Reliable identification of mycobacterial species by PCR-restriction enzyme analysis (PRA)-hsp65 in a reference laboratory and elaboration of a sequence-based extended algorithm of PRA-hsp65 patterns

Detection of Mycobacterium tuberculosis complex by nested polymerase chain reaction in pulmonary and extrapulmonary specimens

OBJECTIVE:

To compare the performance of nested polymerase chain reaction (NPCR) with that of cultures in the detection of the Mycobacterium tuberculosis complex in pulmonary and extrapulmonary specimens.

METHODS:

We analyzed 20 and 78 pulmonary and extrapulmonary specimens, respectively, of 67 hospitalized patients suspected of having tuberculosis. An automated microbial system was used for the identification of Mycobacterium spp. cultures, and M. tuberculosis IS6110 was used as the target sequence in the NPCR. The kappa statistic was used in order to assess the level of agreement among the results.

RESULTS:

Among the 67 patients, 6 and 5, respectively, were diagnosed with pulmonary and extrapulmonary tuberculosis, and the NPCR was positive in all of the cases. Among the 98 clinical specimens, smear microscopy, culture, and NPCR were positive in 6.00%, 8.16%, and 13.26%, respectively. Comparing the results of NPCR with those of cultures (the gold standard), we found that NPCR had a sensitivity and specificity of 100% and 83%, respectively, in pulmonary specimens, compared with 83% and 96%, respectively, in extrapulmonary specimens, with good concordance between the tests (kappa, 0.50 and 0.6867, respectively).

CONCLUSIONS:

Although NPCR proved to be a very useful tool for the detection of M. tuberculosis complex, clinical, epidemiological, and other laboratory data should also be considered in the diagnosis and treatment of pulmonary and extrapulmonary tuberculosis.

Outbreaks due to Mycobacterium abscessus subsp. bolletii in southern Brazil: persistence of a single clone from 2007 to 2011

Outbreaks associated with rapidly growing mycobacteria (RGM) have been increasingly reported worldwide, including in Brazil. Among the RGM, the Mycobacterium abscessus complex is the most pathogenic and related to multidrug resistance. The aim of this study was to evaluate the antimicrobial susceptibility and molecular profile of RGM isolates involved in new postsurgical infection outbreaks in Brazil since 2007. Of the 109 cases reported in the state of Rio Grande do Sul between 2007 and 2011, 43 (39 %) had confirmed mycobacterial growth in culture. Clinical isolates were obtained from biopsy specimens or abscess aspirates. PRA-hsp65 restriction pattern identified the isolates as M. abscessus type 2, and partial rpoB sequencing confirmed the identification as M. abscessus subsp. bolletii. All isolates were susceptible to amikacin and resistant to ciprofloxacin, doxycycline, sulfamethoxazole, moxifloxacin and tobramycin. Most isolates (72 %) were fully susceptible to cefoxitin but six isolates (14 %) were fully resistant to clarithromycin. The latter differed from the susceptibility profiles of the previously described BRA100 clone from other Brazilian regions. Nevertheless, pulsed-field gel electrophoresis analysis revealed that these isolates belonged to a single BRA100 clone. In conclusion, our study reports the persistence of an emergent single and highly resistant clone of M. abscessus subsp. bolletii for several years even after national implementation of infection control measures.

Characterization of the first report of Mycobacterium timonense infecting an HIV patient in an Ecuadorian hospital

Mycobacterium timonense is a non-tuberculous mycobacteria (NTM) described in southern France in 2009, and to our knowledge, not reported again as a human pathogen in indexed literature. The aim of this work was to characterize the first clinical isolate of M. timonense in Ecuador. Time of growth, biochemical tests, thin layer growth test, PCR-RFLP analysis of the hsp65 gene and MALDI-TOF spectra analysis were not able to identify the species. The species identification was achieved through sequencing of rrs, hsp65 and rpoB genes. The results highlight the necessity to set up a sequencing method to identify emerging NTM in Ecuadorian clinical facilities.

Specific amplification of gene encoding N-terminal region of catalase-peroxidase protein (KatG-N) for diagnosis of disseminated MAC disease in HIV patients

Disseminated Mycobacterium avium-intracellulare complex (MAC) infection is considered as severe complication of advanced HIV/AIDS disease. Currently available various laboratory investigations have not only limited ability to discriminate between MAC infection and tuberculosis but are also laborious and time consuming. The aim of this study was, therefore, to design a molecular-based strategy for specific detection of MAC and its differentiation from Mycobacterium tuberculosis (M. tb) isolated from the blood specimens of HIV patients. A simple PCR was developed based on the amplification of 120-bp katG-N gene corresponding to the first 40 amino acids of N-terminal catalase-peroxidase (KatG) protein of Mycobacterium avium that shows only ~13% sequence homology by clustal W alignment to N-terminal region of M. tb KatG protein. This assay allowed the accurate and rapid detection of MAC bacteremia, distinguishing it from M. tb in a single PCR reaction without any need for sequencing or hybridization protocol to be performed thereafter. This study produced enough evidence that a significant proportion of Indian HIV patients have disseminated MAC bacteremia, suggesting the utility of M. avium katG-N gene PCR for early detection of MAC disease in HIV patients.

