Recommendations for the diagnosis of pediatric tuberculosis

Tuberculosis (TB) is still the world's second most frequent cause of death due to infectious diseases after HIV infection, and this has aroused greater interest in identifying and managing exposed subjects, whether they are simply infected or have developed one of the clinical variants of the disease. Unfortunately, not even the latest laboratory techniques are always successful in identifying affected children because they are more likely to have negative cultures and tuberculin skin test results, equivocal chest X-ray findings, and atypical clinical manifestations than adults. Furthermore, they are at greater risk of progressing from infection to active disease, particularly if they are very young. Consequently, pediatricians have to use different diagnostic strategies that specifically address the needs of children. This document describes the recommendations of a group of scientific societies concerning the signs and symptoms suggesting pediatric TB, and the diagnostic approach towards children with suspected disease.

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.

Non Tuberculous Cutaneous Mycobacteriosis in a primary school in Rome: epidemiological and microbiological investigation

During the school years 2009-2010 and 2010-2011 a total of 25 cases of Non Tuberculous Cutaneous Mycobacteriosis (NTCM) were notified in children attending the same school with a swimming pool in Rome. Environmental microbiological and epidemiological investigations (only for suspected outbreaks in 2009-2010) were conducted. We screened students with skin lesions, and environmental samples were collected from the school area and the swimming pool. During the school year 2009-10 18 cases were clinically identified among 514 primary school children (3.50%) and all cases attended the swimming pool. Only 2 out of 18 cultures were positive for Mycobacterium chelonae complex (Group III, M. abscessus). Attack Rate for swimming pool use was 13,10% (17/130), with a Relative Risk 54,70 (95% CI: 9,4 - ∞). In February 2011 additional 7 cases of cutaneous NTM among children - who attended the same primary school and swimming pool were notified to the local public health authority followed by environmental microbiological investigation. Environmental samples were positive for NTM but not for M. abscessus. Mycobacteria are not included in water-quality criteria in Italy for this reason it is important to collect evidences of NTM cases caused by these infrequent pathogens, to be able to perform rapid risk assessment and to identify the best practices in prevention and management of such a risk.

Evaluation of Moxifloxacin ActivityIn VitroAgainstMycobacterium tuberculosis, Including Resistant and Multidrug-Resistant Strains

The new quinolone moxifloxacin was tested against 86 strains of Mycobacterium tuberculosis including 13 resistant and 4 multiresistant strains. The antimicrobial susceptibility was tested, in parallel, using two different liquid media, the radiometric Bactec 12B and the Mycobacteria Growth Indicator Tube (Becton Dickinson, USA). All strains but two were susceptible at 0.5 microg/ml of moxifloxacin; for the remaining two strains, both multidrugresistant, the minimal inhibitory concentrations (MIC) were =2 and >4 microg/ml respectively. Our data confirm the high antitubercular in vitro activity of moxifloxacin.

Impact of immigration on tuberculosis in a low-incidence area of Italy: a molecular epidemiological approach

The effects that immigration might have on the epidemiology of tuberculosis (TB) in a low-incidence area of Italy was investigated by determining, in autochthonous and immigrant TB patients, the molecular characteristics of the Mycobacterium tuberculosis complex (MTBC) isolates, which may provide information on their phylogeographical origin. A total of 1080 MTBC strains, collected during a 4- year period in Tuscany from 614 Italian-born and 466 foreign-born patients, were genotyped by spoligotyping and assigned to the different phylogeographical lineages that constitute the MTBC. The autochthonous Euro-American phylogeographical lineage, which includes the spoligotype families T, Haarlem, Latin American–Mediterranean (LAM), S and X, was highly prevalent among Italian-born patients, with a total of 477 cases (77.7%), and foreign-born TB patients, with a total of 270 cases (57.9%); 24 Italian-born (3.9%) and 141 foreign- born (30.3%) TB cases were due to MTBC genotypic families associated with distant geographical areas, i.e. East African–Indian (EAI), Beijing, Central Asian (CAS), and Mycobacterium africanum. Strains of Mycobacterium bovis and strains of undefined genotype, which are all considered together, as it is not possible to assign a specific geographical origin, accounted for 113 (18.4%) Italian cases and 55 (11.8%) foreign-born cases. A total of 79 Italian TB cases (12.9%) have been attributed to transmission from immigrants to the local population. No significant contribution to drug resistance appeared to be associated with imported MTBC strains. It is concluded that, at present, the overall impact of imported TB on public health in the low-incidence study area is relatively modest and of the same order as in other western countries.

