Molecular Epidemiology of Mycobacterium Tuberculosis Strains in the North-West and West of Iran

Background:

Identifying Mycobacterium tuberculosis (MTB) transmission type is a key step in the control of this disease.

Aim:

This study aimed to determine the path and transmission type of MTB and the insertion sequence IS6110 band number and verify their relationship to demographic and clinical risk factors.

Subjects and Methods:

In this cross-sectional study, 64 MTB patients from three border provinces of Iran were selected after full clinical history and physical evaluation design. The drug susceptibility testing was carried out using the standard proportion technique on sputum samples. Isolates tested with restriction fragment length polymorphism technique used IS6110.

Results:

Recent transmission of disease was 33/50 (66%) based on clustering rate. The IS6110 band number had a significant relationship with drug resistance detected in proportion method tested by univariate linear regression (P < 0.01). Furthermore, the IS6110 band number had association with Bacillus Calmette–Guérin vaccination history (P = 0.02), sex (P < 0.01), and purified protein derivative (PPD) reaction size (P < 0.01) tested by multiple analysis. The risk of recent transmission inferred from the clustering rate was significantly higher in patients from Western provinces compared to those from the North-West province (P = 0.048). However, age (P = 0.39), gender (P = 0.16), vaccination history (P = 0.57), drug susceptibility, and PPD (P < 0.6) were independent of clustering. The largest cluster of up to six subjects was found in the Western provinces.

Conclusion:

Recent MTB transmission was much more common in the West compared to the North-West of Iran. Large MTB clusters with strong epidemiological links may be reflective of a disease outbreak. Correlation noted between the IS6110 band number and vaccination history; PPD size and female gender necessitates further studies.

Revisiting susceptibility testing in MDR-TB by a standardized quantitative phenotypic assessment in a European multicentre study

OBJECTIVES

Treatment outcome of MDR-TB is critically dependent on the proper use of second-line drugs as per the result of in vitro drug susceptibility testing (DST). We aimed to establish a standardized DST procedure based on quantitative determination of drug resistance and compared the results with those of genotypes associated with drug resistance.

METHODS

The protocol, based on MGIT 960 and the TB eXiST software, was evaluated in nine European reference laboratories. Resistance detection at a screening drug concentration was followed by determination of resistance levels and estimation of the resistance proportion. Mutations in 14 gene regions were investigated using established techniques.

RESULTS

A total of 139 Mycobacterium tuberculosis isolates from patients with MDR-TB and resistance beyond MDR-TB were tested for 13 antituberculous drugs: isoniazid, rifampicin, rifabutin, ethambutol, pyrazinamide, streptomycin, para-aminosalicylic acid, ethionamide, amikacin, capreomycin, ofloxacin, moxifloxacin and linezolid. Concordance between phenotypic and genotypic resistance was >80%, except for ethambutol. Time to results was short (median 10 days). High-level resistance, which precludes the therapeutic use of an antituberculous drug, was observed in 49% of the isolates. The finding of a low or intermediate resistance level in 16% and 35% of the isolates, respectively, may help in designing an efficient personalized regimen for the treatment of MDR-TB patients.

CONCLUSIONS

The automated DST procedure permits accurate and rapid quantitative resistance profiling of first- and second-line antituberculous drugs. Prospective validation is warranted to determine the impact on patient care.

Evaluation of a biphasic media assay for pyrazinamide drug susceptibility testing of Mycobacterium tuberculosis

OBJECTIVES

Pyrazinamide is a key first-line tuberculosis drug. Reliable drug susceptibility testing (DST) data are of clinical importance, but in vitro testing is challenging since the activity of pyrazinamide is pH sensitive. The BACTEC MGIT 960 is considered the principal reference technique, but Wayne's test is an alternative, although it may be difficult to interpret. A further alternative is the use of a biphasic media assay (BMA). The objective of this work was to evaluate the BMA against the MGIT method and with screening of pncA gene mutations.

METHODS

Twenty strains were inoculated in tubes containing 2 mL of Löwenstein-Jensen (LJ) medium and 2 mL of semi-solid Kirchner medium with a critical concentration of 66 mg/L pyrazinamide at a pH of 5.2 or 5.5, incubated for 2 weeks and visually read. The results obtained were compared with MGIT 960 and DNA sequencing.

