and also significantly higher than ELISA (p = 0.049), but not higher than PCR (p = 0.143). We conclude that the routine use of ADA activity measurement in pleural fluid can obviate the need for a pleural biopsy in the initial diagnostic approach to pleural effusions, while IgA-ELISA and PCR techniques, potentially more specific tests, need further refinement to improve their accuracy.

IgA antibody responses to Mycobacterium tuberculosis recombinant MPT-64 and MT-10.3 (Rv3019c) antigens in pleural fluid of patients with tuberculous pleurisy.

SETTING: Microbiological tests lack sensitivity for pleural tuberculosis (TB) and histopathology is expensive, time consuming and needs specialised personnel. Immunoassay (ELISA) may be a promising approach in this respect. OBJECTIVE: To evaluate the reactivity of IgA antibody to MPT-64 and MT-10.3 recombinant mycobacterial protein antigens in pleural fluid as a marker of pleural TB, based on the fact that IgA is the main antibody in the mucosa/serosa of the gastrointestinal and respiratory tract. METHOD: Anti-MPT-64 and MT-10.3 IgA response was determined by ELISA in 72 patients with pleural TB and 27 with other pleural conditions. RESULTS: High sensitivities for IgA were measured against MPT-64 (52/72, 72%) and MT-10.3 (52/72,72%) antigens. Combining the sensitivities of both antigens, further increase in sensitivity (55/72, 76%) was obtained with no loss of specificity (96%). Similar IgA reactivity was obtained from culture-negative and culture-positive specimens. In eight pleural TB patients with human immunodeficiency virus (HIV) co-infection, the sensitivity was 88% (7/8). CONCLUSION: To our knowledge, this is the first description of the presence of IgA antibody pleural TB effusion reactive to MPT-64 and MT-10.3, with sensitivity similar to histopathological examination, which is presently considered the gold standard for pleural TB.

Novel allelic variants of Mycobacteria isolated in Brazil as determined by PCR-restriction enzyme analysis of hsp65.

Human isolates of Mycobacterium collected in 16 different states of Brazil were submitted to PCR-restriction analysis (PRA) of a 439-bp fragment of the hsp65 gene with HaeIII and BstEII. Fourteen allelic variants not described in clinical isolates so far were observed among 36 (10%) of 356 Brazilian strains, including a new pattern for Mycobacterium scrofulaceum, M. intracellulare, and M. flavescens, two new patterns for M. fortuitum, three new patterns each for M. gordonae and M. terrae, and one new pattern for M. avium complex-like strains. Two unidentified strains each also presented a new pattern, strongly suggesting that Mycobacterium genotypes are distributed biogeographically. The PRA procedure was also performed with 43 reference isolates belonging to 34 species, adding a further six new patterns to the identification algorithm. A database containing the normalized restriction patterns of both enzymes was constructed. Patterns available on the Internet can be introduced into this database, which will make possible the comparison of genotypes from isolates from different parts of the world.

The usefulness of serum adenosine deaminase 2 (ADA2) activity in adults for the diagnosis of pulmonary tuberculosis.

Rapid diagnosis of Mycobacterium tuberculosis remains an obstacle for therapy of tuberculosis (TB). Adenosine deaminase isoform 2 (ADA2) is produced by activated macrophages and has been used for diagnosis of TB from extra-pulmonary sites. However, few studies adequately address whether serum ADA2 activity is useful for diagnosis of active pulmonary tuberculosis (PTB). We prospectively measured serum ADA2 activity in 110 patients with pulmonary disease (65 cases with active PTB and 45 cases with other respiratory diseases) and 78 healthy volunteers (eight with tuberculin skin test positive). The serum ADA2 for the diagnosis of PTB had the sensitivity of 36.9%, the specificity of 84.5%, the positive predictive value of 10.9% and the negative predictive value of 96.2%. We concluded that serum ADA2 activity is neither useful to diagnosis of active PTB nor to differentiate from other respiratory diseases.

Evaluation of Etest strips for rapid susceptibility testing of Mycobacterium tuberculosis.