Clinical manifestations of nontuberculous mycobacteria infections

The isolation of nontuberculous mycobacteria (NTM) from clinical specimens has become very frequent in the last years. Such organisms are typically environmental and poorly pathogenic for humans; they can, however, be responsible for opportunistic diseases in subjects presenting with various predisposing conditions. Pulmonary infections are responsible for the most frequent disease caused by NTM, although the relevance of mycobacterioses involving other parts of the body is increasing. The risk of disseminated infections characterizing immunocompromised patients is well known, and those numbers are steadily rising. The lymph nodes, cutis and soft tissues, as well as bone and joints, are also important targets of NTM infection. The problems concerning the assessment of the clinical significance of NTM, along with a consideration of the more frequent NTM pathologies, are the major objectives of this review.

Infection due to a novel mycobacterium, mimicking multidrug-resistant Mycobacterium tuberculosis

The treatment of multidrug-resistant tuberculosis (TB) requires the use, for long periods, of drugs liable to cause significant side effects. In the case of misdiagnosis of multidrug-resistant TB, the patient is exposed to toxic substances without any benefit. In low-income countries, where the microbiological diagnosis of TB relies on microscopy only, the misdiagnosis of multidrug-resistant TB is very frequent in patients persistently smear-positive despite anti-TB treatment, with the possibility of an infection due to non-tuberculous mycobacteria (NTM) being neglected. The isolation of a mycobacterium from the sputum of a Somali patient apparently confirmed the previous diagnosis of cavitary pulmonary disease. Preliminary investigations led, at first, to the strain being identified as multidrug-resistant Mycobacterium tuberculosis, with findings fully in agreement with the patient's history, which was characterized by repeated interruptions of anti-TB treatment. Thorough phenotypic and genotypic analyses led subsequently to the recognition that the strain was a previously unreported non-tuberculous mycobacterium. The patient, who was unresponsive to the anti-TB treatment, dramatically improved once a drug combination active against NTM was used. A major objective of this article is to alert the medical community to the risk, present also in settings in which sophisticated diagnostic techniques are used, that a cavitary infection due to NTM, and consequently not responding to the anti-TB standard regimen, will be mistaken for multidrug-resistant TB.

Proposal to elevate Mycobacterium avium complex ITS sequevar MAC-Q to Mycobacterium vulneris sp. nov

The Mycobacterium avium complex (MAC) consists of four recognized species, Mycobacterium avium, Mycobacterium colombiense, Mycobacterium intracellulare and Mycobacterium chimaera, and a variety of other strains that may be members of undescribed taxa. We report on two isolates of a scotochromogenic, slowly growing, non-tuberculous Mycobacterium species within the M. avium complex from a lymph node and an infected wound after a dogbite of separate patients in The Netherlands. The extrapulmonary infections in immunocompetent patients suggested a high level of virulence. These isolates were characterized by a unique nucleotide sequence in the 16S rRNA gene, 99% similar to Mycobacterium colombiense, and the MAC-Q 16S-23S internal transcribed spacer (ITS) sequence. Sequence analyses of the hsp65 gene revealed 97% similarity to M. avium. The rpoB gene sequence was 98% similar to M. colombiense. Phenotypically, the scotochromogenicity, positive semi-quantitative catalase and heat-stable catalase tests, negative tellurite reductase and urease tests and susceptibility to hydroxylamine and oleic acid set these isolates apart from related species. High-performance liquid chromatography analysis of cell-wall mycolic acid content revealed a unique pattern, related to that of M. avium and M. colombiense. Together, these findings supported a separate species status within the Mycobacterium avium complex. We propose elevation of scotochromogenic M. avium complex strains sharing this 16S gene and MAC-Q ITS sequence to separate species status, for which the name Mycobacterium vulneris sp. nov. is proposed. The type strain is NLA000700772T (=DSM 45247T=CIP 109859T).

Use of the INNO LiPA Rif.TB for detection of Mycobacterium tuberculosis DNA directly in clinical specimens and for simultaneous determination of rifampin susceptibility

The INNO LiPA Rif.TB (Innogenetics, Ghent, Belgium) is a reverse hybridization test developed to detect genetic markers of resistance to rifampin in Mycobacterium tuberculosis complex. In the present study, this test was used directly on 3,763 clinical specimens by adopting a nested amplification of the target. The specificity of the system (98.4%) was optimal, but sensitivity (69.5%) was unsatisfactory. However, when use of the system was limited to smear-positive specimens, the sensitivity rose to 91.7%. As expected, the ability of the system to predict rifampin resistance was not influenced by its direct use on clinical specimens and confirmed the favorable results repeatedly reported in the literature.

