Molecular epidemiology and drug resistance of Mycobacterium tuberculosis isolates from Ethiopian pulmonary tuberculosis patients with and without human immunodeficiency virus infection

We have analyzed the molecular epidemiology and drug resistance of 121 Mycobacterium tuberculosis isolates from consecutive patients with culture-positive pulmonary tuberculosis attending a university hospital outpatient department in Addis Ababa, Ethiopia. Restriction fragment length polymorphism analysis and spoligotyping were used to analyze the DNA fingerprinting patterns. Fifty-one (41.2%) of the isolates were found in 13 clusters with two or more identical DNA patterns. Two such clusters contained 49.0% of all clustered isolates. In a multivariate logistic regression model, human immunodeficiency virus (HIV)-positive serostatus was significantly associated with clustering of isolates for patients of both sexes (odds ratio [OR], 2.55; 95% confidence interval [CI], 1.17 to 5.80). There was a trend toward increased clustering of isolates from tuberculous women residing in Addis Ababa (OR, 2.10; 95% CI, 0.85 to 5.25). In total, 17 of 121 isolates (14.0%) were resistant to one or more of the antituberculosis drugs isoniazid (8.3%), streptomycin (7.4%), rifampin (2.5%), and ethambutol (1.7%). The high rate of drug-resistant isolates (29.6%) coincided with the peak prevalence of HIV infection (77.8%) in patients 35 to 44 years old. The majority (62.5%) of resistant isolates in this group were found within clusters. The simultaneous accumulation of certain bacterial clones in a patient population likely reflects recent transmission. Hence, we conclude that tuberculosis is commonly caused by recent infection with M. tuberculosis in HIV-positive Ethiopian patients. Furthermore, with the rapidly increasing prevalence of HIV infection in Ethiopia, the burden of tuberculosis, including drug-resistant tuberculosis, is likely to increase. Strengthening of classical tuberculosis control measures by promoting active case finding among HIV-positive adults with tuberculosis is warranted to reduce rates of transmission.

Direct detection of Mycobacterium tuberculosis in respiratory samples from patients in Scandinavia by polymerase chain reaction

OBJECTIVE: To investigate the use of DNA amplification by the polymerase chain reaction (PCR) for the detection of Mycobacterium tuberculosis directly in human respiratory specimens. METHODS: The PCR assay employed was the Amplicor M. tuberculosis Test (Roche Diagnostics, Switzerland), which uses the 16S rDNA as the target template. Nine hundred and sixty samples from 741 patients in two clinical microbiology laboratories in Norway and Sweden were processed by routine culture analysis and PCR. RESULTS: Of the 56 specimens containing cultivatable M. tuberculosis, 49 (87.5%) were detected by PCR. Among the 904 culture-negative specimens, 897 samples were negative also by PCR and seven (0.8%) were positive by PCR. In comparison with culture, the sensitivity, specificity, and positive and negative predictive values of PCR were 91.7%, 99.6%, 94.2% and 99.4% for laboratory 1 and 80.0%, 98.7%, 76.2% and 99.0% for laboratory 2, respectively. For both laboratories combined the values were 87.5%, 99.2%, 87.5% and 99.2%. CONCLUSIONS: These results indicate that multiple (two or three) respiratory samples from each patients should be tested, to allow sufficient accuracy in detecting M. tuberculosis in the specimens. Still, the labor-intensive format of this test necessitates strong clinical indications and patient prioritization to provide a service feasible within the current limits of routine laboratories.

Global trends in resistance to antituberculosis drugs. World Health Organization-International Union against Tuberculosis and Lung Disease Working Group on Anti-Tuberculosis Drug Resistance Surveillance

BACKGROUND

Data on global trends in resistance to antituberculosis drugs are lacking.

METHODS

We expanded the survey conducted by the World Health Organization and the International Union against Tuberculosis and Lung Disease to assess trends in resistance to antituberculosis drugs in countries on six continents. We obtained data using standard protocols from ongoing surveillance or from surveys of representative samples of all patients with tuberculosis. The standard sampling techniques distinguished between new and previously treated patients, and laboratory performance was checked by means of an international program of quality assurance.

