An improved extraction and nonradioactive thin-layer chromatography detection method of mycolic acid / 生物工程学报

Mycolic acids (MAs), i.e. 2-alkyl, 3-hydroxy long-chain fatty acids, are the hallmark of the cell envelope of Mycobacterium tuberculosis and are related with antibiotic resistance and host immune escape. Nowadays, they've become hot target of new anti-tuberculosis drugs. There are two main methods to detect MAs, 14C metabolic labeling thin-layer chromatography (TLC) and liquid chromatograph mass spectrometer (LC-MS). However, the user qualification of 14C or the lack of standards for LC-MS hampered the easy use of this method. TLC is a common way to analyze chemical substance and can be used to analyze MAs. In this study, we used tetrabutylammonium hydroxide and methyl iodide to hydrolyze and formylate MAs from mycobacterium cell wall. Subsequently, we used diethyl ether to extract methyl mycolate. By this method, we can easily extract and analyze MA in regular biological labs. The results demonstrated that this method could be used to compare MAs of different mycobacterium in different growth phases, MAs of mycobacteria treated by anti-tuberculosis drugs or MAs of mycobacterium mutants. Therefore, we can use this method as an initial validation for the changes of MAs in researches such as new drug screening without using radioisotope or when the standards are not available.

Biomarcadores en tuberculosis / Biomarkers in tuberculosis

Resumen Los métodos diagnósticos clásicos para la tuberculosis son de baja sensibilidad o son muy lentos en la obtención de resultados (baciloscopía, cultivo de Koch). De ahí nace la necesidad de nuevos métodos diagnósticos para esta enfermedad. Los biomarcadores surgen como una opción a esta problemática, con un buen rendimiento diagnóstico, costo y accesibilidad. Ellos permiten identificar la respuesta inflamatoria y/o metabólica del huésped, extrapolando la presencia de Mycobacterium tuberculosis; o identifican moléculas propias del patógeno. En la presente revisión se describen biomarcadores que presentan un buen rendimiento diagnóstico basados en metodologías de investigación de alto nivel (estudio de cohortes, prospectivos, muestreo consecutivo o aleatorizado, comparación de rendimiento diagnóstico frente a cultivo). Es necesario el desarrollo de estas nuevas técnicas con el fin de realizar el diagnóstico precoz de la enfermedad y lograr así su tan ansiada eliminación.

The classical laboratory diagnostic methods for tuberculosis have a low sensitivity or take a long time to know their results. New methods are underway. Biomarkers are a good option to improve our diagnostic approach to this disease. They have good performance, low cost and accessibility. They identify a patient's inflammatory or metabolic response to Mycobacterium Tuberculosis or identifies molecules that are typical of the pathogen. In this paper we sum up the biomarkers with a good diag-nostic performance described in well design investigations. Early diagnosis with these new techniques should contribute to the elimination of the disease.

Acid-Fastness of Histoplasma in Surgical Pathology Practice

BACKGROUND: Histoplasmosis (HP) is diagnosed by visualizing intracellular microorganisms in biopsy and/or culture. Periodic-acid Schiff (PAS) and Gomori methenamine silver (GMS) staining methods are routinely used for identification. The acid-fast property of Histoplasma was identified decades ago, but acid-fast staining has not been practiced in current surgical pathology. Awareness of the acid-fast property of Histoplasma, which is due to mycolic acid in the cell wall, is important in distinguishing Histoplasma from other infective microorganisms. Here, we examined acid-fastness in previously diagnosed cases of Histoplasma using the Ziehl-Neelsen (ZN) stain and correlated those findings with other known fungal stains. METHODS: All cases diagnosed as HP were retrieved and reviewed along with ZN staining and other fungal stains. We also stained cases diagnosed with Cryptococcus and Leishmania as controls for comparison. RESULTS: A total of 54 patients ranging in age from 11 to 69 years were examined. The most common sites of infection were the skin, adrenal tissue, and respiratory tract. Of the total 43 tissue samples, 20 (46.5%) stained positive with the ZN stain. In viable cases, a significant proportion of microorganisms were positive while necrotic cases showed only rare ZN-positive yeasts. In comparison to PAS and GMS stains, there was a low burden of ZN-positive yeasts. Cryptococcus showed characteristic ZN staining and all cases of Leishmania were negative. CONCLUSIONS: Although the morphology of fungal organisms is the foundation of identification, surgical pathologists should be aware of the acid-fast property of fungi, particularly when there is the potential for confusion with other infective organisms.