A Case-Control Study for Multidrug-Resistant Tuberculosis: Risk Factors in Four European Countries

The aim of this study was to detect risk factors for multidrug resistance in patients with pulmonary tuberculosis in four European Union countries: France, Germany, Italy, and Spain. A prospective epidemiological case control study was conducted, made up of patients with clinically diagnosed and microbiologically confirmed pulmonary tuberculosis in the four countries between 1997 and 2000. A total of 138 cases and 276 controls were studied. Considering the four countries as a whole, the most statistically significant risk factors were as follows: intravenous drug use (OR 4.68); asylum-seeker support (OR 2.55) as income factor; living in a nursing home (OR 2.05); previous tuberculosis (OR 2.03) with pulmonary location; prison (OR 2.02); known tuberculosis contacts (OR 2.01); immunosuppression other than human immunodeficiency virus (HIV) (OR 1.96); acquired immunodeficiency syndrome (AIDS) (OR 1.96); current tuberculosis with pulmonary location (OR 1.77); and health-care worker (OR 1.69). These risk factors will have to be taken into account in the European Union as a whole, as well as in each individual country, to establish a health policy of monitoring and control for these cases of multidrug resistance. Although rare, their seriousness makes them particularly important.

Isolation of a novel sequevar of Mycobacterium flavescens from the synovial fluid of an AIDS patient

This report describes the characterisation of a mycobacterium involved in a case of septic arthritis in an AIDS patient that was treated successfully with specific anti-mycobacterial drugs. The biochemical and cultural features, and the mycolic acid pattern as assessed by high-performance liquid chromatography, were fully compatible with the isolate being Mycobacterium flavescens. However, the isolate's 16S rDNA sequence differed by five nucleotides from the two known sequevars of M. flavescens, thus indicating that this isolate belonged to a new 16S rDNA sequevar.

Mutations responsible for Mycobacterium tuberculosis isoniazid resistance in Italy

SETTING

The incidence of tuberculosis (TB) and drug resistance in Italy is low compared to other countries. Mutations in several genomic regions of Mycobacterium tuberculosis are involved in the occurrence of isoniazid (INH) resistance.

OBJECTIVE

To investigate the mutations responsible for INH resistance among Italian isolates of M. tuberculosis, to assess the feasibility of predicting drug resistance using a genetic approach.

DESIGN

The mutations responsible for INH resistance were looked for in selected regions of genes katG, kasA and ndh and in the promoter regions of inhA and ahpC by nucleotide sequencing, and the results were compared with data reported in other studies.

RESULTS

Prevalent INH resistance mutations were found at codon 315 of the katG gene and at position -15 of the inhA regulatory region (respectively 37.8% and 20.0% of isolates). The prevalence of mutations at position -24 of inhA, in ahpC, and in kasA ranged from 2.2% to 4.4%. No mutations were found in 35.6% of the isolates.

CONCLUSION

The identification of INH resistance by genetic analysis of the selected regions may be inappropriate in areas with a low prevalence of TB, such as Italy, as the genetic mechanisms of resistance remain unidentified for approximately one third of the isolates.

Mycobacterial testing in hospital laboratories: results from a questionnaire survey in Italy

Between 1999 and 2001, 355 hospital laboratories in Italy were asked to complete a questionnaire addressing mycobacterial test methods, 1-year workloads and laboratory safety features. Analysis of the data showed that rapid methods for mycobacterial testing were being used by most larger laboratories; however, sub-optimal methods were still in use in small and medium-size laboratories. In a country such as Italy, which has a low prevalence of tuberculosis cases, implementation of rapid technologies, combined with regionalisation of mycobacterial diagnostic services, seems to be the most reasonable and cost-effective strategy.

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

OBJECTIVE

To collect data on non-tuberculous mycobacteria (NTM) isolated from clinical laboratories in different countries to establish: 1) whether the isolation of NTM was increasing, 2) which species were increasing, and 3) whether there was any pattern of geographical distribution.

DESIGN

In 1996, the Working Group of the Bacteriology and Immunology Section of the International Union Against Tuberculosis and Lung Disease contacted 50 laboratories in different countries for the necessary information.

RESULTS

The number of patients reported with NTM was 36099 from 14 countries. Mycobacterium avium complex, M. gordonae, M. xenopi, M. kansasii and M. fortuitum were the five species most frequently isolated. There was a significant upward trend for M. avium complex and M. xenopi. Pigmented mycobacteria predominated in Belgium, the Czech Republic and the Mediterranean coast of Spain. Non-chromogenic mycobacteria were found to be predominant in the area of the Atlantic coast of Brazil and in Turkey, the United Kingdom, Finland and Denmark.

CONCLUSIONS

There was an increase in the number of NTM isolated from clinical samples of patients. Isolation of the most frequent species is constantly changing in most of the geographical areas, and newer species are emerging due to better diagnostic techniques to detect and identify NTM.