RESULTS

Between 1996 and 1999, patients in 58 geographic sites were surveyed; 28 sites provided data for at least two years. For patients with newly diagnosed tuberculosis, the frequency of resistance to at least one antituberculosis drug ranged from 1.7 percent in Uruguay to 36.9 percent in Estonia (median, 10.7 percent). The prevalence increased in Estonia, from 28.2 percent in 1994 to 36.9 percent in 1998 (P=0.01), and in Denmark, from 9.9 percent in 1995 to 13.1 percent in 1998 (P=0.04). The median prevalence of multidrug resistance among new cases of tuberculosis was only 1.0 percent, but the prevalence was much higherin Estonia (14.1 percent), Henan Province in China (10.8 percent), Latvia (9.0 percent), the Russian oblasts of Ivanovo (9.0 percent) and Tomsk (6.5 percent), Iran (5.0 percent), and Zhejiang Province in China (4.5 percent). There were significant decreases in multidrug resistance in France and the United States. In Estonia, the prevalence in all cases increased from 11.7 percent in 1994 to 18.1 percent in 1998 (P<0.001).

CONCLUSIONS

Multidrug-resistant tuberculosis continues to be a serious problem, particularly among some countries of eastern Europe. Our survey also identified areas with a high prevalence of multidrug-resistant tuberculosis in such countries as China and Iran.

Clinical outcomes of Estonian patients with primary multidrug-resistant versus drug-susceptible tuberculosis

Little is known about the clinical outcomes of patients with primary multidrug-resistant (MDR) tuberculosis. Clinical outcomes among 46 patients in Estonia with primary MDR tuberculosis and 46 patients with pansusceptible tuberculosis were compared. Patients with MDR tuberculosis were more likely than those with pansensitive tuberculosis to have treatment failure (odds ratio, 8.9; 95% confidence interval [CI], 3.0-26.3) after adjusting for medical problems and weeks of effective treatment, often with second-line drugs. Ten patients (22%) with MDR tuberculosis and 2 (4%) with susceptible tuberculosis died of tuberculosis (P=.03). MDR tuberculosis (hazard ratio [HR], 7.8; 95% CI, 1.6-37.4), number of medical problems (HR, 2.5; 95% CI, 1.5-4.4), and male sex (HR, 5.8; 95% CI, 1.1-29.6) were associated with death due to tuberculosis in multivariable analysis. Human immunodeficiency virus test results were negative for all 55 patients tested. These findings underscore the urgent need for increased attention to prevention and treatment of MDR tuberculosis globally.

[Tuberculosis a threat again. Multiresistance in the Baltic States and in Russia; Nordic countries initiate cooperation to prevent transmission]

The incidence of tuberculosis (TB) has more than doubled in the Baltic States during the last decade and is now 10-15 times higher than in Sweden. It is also a serious problem in Russia. Strains resistant to one or several of the anti-tuberculous drugs are common as is multi-drug resistance (MDR), i.e. strains resistant to the two most effective drugs rifampicin and isoniazid. MDR-TB is very difficult to treat; the mortality rate is high. Initiatives have been taken in the Nordic countries in order to help to control and improve the situation by way of supportive measures.

Drug-resistant and multidrug-resistant tubercle bacilli

Drug resistant (DR) and multidrug resistant (MDR) tuberculosis (TB) is a consequence of human activity and did not exist before chemotherapeutic drugs were introduced. Monotherapy with various drugs in sequence or other inadequate drug regimens have strongly contributed to the creation of MDR-TB. Such TB strains are mainly prevalent in regions with weak national TB programmes or poor socio-economic environments. Strains may also spread in some communities such as poorly administered prisons. From these and other sources, MDR-TB may spread in the population from which travellers might transfer strains between countries and continents. Therefore an effective surveillance of the resistance pattern of TB bacilli is a demanding task in all countries. In this review some aspects of epidemiology, diagnosis and mechanisms of DR in TB are discussed. MDR-TB is an important international problem of increasing significance for the whole global community.

