EFFICACY OF A VARIETY OF DISINFECTANTS AGAINST ACTINOBACILLUS-PLEUROPNEUMONIAE SEROTYPE-1

The efficacy of 23 disinfectants (including the most commonly used che mical groups) and 6 quaternary ammonium compound based commercial form ulations against Actinobacillus pleuropneumoniae serotype 1 (ATCC 4074 ) was studied. The organisms were tested in suspension and carrier tes ts with serum as the organic matter. Chloramine-T, hydrogen peroxide, glutaraldehyde, and mercurochrome alone, and a quaternary ammonium com pound formulation containing 10% benzalkonium chloride, 2.5% glutarald ehyde, 6.8% glyoxal, and 6% formaldehyde were effective in all tests, regardless of the presence or absence of organic load. All but 2 of th e nonformulated disinfectants (sodium hypochlorite and an iodophor) ca used at least a 3-log(10) reduction in colony-forming units in the sus pension test. However, most of the disinfectants were not as effective in the carrier test as in the suspension test; this difference ranged from a 1- to 5-log(10) reduction in colony-forming units. In addition , the presence of serum considerably reduced the disinfectant capaciti es of most of the compounds tested, particularly in the carrier test. These results indicate the importance of selecting suitable disinfecta nts for routine use on surfaces contaminated with this organism, espec ially in the presence of organic matter. Chloramine-T and the aforemen tioned commercial formulation were also tested directly under field co nditions in pig nurseries, confirming their high effectiveness.