Rapid and accurate identification of genomic species from the Acinetobacter baumannii (Ab) group by MALDI-TOF MS

• Published in: Clinical microbiology and infection Vol. 18; no. 11; pp. 1097 - 1103
• Main Authors: Espinal, P., Seifert, H., Dijkshoorn, L., Vila, J., Roca, I.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Elsevier Ltd 01.11.2012; Blackwell Publishing Ltd; Wiley-Blackwell; Elsevier Limited
• Subjects: Acinetobacter; Acinetobacter baumannii; Acinetobacter baumannii - chemistry; Acinetobacter baumannii - classification; Acinetobacter baumannii - isolation & purification; Acinetobacter Infections - microbiology; Antibodies; ARDRA; Bacterial Proteins - analysis; Bacteriological Techniques - methods; Biological and medical sciences; Epidemiology; genomics; Humans; Infection; Infectious diseases; ITS; MALDI-TOF MS; Medical sciences; recA; RecA protein; rRNA; Sensitivity and Specificity; sequence typing; Spacer; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; ARDRA; MALDI-TOF MS; Acinetobacter; ITS; sequence typing; recA; Typing; Neisseriaceae; Identification; Matrix assisted laser desorption ionization; Infection; Acinetobacter baumannii; Microbiological investigation; Bacteria; Micrococcales; Mass spectrometry
• ISSN: 1198-743X; 1469-0691
• DOI: 10.1111/j.1469-0691.2011.03696.x

The closely related members of the Acinetobacter baumannii (Ab) group (A. baumannii, A. pittii and A. nosocomialis) are difficult to identify with phenotypic tests in diagnostic laboratories. Genotypic identification methods require special skills and most do not provide rapid results. The aim of this study was to investigate the ability of MALDI-TOF MS to identify members of the Ab group. Sixty epidemiologically unrelated Acinetobacter spp. isolates were investigated by MALDI-TOF MS: 18 A. baumannii, 17 A. pittii, 18 A. nosocomialis and seven additional isolates representing other Acinetobacter spp. All strains were verified by ARDRA, rRNA intergenic spacer (ITS), recA sequencing and b/aOXA-51. MALDI-TOF MS correctly identified all the genomic strains but erroneously identified A. nosocomialis as A. baumannii because there was no reference strain within the Bruker database. Peak analysis of individual spectra from representative strains of each member of A. baumannii, A. pittii and A. nosocomialis suggested enough differences between their protein signatures to allow accurate identification using MALDI-TOF MS. Inclusion of specific signature profiles for A. nosocomialis within the Bruker database allowed the correct identification of this genomic species. MALDI-TOF MS spectra can be used as a fast, simple and reliable method to identify members of the Ab group. The rapid and accurate identification of clinically significant Acinetobacter strains will improve insight into their epidemiology and allow for targeted therapeutic and infection control measures against clinically important strains.