In this study, our objective was to evaluate Etest strips containing exponential gradients of isoniazid (INH), rifampin (RIF), and streptomycin (STR) for susceptibility testing of Mycobacterium tuberculosis. M. tuberculosis isolates were tested for antimicrobial susceptibilities by the standard proportion method using Löwenstein-Jensen (LJ) medium and by the Etest. The MICs determined by the Etest were obtained at 5, 7, or 10 days. In some strains with Etest-discrepant results, radiometric susceptibility testing (BACTEC) was performed to determine a consensus result. M. tuberculosis concordance between the two methods was 97% (86 of 89 isolates) for RIF, 96% for INH (84 of 87 isolates), and 80% (61 of 76 isolates) for STR. Most of the MICs determined by the Etest were easy to interpret and readable within 5 days. Results correlated well with those obtained by the LJ proportion and BACTEC methods for INH and RIF. However, a high proportion of false-sensitive and false-resistant results were observed, most often for STR. We also observed that variations in the inoculum size of M. tuberculosis isolates affected the MICs to a substantial degree. These discrepancies, along with the expense of the media, the Etest strips, and the specialized equipment required (CO2 incubator), make this method less useful in developing countries.

Mycobacterium tuberculosis typing: usefulness of DRE-PCR to confirm cross-contamination in the mycobacteriology laboratory of a general reference hospital for AIDS.

In this study two molecular typing methods, a simple double repetitive element PCR-based assay and the standardized restriction fragment length polymorphism (RFLP), were used to confirm cross-contamination in the mycobacteriology laboratory. Clinical specimens from 12 patients, submitted for acid-fast bacilli stain smear and processed for culture in Lowenstein-Jensen on the same day, resulted in positive bacterioscopy (+++) and confluent growth only for one of the patients. The specimens from all the other patients but two were smear-negative and culture-positive, with one or two colonies. None of them had clinical symptoms and radiological findings for active tuberculosis (TB). The suspicion of false-positive cultures arose when a health care worker who had had a PPD skin test conversion, claimed to be healthy and had no TB symptoms, was found to have a positive sputum culture. DRE-PCR demonstrated that all nine cultures typed belonged to one cluster, further confirmed by RFLP. Although DRE-PCR has been found to be poorly reproducible, it has enough discriminatory power to be useful for rapid epidemiological investigation in selected settings.

[Relationship between serological diagnosis (ELISA) and severity of pulmonary tuberculosis in children]. / Relação entre o diagnóstico sorológico (ELISA) e a gravidade da tuberculose pulmonar na infância.

Forty eight children from 0 to 13 years old were submitted to the enzyme-linked immunosorbent assay (ELISA) serological test with a view to detect anti PPD IgG antibodies, for diagnosis of pulmonary tuberculosis and to establish the relationship between immune response and radiological gravity of pulmonary tuberculosis (mild, moderate and severe). There were 29 children with pulmonary tuberculosis and 19 children without tuberculosis. The median ELISA optical density were: 0.098 in children with primary complex (mild); 0.092 in children with pneumonic pattern (moderate) and 0.134 in children with miliary tuberculosis (severe). These data show higher positive serological test results in severe forms of pulmonary tuberculosis (p = 0.0007).

Estudo da transmissão horizontal de Mycobacterium avium-intracellulare em suínos

Experimental infections were performed to study the horizontal transmission of Mycobacterium avium-intracellulare (MAI) in swine. Twelve 35 to 42 day-old pigs were divided into three groups of four pigs each. Each group was housed in separate rooms, and inoculated with three MAI strains: VPS1, SC1 and ATCC-13950. After inoculation, four non-inoculated swines were added to each group and maintained in the same pen up to 150 days of age, when were slaughtered. Other four non-inoculated swines were maintained as a control group. The infection was diagnosed by the tuberculin test at 140 days of age, by detection of macroscopic lesions at slaughter and histopathologic and bacteriologic examination of tissues collected at necropsy. Culture of fecal samples were made during the experiment indicating active excretion of MAI between 14 and 42 days post-inoculation. Transmission of MAI among pigs kept in the same pen was observed with all the three strains used. The most evident transmission was with strain SC1, in which four "in contact" pigs were infected, followed by ATCC-13950 (two pigs) and VPS1 (one pig). These results indicate that infected swine can be an important source of infection, favoring the dissemination of this disease.