RESULTS

Results were obtained in duplicate for 19 strains. One strain failed to grow on two occasions and only one result was available. Reproducibility was 95%. Eleven of the 19 strains were susceptible to pyrazinamide, whereas 7 were resistant. One strain was susceptible initially and pyrazinamide resistant on repeat testing. At pH 5.5, two strains reported as susceptible at pH 5.2 gave resistant results.

CONCLUSIONS

The BMA might serve as a reliable low-cost DST alternative for pyrazinamide, particularly in laboratories using locally made solid media for DST. Its major drawback is the time to result. A reliable and affordable test method for the detection of pyrazinamide resistance is needed, especially in settings where multidrug-resistant tuberculosis is increasing. Proficiency testing should be routinely introduced wherever pyrazinamide DST is performed.

Proficiency of drug susceptibility testing of Mycobacterium tuberculosis against pyrazinamide: the Swedish experience

BACKGROUND

Pyrazinamide (PZA) is a key drug in the treatment of tuberculosis (TB), including multidrug-resistant TB. Drug susceptibility testing (DST) of Mycobacterium tuberculosis against PZA is not included in the World Health Organization's yearly proficiency testing. There is an increasing need to establish quality control of PZA DST.

OBJECTIVE

To evaluate the performance of PZA DST and to introduce a quality assurance system for the test in Sweden.

METHOD

Panels with PZA-susceptible and -resistant isolates were used in three rounds of proficiency testing in all five Swedish clinical TB laboratories and our reference laboratory. All laboratories used the MGIT 960 system. Minimum inhibitory concentrations (MICs) were determined and the pncA gene was sequenced to further characterise the 52 panel strains.

RESULTS

Good agreement was seen between the phenotypic PZA DST and pncA sequence data, and MIC determination confirmed high levels of resistance. However, in contrast to other drugs, for which correct proficiency test results were observed, specificity problems occurred for PZA DST in some laboratories.

CONCLUSIONS

In Sweden, using panel testing, differences were seen in the proficiency of TB laboratories in correctly identifying PZA susceptibility. Improved results were noted in the third round; PZA has therefore been included in yearly proficiency testing.

A snapshot of the biodiversity and clustering of Mycobacterium tuberculosis in Oman using spoligotyping

SETTINGS

National Tuberculosis Reference Laboratory, Central Public Health Laboratory, Ministry of Health, Oman.

OBJECTIVE

To use spoligotyping to explore the genetic population structure and clustering of Mycobacterium tuberculosis isolates among nationals and immigrants in Oman.

METHODS

Using spoligotyping, we characterised all available isolates from 2007, and randomly selected isolates from 2005 and 2006. A total of 312 clinical isolates from the same number of patients diagnosed with tuberculosis (TB) in 2005-2007 were included in the study.

RESULTS

Of 312 isolates, 69% were in clusters ranging from 2 to 38 isolates. The proportion of clustering was 58% among 2005-2006 samples and 67% among 2007 samples, with higher clustering among Omanis than among immigrants. The study showed that M. tuberculosis Indian family lineages, CAS1_Delhi, CAS and EAI5 were the predominant strains. Around 50% of the immigrants shared strains with Omanis. Twelve of the 19 INH-monoresistant strains and the two multidrug-resistant strains were in clusters (P = 0.81).

CONCLUSION

This study demonstrates the predominance in Oman of the strain family commonly found on the Indian sub-continent. A high proportion of immigrant strains were in the same clusters as Omani strains. To better ascertain the transmission dynamics of M. tuberculosis, we recommend that stringent molecular and conventional epidemiological methods be applied.

Evaluation of seven tests for the rapid detection of multidrug-resistant tuberculosis in Uganda

SETTINGS

National Tuberculosis (TB) Reference Laboratory and Department of Medical Microbiology, College of Health Sciences, Makerere University, Kampala, Uganda.

