In vitro PYOCIN activity ofPseudomonas aeruginosa strains pretreated with antibiotics

Abstract

Fifty-six selected strains of Pseudomonas aeruginosa belonging to 8 different pyocin types (H, I, 15, 6, PTI-1, PTI-2, PTI-3, PTI-4) were treated with subinhibitory concentrations (MIC/2) of either gentamicin or carbenicillin. Both treatments induced changes in pyocin patterns for all types but at different levels. The percentage of strains that retained their pyocin pattern were more or less equal in both treatments. In treated and untreated producers, the growth inhibition ability for 5 different strains of Enterobacteriaceae (Escherichia coli K12, E. coli EB, Proteus vulgaris, Salmonella typhi, Shigella flexneri) was also investigated. In all pyocin patterns the number of producers that inhibit the growth of these strains was lower after treatment with gentamicin or with carbenicillin, a smaller decrease was detected in the latter treatment. It appeared that the subinhibitory concentrations of these antibiotics are capable of protecting the Enterobacteriaceae strains from the action of the pyocins.

Bacteriocins, Antimicrobial Peptides from Bacterial Origin: Overview of Their Biology and Their Impact against Multidrug-Resistant Bacteria

“…As examples of colicin-like and phage tail-like bacteriocins, pyocins produced by P. aeruginosa might present a particular interest due to their activities against relevant Gram-negative pathogens [61,78]. Three types of chromosome-encoded pyocins could be found in P. aeruginosa, including R, F, and S-type pyocins [15].…”

Sub-Inhibitory Antibiotic Exposure and Virulence in Pseudomonas aeruginosa

“…[133] Amikacin Comp. [135,136] Cooperation [117] in vitro virul. [133] Amikacin [193] [193] in vivo virulence [143,144,198] Enoxacin [199] [132] in vivo virul.…”

“…Interestingly, exposure to sub-MIC ciprofloxacin has been found to significantly upregulate the expression of genes involved in pyocin production [223]. Sub-MIC polymyxin B was found to protect P. aeruginosa in vitro from pyocins to which it is usually susceptible, possibly by enacting changes in lipopolysaccharide (LPS) composition [136], whilst sub-MIC carbenicillin changed the pyocin type produced by P. aeruginosa and protected various Enterobacteriaceae strains (Escherichia coli, Salmonella typhi, Proteus vulgaris, and Shigella flexneri) [135]. Sub-MIC gentamicin demonstrated the same effects [135,136].…”

“…Sub-MIC polymyxin B was found to protect P. aeruginosa in vitro from pyocins to which it is usually susceptible, possibly by enacting changes in lipopolysaccharide (LPS) composition [136], whilst sub-MIC carbenicillin changed the pyocin type produced by P. aeruginosa and protected various Enterobacteriaceae strains (Escherichia coli, Salmonella typhi, Proteus vulgaris, and Shigella flexneri) [135]. Sub-MIC gentamicin demonstrated the same effects [135,136]. Although the mechanisms behind these findings were not explored at the time, a more recent study helps shed some light on them.…”