An Effective Method of RNA Extraction from Mycobacterium tuberculosis / 대한임상미생물학회지

In the RNA-based study, it is important to extract high-quality RNA. However, RNA extraction from Mycobacterium tuberculosis is problematic due to its thick, waxy cell wall rich in mycolic acid, which renders the cells resistant to lysis. Using TRIzol reagent and several powerful bead-beating steps, a high quantity of RNA was obtained.

A Novel Synthetic Mycolic Acid Inhibits Bronchial Hyperresponsiveness and Allergic Inflammation in a Mouse Model of Asthma

PURPOSE: Recognition of microbes is important to trigger the innate immune system. Mycolic acid (MA) is a component of the cell walls of mycobacteria such as Mycobacterium bovis Bacillus Calmette-Guerin. MA has immunogenic properties, which may modulate the innate and adaptive immune response. This study aimed to investigate whether a novel synthetic MA (sMA) inhibits allergic inflammatory responses in a mouse model of asthma. METHODS: BALB/c mice were injected intraperitoneally with sMA followed by sensitization and challenge with ovalbumin (OVA). Mice were examined for bronchial hyperresponsiveness (BHR), the influx of inflammatory cells into the lung tissues, histopathological changes in the lungs and CD4+CD25+Foxp3+ T cells in the spleen, and examined the response after the depleting regulatory T cells (Tregs) with an anti-CD25mAb. RESULTS: Treatment of mice with sMA suppressed the asthmatic response, including BHR, bronchoalveolar inflammation, and pulmonary eosinophilic inflammation. Anti-CD25mAb treatment abrogated the suppressive effects of sMA in this mouse model of asthma and totally depleted CD4+CD25+Foxp3+ T cells in the spleen. CONCLUSIONS: sMA attenuated allergic inflammation in a mouse model of asthma, which might be related with CD4+CD25+Foxp3+ T cell.

Lepromatous leprosy patients produce antibodies that recognise non-bilayer lipid arrangements containing mycolic acids

Non-bilayer phospholipid arrangements are three-dimensional structures that form when anionic phospholipids with an intermediate structure of the tubular hexagonal phase II are present in a bilayer of lipids. Antibodies that recognise these arrangements have been described in patients with antiphospholipid syndrome and/or systemic lupus erythematosus and in those with preeclampsia; these antibodies have also been documented in an experimental murine model of lupus, in which they are associated with immunopathology. Here, we demonstrate the presence of antibodies against non-bilayer phospholipid arrangements containing mycolic acids in the sera of lepromatous leprosy (LL) patients, but not those of healthy volunteers. The presence of antibodies that recognise these non-bilayer lipid arrangements may contribute to the hypergammaglobulinaemia observed in LL patients. We also found IgM and IgG anti-cardiolipin antibodies in 77% of the patients. This positive correlation between the anti-mycolic-non-bilayer arrangements and anti-cardiolipin antibodies suggests that both types of antibodies are produced by a common mechanism, as was demonstrated in the experimental murine model of lupus, in which there was a correlation between the anti-non-bilayer phospholipid arrangements and anti-cardiolipin antibodies. Antibodies to non-bilayer lipid arrangements may represent a previously unrecognised pathogenic mechanism in LL and the detection of these antibodies may be a tool for the early diagnosis of LL patients.