Nontuberculous mycobacteria in respiratory samples from patients with pulmonary tuberculosis in the state of Rondônia, Brazil

The main cause of pulmonary tuberculosis (TB) is infection with Mycobacterium tuberculosis (MTB). We aimed to evaluate the contribution of nontuberculous mycobacteria (NTM) to pulmonary disease in patients from the state of Rondônia using respiratory samples and epidemiological data from TB cases. Mycobacterium isolates were identified using a combination of conventional tests, polymerase chain reaction-based restriction enzyme analysis of hsp65 gene and hsp65 gene sequencing. Among the 1,812 cases suspected of having pulmonary TB, 444 yielded bacterial cultures, including 369 cases positive for MTB and 75 cases positive for NTM. Within the latter group, 14 species were identified as Mycobacterium abscessus, Mycobacterium avium, Mycobacterium fortuitum, Mycobacterium intracellulare, Mycobacterium gilvum, Mycobacterium gordonae, Mycobacterium asiaticum, Mycobacterium tusciae, Mycobacterium porcinum, Mycobacterium novocastrense, Mycobacterium simiae, Mycobacterium szulgai, Mycobacterium phlei and Mycobacterium holsaticum and 13 isolates could not be identified at the species level. The majority of NTM cases were observed in Porto Velho and the relative frequency of NTM compared with MTB was highest in Ji-Paraná. In approximately half of the TB subjects with NTM, a second sample containing NTM was obtained, confirming this as the disease-causing agent. The most frequently observed NTM species were M. abscessus and M. avium and because the former species is resistant to many antibiotics and displays unsatisfactory cure rates, the implementation of rapid identification of mycobacterium species is of considerable importance.

Mycobacteria mobility shift assay: a method for the rapid identification of Mycobacterium tuberculosis and nontuberculous mycobacteria

The identification of mycobacteria is essential because tuberculosis (TB) and mycobacteriosis are clinically indistinguishable and require different therapeutic regimens. The traditional phenotypic method is time consuming and may last up to 60 days. Indeed, rapid, affordable, specific and easy-to-perform identification methods are needed. We have previously described a polymerase chain reaction-based method called a mycobacteria mobility shift assay (MMSA) that was designed for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) species identification. The aim of this study was to assess the MMSA for the identification of MTC and NTM clinical isolates and to compare its performance with that of the PRA-hsp65 method. A total of 204 clinical isolates (102 NTM and 102 MTC) were identified by the MMSA and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing fragments of the 16S rRNA and hsp65 genes. Both methods correctly identified all MTC isolates. Among the NTM isolates, the MMSA alone assigned 94 (92.2%) to a complex or species, whereas the PRA-hsp65 method assigned 100% to a species. A 91.5% agreement was observed for the 94 NTM isolates identified by both methods. The MMSA provided correct identification for 96.8% of the NTM isolates compared with 94.7% for PRA-hsp65. The MMSA is a suitable auxiliary method for routine use for the rapid identification of mycobacteria.

Hsp65 phylogenetic assay for molecular diagnosis of nontuberculous mycobacteria isolated in Mexico

BACKGROUND AND AIMS

Nontuberculous mycobacteria (NTM) are mainly distributed as important emerging pathogens in patients with chronic or immunosuppressive diseases. Accurate identification of causative species is crucial for proper treatment and patient follow-up. However, several difficulties are associated with phenotypic and molecular diagnostic methods for precise identification at the species level due to shared metabolic and genetic characteristics. We undertook this study to evaluate the application of the phylogenetic method based on hsp65 gene into Telenti's PCR-restriction enzyme analysis (PRA) for molecular identification of NTM.

METHODS

The study population was comprised of 1646 Mycobacterium clinical isolates (AFB positive) collected from 2008-2011, of which 537 (32.6%) were MNT identified by PRA analysis. DNA sequencing of hsp65 in 53 isolates (10%) was performed. Sequence identification through NCBI-Basic Local Alignment Search Tool (BLAST) achieved correct identification in 23 isolates. Phylogenetic trees including hsp65 available GenBank sequences for all described genres of NTM and hsp65 obtained sequences were constructed using Mega 5.05 software. We compared sequence identification based on phylogenetic clustering and BLAST similarity search.