First case of Mycobacterium haemophilum infection in an AIDS patient in Italy

Mycobacterium haemophilum, a strongly acid- and alcohol-fast bacillus belonging to the group of non-tuberculous mycobacteria was first described in 1978 as the cause of cutaneous ulcerating lesions in a woman with Hodgkin's disease. Infection due to M. haemophilum is rare but increasing in prevalence in immnunosuppressed subjects, particularly in patients with acquired immunodeficiency syndrome (AIDS) patients. The skin is the most common site of infection with erythematous or violaceous papules and/or nodules that are usually painless at first, but some elements develop into abscesses or ulcers that can become very painful. The incidence of M. haemophilum is unknown, but cases of infection have been reported in Australia, Canada, the United States, France, Israel, the United Kingdom and Taiwan; to date no cases have been reported in Italy, thus the case reported here is apparently the first one observed in our country.

Nontuberculous mycobacteria in hospital water systems: application of HPLC for identification of environmental mycobacteria

Nontuberculous mycobacteria (NTM), ubiquitous in water environments, are increasingly recognized as nosocomial pathogens. Our study reports a one-year survey of the water system of two hospitals, A and B, in a small town near Florence, Italy. NTM were found throughout the study period in both settings, but B showed a significantly higher mycobacterial load. Mycobacterium gordonae and Mycobacterium fortuitum were the most frequent species isolated. Identification was carried out by conventional techniques and by high performance liquid chromatography (HPLC) analysis of cell wall mycolic acids. HPLC profiling could be used as a first-choice method for identification of environmental mycobacteria.

Evaluation of a rapid immunochromatographic test for the serologic diagnosis of tuberculosis in Italy

OBJECTIVE

To determine specificity, sensitivity and predictive values of a rapid immunochromatographic assay (ICT tuberculosis) for the diagnosis of tuberculosis (TB) in an Italian clinical setting, and to identify tentative new guidance for the interpretation of test results.

METHODS

The ICT tuberculosis test is an immunochromatographic test based on the detection of IgG antibodies directed against five highly purified antigens secreted by Mycobacterium tuberculosis during active growth. Sera from 60 patients with active pulmonary (48 sputum smear-positive and six sputum smear-negative cases) and extrapulmonary (six cases) TB were obtained. Personal, anamnestic and clinical data were investigated and recorded for each patient. The control groups comprised 156 subjects: 40 healthy individuals, half of them Mycobacterium bovis BCG-vaccinated, and 116 patients with mycobacterial diseases other than TB (five cases), with nonmycobacterial lung diseases (30 cases), with nonmycobacterial nonlung diseases (30 cases), with nonmycobacterial diseases and rheumatoid factors positivity (30 cases), and with asymptomatic HIV infection (21 cases). For 21 individuals the test was simultaneously performed with both serum and whole blood sample. Each positive result of the ICT test was reported with regard to the number (1-4), position (A, B, C, D) and color intensity (+ to ++++) of the evidenced lines in order to assess the quality of the antibody response.

RESULTS

The overall sensitivity and specificity were 56.7% and 90.4%, respectively. The sensitivity for pulmonary TB patients was 61.1% (66.7% for smear-positive and 16.7% for smear-negative cases) and 16.7% for extrapulmonary TB patients. The difference between ICT results in pulmonary TB patients and control subjects was statistically significant (P < 0.0001). The analysis of the positive ICT tests revealed that samples with strong color intensity (>/=++) and specific antibodies bound to antigens immobilized on line D were significantly more frequent in TB patients than in controls (P = 0.001 and P= 0.027, respectively). ICT test results with the presence of at least three visible lines were more often observed in the TB patients than in controls, although not reaching statistical significance (P = 0.052). No difference was observed between the results of the ICT test performed both on serum and whole blood sample.

CONCLUSIONS

The ICT tuberculosis test was confirmed to be rapid and easy to perform without requiring special equipment, both on serum and whole blood sample. Our data, in accordance with those obtained in a previous study conducted in extra-European countries, confirmed higher sensitivities for the smear-positive TB patients than for the smear-negative TB patients, and for pulmonary TB patients than for the extrapulmonary TB patients. Data obtained on the quality of antibody response in the ICT positive samples, might be used to improve the performance of the test.

Mycobacterium elephantis: not an exceptional finding in clinical specimens

Following the recent report of new 16S rDNA sequences of Mycobacterium elephantis, three clinical strains suspected to belong to such species were investigated using biochemical and cultural tests, high performance liquid chromatography of cell wall mycolic acids and genetic sequencing. Antimicrobial susceptibility was also determined. The findings confirmed recent data concerning human isolates of this new mycobacterium and identified a new 16S rDNA sequevar for this species.

Mycobacterium doricum sp. nov

A novel mycobacterial species is described in this study. The strain was isolated from the cerebrospinal fluid of a severely immunocompromised AIDS patient. It was scotochromogenic and slow-growing. Characteristic features for its differentiation from other mycobacteria are its lipid pattern and the unique gene sequences within the hypervariable regions of the 16S rDNA. The strain shows susceptibility to current antimycobacterial drugs. The pathogenicity of the novel mycobacterium and its clinical significance are not certain, as the neurological symptoms of the patient could also be due to concomitant infection with Cryptococcus neoformans. The name Mycobacterium doricum sp. nov. is proposed for the novel mycobacterium; the type strain is strain FI-13295T (= DSM 44339T = CIP 106867T).

