AUTHOR=Fernandes Luciana , Fortes Bruna Nakanishi , Lincopan Nilton , Ishida Kelly 

TITLE=Caspofungin and Polymyxin B Reduce the Cell Viability and Total Biomass of Mixed Biofilms of Carbapenem-Resistant Pseudomonas aeruginosa and Candida spp.

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.573263

DOI=10.3389/fmicb.2020.573263

ISSN=1664-302X

ABSTRACT=<p><italic>Pseudomonas aeruginosa</italic> and <italic>Candida</italic> spp. are biofilm-forming pathogens commonly found colonizing medical devices, being mainly associated with pneumonia and bloodstream infections. The coinfection by these pathogens presents higher mortality rates when compared to those caused by a single microbial species. This study aimed to evaluate the antibiofilm activity of echinocandins and polymyxin B (PMB) against polymicrobial biofilms of carbapenem-resistant (CR) <italic>Pseudomonas aeruginosa</italic> and <italic>Candida</italic> spp. (<italic>C. albicans</italic>, <italic>C. parapsilosis</italic>, <italic>C. tropicalis</italic>, and <italic>C. glabrata</italic>). In addition, we tested the antimicrobial effect on their planktonic and monomicrobial biofilm counterparties. Interestingly, beyond inhibition of planktonic [minimum inhibitory concentration (MIC) = 0.5 μg/ml] and biofilm [minimum biofilm inhibitory concentration (MBIC)<sub>50</sub> ≤ 2–8 μg/ml] growth of <italic>P. aeruginosa</italic>, PMB was also effective against planktonic cells of <italic>C. tropicalis</italic> (MIC = 2 μg/ml), and polymicrobial biofilms of CR <italic>P. aeruginosa</italic> with <italic>C. tropicalis</italic> (MBIC<sub>50</sub> ≤ 2 μg/ml), <italic>C. parapsilosis</italic> (MBIC<sub>50</sub> = 4–16 μg/ml), <italic>C. glabrata</italic> (MBIC<sub>50</sub> = 8–16 μg/ml), or <italic>C. albicans</italic> (MBIC<sub>50</sub> = 8–64 μg/ml). On the other hand, while micafungin (MFG) showed highest inhibitory activity against planktonic (MIC ≤ 0.008–0.5 μg/ml) and biofilm (MBIC<sub>50</sub> ≤ 2–16 μg/ml) growth of <italic>Candida</italic> spp.; caspofungin (CAS) displays inhibitory activity against planktonic cells (MIC = 0.03–0.25 μg/ml) and monomicrobial biofilms (MBIC<sub>50</sub> ≤ 2–64 μg/ml) of <italic>Candida</italic> spp., and notably on planktonic and monomicrobial biofilms of CR <italic>P. aeruginosa</italic> (MIC or MBIC<sub>50</sub> ≥ 64 μg/ml). Particularly, for mixed biofilms, while CAS reduced significantly viable cell counts of CR <italic>P. aeruginosa</italic> and <italic>Candida</italic> spp. at ≥32 and ≥ 2 μg/ml, respectively; PMB was effective in reducing viable cells of CR <italic>P. aeruginosa</italic> at ≥2 μg/ml and <italic>Candida</italic> spp. at ≥8 μg/ml. Similar reduction of viable cells was observed for CAS (32–64 μg/ml) combined with PMB (2 μg/ml). These findings highlight the potential of PMB and CAS for the treatment of polymicrobial infections caused by <italic>Candida</italic> spp. and critical priority CR <italic>P. aeruginosa</italic>.</p>