RESULTS

Phylogenetic clustering allowed more specific differentiation of closely related species and clearer identification in comparison with BLAST; 30 Mycobacterium species (this is the first report of isolation of some of these from clinical samples in Mexico) were identified in this way.

CONCLUSIONS

The proposed 440 bp hsp65 phylogenetic method allows a better identification tool to differentiate Mycobacterium species and is useful to complement diagnosis and epidemiological surveillance of NTM.

Nontuberculous mycobacteria in respiratory samples from patients with pulmonary tuberculosis in the state of Rondônia, Brazil

The main cause of pulmonary tuberculosis (TB) is infection with Mycobacterium tuberculosis (MTB). We aimed to evaluate the contribution of nontuberculous mycobacteria (NTM) to pulmonary disease in patients from the state of Rondônia using respiratory samples and epidemiological data from TB cases. Mycobacterium isolates were identified using a combination of conventional tests, polymerase chain reaction-based restriction enzyme analysis of hsp65 gene and hsp65 gene sequencing. Among the 1,812 cases suspected of having pulmonary TB, 444 yielded bacterial cultures, including 369 cases positive for MTB and 75 cases positive for NTM. Within the latter group, 14 species were identified as Mycobacterium abscessus, Mycobacterium avium, Mycobacterium fortuitum, Mycobacterium intracellulare, Mycobacterium gilvum, Mycobacterium gordonae, Mycobacterium asiaticum, Mycobacterium tusciae, Mycobacterium porcinum, Mycobacterium novocastrense, Mycobacterium simiae, Mycobacterium szulgai, Mycobacterium phlei and Mycobacterium holsaticum and 13 isolates could not be identified at the species level. The majority of NTM cases were observed in Porto Velho and the relative frequency of NTM compared with MTB was highest in Ji-Paraná. In approximately half of the TB subjects with NTM, a second sample containing NTM was obtained, confirming this as the disease-causing agent. The most frequently observed NTM species were M. abscessus and M. avium and because the former species is resistant to many antibiotics and displays unsatisfactory cure rates, the implementation of rapid identification of mycobacterium species is of considerable importance.

Non-tuberculous mycobacteria in wild boar (Sus scrofa) from Southern Spain: epidemiological, clinical and diagnostic concerns

Non-tuberculous mycobacteria (NTM) are widely distributed in the environment, particularly in wet soil, marshland, rivers or streams, but also are causative agents of a wide variety of infections in animals and humans. Little information is available regarding the NTM prevalence in wildlife and their effects or significance in the bovine tuberculosis (bTB) epidemiology and diagnosis. This research shows the most frequently NTM isolated in lymph nodes of wild boar (Sus scrofa) from southern Spain, relating the NTM presence with the individual characteristics, the management of animals and the possible misdiagnosis of Mycobacterium bovis in concurrent infections. A total of 219 NTM isolates were obtained from 1249 wild boar mandibular lymph nodes sampled between 2007 and 2011. All but 75 isolates were identified by the PCR-restriction analysis-hsp65, and a partial sequencing of the 16S rDNA was carried out to identify the rest of the isolates. Results showed that Mycobacterium chelonae was the most frequently isolated NTM specie (133 isolates, 60.7%), followed by Mycobacterium avium (24 isolates, 11%). No relation was found regarding sex, body condition and management, but M. chelonae was more frequently detected in adults, whereas M. avium was more prevalent in subadults. The high NTM prevalence observed in the studied wild boar populations could make difficult the bTB diagnostic.

Different immunosuppressive mechanisms in multi-drug-resistant tuberculosis and non-tuberculous mycobacteria patients

