Discrimination of the Acinetobacter calcoaceticus–Acinetobacter baumannii complex species by Fourier transform infrared spectroscopy
The main goal of this work was to assess the ability of Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) to discriminate between the species of the Acinetobacter calcoaceticus–Acinetobacter baumannii (Acb) complex, i.e. A. baumannii, A. nosocomialis, A. pittii, A. calcoaceticus, genomic species “Between 1 and 3” and genomic species “Close to 13TU”. A total of 122 clinical isolates of the Acb complex previously identified by rpoB sequencing were studied. FTIR-ATR spectra was analysed by partial least squares discriminant analysis (PLSDA) and the model scores were presented in a dendrogram form. This spectroscopic technique proved to be effective in the discrimination of the Acb complex species, with sensitivities from 90 to 100 %. Moreover, a flowchart aiming to help with species identification was developed and tested with 100 % correct predictions for A. baumannii, A. nosocomialis and A. pittii test isolates. This rapid, low cost and environmentally friendly technique proved to be a reliable alternative for the identification of these closely related Acinetobacter species that share many clinical and epidemiological characteristics and are often difficult to distinguish. Its validation towards application on a routine basis could revolutionise high-throughput bacterial identification.
KeywordsAttenuate Total Reflectance Partial Little Square Discriminant Analysis Acinetobacter Baumannii Multivariate Data Analysis Test Isolate
Liliana Silva was supported by a doctoral grant from Fundação para a Ciência e a Tecnologia (SFRH/BD/88028/2012) and Clara Sousa was supported by a post-doctoral grant from Fundação para a Ciência e a Tecnologia (SFRH/BPD/70548/2010). Alexandr Nemec was supported by grant 13-26693S from the Czech Science Foundation.
We thank Lenie Dijkshoorn (Leiden) for the kind provision of several strains used in this study.
Conflict of interest
The authors declare that they have no conflict of interest.
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