OBJECTIVE

To evaluate head-to-head rapid tests for drug susceptibility testing (DST) of Mycobacterium tuberculosis against rifampicin (RMP) and isoniazid (INH) in a resource-limited setting.

METHODS

Thirty-one well-characterised strains of M. tuberculosis were tested with the nitrate reductase assay (NRA), microscopic observation drug susceptibility (MODS), MGIT 960 (Mycobacterium Growth Indicator Tube 960), Genotype MTBDRplus, Alamar blue, MTT and resazurin assays. The proportion method on Löwenstein-Jensen medium was used as the reference test.

RESULTS

NRA correctly identified the resistant strains, with 100% sensitivity and specificity. MGIT 960 detected all multidrug-resistant strains but missed one RMP-monoresistant strain. Genotype MTBDRplus detected all RMP-resistant strains, but the sensitivity for detection of INH resistance was lower (88%). Sensitivity and specificity ranged from 86% to 100% for MODS and from 57% to 100% for the Alamar blue, MTT and resazurin assays. Test results were obtained within 2-14 days.

CONCLUSION

In the study setting, NRA, MGIT 960 and Genotype MTBDRplus gave excellent detection of multidrug-resistant tuberculosis, with significantly shorter time to results compared to conventional testing.

Genetic characterisation of drug-resistant Mycobacterium tuberculosis in rural China: a population-based study

OBJECTIVES

A population-based study was performed to characterise the genotype and phenotype of drug-resistant tuberculosis (TB) in the year 2004-2005 in two Chinese rural counties with different durations of DOTS implementation, Deqing and Guanyun.

METHODS

Mycobacterium tuberculosis strains were isolated from respectively 164 and 187 patients registered at local TB dispensaries of Deqing and Guanyun. Drug susceptibility profiling and DNA sequencing were performed on the isolates.

RESULTS

A total of 223 isolates from 223 patients were identified as resistant to first-line drugs, of which 53 were multidrug-resistant TB (MDR-TB, i.e., resistant to isoniazid [INH] and rifampicin [RMP]). Mutations in katG were identified in 81 of 131 INH-resistant isolates (61.8%), all of which harboured the mutation in codon 315. Mutations related to RMP resistance occurred mostly in codon 531, 526 and 516 of the rpoB gene. Seventy-eight of the 115 streptomycin-resistant isolates carried a mutation in the rpsL gene at codon 43 or 88. A mutation in codon 306 of embB occurred in 21 ethambutol (EMB) resistant and 19 EMB-susceptible isolates.

CONCLUSIONS

Our data indicated that DNA sequencing of specific codons of the rpoB gene should be effective for predicting RMP resistance and MDR-TB in rural China.

The added value of a European Union tuberculosis reference laboratory network – analysis of the national reference laboratory activities

National reference laboratories (NRL) and other laboratories are the cornerstones of well-functioning tuberculosis programmes and surveillance activities. However, the scope and activity of NRL services for mycobacterial identification and drug susceptibility testing (DST) has not been examined in detail across the European Union (EU), nor has the added value of cooperation and networking at the European level been explored with regard to strengthening laboratory services. Therefore, the European Centre for Disease Prevention and Control (ECDC) has commissioned a survey to explore these issues and to identify areas of work that could bring added value by supporting networking activities of tuberculosis (TB) reference laboratories in the EU. Structured questionnaires were sent to TB reference laboratory experts in the EU and European Economic Area (EEA) countries, and in three additional countries selected on the basis of their networking activities with EU projects and other initiatives (Switzerland, Croatia and Israel). The compiled results describe the activities and structure of 32 NRLs (29 countries replied, a response rate of 91%). The analysis of the survey led to the following recommendations for strengthening TB laboratory services: (1) implementing of the published European standards for TB laboratory services with respect to infrastructure, national reference functions, biosafety, human resources, quality assurance, operational research (including evaluation of new medical diagnostics), accuracy and speed, appropriately trained staff; (2) ensuring that laboratories only perform activities for which they have demonstrated proficiency; (3) implement validated and standardised second-line drug susceptibility testing (DST), including drugs used to define extensively drug-resistant tuberculosis (XDR TB); (4) aiming to identify Mycobacterium tuberculosis complex (MTBC) and rifampicin (RIF) resistance in over 90% of cultures and cases from smear-positive sputum directly within one to two working days. To realise some of the above recommendations and to strengthen links of TB surveillance and microbiology activities in the EU, a list of suggested generic areas of activities for an EU network of reference laboratories is presented. Such a network would build on and link to existing networks and initiatives at the European and global level.