Previous studies have demonstrated that cells from both multi-drug-resistant tuberculosis (MDR-TB) and non-tuberculous mycobacteria (NTM) patients respond poorly to mycobacterial antigens in vitro. In the present study, we compared the in vitro response of cells isolated from sensitive TB (NR-TB)-, MDR-TB- and NTM-infected patients. Analysis of T cell phenotype ex vivo revealed that both MDR-TB and NTM patients present an increased percentage of CD4(+) CD25(+-) forkhead box protein 3 (FoxP3)(+) and CD4(+) CD25(+) CD127(-) regulatory T (T(reg) ) cells when compared to NR-TB. Increased numbers of T(reg) cells and interleukin (IL)-10 serum levels were detected in MDR-TB, whereas elevated serum transforming growth factor (TGF)-β was found in the NTM group. Cells of MDR-TB patients stimulated with early secretory antigenic target (ESAT)-6, but not purified protein derivative (PPD), showed a lower frequency of CD4(+) /interferon (IFN)-γ(+) T cells and enhanced CD4(+) CD25(+) FoxP3(+) , CD4(+) CD25(+) CD127(-) and CD4(+) CD25(+) IL-10(+) T cell population. In addition, increased IL-10 secretion was observed in cultured MDR-TB cells following ESAT-6 stimulation, but not in NR-TB or NTM patients. In vitro blockade of IL-10 or IL-10Rα decreased the CD4(+) CD25(+) FoxP3(+) frequencies induced by ESAT-6 in MDR-TB, suggesting a role of IL-10 on impaired IFN-γ responses seen in MDR-TB. Depletion of CD4(+) CD25(+) T lymphocytes restored the capacity of MDR-TB T cells to respond to ESAT-6 in vitro, which suggests a potential role for T(reg) /T regulatory 1 cells in the pathogenesis of MDR-TB. Together, our results indicate that although the similarities in chronicity, NTM- and MDR-TB-impaired antigenic responses involve different mechanisms.

The first case of pulmonary disease caused by Mycobacterium septicum in China

Mycobacterium septicum is a rapidly growing Mycobacterium (RGM) that rarely causes pulmonary disease globally. We describe a case of M. septicum pulmonary disease, which to our knowledge is the first reported in China. The isolates were identified as M. septicum and were susceptible in vitro to amikacin, ciprofloxacin, ofloxacin, levofloxacin, kanamycin, and sulfamethoxazole.

Combined rpoB duplex PCR and hsp65 PCR restriction fragment length polymorphism with capillary electrophoresis as an effective algorithm for identification of mycobacterial species from clinical isolates

Background

Mycobacteria can be quickly and simply identified by PCR restriction-enzyme analysis (PRA), but misidentification can occur because of similarities in band sizes that are critical for discriminating among species. Capillary electrophoresis can provide computer-aided band discrimination. The aim of this research was to develop an algorithm for identifying mycobacteria by combined rpoB duplex PRA (DPRA) and hsp65 PRA with capillary electrophoresis.

Results

Three hundred and seventy-six acid-fast bacillus smear-positive BACTEC cultures, including 200 Mycobacterium tuberculosis complexes (MTC) and 176 non-tuberculous mycobacteria (NTM) were analyzed. With combined hsp65 and rpoB DPRA, the accuracy rate was 100% (200 isolates) for the MTC and 91.4% (161 isolates) for the NTM. Among the discordant results (8.6%) for the NTM, one isolate of Mycobacterial species and an isolate of M. flavescens were found as new sub-types in hsp65 PRA.

Conclusions

This effective and novel identification algorithm using combined rpoB DPRA and hsp65 PRA with capillary electrophoresis can rapidly identify mycobacteria and find new sub-types in hsp65 PRA. In addition, it is complementary to 16 S rDNA sequencing.

Molecular Characterization of Environmental Non-Tuberculous Mycobacteria Using PCR- RFLP Analysis of 441 Bp Heat Shock Protein 65 Fragments

BACKGROUND

Non- Tuberculous Mycobacteria are environmental opportunistic pathogens that can be found in various terrestrial and aquatic habitats. There are an epidemiological links between species isolated in tap water and those isolated from patients. hsp65 gene has more variability in its sequences, compared to the some more conserved genes in NTM, for identification of mycobacteria to species level. In this study, the prevalence of NTM in Isfahan City water samples was determined using culture, biochemical tests and PCR-RFLP analyses of hsp65 gene.

METHODS

Eighty-five water samples were collected and cultured. The mycobacterial isolates were identified by conventional biochemical tests. A 441 bp fragment of hsp65 genes was amplified and digested by two restriction enzymes, BstEII and HaeII. Digested products were analyzed using polyacrilamid gel electrophoresis (PAGE).

RESULTS

25.9% of the water samples contained different species of NTM. Dominant isolates were M. fortuitum (26.7%), M. chelonae like organism (13.3%) and M. mucogenicum (13.3%). Nineteen isolates of Mycobacteria were differentiated using hsp65 genes PCR-RFLP. Three isolates could not be identified at the species level because their RFLP patterns were different from other known PCR-RFLP profiles. There were different hsp65 gene PCR-RFLP profiles produced by digestion with BstEII and HaeIII.

CONCLUSION

This study showed that PCR-RFLP of hsp65 gene in mycobacteria is more reliable method for identification of NTM at the specie level than conventional phenotypic methods (P<0.05). In comparing of RFLP patterns of this study to other investigation, some minor differences were negligible.

