Abstract

Infections caused by biofilm-embedded pathogens decrease the efficacy of traditional treatments and increase antibiotic tolerance up to 1000-fold. More than 80% of all human bacterial infections are biofilm-associated. Therefore, this study aimed to investigate the antimicrobial as well as antibiofilm activity of papain enzyme on drug resistant biofilm producing Klebsiella pneumoniae. Effect of papain enzyme was tested on Klebsiella pneumonia planktonic cells as well as on the formation, eradication and cells viability of biofilm. Although no antimicrobial activity of papain enzyme was detected against planktonic cells, significant biofilm inhibition and eradication were recorded. Biofilm inhibition of different K. pneumonia strains ranged from (10.6-56.2%) at concentration 50 mg/mL and increased to (21.4-59.0%) at 100 mg/mL papain. Furthermore, noticeable biofilm eradication was recorded (7.7-54.9%) and (9.6-55.6%) at 50 mg/mL and 100 mg/mL papain concentration respectively. Nevertheless, no significant activity was detected on biofilm cells viability. Scanning electron microscopy (SEM) confirmed the inhibitory and eradication activity of papain on K. pneumoniae biofilm. This study demonstrated for the first time that papain enzyme exerts an antibiofilm effect against drug resistant K. pneumoniae, but no antibacterial activity was detected, suggesting its potential application as an antibiofilm agent in combination with traditional antibacterial agents.

Key words: Biofilm; SEM; Papain; MDR; Klebsiella pneumoniae