Lung Infection Caused by Mycobacterium riyadhense Confused with Mycobacterium tuberculosis: The First Case in Korea

A slowly growing, non-chromogenic mycobacterial strain was isolated from sputum and bronchial lavage fluid samples of a patient presenting with productive cough, blood-tinged sputum, low-grade fever, and weakness. A positive acid-fast bacilli sputum smear result prompted the initiation of an anti-tuberculosis regimen. Multiplex real-time PCR showed a negative result for Mycobacterium tuberculosis complex and a positive result for nontuberculous mycobacteria. The DNA chip test confirmed this organism as a member of the genus Mycobacterium, but could not specify the species. Interestingly, the mycolic acid patterns obtained by HPLC nearly overlapped with those of M. simulans. The sequences of the Mycobacterium 16S rRNA gene and 16S-23S internal transcribed spacer region were unique and were found to have 100% similarity with those of M. riyadhense. After a review of the literature, we report this case as the first Korean case of M. riyadhense lung infection.

Distribution and Clinical Significance of Nontuberculous Mycobacteria Identified by High Performance Liquid Chromatography in Clinical Specimens / 대한임상미생물학회지

BACKGROUND: Infections caused by nontuberculous mycobacteria (NTM) are significantly increasing over the last decade. Due to the uncertainty in the clinical significance of these organisms, their effective diagnosis and treatment has been challenging. The purpose of this study was to investigate the distribution and clinical significance of NTM in clinical specimens. METHODS: Acid-fast culture positive 3,107 clinical specimens were identified by mycolic acid analysis using high performance liquid chromatography (HPLC.) The HPLC patterns of 384 NTM strains were compared with those of standard mycobacterium species. Clinical significance of NTM was investigated by a retrospective study including acid-fast stain and culture, medical history, symptoms and signs, radiological and other laboratory findings, pathologic findings, response to treatment, and follow-up study, and was confirmed according to the guideline of American Thoracic Society. RESULTS: Among the 3,107 Mycobacterium-positive specimens, 384 (12.4%) were found to be positive for NTM. Of these, 367 (95.6%) were successfully identified by HPLC as 19 different species, each of which comprising 0.3% to 15.9% of the total NTM, Studies on the pathogenic role of NTM showed that 0~79.6% of each species or 0~100% of isolates from each specimen could be considered clinically significant. CONCLUSION: HPLC method is highly discriminative for the identification of NTM in clinical specimens. When NTM is isolated from clinical specimens in the Ulsan area, the findings from this study could serve as a database on which to determine its clinical significance depending on species type and also specimen type.

Identification of Mycobacteria Species by HPLC and Species Distribution during Five Years at Ulsan University Hospital / 대한진단검사의학회지

BACKGROUND: Infections caused by mycobacteria have been significantly increasing. Due to the difficulty of making a decision about the pathogenicity of mycobacteria, species-level identification is very important for patients' diagnosis and treatment. The purpose of this study was to identify mycobacteria species using a high performance liquid chromatography (HPLC) method and to provide an initial database for the distribution of mycobacteria in Korea. METHODS: Acid fast bacteria isolated from 3,107 clinical specimens were identified by mycolic acid analysis using HPLC. The HPLC patterns were compared with those of standard mycobacteria species. RESULTS: The HPLC patterns were divided into single, double, and triple cluster groups, each group comprising 9, 20, and 4 species, respectively. Mycobacteria and non-tuberculous mycobacteria (NTM) were identifies by HPLC at the rates of 99.5% and 95.6%, respectively. NTM was isolated in 12.4% of the mycobacteria positive specimens. This study also found that there were 20 different NTM species with the distribution of each species ranging from 0.3% to 15.9% of the total NTM. While the rate of NTM has been increasing in Korea, M. avium-intracellulare, M. fortuitum, and M. chelonae are relatively decreasing, and M. kansasii and M. gordonae are relatively increasing. CONCLUSIONS: HPLC method was highly discriminative for the identification of NTM in clinical specimens.