Antimicrobial susceptibility testing of Mycobacterium tuberculosis (EUCAST document E.DEF 8.1)--report of the Subcommittee on Antimicrobial Susceptibility Testing of Mycobacterium tuberculosis of the European Committee for Antimicrobial Susceptibility Testing (EUCAST) of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID)

This review describes the methods available for drug susceptibility testing of Mycobacterium tuberculosis. The methods have been developed over several decades and are restricted to specialised centres in most European countries, as they are technically demanding, require appropriate isolation facilities and can be difficult to interpret. The absolute concentration, resistance ratio and proportion methods can all give accurate results, provided that they are carefully quality-controlled and standardised. Automated rapid culture and molecular methods have been evaluated at large reference centres and in multicentre collaborations, and perform well for testing susceptibility to most first- and second-line anti-tuberculosis drugs. Accuracy is more important than rapid testing, and this is most reliably achieved if drug susceptibility tests are done in a small number of well-equipped, experienced laboratories that participate and perform well in an international drug susceptibility testing quality assessment scheme. The WHO Supranational Laboratory Quality Control Network offers a global scheme that assesses the ability of participating laboratories to identify isoniazid, rifampicin, ethambutol and streptomycin resistance. Second-line drug resistance testing is currently being standardised, and such testing should only be performed at the national reference laboratories in western and central European countries because of the relatively small number of cases and the concomitant difficulty of maintaining testing proficiency in multiple centres performing small numbers of tests. There is a need to expand international external quality assessment to include second-line drug susceptibility testing.

Recommended standards for modern tuberculosis laboratory services in Europe

The principles underpinning these standards are that any tuberculosis laboratory-based diagnostic procedure should be performed by appropriately trained staff, working to standardised operating procedures in appropriately equipped and safe laboratories, against clear national and international proficiency and quality standards. Quality should be the pre-eminent criteria, not cost. The standards are technologically feasible, but initially may not be within the financial capacity of all laboratories. There is a requirement for government and international donors to adequately fund an appropriate safe infrastructure to enable staff to deliver accurate and timely results at whatever level of activity they are performing. There is a need for national reference laboratories to train a new cadre of mycobacterial laboratory experts. This will require the funding of appropriate individuals at these centres to train and assist in the implementation of good laboratory practice and evaluation to build sustainable capacity. Further operational research is needed to establish the optimal configuration of new technologies to determine isoniazid, rifampicin and second-line drug susceptibility in mycobacterial cultures and also, increasingly, directly on specimens. Improved integration of laboratory medicine as a core part of all tuberculosis programmes is needed to achieve and maximise the potential of new developments.

Rhodococcus and Mycobacterium Tuberculosis: masquerade or mixed infection

Rhodocci have a morphology similar to that of Mycobacterium tuberculosis (TB), and are indistinguishable from normal diphtheroid flora. Symptoms include fever, productive/non-productive cough and pleuritic chest pain. Rhodococcal infections, being resistant to routine anti-tuberculosis medications, may be misdiagnosed as drug-resistant TB, thus prompting treatment for TB with rifampicin-containing regimens that promote the emergence of resistance. We present here a sputum smear AFB-positive case who, although clinically cured, remains unresolved despite a series of technological investigations as to the cause of infection being purely rhodococci or mixed infection with M. tuberculosis.

