AMONG the intestinal spirochaete species of pigs, Brachyspira hyodysenteriae and Brachyspira pilosicoli are important agents of disease. B pilosicoli infection is variously termed spirochaetal diarrhoea (Taylor 1992), porcine colonic spirochaetosis (Muniappa and others 1997) or porcine intestinal spirochaetosis (Duhamel 1995). A recent study on pig herds with infectious colitis in the UK showed that Bpilosicoli was found in 25-0 per cent as a single pathogen, and in another 27-0 per cent as a copathogen (Thomson and others 1998). Transmission of Bpilosicoli occurs either through contamination of the immediate environment, or by direct contact between pigs. B pilosicoli can remain viable in contaminated water for 66 days (Oxberry and others 1998), thus increasing the potential for transmission. As there is no information on the activity of disinfectants against B pilosicoli, this short communication describes a study of the efficacy of seven disinfectant sanitisers against six field isolates and the type strain, ATCC-51139, of B pilosicoli, in the absence and presence of organic matter.The field isolates were from cases of porcine colitis, obtained as part of a surveillance programme for porcine colitis conducted by the Scottish Agricultural College (SAC). B pilosicoli grown anaerobically in brain heart infusion broth (Oxoid) supplemented with 5 per cent (w/v) filter-sterilised rabbit serum at 380C for two days was used as a bacterial suspension for assessing the disinfectant sanitisers.The tested products were of four different chemical groups, all manufactured by Antec International, and included three quaternary ammonium compounds, Ambicide (a disinfectant), DSC-1000 (a sanitiser) and HD-3 (a sanitiser); one amphoteric surfactant-caustic soda compound, Heavy Duty (a sanitiser); two tar organic acid compounds, Farm Fluid (a disinfectant) and Long Life (a disinfectant); and one peroxygen compound, Virkon S (a disinfectant).The efficacy tests were carried out according to the recommendations of the National Committee for Clinical Laboratory Standards for (NCCLS) antimicrobial susceptibility on anaerobic bacteria (NCCLS 1989), and adapted for testing the disinfectants. Ten-fold dilutions ( 1:10 up to 1 :100,000) of the disinfectant sanitisers were prepared in sterile deionised water (SDW) (for testing in the absence of organic matter) or in a suspension of sterile pig faeces (SPF) (for testing in the presence of organic matter) diluted 1:20 in phosphatebuffered saline solution. An aliquot of 0-1 ml ofbacterial suspension (approximately 105 colony-forming units/ml) was added to 0-9 ml of each serial dilution and the mixture was left for contact times of 30 or 60 minutes at room temperature (220C). Each suspension was then inoculated in triplicate on to blood agar plates, allowed to dry, and incubated anaerobically at 380C for three to four days. Control inocula, with no disinfectant, of each isolate were included.