Importância do diagnóstico laboratorial na busca de casos de tuberculose em um hospital psiquiátrico / Searching tuberculosis cases in a psychiatric hospital: importance of laboratory diagnosis

Durante o período de fevereiro a agosto de 2002, a pesquisa de M. tuberculosis foi realizada entre 74 internos de um Hospital Psiquiátrico no interior do Estado de Goiás - Brasil. Micobactérias foram isoladas de cinco (6,8 %) dos pacientes analisados, sendo identificados quatro Mycobacterium tuberculosis e um Mycobacterium chelonae. A baciloscopia foi positiva apenas para a amostra de escarro contendo M. chelonae. O cultivo possibilitou o isolamento de M. tuberculosis a partir de espécimes clínicos de quatro pacientes com baciloscopia negativa. As micobactérias foram identificadas por meio de metodologia clássica, análise de ácidos micólicos e biologia molecular (PCR). A técnica de PCR, por tratar-se de um método mais sensível e específico, detectou M. tuberculosis em uma cultura em que apenas M. chelonae foi identificado por meio de técnicas convencionais. Os quatro isolados de M. tuberculosis foram sensíveis a isoniazida e rifampicina no método das proporções de sensibilidade as drogas, empregado neste trabalho

Linfadenitis causada por Mycobacterium malmoense en paciente infectado con virus de inmunodeficiencia humana / Lymphadenitis caused by Mycobacterium malmoense in HIV infected patient

Se reporta el primer caso cubano de micobacteriosis causada por Mycobacterium malmoense en un paciente infectado por el virus de inmunodeficiencia humana (VIH), el cual presentaba adenopatías ulcerativas submandibulares. A partir de las muestras tomadas de las lesiones ulceradas, se aisló una cepa de micobacteria no pigmentada de crecimiento lento, perteneciente al grupo I de Runyon, posteriormente fue clasificada por test bioquímico y por el análisis de las fracciones de ácidos micólicos, como Mycobacterium malmoense.

Micobacterias no tuberculosas recientemente identificadas en humanos / Non-tuberculous mycobacteria recently identified in humans

Historically, the taxonomy of the nontuberculous mycobacteria (NTM) has relied upon the grouping of organisms based on phenotypic characterizations, DNA-DNA homology studies, and chemotaxonomic studies which analyze mycolic acids and fatty acids by methods including high performance liquid chromatography (HPLC), gas liquid chromatography (GLC), and thin layer chromatography (TLC). Unfortunately, few laboratories were equipped to perform these studies. For the past two decades, however, the comparison of relatedness of the 16S rRNA gene sequence has become the standard for new species identification. The ease with which this is performed and compared to established species maintained in public data bases has resulted in a dramatic increase in the number of NTM species. New species are being described each year, and the number of NTM species is now almost 100. The present article summarizes some salient laboratory and clinical identifying characteristics of these newly described species.

Históricamente, la taxonomía de las micobacterias no tuberculosas (MNT) ha dependido del agrupamiento de organismos basado en caracterizaciones fenotípicas, ensayos de homología ADN-ADN, y estudios quimiotaxonómicos que analizan los ácido micólicos y los ácidos grasos a través de métodos que incluyen la cromatografía líquida de alta resolución, la cromatografía gas-líquido y la cromatografía de capa fina. Desafortunadamente, hay pocos laboratorios equipados como para poder realizar estos estudios. Sin embargo, durante las últimas dos décadas, la comparación de la relación de las secuencias genéticas del ARNr 16S se ha transformado en el estándar para la identificación de nuevas especies. La facilidad con que se la puede realizar y comparar con especies establecidas en bases de datos públicas produjo gran incremento en el número de especies de MNT. Cada año se detectan nuevas especies, y actualmente el número de MNT es de casi 100. El presente artículo resume algunas características clínicas y de laboratorio sobresalientes de las especies recientemente descritas.

