FACTORS CONTRIBUTING TO THE SURVIVAL OF POULTRY ASSOCIATED PSEUDOMONAS SPP EXPOSED TO A QUATERNARY AMMONIUM COMPOUND

Resistance to benzalkonium chloride (BC) among Pseudomonas spp. isolat ed from poultry carcasses was determined and strategies for eliminatio n of resistant strains evaluated. This investigation showed that resis tance was quite common, about 30% of the isolates being able to grow i n 200 mu g ml(-1) BC. Pseudomonas fluorescens strains were generally l ess susceptible than strains of Ps. lundensis and Ps. fragi. An overni ght incubation in medium containing 200 mu g ml(-1) BC was sufficient to reduce the susceptibility of two Pseudomonas strains to the lethal effect of BC significantly. Adding EDTA enhanced the lethal effect of BC, but the effect was reduced after growing cells in medium containin g BC and EDTA. Growth in medium with a quaternary ammonium compound (Q AC) rendered the cells more susceptible to chlorine, phenolics and alk ylaminoacetate. These results indicate that alternating use of QACs wi th these compounds can be used to avoid build-up of resistant strains. In addition, increased temperatures improved the lethal effect of BC and should be considered when planning disinfection routines.