Drug susceptibility testing of Mycobacterium tuberculosis to fluoroquinolones: first experience with a quality control panel in the Nordic-Baltic collaboration

In the first attempt to establish a quality assurance programme for susceptibility testing of Mycobacterium tuberculosis to fluoroquinolones, 20 strains with different fluoroquinolone susceptibility patterns were distributed by the Supranational Reference Laboratory in Stockholm to the other mycobacterial reference laboratories of the Nordic and Baltic countries. Susceptibility testing to fluoroquinolones was performed according to routine procedures in each laboratory. Results were compared to sequence analysis of the gyrA gene and minimal inhibitory concentration determination. Most laboratories found identical susceptibility patterns. The two resistant strains were correctly identified by all laboratories, but three laboratories each falsely reported one susceptible strain as resistant. These results indicate that the participating laboratories yield reliable results in detection of fluoroquinolone-resistant strains, although the need for a standardised quality assurance programme for drug susceptibility testing for fluoroquinolones is stressed by the strains falsely reported as resistant.

Measurement of gastric emptying by 13C-octanoic acid breath test versus scintigraphy in diabetics

In this prospective study, we compared the assessment of gastric emptying by the 13C-octanoic acid breath test to gastric emptying scintigraphy in diabetics. We also examined the relationship between gastric emptying parameters and gastric symptoms and cardiovascular autonomic function. The 13C-octanoic acid breath test and scintigraphy were performed simultaneously in 24 diabetics with a solid test meal (1 egg, doubly labelled with 91 mg 13C-octanoic acid and 50 MBq 99mTechnetium-Nanocoll, 60 g white bread, 5 g margarine and 150 ml water). At fifteen-minute intervals, breath samples were taken over 4 hours and examined by mass spectrometry. In parallel, scintigraphy was performed for 2 hours at one minute intervals. Using breath test data, gastric emptying half time (t (1/2) ), lag-phase (t lag ) and gastric emptying coefficient (GEC) were calculated. Subsequently, the correlation of these results with the equivalent data from scintigraphy were determined employing a regression method. To detect a cardiovascular autonomic neuropathy, a 24-h ECG recording was performed. The prevalence of gastrointestinal symptoms in our collective was assessed by a standardized questionnaire. There was a highly significant positive correlation of both 13C-octanoic acid breath test t (1/2) and scintigraphic t (1/2) (r = 0.8257; p < 0.0001) and 13C-octanoic acid breath test t lag and scintigraphic t lag (r = 0.6302; p < 0.001). The sensitivity of the 13C-octanoic acid breath test was 1 and the specificity was 0.73. In our study, there was no significant association of cardiovascular and gastrointestinal autonomic neuropathy. Furthermore, there was no significant relationship between the prevalence of gastrointestinal symptoms and gastric emptying disorders. We conclude that the 13C-octanoic acid breath test represents a suitable method to measure disordered gastric emptying in diabetics due to its highly significant positive correlation to scintigraphy and due to its validity. It is not possible to predict diabetic gastroparesis on the basis of other autonomic function disorders or because of dyspeptic symptoms.

[Diagnosis of hyperparathyroidism]

AIM

To preoperatively localize enlarged parathyroid glands in patients with hyperparathyroidism (HPT).

METHODS

Besides clinical and biochemical workup, high-resolution ultrasonography (US) is the most commonly used imaging method.Additionally,Tc-99m-MIBI scintigraphy in subtraction or biphasic technique, computed tomography (CT) and magnetic resonance imaging (MRI) are used.

RESULTS

US fails to detect a minimum of 10% of enlarged parathyroid glands,most commonly due to ectopic location, or difficult examination conditions, such as nodular goiter or previous surgery. If attempted US localization is unsuccessful, multiphase scintigraphy, using Tc-99m-sestamibi, can help to locate ectopic adenomas in the mediastinum. With SPECT, ademomas can be found which escape detection on planar scans due to their small size. With combined use of US and scintigraphy, a correct localization of parathyroid adenomas is possible in up to 90%. CT and MRI are of limited value due to their low specificity.

CONCLUSION

For newly diagnosed hyperparathyroidism, high-resolution US is the method of choice for localizing parathyroid adenomas. If ultrasound fails to detect a lesion, Tc-99m-MIBI scintigraphy is recommended. In patients scheduled for re-operation for recurrent or persistent HPT, a preoperative detection of a parathyroid adenoma should be attempted whenever possible, in order to minimize the extent of surgery. The role of CT or MRI is mainly to help to better anatomically localize a suspected adenoma previously detected with scintigraphy.

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.

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.