Comparison of Mycobacterial Culture by Mycobacterium Growth Indicator Tube and Ogawa Media / 대한임상미생물학회지

BACKGROUND: Mycobacterial disease is still greatly concerned in the developing and industrialized countries. Ogawa media has been used to diagnose mycobacterial disease in Korea in spite of a low sensitivity and long incubation time. Mycobacterium Growth Indicator Tube (MGIT) 960 system has been developed to overcome the pitfalls of Ogawa media. So, we investigated improvement in dectection rate and the detection time of mycobacteria using the MGIT 960 system along with 3% Ogawa media. METHODS: A total of 8,045 clinical specimens referred to the department of laboratory medicine in Ulsan University Hospital from January in 2001 to June in 2002 were cultured for mycobacteria. Specimens were processed with the NALC-NAOH (final concentration of NaOH: 1%) and inoculated into both MGIT and Ogawa media. Mycolic acid in the cultured products were analyzed by High performance liquid chromatography to discriminate between Mycobacterium tuberculosis and nontuberculous mycobacteria. RESULTS: Of 8,045 clinical specimens cultured, mycobacteria grew in 957 (11.9%) specimens, 840 (87.8%) M. tuberculosis and 117 (12.2%) nontuberculous mycobacteria. Mycobacteria were detected in 939 specimens (98.1%) by MGIT and 771 (80.6%) specimens by Ogawa media; 753 (78.7%) were detected by both media, 186 (19.4%) by MGIT only, and 18 (1.9%) by Ogawa media only. Mycobacteria were detected in 11.7 days by MGIT 960 and 28.4 days by Ogawa media. CONCLUSIONS: The detection rate and detection time of mycobacteri are improved considerably by the MGIT system; however a combined use of MGIT system and Ogawa media is the most ideally recommended for increasing the detection rate and shortening the detection time.

Isolation and identification of mycobacteria from livestock specimens and milk obtained in Brazil

The prevalence of Mycobacterium bovis and other mycobacterial species in livestock specimens and milk was evaluated. An emphasis was placed upon the distribution of these organisms in milk that is readily available to the public that was either untreated, pasteurized, or treated using ultra high temperature. Twenty-two pathologic specimens from livestock (bovine, swine and bubaline) in five Brazilian states and 128 bovine milk samples from retail markets in the State of São Paulo were examined for mycobacteria. Identification was made by classical biochemical tests, thin layer chromatography of mycolic acids and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Mycobacteria were isolated from 15 (68.2 percent) caseous lesions and from 23 (18 percent) milk samples. Eleven isolates were identified as M. bovis, and the remaining 27 nontuberculous mycobacterial isolates were represented by five species and six unidentified rapidly growing mycobacterial strains. The data demonstrate that animal products in Brazil are frequent reservoirs of mycobacteria and may pose a risk to the public

Planejamento racional de tuberculostáticos com base na estrutura dos ácidos micólicos da parede celular do Mycobacterium tuberculosis / Rational design of tuberculostatic based on the structure of mycolic acids of the cell wall of Mycobacterium tuberculosis

Os ácidos micólicos, principais componentes da parede celular do M. tuberculosis, são alvos específicos para o planejamento de novos agentes potenciais contra a tuberculose (TB) e o estudo de seu processo biossintético é de importância fundamental no desenvolvimento de inibidores mais seletivos. À vista de tal fato, desenvolveu-se estudo utilizando técnicas de modelagem molecular (CADD) com o objetivo de contribuir para o planejamento racional de protótipos de atividade tuberculostática potencial, com base em análogos estruturais da isoniazida (INH), cujo mecanismo de ação está ligado à inibição da síntese de ácidos micólicos...

Biochemical effects of sparfloxacin on cell envelope of mycobacteria.