O trabalho teve como objetivo estudar a transmissão horizontal de Mycobacterium avium-intracellulare (MAI) entre suínos. Doze suínos com 35 a 42 dias de idade, divididos em três grupos de quatro e alojados em salas independentes, foram inoculados por via oral com as cepas VPS1, SC1 e ATCC-13950 de Mycobacterium avium-intracellulare. A seguir, quatro suínos não inoculados foram colocados em cada grupo e mantidos na mesma baia até o abate aos 150 dias da idade. Outro grupo de quatro suínos não inoculados foi utilizado como controle. Pelo exame de fezes verificou-se que houve excreção ativa de MAI entre 14 e 42 dias pós-inoculação. A transmissão da infecção foi avaliada pelo teste de tuberculina aos 140 dias de idade e pelos exames de patologia macro e microscópica e de isolamento do MAI de órgãos. Os quatro suínos em contato com aqueles inoculados com a cepa SC1 foram contaminados, enquanto que com a cepa VPS1 apenas um e com a ATCC-13950 somente dois. Concluiu-se que houve transmissão de MAI entre os suínos mantidos na mesma baia, com as três cepas utilizadas, mas foi mais evidente com a cepa SC1, indicando que o suíno pode ser importante fonte de infecção na disseminação da doença.

Multiple isolates from aids patients: aspects of an analysis by a genotypic marker and antimicrobial susceptibilities variations.

Twenty-one Mycobacterium avium multisolates, from ten human immunodeficiency virus-infected patients, were typed by restriction fragment length polymorphism using as marker the IS1245 and characterized by minimum inhibitory concentration for nine different antibiotics. Two out of four patients harboring multisolates with different fingerprint profile, were therefore considered as having a polyclonal infection, since their isolates were taken from sterile site. This result confirms that polyclonal infection caused by M. avium occurs with a nonnegligenciable frequency. Analyzing the multisolates susceptibility profile of each patient it was observed that most of them were infected with strains having appreciably different antimicrobial susceptibility patterns, no matter what the genotypic pattern of the strains was. These results have strong implication for the treatment of the patients.

RFLP patterns and risk factors for recent tuberculosis transmission among hospitalized tuberculosis patients in Rio de Janeiro, Brazil.

Isolates of Mycobacterium tuberculosis from 120 tuberculosis patients seen in the 12 months ending September 1994 at 2 tertiary-care centres in Rio de Janeiro were characterized by IS6110 restriction fragment length polymorphism (RFLP) analysis. Ninety-seven patients (81%) had isolates with unique RFLP patterns, while 23 patients (19%) had isolates that belonged to 11 different RFLP cluster patterns. The strains from the latter patients were distributed among 1 group of 3 patients and 10 groups of 2 patients each. The cluster-pattern strains were not associated with gender, age, HIV infection, type of residence, living in shelter, homelessness or previous history of tuberculosis. However, clustering was strongly associated with multidrug resistance (P = 0.006). These data suggest that recent exogenous transmission may be important for the development of new cases of multidrug-resistant disease in patients attending tertiary-care centres in Rio de Janeiro, Brazil.

Genotypic patterns of multiple isolates of M. tuberculosis from tuberculous HIV patients.

We investigated whether the recurrence of tuberculosis in HIV-infected patients is due to an exogenous reinfection or relapses after antituberculosis chemotherapy. We reviewed clinical information on 32 patients at a Rio de Janeiro hospital from whom multiple Mycobacterium tuberculosis isolates were taken. All isolates were analysed by DRE-PCR fingerprinting technique, and those with identical DRE-PCR patterns were analysed by the RFLP method. Twenty patients had M. tuberculosis simultaneously isolated from different organs. These patients and nine others with sequential positive cultures after 2 months of therapy showed stable DRE-PCR and RFLP patterns. One patient's isolate became resistant to isoniazid, but the molecular pattern remained unchanged despite the development of drug resistance. In three patients, the DRE-PCR patterns of the isolates changed dramatically. Clinical and microbiological evidence was consistent with active tuberculosis caused by a new strain of M. tuberculosis. The exogenous reinfection of the three patients was not due to an outbreak, but the isolates from each patient showed unique patterns.

