Comparative efficacy of several disinfectants in suspension and carrier tests against Haemophilus parasuis serovars 1 and 5

Abstract

The comparative efficacy of 16 active compounds (including the most commonly used chemical groups) 19 and 10 commercial formulations against Haemophilus parasuis serovars 1 and 5 was studied. These organ- 20 isms were tested in suspension and carrier tests in the presence and absence of serum as representative 21 of organic matter. Chloramine-T and half of the formulations from commercial sources (most of them 22 including quaternary ammonium compounds) were effective in both in vitro tests, regardless of the pres- 23 ence or absence of organic load. All 26 disinfectants except for an iodophor (0.1% available iodine) 24 resulted in at least 3-log10 reduction in colony-forming units in suspension test, and most of them 25 resulted in the maximal level of detection (>6-log10 reduction). On the other hand, disinfectants were 26 not as effective in carrier test as in suspension test, and the presence of serum considerably reduced 27 the activities of most of the compounds tested, especially in carrier test. These results suggest the impor- 28 tance of selecting suitable disinfection for routine use on surfaces contaminated with H. parasuis, partic- 29 ularly when organic matter is present. Chloramine-T and formulations 2 and 7–10 are recommended for a 30 complete inactivation of H. parasuis in swine herds