Sparfloxacin, a difluorinated quinolone is a potent anti-mycobacterial agent used in the treatment of mycobacterial infections. We have investigated whether sparfloxacin had other, more subtle effects on mycobacteria besides its interaction with DNA gyrase that could contribute to its therapeutic efficacy. Mycobacterium smegmatis cells grown in media with sub-inhibitory concentration of sparfloxacin were observed to have significant reduction in the biosynthesis of vital macromolecules, as shown by the incorporation of various radiolabelled precursors. The analysis of subcellular distribution of phospholipids of sparfloxacin-treated cells demonstrated an increase in the cell membrane and reduction in the cell wall, suggesting changes in the cell envelope architecture by sparfloxacin. Significant changes were also observed in other chemical constituents of the cell wall, especially in the arabinose and glucosamine contents. Mycolic acids, the major component of mycobacterial cell wall were reduced in the presence of MIC50 of sparfloxacin. There was a decrease in the limiting fluorescence intensity (Fmax) of 1-anilinonaphthalene 8-sulfonate (ANS) indicating alterations in the organization and conformation of mycobacterial cell surface. These results suggest that the mechanism of action of anti-mycobacterial action of sparfloxacin involves mycobacterial cell envelope.

Identification of mycobacteria by mycolic acid pattern

Background. Tuberculosis caused by Mycobacterium tuberculosis is a public health problem which has increased in importance during the last 12 years, due in part to the increasing number of cases cuased by the association of acquired immunodeficiency syndrome (AIDS) and the appearance of multiple drug-resistant strains. Other mycobacteria which are often indistinguishable from tuberculosis have also increased. Methods. Mycolic acid patterns were obtained from 53 clinical isolated of sputum, cerebrospinal fluid, bronchial washing, corneal ulcer, and bone marrow, as well as from 11 acid-fast stain smear-positive clinical specimens. Standardized mycolic acid extraction method was used to ensure the maximal extraction of mycolic acid derivates to enhace the sensitivity of the method. A chromatographic column different from what others have employed and a different gradient elution from those reported in the literature were used, making a correlation between retention times of the chromatographic peaks obtained in this study and those previously reported for mycolic acid patterns from a strain of Mycobacterium avium necessary. Then, a comparison of retention times of mycolic acid pattern obtained in this study and those previously reported in the literature was carried out. Strains were identified as Mycobacterium tuberculosis complex, Mycobacterium avium complex, Mycobacterium fortuitum, Mycobacterium chelonae and Mycobacterium kansasii in less than 24 hours. Results. In direct analysis of acid-fast stain smearpositive from 1+ to 4+ specimens, mycolic acid patterns were identified as Mycobacterium tuberculosis complex, Mycobacterium avium complex, Mycobacterium chelonae, and Mycobacterium kansasii, with a strong signal even in light 1+ positive samples. conclusions: The results showed that identification of mycobacteria through mycolic acid pattern is a rapid, sensitive, and very useful method for identification of mycobacteria in the early diagnosis of the mycobacteriosis

Identification of Mycobacteria by thin layer chromatographic analysis of mycolic acids and conventional biochemical method: four years of experience

Mycolic acids analysis by thin-layer chromatography (TLC) has been employed by several laboratories worldwide as a method for fast identification of mycobacteria. This method was introduced in Brazil by our laboratory in 1992 as a routine identification technique. Up to the present, 861 strains isolated were identified by mycolic acids TLC and by standard biochemical tests; 61 per cent out of these strains came as clinical samples, 4 per cent isolated from frogs and 35 per cent as environmental samples. Mycobacterium tuberculosis strains identified by classical methods were confirmed by their mycolic acids contents (I, III and IV). The method allowed earlier differentiation of M. avium complex - MAC (mycolic acids I, IV and VI) from M. simiae (acids I, II and IV), both with similar biochemical properties. The methods also permitted to distinguish M. fortuitum (acids I and V) from M. chelonae (acids I and II), and to detect mixed mycobacterial infections cases as M. tuberculosis with MAC and M. fortuitum with MAC. Concluding, four years experience shows that mycolic acids TLC is an easy, reliable, fast and inexpensive method, an important tool to put together conventional mycobacteria identification methods.