Direct identification of mycobacteria from smear-positive sputum samples using an improved multiplex polymerase chain reaction assay

The rapid identification of mycobacteria from smear-positive sputum samples is very important. To identify the Mycobacterium tuberculosis complex (MTBC) and frequently isolated nontuberculous mycobacteria strains directly from smear-positive sputum samples, an improved multiplex polymerase chain reaction (PCR) assay was developed. Nine pairs of primers targeting the 16S-23S rDNA internal transcribed spacer-1, hsp65, and the early secretory antigen (ESAT-6) gene sequences were developed, and their efficacy was evaluated in comparison to traditional culturing and 16S rRNA gene sequencing methods. A total of 200 smear- and culture-positive sputum specimens collected between November 2005 and May 2006 were used for the analysis. The results of the assay showed an accurate identification rate for acid-fast bacilli (AFB) 3+, AFB 2+, and AFB rare/1+ samples of 98%, 95%, and 53%, respectively. The improved multiplex PCR method saves time and has advantages for identifying mycobacteria from AFB 2+ and 3+ sputum samples. The method is suitable for use in countries with a high MTBC prevalence rate.

hsp65 PCR-restriction analysis (PRA) with capillary electrophoresis for species identification and differentiation of Mycobacterium kansasii and Mycobacterium chelonae-Mycobacterium abscessus group

OBJECTIVES

The aim of the present study was to identify and differentiate Mycobacterium kansasii and Mycobacterium chelonae-Mycobacterium abscessus group strains isolated from clinical and environmental sources in different countries.

METHODS

PCR-restriction analysis of the hsp65 gene (PRA) with automated capillary electrophoresis was applied to the isolates previously identified by conventional biochemical testing and the molecular INNO-LiPA MYCOBACTERIA assay.

RESULTS

PRA performed very well in comparison with the two other methods (96.4% concordance). Among 27 M. kansasii isolates, this method detected five genetic types, of which type 1 represented the most common clinical isolate, as it is worldwide. PRA differentiated 29 M. chelonae-M. abscessus group isolates into Mycobacterium immunogenum type 2 (n=13), M. chelonae (n=12), and M. abscessus types 1 (n=1) and 2 (n=1). M. immunogenum was the most frequent (69%) isolate from humans, but only one of 11 cases was clinically significant. M. chelonae was the most commonly (83%) recovered from water. PRA also identified two isolates with hsp65 alleles representing previously unreported patterns.

CONCLUSIONS

PRA based on automated capillary electrophoresis is a rapid, simple, and reliable method for the identification and differentiation of both clinically relevant and environmental isolates of M. kansasii and M. chelonae-M. abscessus group.

Mycobacterium marinum infections in humans and tracing of its possible environmental sources

The low frequency of nontuberculous mycobacterial infections, nonspecific symptoms for individual mycobacteria, and the lack of specific identification methods could alter correct diagnosis. This study presents a combined microbiology and molecular-based approach for Mycobacterium marinum detection in four aquarists with cutaneous mycobacterial infection. Simultaneously, ecology screening for M. marinum presence in the aquarists' fish tanks was performed. A total of 38 mycobacterial isolates originated from four human patients (n = 20), aquarium animals (n = 8), and an aquarium environment (n = 10). Isolate identification was carried out using 16S rRNA sequence analysis. A microbiology-based approach, followed by 16S rRNA sequence analysis, was successfully used for detection of M. marinum in all four patients. Animal and environmental samples were simultaneously examined, and a total of seven mycobacterial species were isolated: Mycobacterium chelonae , Mycobacterium fortuitum , Mycobacterium gordonae , Mycobacterium kansasii , Mycobacterium mantenii , Mycobacterium marinum , and Mycobacterium peregrinum . The presence of M. marinum was proven in the aquarium environments of two patients. Although M. marinum is described as being present in water, it was detected only in fish.

[Use of different PCR-based techniques integrated into a non-tuberculous identification algorithm]

INTRODUCTION

The aim of the present work was to demonstrate the utility of a non-tuberculous mycobacteria (NTM) identification algorithm, which integrates different PCR-based techniques and basic phenotypic features. Moreover, the algorithm for pattern restriction analysis of hsp65 (hsp65 PRA) interpretation has been updated.

METHODS

The workflow chosen consisted of the identification by a DNA hybridization probe method, followed by PCR-restriction enzyme analysis of hsp65 (hsp65 PRA) in those isolates that cannot be identified by hybridization probes. If necessary, 16S rRNA gene and hsp65 gene sequencing were used for speciation.

