How to: identify non-tuberculous Mycobacterium species using MALDI-TOF mass spectrometry.

BACKGROUND: The implementation of MALDI-TOF MS for microorganism identification has changed the routine of the microbiology laboratories as we knew it. Most microorganisms can now be reliably identified within minutes using this inexpensive, user-friendly methodology. However, its application in the identification of mycobacteria isolates has been hampered by the structure of their cell wall. Improvements in the sample processing method and in the available database have proved key factors for the rapid and reliable identification of non-tuberculous mycobacteria isolates using MALDI-TOF MS. AIMS: The main objective is to provide information about the proceedings for the identification of non-tuberculous isolates using MALDI-TOF MS and to review different sample processing methods, available databases, and the interpretation of the results. SOURCES: Results from relevant studies on the use of the available MALDI-TOF MS instruments, the implementation of innovative sample processing methods, or the implementation of improved databases are discussed. CONTENT: Insight about the methodology required for reliable identification of non-tuberculous mycobacteria and its implementation in the microbiology laboratory routine is provided. IMPLICATIONS: Microbiology laboratories where MALDI-TOF MS is available can benefit from its capacity to identify most clinically interesting non-tuberculous mycobacteria in a rapid, reliable, and inexpensive manner.

Implementation of MALDI-TOF MS technology for the identification of clinical isolates of Mycobacterium spp. in mycobacterial diagnosis.

A total of 243 clinical isolates of the Mycobacterium genus were studied, 143 and 100 using two protocols (Protocol v2 and Protocol v3, respectively) provided by the manufacturer. The overall correlation of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with the standard identification methods was 63.8 %. The rate of misidentification was 3.2 %, mainly affecting very close species. In Protocol v2, the correlation was 57.3 %, being greater in solid than in liquid media (71.7 % vs. 44.7 %, p < 0.05). Albeit not significant, a trend to a greater correlation for M. tuberculosis complex compared to non-tuberculous mycobacteria (NTM) (63.6 % vs. 55.5 %) was observed. In Protocol v3, the correlation was 73 %, with no significant differences between solid and liquid media (70.8 % vs. 75 %). In conclusion, MALDI-TOF MS may play a role in identifying mycobacterial species isolated from clinical samples, being faster than sequencing and hybridization-based techniques.

[Investigation on health status of silica exposed workers in "cotto Fiorentino" companies]. / Indagine sullo stato di salute degli esposti a silice nelle aziende del cotto Fiorentino.

The manufactured in "cotto" is typical of Chianti Fiorentino with about 400 employees. In 2005. the UF PISLL encountered an exposure to silica more than TLV, particularly for some tasks; were prescribed interventions of prevention and was undertaken an investigation of the occupational health status with occupational health physician. We observed 227 workers, 208 males and 19 females, with average age of 43 years and average age working of 15 years. The habit of smoking tobacco was higher than for the general population. The assessment of exposure to silica has been detected for 59 workers (mean 0.05 mg / mc); at pulmonary function testing resulted: 10 with airway obstruction and 4 airflow limitation; by 140 chest X - ray acquired 1 was interstitial pulmonary disease and 1 was bronchopneumonia. Among the diseases not related to exposure to silica, emerging 42 cases of low back pain, 28 hearing loss, 7 with hypertension. Non uniformity in health surveillance and diagnostic criteria highlights the need to cooperate between occupational doctor in public prevention and control service and qualified occupational doctor to ensure a standard of quality in the prevention of disease in exposed to silica.