Identification of 273 Clinical Aeromonas Strains with a Gold Standard Method and MALDI-TOF: A Review on the Limitations of the Method

Abstract

The genus Aeromonas comprises Gram-negative bacteria widely distributed in aquatic environments, with some species able to cause disease in humans, fish, and other aquatic animals. The dominating species in human infections are Aeromonas caviae, Aeromonas dhakensis, Aeromonas hydrophila, and Aeromonas veronii and the disease presentations gastroenteritis, bacteremia, and wound infections. Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) is an extremely rapid method used in clinical microbiology laboratories to identify bacterial isolates at the genus and species level. The present study aimed to evaluate the usefulness of the MALDI-TOF MS to identify 273 clinical isolates of Aeromonas that were also identified by rpoD gene. The latter recognized eight different species, but only 73.6% of the strains of six species were correctly identified with MALDI-TOF MS and results depended upon the species. The higher concordance was with A. veronii (92.8%), A. hydrophila (83.3%), A. caviae (73.1%), and Aeromonas media (60.0%). Our results and those of the reviewed literature corroborate that MALDI-TOF is a promising identifying method being the poorly updated database the main limitation. Improvement requires including a higher diversity of strains from all the described species which should be the responsibility of the provider.