[Mycobacterial infections: yield of bacillary microscopy in different clinical samples (1975-1988)]. / Infecciones por micobacterias: rendimiento de la baciloscopia en diferentes muestras clínicas (1975-1988).

BACKGROUND: The yield of microscopy examination as a quick diagnostic test in several pulmonary and nonpulmonary samples referred to the mycobacterial laboratory of a general hospital is reviewed. METHODS: During a 14-year period (1975-1988), 113,836 biological products were investigated. In 9,972 a positive culture for mycobacteria was obtained. For the microscopy examination the auramin technique was used; if positive, acid-alcohol resistance was confirmed by overstaining with the Ziehl-Neelsen technique. The culture was used as the reference method. RESULTS: Microscopic examination was positive in 34% of samples with a positive culture, being 39% for Mycobacterium tuberculosis and 10% for environmental mycobacteria. The overall specificity was 99%, the positive predictive value was 91% and the negative predictive value was 94%. In pleuropulmonary samples the sensitivity ranged from 48% in sputum and 2% in pleural biopsy, with specificity higher than 99%. In nonpulmonary samples, sensitivity, specificity and positive and negative predictive values varied with the type of sample. The false positive rate (positive microscopy with negative culture) was 0.3, and it was shown that 80% of these patients had received previous therapy. In organic fluids (pleural, peritoneal, cerebrospinal), the sensitivity was not greater than 13%. CONCLUSIONS: Sputum, bronchoaspirate and bronchoalveolar lavage were better for the diagnosis of tuberculosis than gastric aspirate. Approximately 1 in each positive microscopy examinations corresponded to environmental mycobacteria. In some nonpulmonary samples with high sensitivity the positive predictive value was low. 80% of the false positive results corresponded to previously treated patients.

[Isolation of M. tuberculosis in abdominal specimens]. / Aislamiento de M. tuberculosis en muestras de origen abdominal.

The isolation of mycobacteria in abdominal specimens during a 10 years period is presented. Twenty-three clinical cases have been reviewed; patients were divided in three groups: 1) Peritoneal and intestinal tuberculosis. 2) Pulmonary tuberculosis with isolation of M. tuberculosis in feces, and 3) Miliary tuberculosis. We emphasize the low yielding of bacilloscopy, the low number of colonies in cultures and the importance of the microbiological study of abdominal specimens in the confirmatory diagnosis. The predominant symptoms of peritoneal tuberculosis were abdominal pain and distention and fever. The study of the ascitic fluid showed in most of the cases lymphocytic exudate and the pathological study of biopsies showed granulomas with caseous necrosis. Three patients had another associated abdominal disease. Isolation of M. tuberculosis in feces does not invariably mean the presence of intestinal tuberculosis. We confirm the frequent association of disseminated tuberculosis and HIV1 infection.

[Moraxella (Branhamella) catarrhalis: its isolation in the respiratory secretions of adult patients]. / Moraxella (Branhamella) catarrhalis: aislamiento en secreciones respiratorias de pacientes adultos.

OBJECTIVE: We have designed a retrospective study in order to know the clinical significance of the isolation of Moraxella (Branhamella) catarrhalis (MC) in respiratory specimens of adult hospitalized patients. METHODS: We performed a Gram stain and culture on blood-agar, MacConkey media and quantitative culture in chocolate-agar to all respiratory samples. In patients with a clinical diagnosis of pneumonia BCYE-alpha was added. During 2 years (1992-1993) MC was isolated in respiratory specimens from 52 patients. We revised the clinical history of all these patients. RESULTS: MC was isolated in 60 respiratory specimens (sputum and/or tracheobronchial aspirates) from 52 patients. The Gram stain showed gram-negative cocci in 77% and gram-positive cocci in 17% of the cases. MC grew in pure culture in 28 specimens (46.6%). In 23% of cases MC was isolated with Streptococcus pneumoniae and in 21% with Haemophilus influenzae. Fifty-two stocks (86.6%) produced beta-lactamase. Twelve patients had a clinical diagnosis of pneumonia, 8 of them had an underlying chronic respiratory disease. Other 24 patients with an underlying chronic respiratory disease had a bronchial infection as a cause of exacerbation of their respiratory disease. Seven patients without an underlying chronic respiratory disease had a clinical episode of acute bronchitis. Finally, in 9 patients the isolation of MC was considered a colonization. CONCLUSIONS: In 17% cases MC was identified as a gram-positive cocci in the Gram stain, which may cause false diagnosis. The etiological importance of MC in episodes of acute exacerbation of patients with an underlying chronic respiratory disease is high.