Burden of unidentifiable mycobacteria in a reference laboratory

Modern identification techniques at the genomic level have greatly improved the taxonomic knowledge of mycobacteria. In adjunct to nucleic acid sequences, mycobacterial identification has been endorsed by investigation of the lipidic patterns of unique mycolic acids in such organisms. In the present investigation, the routine use of high-performance liquid chromatography (HPLC) of mycolic acids, followed by the sequencing of the 16S rRNA, allowed us to select 72 mycobacterial strains, out of 1,035 screened, that do not belong to any of the officially recognized mycobacterial species. Most strains (i.e., 47) were isolated from humans, 13 were from the environment, 3 were from animals, and 9 were from unknown sources. The majority of human isolates were grown from the respiratory tract and were therefore most likely not clinically significant. Some, however, were isolated from sterile sites (blood, pleural biopsy, central venous catheter, or pus). Many isolates, including several clusters of two or more strains, mostly slow growers and scotochromogenic, presented unique genetic and lipidic features. We hope the data reported here, including the results of major conventional identification tests, the HPLC profiles of strains isolated several times, and the whole sequences of the 16S rRNA hypervariable regions of all 72 mycobacteria, may encourage reporting of new cases. The taxonomy of the genus Mycobacterium is, in our opinion, still far from being fully elucidated, and the reporting of unusual strains provides the best background for the recognition of new species. Our report also shows the usefulness of the integration of novel technology to routine diagnosis, especially in cases involving slow-growing microorganisms such as mycobacteria.

Identification of 54 mycobacterial species by PCR-restriction fragment length polymorphism analysis of the hsp65 gene

A total of 121 reference and clinical strains of both slowly and rapidly growing mycobacteria belonging to 54 species were studied for restriction fragment length polymorphism of a PCR-amplified 439-bp segment of the gene encoding the 65-kDa heat shock protein. Restriction digests were separated by 10% polyacrylamide gel electrophoresis (PAGE). By including a size standard in each sample, the restriction fragment profile was calculated using a computer-aided comparison program. An algorithm describing these 54 species (including 22 species not previously described) is proposed. We found that this assay based on 10% PAGE provided a more precise estimate than that based on agarose gel electrophoresis of the real size of restriction fragments as deduced from the sequence analysis and allowed identification of mycobacteria whose PCR-restriction fragment length polymorphism analysis patterns were unequivocally identified by fragments shorter than 60 bp.

Rapid, simple, and culture-independent detection of rpsL codon 43 mutations that are highly predictive of streptomycin resistance in Mycobacterium tuberculosis

The substitution of codon 43 in the gene rpsL is the single most common mutation found in streptomycin-resistant Mycobacterium tuberculosis. The characterization of this mutation has been hampered by the need for prior cultivation of the mycobacteria, the need for DNA sequencing, or both. In this report we describe a simple and culture-independent technique to detect this mutation directly from sputum samples, requiring little more than a polymerase chain reaction (PCR) machine and a simple agarose minigel. There is no need for labeled probes or DNA sequencing. In a preliminary test of feasibility, interpretable results were obtained from all of 16 smear-positive and 1 of 4 smear-negative, culture-positive samples. Two of two samples containing M. tuberculosis with rpsL codon 43 mutations were correctly identified.

Performance assessment of new multiplex probe assay for identification of mycobacteria

A new DNA probe assay (INNO LiPA Mycobacteria; Innogenetics, Ghent, Belgium) for the simultaneous identification, by means of reverse hybridization and line-probe technology, of Mycobacterium tuberculosis complex, Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium gordonae, the species of the Mycobacterium avium complex (MAC), Mycobacterium scrofulaceum, and Mycobacterium chelonae was evaluated on a panel of 238 strains including, besides representatives of all the taxa identifiable by the system, a number of other mycobacteria, some of which are known to be problematic with the only other commercial DNA probe system (AccuProbe; Gen-Probe, San Diego, Calif.), and two nocardiae. The new kit, which includes a control probe reacting with the whole genus Mycobacterium, correctly identified 99.6% of the strains tested; the one discrepancy, which remained unresolved, concerned an isolate identified as MAC intermediate by INNO LiPA Mycobacteria and as Mycobacterium intracellulare by AccuProbe. In five cases, because of an imperfect checking of hybridization temperature, a very slight, nonspecific, line was visible which was no longer evident when the test was repeated. Two strains whose DNA failed amplification at the first attempt were regularly identified when the test was repeated. Interestingly, the novel kit dodged all the pitfalls presented by the strains giving anomalous reactions with AccuProbe. A unique feature of INNO LiPA Mycobacteria is its ability to recognize different subgroups within the species M. kansasii and M. chelonae, while the declared overlapping reactivity of probe 4 with some M. kansasii and Mycobacterium gastri organisms and of probe 9 with MAC, Mycobacterium haemophilum, and Mycobacterium malmoense, may furnish a useful aid for their identification. The turnaround time of the method is approximately 6 h, including a preliminary PCR amplification.