Improved extraction and assay of mycobacterial ATP for rapid drug susceptibility testing

The firefly luciferase assay of ATP is a rapid and convenient technique for monitoring growth of mycobacteria. The time needed to obtain a drug susceptibility pattern can be reduced to less than 1 week as compared to 4 weeks with conventional methods. The ATP assay is simple and reliable. However, the extraction of bacterial ATP is not a trivial problem. Lysing the cells will immediately activate ATP-degrading enzyme systems. The extractant must therefore lyse the cells and simultaneously inactivate ATP-degrading enzyme systems. Only by comparing the ATP yields obtained with different extractants we will know something about the intracellular ATP level. In the present study various extractants were compared for the extraction of ATP from Mycobacterium bovis (BCG) cultures. Dodecyl trimethyl ammonium bromide (DTAB) in Tris-buffer with EDTA resulted at 100 degrees C in an ATP yield that was approximately twice as high as the same buffer without DTAB. The optimum temperature was 80-100 degrees C. With the optimized extraction procedure the coefficient of variation for the entire assay of ATP in BCG cultures was 5%. The analytical interference from DTAB with the firefly reaction was obviated by neutralization with alpha-cyclodextrin, making it possible to increase the sensitivity by assaying 0.5 mL rather than 0.01 mL extract.

Identification of Mycobacterium kansasii by using a DNA probe (AccuProbe) and molecular techniques

The newly formulated Mycobacterium kansasii AccuProbe was evaluated, and the results obtained with the new version were compared to the results obtained with the old version of this test by using 116 M. kansasii strains, 1 Mycobacterium gastri strain, and 19 strains of several mycobacterial species. The sensitivity of this new formulation was 97.4% and the specificity was 100%. Still, three M. kansasii strains were missed by this probe. To evaluate the variability within the species, genetic analyses of the hsp65 gene, the spacer sequence between the 16S and 23S rRNA genes, and the 16S rRNA gene of several M. kansasii AccuProbe-positive strains as well as all AccuProbe-negative strains were performed. Genetic analyses of the one M. gastri strain from the comparative assay and of two further M. gastri strains were included because of the identity of the 16S rRNA gene in M. gastri to that in M. kansasii. The data confirmed the genetic heterogeneity of M. kansasii. Furthermore, a subspecies with an unpublished hsp65 restriction pattern and spacer sequence was described. The genetic data indicate that all M. kansasii strains missed by the AccuProbe test belong to one subspecies, the newly described subspecies VI, as determined by the hsp65 restriction pattern and the spacer sequence. Since the M. kansasii strains that are missed are rare and all M. gastri strains are correctly negative, the new formulated AccuProbe provides a useful tool for the identification of M. kansasii.

Prospective 7-year monitoring of MAC bacteremia in HIV-positive Swedish patients

OBJECTIVE: To record the cumulative incidence of Mycobacterium avium complex (MAC) bacteremia among HIV-infected patients and to study colonization in relation to symptoms of infection. METHODS: In a prospective study, 61 patients with a CD4 count less-than-or-eq, slant200x106/L were followed by cultures from sputum, feces and blood every 3--6 months and for development of MAC bacteremia and clinical symptoms. The main end-points were MAC bacteremia and death. RESULTS: From the start in November 1989 to January 1997 about 34% had developed MAC bacteremia with a median follow-up of 22 months. At the time of positive blood cultures, all but one patient had symptoms consistent with disseminated MAC infection. Positive cultures from respiratory and gastrointestinal tract were recorded before MAC bacteremia in only four patients. All but one had symptoms at the time of positive blood culture. CONCLUSIONS: The incidence of MAC bacteremia was similar to figures in other studies. The presence of symptoms in close relation to positive blood cultures supports late colonization and late infection in HIV disease. Screening patients with samples from the respiratory and gastrointestinal tracts is not useful

Multiple serovars of Mycobacterium avium complex in patients with AIDS

Mycobacterium avium complex (MAC) was isolated and serotyped from 127 samples from 43 HIV-infected patients with disseminated disease in Sweden. Thirteen different serovars were observed. Serovar 6 was the most common, followed by 4, 9 and 11. Serovar 8 was rare. In 22 of the patients the same serovar was found in blood and at other sites. Clinical symptoms and outcome were compared in patients with different serovars. Analysis of patient records revealed no association between clinical picture and any specific serovar. The median survival time after MAC infection was 7 months. Somewhat shorter survival was observed in patients with serovar 4 than in those with serovar 6.

