Comparing inactivation protocols of Yersinia organisms for identification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
BACKGROUND
It is recommended that harmful Biosafety Level 3 (BSL-3) bacteria be inactivated prior to identification by mass spectrometry, yet optimal effects of inactivation protocol have not been defined.


METHODS
Here, we compare trifluoroacetic acid inactivation (protocol A) with ethanol inactivation (protocol B) of Yersinia organisms prior to identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS).


RESULTS
The total number of peaks detected was 10.5 ± 1.7 for protocol A and 15.7 ± 4.2 for protocol B (ρ <0.001, ANOVA test). The signal-to-noise ratio for the m/z 6049 peak present in all of the tested Yersinia isolates was 9.7 ± 3.1 for protocol A and 18.1 ± 4.6 for protocol B (ρ < 0.001). Compared with spectra in our local database containing 48 Yersinia spp., including 20 strains of Y. pestis, the identification score was 1.79 ± 0.2 for protocol A and 1.97 ± 0.19 for protocol B (ρ = 0.0024).


CONCLUSIONS
Our observations indicate that for the identification of Yersinia organisms, ethanol inactivation yielded MALDI-TOF-MS spectra of significantly higher quality than spectra derived from trifluoroacetic acid inactivation. Combined with previously published data, our results permit the updating of protocols for inactivating BSL-3 bacteria.
Fédération de Microbiologie Clinique, Assistance Publique des Hôpitaux de Marseille, Institut Hospitalier Universitaire POLMIT, Marseille, France.
Carine
C
Couderc
Claude
C
Nappez
Michel
M
Drancourt
D000431:Ethanol / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014269:Trifluoroacetic Acid / Q000378:metabolism; D015007:Yersinia / Q000737:chemistry / Q000302:isolation & purification* / Q000502:physiology; D015009:Yersinia Infections / Q000382:microbiology*
D000431:Ethanol; D014269:Trifluoroacetic Acid