The Brief case: Misidentification of Cardiobacterium valvarum as Biosafety Level 3 organism Francisella tularensis by VITEK® automated system and diagnostic approach using a "rule out or refer" algorithm.

Automated systems like VITEK® or MALDI-TOF MS have become the most reliable modern basis pathogen identification. Rarely, identification is not possible, mostly in case of closely related or very rare microorganisms. Decision between two unconfirmed identified rare microorganisms can be very challenging. This is especially important if one of these microorganisms is a Biological safety Level 3 (BSL-3) organism. Here we present a bacterial isolate that was identified as Francisella tularensis by VITEK® while MALDI could not identify the true pathogen, Cardiobacterium valvarum. According to a "rule out or refer" algorithm F. tularensis was ruled out based on clinical evaluation, culture, biochemical tests and susceptibility testing. The definite confirmation was done by 16S rRNA sequencing. The case highlights the need for vigilance for highly pathogenic pathogens. While reference methods are molecular techniques, seemingly outdated microbiological techniques should be hold available even when automated systems have become increasingly available and reliable.