Discovery of a Novel hsp65 Genotype within Mycobacterium massiliense Associated with the Rough Colony Morphology

So far, genetic diversity among strains within Mycobacterium massiliense has rarely been studied. To investigate the genetic diversity among M. massiliense, we conducted phylogenetic analysis based on hsp65 (603-bp) and rpoB (711-bp) sequences from 65 M. massiliense Korean isolates. We found that hsp65 sequence analysis could clearly differentiate them into two distinct genotypes, Type I and Type II, which were isolated from 35 (53.8%) and 30 patients (46.2%), respectively. The rpoB sequence analysis revealed a total of four genotypes (R-I to R-IV) within M. massiliense strains, three of which (R-I, R-II and R-III) correlated with hsp65 Type I, and other (R-IV), which correlated with Type II. Interestingly, genotyping by the hsp65 method agreed well with colony morphology. Despite some exceptions, Type I and II correlated with smooth and rough colonies, respectively. Also, both types were completely different from one another in terms of MALDI-TOF mass spectrometry profiles of whole lipid. In addition, we developed PCR-restriction analysis (PRA) based on the Hinf I digestion of 644-bp hsp65 PCR amplicons, which enables the two genotypes within M. massiliense to be easily and reliably separated. In conclusion, two distinct hsp65 genotypes exist within M. massiliense strains, which differ from one another in terms of both morphology and lipid profile. Furthermore, our data indicates that Type II is a novel M. massiliense genotype being herein presented for the first time. The disparity in clinical traits between these two hsp65 genotypes needs to be exploited in the future study

Evaluation of Amplicor MTB test as adjunct to smears and culture for direct detection of Mycobacterium tuberculosis in the French Caribbean.

International audienceA total of 784 specimens collected from 370 individuals between January and August 1995 were analyzed by using the Amplicor Mycobacterium tuberculosis test (Roche Diagnostic System, Basel, Switzerland), a PCR-based test for the direct detection of organisms of the M. tuberculosis complex. The PCR results were compared with standard bacteriological data, including those obtained by acid-fast microscopy, culture, and biochemical identification as well as final clinical diagnosis for each patient. Several parallel controls were used: the kit DNA positive control, 10(3) CFU of M. tuberculosis, and three negative controls for each independent assay. No false-positive PCR results were obtained, and overall, M. tuberculosis was detected in 20 of 370 individuals screened. Five additional patients during the same time were found to be infected with mycobacteria other than tubercle bacilli; their specimens gave positive smear and/or culture test results, but Amplicor tests were always negative. The sensitivity, specificity, positive predictive value, and negative predictive value for the Amplicor MTB test compared with culture per specimen were 76.7, 97.7, 66.0, and 98.6%, respectively. For resolved cases, these values were, respectively, 69.4, 100, 100, and 96.8%; however, the sensitivity and negative predictive value increased to 90.9 and 99.2%, respectively, if PCR-negative nonrespiratory specimens (gastric washings) were not considered. When only specimens from proven tuberculosis patients were considered (n = 114) and the sum of PCR-positive and/or culture-positive samples from proven tuberculosis patients was considered the total number of positive samples, PCR had a sensitivity of 83.3% compared with 71.6% for culture. Results per patient (about three samples each) yielded 100% sensitivity and 100% specificity. We conclude that the Amplicor MTB test is highly specific and rapid for routine use in a clinical laboratory. However, in order to obtain a higher degree of sensitivity, it should be run as an adjunct to smears and culture with at least three samples for each patient, and a single-sample PCR-negative results must be considered carefully because of potential false-negatives

Evaluation of Amplicor MTB test as adjunct to smears and culture for direct detection of Mycobacterium tuberculosis in the French Caribbean