Mycobacterium avium complex sputum isolates from patients with respiratory symptoms in Guinea-Bissau

In total, 814 patients with clinically suspected tuberculosis were examined at the Raoul Follerau Hospital in Bissau, Guinea-Bissau. Sputum samples were collected, and cultures were grown on Löwenstein-Jensen medium. Isolates were further characterized by standard biochemical methods and nucleic acid probes for Mycobacterium tuberculosis and Mycobacterium avium complex (MAC). Serum samples were collected and analyzed for antibodies against human immunodeficiency virus (HIV) types 1 and 2. Of 17 patients who had MAC organisms in sputum, 2 were HIV-2-positive and none was HIV-1-positive. Of the total 814 patients, 189 had culture-verified tuberculosis; 36 (19%) of them were HIV-2-positive. Thus, of 206 patients with sputum culture positive for M. tuberculosis or MAC, 17 (8%) had MAC organisms in sputum. MAC infection may be the cause of some treatment failures in areas where MAC pulmonary infection is common.

Tuberculostearic acid in lymph nodes from patients with sarcoidosis

It has earlier been suggested that mycobacteria may play an aetiological role in the development of sarcoidosis. To investigate this further we analyzed the presence of a characteristic mycobacterial constituent, tuberculostearic acid (TS, 10-methyloctadecanoic acid), in lymph nodes from 22 patients with sarcoidosis and in eleven children and three adult controls. To detect TS gas chromatography/mass spectrometry was used. These findings were compared with the results from conventional mycobacterial culture and radiometric respirometry. Although the latter techniques failed to detect mycobacteria in all the tested tissue samples, TS was found in various amounts. Thus, 0-3 micrograms TS/g freeze-dried tissue was noted in eight sarcoid patients, 3-50 micrograms TS/g in eight and 51-400 micrograms TS/g in the remaining six patients. Among the controls only 1/14 had detectable TS. In one patient with lymph node tuberculosis TS was in the range 51-400 micrograms/g. We conclude that the findings could be explained by the presence of mycobacteria not cultivable with the studied techniques or with the presence of remnants after an earlier colonisation with mycobacteria, e.g. BCG-vaccination. Mycobacteria or mycobacterial cell-envelope in sarcoid tissue may possibly act as cofactors in the development of the disease, i.e. they might function as triggering agents (adjuvans) of the immune response. On the other hand the findings may be without any aetiological significance. In that latter case a hitherto unknown lack of wax decomposition during several decades has to be considered.

Nosocomial Legionnaires' disease following renal transplantation

A cluster of five cases of Legionnaires' disease in renal transplant patients is described. They were treated with erythromycin and rifampicin, and all five survived. Two of them had rejected their grafts prior to their Legionella pneumonia; two rejected their transplants after reduction of immunosuppressive therapy to combat the infection. L pneumophila was present in the water distribution system of the hospital. Eradication measures included flushing the water pipes to the transplantation ward with hot and hyperchlorinated water, raising the warm water temperature to 60 degrees C, and installing ultraviolet (UV) irradiation units on the warm and cold water pipes to the ward. These measures were successful in that no new cases of legionellosis occurred after wards. L pneumophila could subsequently not be demonstrated by culture in plastic shower hoses supplied with UV-irradiated water. L pneumophila could be demonstrated by direct fluorescent antibody technique, but nonspecific reactions cannot be excluded. A higher prevalence of elevated L pneumophila antibody titers was observed in patients nursed for more than four weeks in the hospital than in patients with a shorter hospital stay, in hospital staff members, or in the general population. It seems that, with appropriate control measures, transplantation activities need not be discontinued in the presence of a minor cluster of Legionnaires' disease in renal transplant patients.

Penetration of ampicillin into urethral and cervical secretions after oral administration of bacampicillin

The study comprised 24 male and 24 female patients treated either for uncomplicated gonorrhoea or as a prophylaxis. A single dose of 800 mg of bacampicillin + 1.0 g probenecid was administered orally to each patient. The concentrations of ampicillin in urethra and cervix were assayed by means of alginate swabs that were used as diffusion centres on agar diffusion plates. The inhibition zones were compared with a standard series of swabs containing known amounts of ampicillin. The amounts of secretions absorbed into the swabs were determined by weighing each swab before and after taking the specimen. The median ampicillin concentration in the male urethra one hour after the single dose of bacampicillin plus probenecid was 2.0 micrograms/ml of urethral secretion and increased to 3.2 micrograms/ml two hours after administration of the antibiotic. In the female urethra, the median concentrations of ampicillin were 1.5 micrograms/ml and 2.3 micrograms/ml of urethral secretion one and two hours, respectively, after the same dosage as above. The corresponding ampicillin concentrations in the cervical secretion were 1.6 micrograms/ml and 2.9 micrograms/ml, respectively.