RESULTS

A total of 236 NTM were collected, in which 102 (43.2%) isolates were identified by DNA specific probes and 76 (32.2%) isolates were identified with hsp65 PRA. Partial sequencing of the 16S rRNA gene was used for species identification of the remaining 58 (24.5%) isolates. Fifty-three (22.4%) were identified using this method. Five isolates (2.1%) were submitted for partial sequencing of hsp65 gene and one isolate was identified with this method. Four strains (1.7%) could not be identified at species level. Three new PRA patterns were found. Seven isolates tested positive with the AccuProbe Mycobacterium avium complex identification test but did not test positive with the M. avium or Mycobacterium intracellulare specific probes. Five and two of these isolates were identified as M. intracellulare and Mycobacterium colombiense, respectively.

CONCLUSION

This approach allowed us to identify almost all NTM isolates found in this study, including some recently described species.

Potentially pathogenic nontuberculous mycobacteria found in aquatic systems. Analysis from a reclaimed water and water distribution system in Mexico City

We investigated the presence of nontuberculous mycobacteria (NTM) in three Mexican aquatic systems to evaluate the prevalence with the distribution of NTM species. Key physicochemical parameters of the water samples were determined to find correlations with the species' distributions. We used multilocus sequence analysis (MLSA) based on hsp65, rpoB, and 16S rRNA fragments to determine their taxonomic affiliations. NTM were recovered from water distribution systems and reclaimed water from the Mexico City Metropolitan Area (MCMA). The isolated species were associated with a temperature of 21°C and pH >7.7. The phylogenetic analysis showed that eight of the 14 different NTM strains were unambiguously classifiable: Mycobacterium peregrinum, M. nonchromogenicum (2), M. smegmatis (2), M. fortuitum, M. avium ssp. hominissuis, M. arupense, M. gordonae, and M. chitae. One strain was tentatively identified as M. mantenni/ scrofulaceum and another strain was related to M. porcinum/M. septicum. All NTM species identified in the water distribution system were also detected in the reclaimed water, but some species from the reclaimed water were not found in the water distribution systems. Two of the identified species found in the reclaimed water, M. avium and M. fortuitum, are considered important human opportunistic pathogens.

First report on isolation of Mycobacterium monacense from sputum specimen in India

We report a case of Mycobacterium monacense (M. monacense) isolated from sputum of a female patient for the first time in India. The chest radiograph and symptoms were suggestive of pulmonary tuberculosis. M. monacense was isolated from the sputum specimen at the end of 11 days of incubation. The identification was confirmed by conventional biochemical tests and polymerase chain reaction (PCR) -based Restriction Fragment Length Polymorphism (RFLP) and DNA sequencing targeting Internal Transcribed Spacer (ITS) region and hsp65 gene. The patient was treated with conventional anti-tuberculous drugs.

Diversity of pulsed-field gel electrophoresis patterns of Mycobacterium abscessus type 2 clinical isolates

An epidemic of infections by rapidly growing mycobacteria related to surgical procedures between 2004 and 2008 in Brazil was caused by a unique strain showing the Mycobacterium abscessus type 2 pattern when it was analyzed by the molecular method of PCR-restriction enzyme analysis of the hsp65 gene (PRA-hsp65). In order to investigate the diversity of M. abscessus type 2 clinical isolates and to assess whether this epidemic strain was present in specimens from nonsurgical patients, we studied 52 isolates from 38 patients showing this characteristic PRA-hsp65 pattern obtained between 2005 and 2009. All isolates were identified by sequencing of region V of the rpoB gene and typed by pulsed-field gel electrophoresis (PFGE) using two restriction enzymes, DraI and AseI. Seven isolates obtained from sputum, bronchoalveolar lavage fluid, and urine in three different Brazilian states showed rpoB sequences 100% similar to the rpoB sequence of epidemic strain INCQS 594 and PFGE patterns highly related to the patterns of isolates, evidencing the presence of the epidemic strain in isolates from patients not associated with the surgical epidemic. The remaining isolates showed diverse rpoB sequences, with the highest similarities being to the corresponding sequences of M. massiliense(T) CIP 108297 (21 isolates), M. bolletii(T) CIP 108541 (19 isolates), or M. abscessus(T) ATCC 19977 (5 isolates). Two additional clusters could be detected by PFGE. PFGE showed 100% typeability and reproducibility and discriminatory powers, calculated by Simpson's index of diversity, of 0.978 (DraI) and 0.986 (AseI), confirming its suitability for the discrimination of M. abscessus type 2 isolates.