Estudo da transmissão horizontal de Mycobacterium avium-intracellulare em suínos

Experimental infections were performed to study the horizontal transmission of Mycobacterium avium-intracellulare (MAI) in swine. Twelve 35 to 42 day-old pigs were divided into three groups of four pigs each. Each group was housed in separate rooms, and inoculated with three MAI strains: VPS1, SC1 and ATCC-13950. After inoculation, four non-inoculated swines were added to each group and maintained in the same pen up to 150 days of age, when were slaughtered. Other four non-inoculated swines were maintained as a control group. The infection was diagnosed by the tuberculin test at 140 days of age, by detection of macroscopic lesions at slaughter and histopathologic and bacteriologic examination of tissues collected at necropsy. Culture of fecal samples were made during the experiment indicating active excretion of MAI between 14 and 42 days post-inoculation. Transmission of MAI among pigs kept in the same pen was observed with all the three strains used. The most evident transmission was with strain SC1, in which four "in contact" pigs were infected, followed by ATCC-13950 (two pigs) and VPS1 (one pig). These results indicate that infected swine can be an important source of infection, favoring the dissemination of this disease.

O trabalho teve como objetivo estudar a transmissão horizontal de Mycobacterium avium-intracellulare (MAI) entre suínos. Doze suínos com 35 a 42 dias de idade, divididos em três grupos de quatro e alojados em salas independentes, foram inoculados por via oral com as cepas VPS1, SC1 e ATCC-13950 de Mycobacterium avium-intracellulare. A seguir, quatro suínos não inoculados foram colocados em cada grupo e mantidos na mesma baia até o abate aos 150 dias da idade. Outro grupo de quatro suínos não inoculados foi utilizado como controle. Pelo exame de fezes verificou-se que houve excreção ativa de MAI entre 14 e 42 dias pós-inoculação. A transmissão da infecção foi avaliada pelo teste de tuberculina aos 140 dias de idade e pelos exames de patologia macro e microscópica e de isolamento do MAI de órgãos. Os quatro suínos em contato com aqueles inoculados com a cepa SC1 foram contaminados, enquanto que com a cepa VPS1 apenas um e com a ATCC-13950 somente dois. Concluiu-se que houve transmissão de MAI entre os suínos mantidos na mesma baia, com as três cepas utilizadas, mas foi mais evidente com a cepa SC1, indicando que o suíno pode ser importante fonte de infecção na disseminação da doença.

IS1245 genotypic analysis of Mycobacterium avium isolates from patients in Brazil.

OBJECTIVE: Disseminated Mycobacterium avium infection is an emerging opportunistic disease among patients with acquired immunodeficiency syndrome (AIDS) in Brazil. The mode of transmission of M. avium in a developing country setting needs to be better characterized. METHODS: Mycobacterium avium strain collections in São Paulo and Rio de Janeiro were analyzed according to the strains' IS1245 DNA gel electrophoretic migration patterns. Medical records of the patients from whom M. avium isolates were available were reviewed, and their demographic characteristics were stratified according to the isolates' IS1245 DNA fingerprint patterns. RESULTS: Of 105 patients, 33 (31%) with M. avium isolated between 1990 and 1994 had strains having IS1245 patterns identical in patterns seen in isolates from two or more patients (designated as cluster pattern strains). Cluster pattern strains were isolated from 21 (39%) of 54 patients with disseminated infection (defined as infection due to M. avium isolated from a sterile site in an adult patient). Six of the cluster pattern strains were isolated only from sterile sites. In São Paulo, cluster pattern strains were significantly more likely to be isolated from patients with disseminated disease. CONCLUSIONS: These preliminary observations suggest that in large cities of Brazil, a high proportion (at least 39%) of disseminated M. avium infections in patients with AIDS results from a recent transmission. Some strains of M. avium may be more likely to cause disseminated disease than others after an infection.

Analysis of Mycobacterium avium complex serovars isolated from AIDS patients from southeast Brazil.

The purpose of this study was to assess the distribution of Mycobacterium avium serovars isolated from AIDS patients in São Paulo and Rio de Janeiro. Ninety single site or multiple site isolates from 75 patients were examined. The most frequent serovars found were 8 (39.2%), 4 (21.4%) and 1 (10.7%). The frequency of mixed infections with serovar 8 or 4 was 37.8%. Among the 90 strains examined, M. intracellulare serovars (7 strains) and M. scrofulaceum (4 strains) were found in 11 isolates (12%) indicating that M. avium (88%) was the major opportunistic species in the M. avium complex isolates in Brazilian AIDS patients.