[DNA amplification using PCR in the diagnosis of tuberculosis]. / Amplificación de ADN mediante RCP en el diagnóstico de la tuberculosis.

BACKGROUND: To evaluate the DNA amplification technique of M. tuberculosis with PCR in clinical samples. METHODS: We have studied 57 clinical samples of 49 patients using PCR and culture in conventional media. We evaluate the final diagnosis of tuberculosis depending upon the bacteriologic results of all available samples. RESULTS: We reached a 58% sensitivity and 100% specificity. In 9 samples with positive PCR the culture was negative. The samples belonged to 9 patients with tuberculosis (4 with active disease and 5 with past microbiological diagnosis). In 32 samples with negative PCR test, the microorganism was isolated in 9 cases. SUMMARY: More studies are needed before PCR technique could be recommended for widespread use in the diagnosis of tuberculosis. Its long duration, the equipment needed and the false negative results are among its limitations.

[Use of DNA probes labelled with radioisotopes in the mycobacteria laboratory]. / Utilidad de las sondas de ADN, marcadas con isótopos radiactivos en el laboratorio de micobacterias.

We have studied 540 mycobacterial strains isolated in Lowestein-Jensen medium and 133 samples of different pathologic products against commercialized 125I-DNA Mycobacterium tuberculosis complex, Mycobacterium avitum-intracellulare and Mycobacterium gordonae. The sensitivity, specificity and positive and negative predictive values against isolated strains was 100% for the 3 studied probes. The 125I-DNA probe specific for M. tuberculosis complex is studied in samples with positive bacciloscopy; statistic values vary according to the cutting point of the different percentages of hybridization: at 1.5% the sensitivity, specificity and predictive negative and positive values are 38.6%, 71.4%, 97.5%, and 9.4% respectively, while if the cutting point percentage is 3% these values are: 33.1%, 100%, 100%, and 7.8% respectively. We believe that with these probes the identification time is limited to time needed for the incubation of prime cultures, and in some cases it can be performed on the day the samples reach the laboratory.

[Evaluation of the serological follow-up of newborn infants, carriers of HIV-1 antibodies]. / Valoración del seguimiento serológico en recién nacidos portadores de anticuerpos anti VIH 1.

Serological follow-ups were performed in 19 newborns carrying HIV 1 antibodies over a period ranging between 9 and 62 months. Eight children developed AIDS ans 11 remained asymptomatic. Anti-HIV 1 antibodies were determined by ELISA and Western blot and p 24 antigen was detected by ELISA. Antibodies to HIV 1 disappeared in most children without AIDS symptoms between 10 and 12 months after birth, with antibodies against gp 41 being lost first. Children with AIDS remained positive during follow-up, although in 3 cases with positive was absent in all the asymptomatic children, while it was present in 75% of the patients with AIDS.

Evaluation of a phenolglycolipid antigen (PGL-Tb 1) from M. tuberculosis in the serodiagnosis of tuberculosis: comparison with PPD antigen.

Sera from 38 tuberculous patients and 62 healthy controls (31 PPD skin test positive and 31 negative) were assayed, by enzyme-linked immunosorbent assay (ELISA), to test the activity of IgG and IgM antibodies against purified protein derivative (PPD) antigen and a phenolglycolipid antigen (PLG-Tb 1) isolated and purified from Mycobacterium tuberculosis strain Canetti. Using PPD antigen, the sensitivity and specificity were respectively, 50 and 93.5% for IgG and 71.1 and 59.7% for IgM antibody activity. Against PGL-Tb 1 antigen, IgG had a sensitivity of 94.7% and the specificity was 96.8%, for IgM antibody they were 65.8% and 75.8% respectively. The ELISA using PGL-Tb 1 antigen could be a useful way to develop a rapid technique to aid in the diagnosis of tuberculosis.

