263522 Effects of chlorophyll-derived efflux pump inhibitor pheophorbide a and pyropheophorbide a on erythromycin resistance of Staphylococcus aureus, Enterococcus faecalis, Salmonella Typhimurium and Escherichia coli

Tuesday, October 30, 2012

Mareike Kraatz, Dr vet med , United States Department of Agriculture (USDA), Agricultural Research Service (ARS), National Center for Agricultural Utilization Research (NCAUR), Peoria, IL
Terence Whitehead, PhD , United States Department of Agriculture (USDA), Agricultural Research Service (ARS), National Center for Agricultural Utilization Research (NCAUR), Peoria, IL
Michael Cotta, PhD , United States Department of Agriculture (USDA), Agricultural Research Service (ARS), National Center for Agricultural Utilization Research (NCAUR), Peoria, IL
Mark Rasmussen, PhD , Leopold Center for Sustainable Agriculture, Iowa State University, Ames, IA
The purpose of this study was to validate the hypothesis that pheophorbide a and pyropheophorbide a reduce erythromycin resistance of reference strains of facultative anaerobic bacteria with multidrug or macrolide efflux pumps, as indicative of their effect on bacteria indigenous to anaerobic swine waste (feces and stored manure). Minimal inhibitory concentrations of erythromycin (MICs; g erythromycin ml-1) were determined for erythromycin-nave and serial passage-selected mutant Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Salmonella enterica serovar Typhimurium ATCC 14028 and porcine Escherichia coli P286.10.99.C3 and P475.10.99 using CLSI-standard broth macrodilution assays with or without pheophorbide a or pyropheophorbide a (0.5 and 50 g ml-1) under static aerobic and anaerobic (100 % CO2; Coy Anaerobic chamber) conditions for up to seven days. The results showed that the greatest effects were obtained using pyropheophorbide a against S. aureus: MICs for nave cultures were low (max. 1) and reduced twofold by 0.5 and 50 g pyropheophorbide a ml-1 under both aerobic and anaerobic conditions. Mutant cultures exhibited a 4096-fold increase of basal MICs, whereby 50 g pyropheophorbide a ml-1 caused an up to threefold reduction under anaerobic conditions. Effects on the other strains were not noticed (E. faecalis, E. coli P286.10.99.C3) or significant only on mutant cultures under anaerobic conditions (twofold MIC reduction for E. coli P475.10.99 and S. Typhimurium by 50 g pyropheophorbide a ml-1). In conclusion, this is the first study indicating that chlorophyll-derived pyropheophorbide a can reduce antibiotic resistance of bacteria in anaerobic habitats, such as food chain-relevant swine waste.

Learning Areas:
Basic medical science applied in public health
Environmental health sciences
Public health biology

Learning Objectives:
Identify pyropheophorbide a as a novel natural (i.e. green plant-derived) compound with antibiotic resistance-reducing effect against food chain-relevant facultative anaerobic bacteria

Keywords: Antibiotic Resistance, Animal Waste

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I hold a PhD degree in veterinary medicine and have been the first author of two valid taxonomic descriptions of novel species of anaerobic bacteria from the swine gut (Veillonella magna, Olsenella umbonata). Therefore, I am professionally qualified to conduct and present basic microbiological research with public health impact, such as the research described in the abstract.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.