PIP: Mycobacterium avium complex (MAC) organisms have been associated with severe opportunistic infections in patients with AIDS in the US. The present study analyzed the distribution of 90 MAC serovars isolated from 75 AIDS patients from Sao Paulo and Rio de Janeiro, Brazil, in 1990-94. 56 isolates (62.2%) showed a single serovar--predominantly serovars 8 (39.2%), 4 (21.4%), and 1 (10.7%). In the 34 isolates (37.8%) in which more than one serovar was identified, 19 (55.9%) were from a single site and 15 (44.1%) were isolated from different sites or from the same site but at different times. The most common serovars in mixed infections from both single and different sites were 8 (34.2% and 37%, respectively)) and 4 (21.1% and 25.9%, respectively). Only 11 isolates (12%) were M. intracellulare or M. scrofulaceum strains, indicating that M. avium was the opportunistic species in 88% of the MAC isolates in these Brazilian AIDS patients. Although the serovars detected in this series are similar to those found in US AIDS patients, the occurrence of mixed serovars was substantially higher in Brazilian AIDS patients. The clinical implications of polyclonal infections in Brazilian AIDS patients require further investigation, especially since serovars from distinct sites may have distinct drug resistance patterns.

Borderline--tuberculoid leprosy: clinical and immunological heterogeneity.

The authors analysed some immunological criteria in leprosy patients diagnosed as borderline tuberculoid by the presentation of different grades of skin lesions as well as different grades of nerve involvement. Only 50% of the patients presented a single skin lesion and 58% had none or only one affected nerve. Nineteen patients (39.6%) showed a positive lepromin reaction (induration > or = 5 mm). Patients with a positive skin test had a greater number of skin lesions when compared with patients with a negative lepromin test. Fifty-seven percent of the patients were found to be positive using a lymphoproliferation test (LTT) in response to Mycobacterium leprae antigens. Positive LTT results did not correlate with the number of skin lesions, but patients unresponsive to LTT had a lesser extent of nerve involvement. Four out of 18 patients (22%) released high IFN gamma levels in PBMC culture stimulated by M. leprae. (mean U/ml +/- SD = 142 +/- 72). All of these 4 patients presented only one skin lesion, although three of them had more than one affected nerve. Nineteen out of 21 patients (90.5%) showed no anti-PGL-1 antibodies in their serum. The low levels of anti-PGL-1 antibodies among these patients confirmed their tuberculoid background even in those with multiple skin lesions. These findings seem to attribute an important role to IFN gamma in restraining the spreading of the infection in the skin, but IFN gamma may have an opposite effect on the nerves. The potential pathological effects of IFN gamma during the delayed type of hypersensitivity can be related to its ability to synergise with other inflammatory cytokines such as TNF alpha, IL-1 beta, and others.

Use of the 2,3-diacyl-trehalose and the purified protein derivative in the serodiagnosis of tuberculosis in AIDS.

The effect of the human immunodeficiency virus (HIV) infection on IgG production against purified protein derivative (PPD) and 2,3-diacil-trehalose (SL-IV) was investigated by an enzyme-linked immunosorbent assay (ELISA) test. Comparison between the antigens showed that immunocompetent patients produce preferentially antibodies to SL-IV than to PPD (73.3% versus 63.3%). Combination of these results showed an increase of the sensitivity to 80%, which decreased over the spectrum of immunodepression caused by HIV. In the tuberculous HIV seropositive group the sensitivities of SL-IV and PPD were 36.4% versus 40% and 0% versus 22.2% in the tuberculosis/acquired immunodeficiency syndrome (TB/AIDS) group. Combination of these results gave respectively 54.5% and 20%, showing that serological tests have limited value for diagnosis of tuberculosis in HIV infected patients. High antibody levels were observed in HIV seropositive asymptomatic group, but only two individuals were positive for both antigens. In the follow up, one of them developed tuberculous lymphadenitis, indicating that further work is needed to access the value of serological tests in predicting tuberculosis in HIV infected individuals.