[The cut-off points used in chemiluminescent probes for the identification of mycobacteria]. / Estudio de los puntos de corte usados en sondas quimioluminiscentes para la identificación de micobacterias.

441 strain of mycobacteria were exposed to probes marked with luminous material belonged to M. tuberculosis complex and M. avium complex. We analyzed the following points: 1. If the cut-off points obtained with our strains were in accordance to those recommended by the manufacturer, using two different luminometers. 2. If the correlation constant makes possible the conversion of the units form one luminometer to the units obtained with the other one. 3. Data for sensibility, specificity and predictive positive and negative values using different cut-off points. Cut-off points were different in all cases except for the data obtained with one luminometer using a probe belonged to M. tuberculosis complex. In this case the correlation constant could not be used. In contrast, whichever the luminometer employed was, we found no significant differences between sensibility, specificity and predictive values.

Diagnosis of mycobacterial infection in acquired immunodeficiency syndrome (AIDS) patients and HIV carriers.

Differences in tuberculosis diagnosis between infected and non-infected HIV patients were described. In Barcelona, tuberculosis is present in 41.6% of 851 patients in whom AIDS was detected between 1981 and the first quarter of 1990. We reviewed the results of the methods used for tuberculosis diagnosis in 270 AIDS patients controlled in our hospital, in whom tuberculosis was detected (33.3%), and we compared these data with the results obtained in HIV carriers with tuberculosis and with tuberculous patients without HIV infection. Statistically significant differences were found between the three groups with respect to sex, age, results of Ziehl-Neelsen stain in pulmonary specimens and skin test reaction; between AIDS patients and the non-HIV infected population differences were observed in tuberculosis site. Positive skin test reaction diminished from tuberculous individuals non-HIV infected (95%), to HIV carriers with tuberculosis (71.8%) and AIDS patients with tuberculosis (21.8%). Acid-fast smears from pulmonary specimens were positive in 35.7%, 23.5% and 43.7% respectively. Statistically significant differences were found in tuberculosis localization between tuberculous patients non-HIV infected and tuberculous patients with AIDS, in the last group tuberculosis lymphadenitis was the most frequent localization (33.3%) of extrapulmonary tuberculosis, followed by abdominal tuberculosis (15.5%). The incidence of HIV infection among tuberculous patients was 4.6 in our study, but could be higher if patients between 19 and 30 years old were always checked for anti-HIV antibodies.

Time course of anti-SL-IV immunoglobulin G antibodies in patients with tuberculosis and tuberculosis-associated AIDS.

Immunoglobulin G (IgG) and IgM antibodies against the SL-IV antigen of Mycobacterium tuberculosis in the sera of patients with tuberculosis with negative serology for human immunodeficiency virus (HIV) infection (TB group; n = 97), patients with tuberculosis with positive serology for HIV infection (TB-HIV group; n = 59), and healthy controls (n = 289) were determined by enzyme-linked immunosorbent assay. All sera were obtained at the onset of tuberculosis, i.e., when clinical symptoms appeared. Clinical specimens were collected and cultured for the isolation of M. tuberculosis, and treatment with antituberculous drugs was started. Sera were also obtained from patients in the TB group at fixed intervals during treatment; sera were available from 13 patients in the TB-HIV group before the onset of tuberculosis. The best specificity and positive predictive values were obtained with the IgG assays. In the IgG assays at specificities above 96.0%, the sensitivities of the tests were 45.3 and 72.8% for the TB and TB-HIV groups, respectively, and the sensitivity was 51.9% when data from both groups were combined for analysis. For the TB group, results of this study indicated that the levels of IgG antibodies remain high during treatment. Thus, repetitive serological assays may not be useful for treatment follow-up. In the TB-HIV group, 12 of 13 patients had IgG-specific antibodies against the SL-IV antigen between 1 and 30 months before the onset of tuberculosis, so we suggest that the IgG antibody assay against SL-IV may be helpful for identifying tuberculosis in patients infected with HIV.