Identification and evaluation of a new nucleic acid amplification test target for specific detection of Mycobacterium tuberculosis

BACKGROUND

Accurate and early diagnosis of tuberculosis (TB) is of major importance in the management and control of TB. Because the conventional bacteriological diagnosis of TB has several limitations, nucleic acid amplification (NAA) tests have emerged as promising alternatives. A potential problem with NAA tests is that some strains lack a target, which may be the one of main reasons for the much lower and highly variable accuracy in diagnosis. A possible solution may be to use more valid and applicable targets to increase detection accuracy.

METHODS

In this paper, we designed a two-step program to obtain NAA test targets. Inter-simple sequence repeats (ISSR) based on oligonucleotide (GTG)(5) were first constructed to genotype Mycobacterium strains to obtain Mycobacterium tuberculosis (MTB)-specific fragment. Second, sequence characterized amplified region (SCAR) markers were developed from these species-specific sequences to identify MTB. Some 312 Mycobacterium strains were used to evaluate the efficacy of the SCAR markers, IS6110 element [specific identification of Mycobacterium tuberculosis complex (MTC)] and 16SrRNA gene (specific identification of Mycobacterium) amplification, together with traditional bacteriology testing was used as a control.

RESULTS

MTB-specific sequences located in a gene coding for Rv1508c, as a new NAA test target, were obtained using ISSR-PCR genotyping. Based on these sequences, the SCAR primer pairs MISP1 and MISP2 were designed. All 312 strains from Mycobacterium accurately produced the genus-specific 16SrRNA amplicon. 271 MTB strains and M. africanum were positive. However, all nontuberculous mycobacteria (NTM) strains and 1 MTB strain named 1143 were negative in both SCAR and IS6110 PCR amplification. M. bovis, bacille Calmette-Guérin (BCG) were IS6110-PCR positive, while SCAR-PCR was negative. Strain 1143 was defined as M. arupense with 99% identity by 16SrRNA gene sequencing identification, despite being diagnosed as MTB using traditional testing.

CONCLUSIONS

SCAR markers developed with this two-step program can be used as a new NAA test target to correctly detect MTB.

Cord factor detection and macroscopic evaluation of mycobacterial colonies: an efficient combined screening test for the presumptive identification of Mycobacterium tuberculosis complex on solid media

OBJECTIVE

The rapid differentiation between Mycobacterium tuberculosis and nontuberculous mycobacteria is fundamental for patients co-infected with tuberculosis and HIV. To that end, we use two methods in our laboratory: detection of cord factor and PCR-restriction enzyme analysis (PRA). The objective of this study was to evaluate the accuracy of a screening test on solid medium as a rapid method for the presumptive identification of M. tuberculosis complex, considering costs and turnover time.

METHODS

A total of 152 strains were submitted to a combined screening test, consisting of the detection of cord factor under microscopy (Ziehl-Neelsen staining) and evaluation of the macroscopic aspect of colonies, as well as to PRA, which was used as the gold standard. Costs were estimated by calculating the price of all of the materials needed for each test.

RESULTS

The overall accuracy of cord factor detection alone was 95.4% (95% CI: 90.7-98.1%), and that of the combined screening test was 99.3% (95% CI: 96.4-100%). Cord factor detection costs US$ 0.25, whereas the PRA costs US$ 7.00. Results from cord factor detection are ready in 2 days, whereas PRA requires 4 days to yield results.

CONCLUSIONS

The presumptive identification of M. tuberculosis using the macroscopic evaluation of colonies combined with cord factor detection under microscopy is a simple, rapid and inexpensive test. We recommend the combined screening test to rapidly identify M. tuberculosis in resource-poor settings and in less well-equipped laboratories while awaiting a definite identification by molecular or biochemical methods.

Epidemic of surgical-site infections by a single clone of rapidly growing mycobacteria in Brazil

Aim: Our aim is to investigate if the clusters of postsurgical mycobacterial infections, reported between 2004 and 2008 in seven geographically distant states in Brazil, were caused by a single mycobacterial strain. Materials & methods: Available information from 929 surgical patients was obtained from local health authorities. A total of 152 isolates from surgical patients were identified by PCR restriction enzyme analysis of the hsp65 gene (PRA-hsp65) and sequencing of the rpoB gene. Isolates were typed by pulsed-field gel electrophoresis (PFGE) using two restriction enzymes, DraI and AseI. A total of 15 isolates not related to surgical cases were analyzed for comparison. Results: All isolates were identified as Mycobacterium abscessus ssp. massiliense. Isolates from surgical patients and one sputum isolate grouped in a single PFGE cluster, composed of two closely related patterns, with one band difference. A total of 14 other isolates unrelated to surgical cases showed distinctive PFGE patterns. Conclusion: A particular strain of M. abscessus ssp. massiliense was associated with a prolonged epidemic of postsurgical infections in seven Brazilian states, suggesting that this strain may be distributed in Brazilian territory and better adapted to cause surgical-site infections.

