S-Pyocins as potential antimicrobial agents for eradicating pseudomonas aeruginosa biofilms

Official URL: http://risc01.sabanciuniv.edu/record=b1589823 (Table of Contents)

Pseudomonas aeruginosa (Pa) is a gram-negative opportunistic pathogen associated with life-threatening hospital-acquired and community-acquired infections affecting urinary tract, skin, eye, ear, and lungs. Antipseudomonal antibiotics are the most potent arsenals to treat Pa infections. However, Pa infections are still common and stubborn bacterial infections due to elevated resistance levels against most of the antibiotics used in clinics. Treating Pa infections becomes even harder especially if antibiotic resistant Pa strains form biofilms and cystic structures in human body. In such cases, drug doses for treating bacterial infections can be up to one thousand fold higher than the necessary dose for treating infections caused by planktonic bacteria. Thus, there is an obvious need for novel therapies for fighting against Pa infections and Pa biofilms. Recently, several studies performed on pyocins, proteinaceous bacterial toxins produced by Pa, to explore the potential of pyocins as novel antibiotics to treat Pa infections. Similar to other members of the bacteriocin family, pyocins mostly kill strains of the related species. There are three types of pyocins: S, R, and F pyocins. S-type pyocins are high molecular weight proteins and RF-type pyocins resemble bacteriophage tails. In this study, we applied four S-pyocins (S1, S2, S3, AP41) on Pa biofilms separately and in combination with six commonly used antibiotics (Tobramycin, Gentamicin, Colistin, Piperacillin, Ceftazidime, Ciprofloxacin) to determine the efficacy of S-pyocins in eradicating Pa biofilms and interactions between S-pyocins and antibiotics. We created Pa biofilms using Calgary Biofilm Device (CBD) to determine minimum biofilm eradication concentration (MBEC) of each antibiotics and S-pyocins separately and in combination. This study aims to explore the potential use of S-pyocins as alternative drugs for eradicating biofilms where Pa biofilms show high resistance to antibiotics. Our preliminary results suggest wild type pyocins have a slight effect on Pa biofilms but there is an antagonism between pyocin AP41 and drugs Ciprofloxacin, and Colistin which can be used for selecting against drug resistant Pa strains.