Mycolic Acid Analysis for Identification of Mycobacterium spp. using High-Performance Liquid Chromatography / 대한임상병리학회지

BACKGROUND: Mycobacteria are traditionally identified with biochemical reactions. Since it takes 2 to 6 weeks, more rapid method is needed for timely treatment of mycobacterial infection. Mycolic acid analysis by high-performance liquid chromatography (HPLC) was recently introduced, which showed species-specificity with more than 95% sensitivity and 100% specificity for identifing Mycobacterium spp. within 2-4 hours. In this study, We performed mycolic acid analyses of standard strains of Mycobacterium spp. and two clinical isolates of known M. tuberculosis for demonstrating their species-specific nature and evaluated its reproduciblity. METHODS : 8 standard strains of Mycobacterium spp. (M. tuberculosis H37Rv, M. intracellurae, M. avium, M. fortuitum, M. chelonae subsp. chelonae, M. scrofulaceum, M. kansasii, M. gordonae) and 2 clinical isolates of known M. tuberculosis were analyzed. The extracted mycolic acids which were prepared by 3 steps were analyzed by HPLC with rC18 column. RESULTS: Mean retention time (MRT) of low and high molecular weight internal standards were 3.757min+/-0.017 (C.V. <0.455%) and 9.829min+/-0.015 (C.V. <0.015%), respectively (n=30). The C.V. of MRT for M. intracellurae for positive control showing double cluster pattern was less than 0.3% from 4 injection. The C.V. of MRT for M. tuberculosis H37Rv and 2 clinical isolates of M. tuberculosis with single cluster pattern were less than 0.4%, and 0.9%, respectively. The chromatographic patterns of M. kansasii and M. gordonae showed a single cluster pattern, and M. avium, M. fortuitum, M. chelonae subsp. chelonae, and M. scrofulaceum showed a double cluster pattern which were species-specific nature. CONCLUSIONS: We demonstrated HPLC method was rapid and highly reproducible.

Caracterización de ácidos grasos y productos de degradación de ácidos micólicos en especies micobacterianas de mayor incidencia en Argentina / Characterization of fatty acids and mycolic acid cleavage products in mycobacteria of major incidence in Argentina

El virus de la inmunodeficiencia humana (HIV) causa un profundo impacto sobre el problema de la tuberculosis tanto en los países industrializados como en los en vías de desarrollo. Enfermedades graves causadas por micobacterias no tuberculosas, la mayoría correspondiente al complejo Mycobacterium avium-intracellulare (MAC), se han vuelto muy comunes en asociación con la inmunosupresión severa. El aumento de la complejidad de las enfermedades micobacterianas ha estimulado el desarrollo de métodos de diagnóstico más rápidos y eficientes. En el presente estudio se caracterizaron los ácidos grasos y los productos de degradación de los ácidos micólicos celulares de las especies micobacterianas más frecuentes en la Argentina empleando cromatografía gaseosa (CG), para luego poder desarrollar una técnica rápida de identificación de especies. Los ácidos grasos y los ácidos micólicos de las células micobacterianas saponificadas fueron analizados como ésteres metílicos por CG capilar. Los principales ácidos grasos detectados en todas las especies estudiadas, con excepción de M. smegmatis, fueron los ácidos octadecenoico (18:1) y hexadecanoico (16:0). Los perfiles cromatográficos presentaron diferencias cuantitativas y no cualitativas entre las distintas especies. El ácido tuberculoesteárico se detectó en todas las micobacteias analizadas. Se observaron diferencias significativas (p<0,01) en las medias de las cantidades relativas de algunos ácidos grasos entre aislamientos clínicos de M. tuberculosis, M. bovis y MAC. Se detectaron trazas de 2-elcosanol en cepas de M. tuberculosis H37Rv. Aunque se estudió un número limitado de cepas y de especies, los resultados preliminares indican que este método podría ser usado para caracterizar cultivos micobacterianos