Isolation of novel mycobacteria contaminating an aquarium fish tank in a Japanese university hospital

AIMS

To better understand nontuberculous mycobacteria (NTM) contamination in a hospital setting, six freshwater fish gut homogenates and water in an aquarium fish tank placed on the reception counter of a nursing station were cultured for mycobacteria.

METHODS AND RESULTS

By direct sequencing of 16s rRNA, rpoB and hsp65, scotochromogenic and nonchromogenic Mycobacterium szulgai isolates containing hsp65 type II (GenBank accession nos. FJ384762 and FJ384764, respectively), Mycobacterium gordonae isolates containing rpoB clusters B and E (GenBank accession no. FJ384766), and Mycobacterium kansasii isolates containing hsp65 type VI were collected from the gut homogenates and water from the fish tank. However, no isolates were obtained from the tap water used to refill the fish tank. A randomly amplified polymorphic DNA (RAPD) analysis using a 10-mer primer (5'-TGGTCGCGGC) showed that some NTM from the fish tank water were identical to those obtained from the gut homogenates.

CONCLUSIONS

Fish and water in the tank were contaminated by the novel NTM.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings could help to elucidate infection routes and contamination sources of novel NTM from water sources.

Rapid Identification of Mycobacterium tuberculosis and nontuberculous mycobacteria by multiplex, real-time PCR

The rapid identification of mycobacteria from culture is of primary importance for the administration of empirical antibiotic therapy and for the implementation of public health measures, yet there are few commercially available assays that can easily and accurately identify the mycobacteria in culture in a timely manner. Here we report on the development of a multiplex, real-time PCR assay that can identify 93% of the pathogenic mycobacteria in our laboratory in two parallel reactions. The mycobacteria identified by this assay include the Mycobacterium tuberculosis complex (MTC), the M. avium complex (MAC), the M. chelonae-M. abscessus group (MCAG), the M. fortuitum group (MFG), and M. mucogenicum. The primer targets included the 16S rRNA gene and the internal transcribed spacer. The assay was initially validated with a repository of reference strains and was subsequently tested with 314 clinical cultures identified by the AccuProbe assay or high-performance liquid chromatography. Of the 314 cultures tested, multiplex, real-time PCR produced congruent results for 99.8% of the 1,559 targets evaluated. The sensitivity and the specificity were each 99% or greater for MTC (n = 96), MAC (n = 97), MCAG (n = 68), and M. mucogenicum (n = 9) and 95% and 100%, respectively, for MFG (n = 19). We conclude that this multiplex, real-time PCR assay is a useful diagnostic tool for the rapid and accurate identification of MTC and clinically relevant nontuberculous mycobacteria.

Isolamento de micobactérias não-tuberculosas em São José do Rio Preto entre 1996 e 2005

OBJETIVO: Estudar a ocorrência de micobactérias não-tuberculosas e a variabilidade das espécies isoladas na região atendida pelo Instituto Adolfo Lutz-Regional de São José do Rio Preto-no período entre 1996 e 2005, assim como mostrar a importância do diagnóstico laboratorial. MÉTODOS: A partir de amostras pulmonares e extrapulmonares, foi realizado o isolamento de micobactérias, e estas foram identificadas por métodos fenotípicos e pelo método molecular polymerase chain reaction-restriction enzyme analysis. RESULTADOS: Foram isoladas 317 cepas de micobactérias não-tuberculosas: complexo Mycobacterium avium, 182 (57,4%); M. gordonae, 33 (10,4%); M. fortuitum, 25(7,9%); M. chelonae, 8 (2,5%); complexo M. terrae, 8 (2,5%); M. kansasii, 7 (2,2%); e espécies menos freqüentes, 54 (17%). No período, foram caracterizados 72 casos (33,3%) de micobacterioses, de acordo com os critérios bacteriológicos estabelecidos pela American Thoracic Society (2007).Desses, complexo M. avium foi responsável por 56 casos, sendo que 29 (51,8%) foram caracterizados como doença disseminada. M. fortuitum foi responsável por 6 casos; M. gordonae, 3; M. chelonae, 2; M. abscessus, 1; M. kansasii, 1; M. intracellulare, 1; M. malmoense, 1; e Mycobacterium ssp., 1. CONCLUSÕES: Os resultados obtidos mostraram a importância do diagnóstico bacteriológico das micobacterioses, pois a identificação das espécies possibilita a introdução de um tratamento adequado precocemente.