A total of 784 specimens collected from 370 individuals between January and August 1995 were analyzed by using the Amplicor Mycobacterium tuberculosis test (Roche Diagnostic System, Basel, Switzerland), a PCR-based test for the direct detection of organisms of the M. tuberculosis complex. The PCR results were compared with standard bacteriological data, including those obtained by acid-fast microscopy, culture, and biochemical identification as well as final clinical diagnosis for each patient. Several parallel controls were used: the kit DNA positive control, 10(3) CFU of M. tuberculosis, and three negative controls for each independent assay. No false-positive PCR results were obtained, and overall, M. tuberculosis was detected in 20 of 370 individuals screened. Five additional patients during the same time were found to be infected with mycobacteria other than tubercle bacilli; their specimens gave positive smear and/or culture test results, but Amplicor tests were always negative. The sensitivity, specificity, positive predictive value, and negative predictive value for the Amplicor MTB test compared with culture per specimen were 76.7, 97.7, 66.0, and 98.6%, respectively. For resolved cases, these values were, respectively, 69.4, 100, 100, and 96.8%; however, the sensitivity and negative predictive value increased to 90.9 and 99.2%, respectively, if PCR-negative nonrespiratory specimens (gastric washings) were not considered. When only specimens from proven tuberculosis patients were considered (n = 114) and the sum of PCR-positive and/or culture-positive samples from proven tuberculosis patients was considered the total number of positive samples, PCR had a sensitivity of 83.3% compared with 71.6% for culture. Results per patient (about three samples each) yielded 100% sensitivity and 100% specificity. We conclude that the Amplicor MTB test is highly specific and rapid for routine use in a clinical laboratory. However, in order to obtain a higher degree of sensitivity, it should be run as an adjunct to smears and culture with at least three samples for each patient, and a single-sample PCR-negative results must be considered carefully because of potential false-negatives.</jats:p

Rapid identification of mycobacteria to species level by PCR-restriction fragment length polymorphism analysis of the hsp65 gene and proposition of an algorithm to differentiate 34 mycobacterial species.

International audiencePCR-restriction fragment length polymorphism analysis (PRA) of the hsp65 gene (A. Telenti, F. Marchesi, M. Balz, F. Bally, E. C. Böttger, and T. Bodmer, J. Clin. Microbiol. 31:175-178, 1993) was applied to 108 mycobacterial isolates representing 34 species to evaluate its potential as a rapid reference method. A total of 49 distinct patterns were obtained; 25 species were characterized by a single PRA pattern, while 9 species gave more than one specific pattern. An algorithm describing these 34 species (which includes five additional species and new subgroups of Mycobacterium kansasii, M. abscessus, and M. peregrinum) is proposed. A relatively simple and inexpensive method, PRA may be particularly helpful in routine clinical microbiology laboratories

Spectrum of activity of levofloxacin against nontuberculous mycobacteria and its activity against the Mycobacterium avium complex in combination with ethambutol, rifampin, roxithromycin, amikacin, and clofazimine.

International audienceThe spectrum of activity of levofloxacin was initially determined against 29 strains belonging to 16 species of atypical mycobacteria by measuring radiometric MICs. Levofloxacin MICs were 1 to 2 dilutions lower compared with those obtained for ofloxacin and 8 to 64 dilutions lower compared with those obtained for its D-isomer. Levofloxacin MICs were below its peak level in serum (5.5 micrograms/ml following administration of a single oral dose of 350 mg) for 25 of 29 isolates tested. It possessed MICs below its peak level in serum for M. scrofulaceum, M. szulgai, M. malmoense, M. xenopi, M. marinum, M. kansasii, M. chelonei, M. abcessus, M. fortuitum, and M. peregrinum. Regarding the M. avium complex, the MICs of levofloxacin for 11 clinical isolates (7 from human immunodeficiency virus-positive patients and 4 from human immunodeficiency virus-negative patients) were 1 to 2 dilutions lower than those of ofloxacin. Among 20 isolates belonging to 12 pathogenic mycobacterial species, the MBC/MIC ratios varied from 1 to 4 for levofloxacin and 2 to 4 for ofloxacin. When drug combinations were screened by using the radiometric x/y quotient methodology against five M. avium complex isolates, levofloxacin activity against all five isolates was enhanced by ethambutol and activity against three isolates was enhanced by clofazimine. Screening of three-drug combinations showed that the combination levofloxacin-ethambutol with a third potential anti-M. avium drug (rifampin, roxithromycin, amikacin, or clofazimine) resulted in enhanced activity for all 20 drug combinations screened