LAUSR

M. atlantae is a short, immobile, Gram-negative bacillus that grows in standard culture media. It is catalaseand oxidasepositive, cannot acidify sugar, is negative for nitrate reduction and assimilates acetate and nitrate. It is alkaline phosphatase-positive and pyrrolidone carboxyl peptidase-positive.2 It is underdiagnosed because it is difficult to isolate using classic methods and due to its sensitivity to routine antibiotics. Despite continuous advances in microorganism identification using classic phenotyping techniques, such as the API ® HK method (BioMérieux, Marci L’ Étoile, France), or by automated methods, the identification of certain species like M. atlantae continues to pose a challenge both due to difficulties with the culture as well as the excessively long identification time.4 For these reasons, and to prevent diagnostic delays, new rapid-detection methods are being developed, such as MALDI-TOF mass spectrometry.5 The first reference to this method of bacterial identification dates back to 1996 and was performed by Holland et al.6 and Krishnamurthy et al.7. As well as being an easy and cost-effective method, it is also the quickest method to identify bacteria in blood cultures. Its efficacy varies from 43% to 94% depending on the pathogen. By analysing proteins, particularly ribosomal proteins, this technology can identify microorganisms from colonies or directly from samples by creating a mass spectrum (that is specific to each species). It can identify both the genus and species of microorganism depending on the reliability score, the limits of which are set by the manufacturer (<1.7 not reliable for genus or species, 1.7–2 reliable for genus, not for species, >2 very reliable for both genus and species).8 Its high cost and the need to produce an antibiogram using classic methods constitute its main limitations. To address these limitations, new antibacterial resistance rapiddetection techniques, such as detection of beta-lactam antibiotics and methicillin-resistant Staphylococcus aureus strains by MALDITOF, are being developed.9