PURPOSE: PCR is widely used for rapidly and accurately detecting Mycobacterium Species. The purpose of this study was to assess the diagnostic performance of three real-time PCR kits and evaluate the concordance with two older PCR methods. MATERIALS AND METHODS: Using 128 samples, the five PCR methods were assessed, including an in-house PCR protocol, the COBAS Amplicor MTB, the COBAS TaqMan MTB, the AdvanSure TB/NTM real-time PCR, and the Real-Q M. tuberculosis kit. The discrepant results were further examined by DNA sequencing and using the AdvanSure Mycobacteria Genotyping Chip for complete analysis. RESULTS: For Mycobacterium tuberculosis (MTB) detection, all five kits showed 100% matching results (positive; N = 11 and negative; N = 80). In non-tuberculous mycobacterium (NTM) discrimination, the AdvanSure yielded two true-positive outcomes from M. intracellulare and one false positive outcome, while the Real-Q resulted in one true-positive outcome and one false negative outcome for each case and another false negative result using the provided DNA samples. CONCLUSION: Real-time PCR, yielded results that were comparable to those of the older PCR methods for detecting MTB. However, there were disagreements among the applied kits in regard to the sample test results for detecting NTM. Therefore, we recommend that additional confirmatory measures such as DNA sequencing should be implemented in such cases, and further research with using a larger numbers of samples is warranted to improve the detection of NTM.
DNA, Bacterial/genetics ; Humans ; Mycobacterium/*genetics ; Mycobacterium Infections/*diagnosis/microbiology ; Mycobacterium avium Complex/genetics ; Mycobacterium avium-intracellulare Infection/diagnosis ; Mycobacterium tuberculosis/genetics ; Polymerase Chain Reaction/*standards ; Reagent Kits, Diagnostic/*standards ; Tuberculosis/diagnosis

OBJECTIVEMycobacterium avium (M. avium) and Mycobacterium intracellulare (M. intracellulare) are the major causative agents of nontuberculous mycobacteria (NTM)-related pulmonary infections. However, little is known about the differences in drug susceptibility profiles between these two species.

METHODSA total of 393 NTM isolates were collected from Shanghai Pulmonary Disease Hospital. Sequencing of partial genes was performed to identify the strains at species level. The minimum inhibitory concentration (MIC) was used to evaluate the drug susceptibility against 20 antimicrobial agents. Variable number of tandem repeat (VNTR) typing was conducted to genotype these two species.

RESULTSA total of 173 (44.0%) M. avium complex (MAC) isolates were identified, including 41 (10.4%) M. avium isolates and 132 (33.6%) M. intracellulare isolates. Clarithromycin and amikacin were the two most effective agents against MAC isolates. The Hunter-Gaston Discriminatory Index (HGDI) values for VNTR typing of M. avium and M. intracellulare isolates were 0.993 and 0.995, respectively. Levofloxacin resistance was more common among the unclustered strains than among the clustered strains of M. intracellulare.

CONCLUSIONM. intracellulare was the most common NTM species in China. Clarithromycin and amikacin had high antimicrobial activities against MAC. VNTR typing of MAC isolates revealed a high discriminatory power. Levofloxacin resistance was associated with unclustered strains of M. intracellulare.

Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Bacterial ; Genotype ; Humans ; Mycobacterium avium Complex ; drug effects ; genetics ; Mycobacterium avium-intracellulare Infection ; epidemiology ; microbiology

Isolated bone marrow infection by nontuberculous mycobacteria (NTM) is extremely rare. Recently, we encountered a case of bone marrow Mycobacterium avium complex (MAC) infection, which presented as a fever of unknown origin shortly after starting continuous ambulatory peritoneal dialysis (CAPD). The patient was diagnosed with MAC infection on the basis of PCR-restriction fragment length polymorphism analysis and sequencing of DNA obtained from bone marrow specimens. Although this was a case of severe MAC infection, there was no evidence of infection of other organs. End-stage renal disease (ESRD) patients undergoing dialysis can be considered immunodeficient; therefore, when these patients present with fever of unknown origin, opportunistic infections such as NTM infection should be considered in the differential diagnosis.
Aged ; Anti-Bacterial Agents/therapeutic use ; Bacterial Proteins/genetics ; Bone Marrow/microbiology/pathology ; Diagnosis, Differential ; Female ; HIV Infections/diagnosis ; Humans ; Kidney Failure, Chronic/therapy ; *Mycobacterium avium Complex/genetics/isolation &purification ; Mycobacterium avium-intracellulare Infection/*diagnosis/drug therapy/microbiology ; *Peritoneal Dialysis, Continuous Ambulatory ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Sequence Analysis, DNA