AUTHOR=Fernández-Barat Laia , Vázquez Burgos Nil , Alcaraz Victoria , Bueno-Freire Leticia , López-Aladid Ruben , Cabrera Roberto , Gabarrús Albert , Palomeque Andrea , Oscanoa Patricia , Ceccato Adrian , Motos Ana , Amaro Rosanel , Bernardi Thierry , Provot Christian , Soler-Comas Alba , Muñoz Laura , Vila Jordi , Torres Antoni 

TITLE=The value of biofilm testing to guide antimicrobial stewardship in chronic respiratory diseases

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 13 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2023.1142274

DOI=10.3389/fcimb.2023.1142274

ISSN=2235-2988

ABSTRACT=Biofilm capacity is not currently included in diagnostic microbiology and has implications in antimicrobial therapy and clinical management of patients. We aimed to validate and identify BioFilm Ring Test® (BRT) applications in Pseudomonas aeruginosa (PA) isolates from bronchiectasis (BE) patients. Sputa were collected from BE patients with at least one PA positive culture in the last year, immersed in 1:1 Dithiothreitol (DTT) solution and sonicated for 5 min at 40kHz. PA confirmed by MALDI-TOF were classified as mucoid or non-mucoid. Susceptibility to EUCAST recommended antimicrobials using disk diffusion method was performed. mucA gene was amplified by PCR, sequenced by Sanger method, and analyzed using GenBank. The Biofilm index (BPI) was obtained at 5 and 24 h following manufacturer’s instructions. Biofilm visualization by Gram staining was included. Sixty-nine PA isolates, 33 mucoid and 36 non-mucoid were collected. Non-mucoids and ciprofloxacin susceptible PA presented higher BPI than mucoids and ciprofloxacin resistant strains. BPI <14.75 or BPI<19.28 predicted mucoid phenotype or ciprofloxacin resistance with 64-75% sensitivity and 72-52% specificity. A Sub analysis of BRT at 5 vs 24h was performed. Mucoids presented a significant increase in BPI at 24h. In addition, significant association was found between mutations in mucA and time-dependent BPI (5-24h). Our study confirms that biofilm testing is a currently underestimated diagnostic tool with potential applications for phenotype and antimicrobial resistance guidance.