Detection of embB codon 306 mutations in ethambutol resistant Mycobacterium tuberculosis directly from sputum samples: a low-cost, rapid approach

Substitutions of codon 306 in the gene embB are the most common mutations found in ethambutol resistant Mycobacterium tuberculosis. The characterization of these mutations has been hampered by the need for prior cultivation of the mycobacteria, or the need for DNA sequencing, or both. Here, we describe a simple and culture-independent technique to detect embB codon 306 mutations directly from sputum samples, requiring little more than a PCR machine and a simple agarose minigel. There is no need for labelled probes or DNA sequencing. In a preliminary test of feasibility, interpretable results were obtained from 21 of 24 selected sputum samples, 12 of which were determined to contain ethambutol resistant M. tuberculosis after culture. All of six samples with embB codon 306 mutations were correctly identified. Although an exact validation of this technique is beyond the scope of this technical report, we conclude from well-known embB codon 306 mutation prevalence figures that approximately one half of EMB resistant cases could already be predicted within 2 working days, with little equipment or hands-on time needed, instead of weeks required for conventional resistance testing.

Characterization of Mycobacterium bohemicum isolated from human, veterinary, and environmental sources

Chemotaxonomic and genetic properties were determined for 14 mycobacterial isolates identified as members of a newly described species Mycobacterium bohemicum. The isolates recovered from clinical, veterinary, and environmental sources were compared for lipid composition, biochemical test results, and sequencing of the 16S ribosomal DNA (rDNA) and the 16S-23S rDNA internal transcribed spacer (ITS) regions. The isolates had a lipid composition that was different from those of other known species. Though the isolates formed a distinct entity, some variations were detected in the features analyzed. Combined results of the phenotypic and genotypic analyses were used to group the isolates into three clusters. The major cluster (cluster A), very homogenous in all respects, comprised the M. bohemicum type strain, nine clinical and veterinary isolates, and two of the five environmental isolates. Three other environmental isolates displayed an insertion of 14 nucleotides in the ITS region; they also differed from cluster A in fatty alcohol composition and produced a positive result in the Tween 80 hydrolysis test. Among these three, two isolates were identical (cluster B), but one isolate (cluster C) had a unique high-performance liquid chromatography profile, and its gas liquid chromatography profile lacked 2-octadecanol, which was present in all other isolates analyzed. Thus, sequence variation in the 16S-23S ITS region was associated with interesting variations in lipid composition. Two of the isolates analyzed were regarded as potential inducers of human or veterinary infections. Each of the environmental isolates, all of which were unrelated to the cases presented, was cultured from the water of a different stream. Hence, natural waters are potential reservoirs of M. bohemicum.

Comparison of Mycobacterium tuberculosis susceptibility testing performed with BACTEC 460TB (Becton Dickinson) and MB/BacT (Organon Teknika) systems

The recently introduced automated culture systems MB/BacT (Organon Teknika, Belgium) was compared with radiometric BACTEC 460TB (Becton Dickinson, USA) to test antimicrobial susceptibility of Mycobacterium tuberculosis to first line drugs. On 113 strains 97.5% agreement was obtained, with the difference being not significant. Concordance was practically complete for the most important drugs, isoniazid and rifampin. The two methods however significantly differed for the time needed to complete the test; in fact MB/BacT required on the average five days more than BACTEC 460TB. Despite the delay in the completion of the test, the excellent reliability along with the elimination of radioactivity and full automation make MB/BacT an attractive alternative for susceptibility testing of M. tuberculosis.

Disseminated Mycobacterium terrae infection in a patient with advanced human immunodeficiency virus disease

Mycobacterium terrae has been rarely implicated in human disease and never in patients infected with human immunodeficiency virus (HIV). We describe an HIV-infected patient with disseminated infection by M. terrae with pulmonary and cutaneous clinical manifestations. M. terrae was isolated from both sputum and urine, and identified by both conventional tests and high-performance liquid chromatography. Clinical and microbiological characteristics of this case are compared with those reported in the literature.

Activity of 16 antimicrobial agents against drug-resistant strains of Mycobacterium tuberculosis

The in vitro activity of 16 antimicrobial agents against 46 drug-resistant strains of Mycobacterium tuberculosis recently isolated from Italian patients was determined. As for first-line antituberculosis drugs, while isoniazid was ineffective against all the strains tested, resistance to streptomycin, rifampicin, pyrazinamide, and ethambutol was 80.4%, 71.7%, 39.1%, and 8.7%, respectively. Among second-line antituberculous drugs, resistance to ciprofloxacin, ofloxacin, and sparfloxacin and to amikacin and kanamycin was around 20%. About 10% of the strains were resistant to capreomycin and cycloserine and 4.3% were resistant to ethionamide; no strain was found to be resistant to thiacetazone, para-aminosalicylic acid, and viomycin. Although all strains displayed a rather continuous distribution of minimal inhibitory concentrations (MICs), a bimodal distribution was observed for rifampicin, amikacin, and kanamicin, with very high MIC values for resistant strains; relatively low MICs were found for fluoroquinolone-resistant strains. Among the small number of strains resistant to second-line agents, low resistant levels were observed. Restriction fragment length polymorphism analysis showed few strain clusters with resistance to first-line antituberculous drugs and aminoglycosides, fluoroquinolones, or both. Altogether, these results showed that second-line agents were still active against the isoniazid-resistant and multiply first-line resistant strains tested, with none or low resistance levels; these observations can be of importance for the treatment of multidrug-resistant tuberculosis in Italy.

Mycobacterium xenopi and related organisms isolated from stream waters in Finland and description of Mycobacterium botniense sp. nov

Three scotochromogenic Mycobacterium xenopi-like organisms were isolated from stream waters in Finland. These strains grew at 36-50 degrees C but not at 30 degrees C. One of the three strains was fully compatible with the M. xenopi type strain according to GLC-MS, biochemical tests, and 16S rDNA and 16S-23S rDNA internal transcribed spacer (ITS) sequencing. Two of the strains closely resembled M. xenopi in lipid analyses and biochemical tests, but analysis by GLC-MS verified the presence of two new marker fatty acids (2,4,6,x-tetramethyl-eicosanoic acid and 2,4,6,x,x-pentamethyl-docosanoic acid). The 16S rDNA and ITS region sequences of these two strains differed from those of M. xenopi and other previously described mycobacterial sequences. Therefore, the strains are regarded as new species of slow-growing mycobacteria, for which the name Mycobacterium botniense sp. nov. is proposed. The chemical, physical and microbiological quality of the water reservoirs of M. xenopi and M. botniense are described. As far as is known, this is the first time that M. xenopi has been isolated from natural waters. The strains of M. botniense sp. nov. (E347T and E43) have been deposited in the ATCC as strains 700701T and 700702, respectively.

Use of BACTEC MGIT 960 for recovery of mycobacteria from clinical specimens: multicenter study

The BACTEC MGIT 960 instrument is a fully automated system that exploits the fluorescence of an oxygen sensor to detect growth of mycobacteria in culture. Its performance was compared to those of the radiometric BACTEC 460 instrument and egg-based Lowenstein-Jensen medium. An identical volume of sample was inoculated in different media, and incubation was carried out for 6 weeks with the automatic systems and for 8 weeks on solid media. A total of 2,567 specimens obtained from 1,631 patients were cultured in parallel. Mycobacteria belonging to nine different taxa were isolated by at least one of the culture systems, with 75% of them being represented by Mycobacterium tuberculosis complex. The best yield was obtained with the BACTEC 460 system, with 201 isolates, in comparison with 190 isolates with the BACTEC MGIT 960 system and 168 isolates with Lowenstein-Jensen medium. A similar but not significant difference was obtained when the most-represented organisms, the M. tuberculosis complex, Mycobacterium xenopi, and the Mycobacterium avium complex, were analyzed separately and when combinations of a solid medium with the BACTEC MGIT 960 system and with the BACTEC 460 system were considered. The shortest times to detection were obtained with the BACTEC MGIT 960 system (13.3 days); 1.5 days earlier than that with the BACTEC 460 system (14.8 days) and 12 days earlier than that with Lowenstein-Jensen medium (25.6 days). The BACTEC MGIT 960 system had a contamination rate of 10.0%, intermediate between those of the radiometric system (3.7%) and the egg-based medium (17.0%). We conclude, therefore, that the BACTEC MGIT 960 system is a fully automated, nonradiometric instrument that is suitable for the detection of growth of tuberculous and other mycobacterial species and that is characterized by detection times that are even shorter than that of the "gold standard," the BACTEC 460 system. The contamination rate was higher than that for the radiometric BACTEC 460 system and needs to be improved.

Mycobacterium tusciae sp. nov

A new, slow-growing, scotochromogenic mycobacterium was isolated from a lymph node of an immunocompromised child and subsequently from tap water and from a respiratory specimen of a patient with chronic fibrosis. Alcohol-acid-fastness, lipid patterns and the G + C content clearly support the placement of this organism in the genus Mycobacterium. The isolates grew very slowly at temperatures ranging from 25 to 32 degrees C and showed activities of nitrate reductase, catalase, urease, arylsulfatase and Tween 80 hydrolysis. The organism was susceptible to all antimycobacterial drugs tested. The 16S rDNA sequence was unique and phylogenetic analysis placed the organism close to fast-growing species such as Mycobacterium farcinogenes, Mycobacterium komossense and Mycobacterium aichiense. These data support the conclusion that the isolates represent a new mycobacterial species, for which the name Mycobacterium tusciae sp. nov. is proposed. The type strain is strain FI-25796T; a culture of this strain has been deposited in the DSMZ as strain DSM 44338T.

Culture-independent prediction of isoniazid resistance in Mycobacterium tuberculosis by katG gene analysis directly from sputum samples

BACKGROUND

The molecular prediction of isoniazid (INH) resistance in Mycobacterium tuberculosis is hampered by the need for specialized equipment, expertise, high costs, a limited range of detectable mutations, or several of these factors. The rationale for the study was to find a practical alternative and to demonstrate generally valid problems.

METHODS AND RESULTS

DNA extracted from decontaminated sputum pellets was used to amplify a 0.26 kb target sequence within the katG gene. Mutations of codon 315, frequently found in isoniazid-resistant isolates, could be discriminated in a simple agarose minigel format following an AciI digest of the nested polymerase chain reaction (PCR) product. Within a panel of 22 sputum samples, INH resistance could be predicted in 5 of 10 samples containing isoniazid-resistant M. tuberculosis. The protocol is robust, requires little expertise and no specialized equipment, and provides the test results within 2 days.

CONCLUSION

The results show the feasibility to rapidly and easily detect mutations highly predictive of isoniazid resistance. Nevertheless, this, like any other molecular resistance prediction test, is affected by often neglected factors, including mutation prevalences, the phenomenon of heteroresistance, and a possible bias toward one's own method.

HPLC does not differentiate Mycobacterium paratuberculosis from Mycobacterium avium

HPLC, which is gaining its place as identification tool in mycobacteriology laboratories, has been proposed to distinguish Mycobacterium paratuberculosis from Mycobacterium avium. We had reported no significant difference between M. avium and M. paratuberculosis reference strain ATCC 19698. Because of the advantages offered by such a method, we enlarged our observations to include more isolates of M. paratuberculosis. Within the double cluster of peaks obtained by both M. avium and M. paratuberculosis, we could not find a consistent difference typical of M. paratuberculosis. Therefore, the present study confirmed that M. avium and M. paratuberculosis could not be distinguished by HPLC, raising doubts of a straightforward use of HPLC to identify M. paratuberculosis.

Primary tuberculosis of the penis

We present a case of primary tuberculosis of the inner lining of the prepuce in a 63-year-old man. The condition resembled carcinoma. The diagnosis was based on histopathology and on M. tuberculosis culture. Successful treatment was by a combined medical and surgical approach. The rarity of the case is emphasized.

Multicenter evaluation of two commercial amplification kits (Amplicor, Roche and LCx, Abbott) for direct detection of Mycobacterium tuberculosis in pulmonary and extrapulmonary specimens

Direct detection of Mycobacterium tuberculosis was performed in parallel with the Amplicor M. tuberculosis test (Roche Diagnostic System, USA) and the LCx M. tuberculosis (Abbott Diagnostic Division, USA) on 697 samples, collected from 481 patients, in three different Italian laboratories. Though both systems are licensed only for pulmonary specimens, 113 extrapulmonary specimens (represented mainly by pleural fluids, cerebrospinal fluids and urines) were included in the study. Amplification results were compared with acid-fast microscopy, culture, and identification of isolates. Final clinical diagnosis was used to resolve discrepant results. M. tuberculosis was detected in 105 specimens by both assays, whereas 561 were agreeing negatives; 21 and 6 of the remaining true-positive samples scored positive with LCx only and with Amplicor only, respectively. There were three false-positives with LCx and one false-positive with Amplicor. The diagnostic sensitivity of both methods was significantly better when only respiratory specimens were considered (78% versus 59% in nonrespiratory samples with Amplicor, and 88% versus 65% with LCx). Our data reveal a significantly better sensitivity of the LCx (p = 0.026) and a slight better specificity of the Amplicor assay. It is noteworthy that 16 of the 21 Amplicor-negative specimens in which LCx detected M. tuberculosis were culture negative, thus suggesting that the higher diagnostic sensitivity of the latter assay is attributable to its better analytical sensitivity. However, the majority of such samples originated from patients under antimicrobial treatment, which makes uncertain the clinical significance of such increased sensitivity. Considering true-positive for LCx and true-negative for Amplicor, the 16 culture-negative/LCx-positive/Amplicor-negative specimens resulted true-positives after the resolution of discrepancies, the final overall sensitivity and specificity values of the LCx assay were not significantly different from the ones of the Amplicor assay.