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Porcine intestinal spirochaetes are fastidious anaerobic organisms and, as a consequence, it has been necessary to develop various protocols to enhance their isolation from or detection in faeces.Immunomagnetic separation (IMS) is a method developed recently to improve separation of target cells from mixed cell suspensions. The purpose of the present study was to compare the relative sensitivity of IMS for isolation of Brachyspira pilosicoli and Brachyspira hyodysenteriae with current routine diagnostic methods (culture on selective media and PCR) for detection of these microorganisms in pig faeces. Neither direct nor indirect IMS methods enhanced the sensitivity of detection of either organism when performed with the recommended washings during sample processing. Performance of the IMS procedure without washing gave sensitivity at levels similar to direct culture onto selective medium. Further development of IMS techniques is required to improve isolation rates of Brachyspira species from faecal samples. INTRODUCTIONIntestinal spirochaetes are mainly members of the genus Brachyspira, which includes species commensal and pathogenic for pigs and other animals and humans. Brachyspira hyodysenteriae is recognized as the aetiological agent of swine dysentery (SD) (Taylor & Alexander, 1971) and Brachyspira pilosicoli is the aetiological agent of a disease of pigs known as intestinal spirochaetosis (Taylor et al., 1980) or porcine colonic spirochaetosis (PCS;Duhamel et al., 1998). Infection with B. pilosicoli has been reported in a wide range of hosts, including dogs (Duhamel et al., 1995), chickens and other avian species (Dwars et al., 1992;McLaren et al., 1997), guinea pigs (Vanrobaeys et al., 1998), non-human primates (Takeuchi et al., 1974) and humans (Cooper et al., 1986; Surawicz et al., 1987). As interest in the field of intestinal spirochaetes has grown, further species have been identified recently as pathogens in animal species other than pigs. For instance, Brachyspira alvinipulli has been described and shown to be pathogenic for chickens (Stanton et al., 1998) and the provisionally designated 'Serpulina canis' has been found in dogs (Duhamel et al., 1998).Porcine intestinal spirochaetes are Gram-negative, anaerobic and fastidious organisms. As a result, various culture media and incubation conditions have been assessed in order to develop the most reliable and efficient method for their isolation from faecal samples. Typically, isolation of these bacteria is achieved by culture on selective media based on trypticase soy agar or Columbia agar base supplemented with blood and multiple antibiotics to reduce the growth of other bacteria. Various antibiotic combinations have been utilized including spectinomycin (TSA-S400 medium; Songer et al., 1976), spiramycin-colistin-vancomycin (TSA-CVS medium;Jenkinson & Wingar, 1981) and spectinomycin-colistinvancomycin-spiramycin-rifampicin (BJ medium; Kunkle & Kinyon, 1988). In a comparative study of these media, BJ proved to be the most efficient in eliminating norm...

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.

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Background and Aim: Brachyspira are Gram-negative, aerotolerant spirochetes that colonize the large intestine of various species of domestic animals and humans. The aim of this study was to determine the presence and distribution of different species of Brachyspira presents in feces from finishing pigs in Argentina. Materials and Methods: Fecal samples (n=1550) were collected from finishing pigs in 53 farms of the most important swine production areas of Argentina, and Brachyspiras species were identified by bacteriological and molecular methods. Results: The regional prevalence of Brachyspira spp. was at the level of 75.5% (confidence interval 95%, 62.9-87.9), and it was lower among those farms with >1001 sows. One hundred and twenty-eight isolates of Brachyspira were properly identified and the species found were: Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira innocens, and Brachyspira murdochii. B. hyodysenteriae and B. pilosicoli had low prevalence (1.9% and 7.5%, respectively), B. innocens was isolated from 34% of the farms and B. murdochii was found in 39.6%. Conclusion: The present study provides epidemiological data about herd prevalence of the different Brachyspira species in Argentina, showing that the prevalence figure seems to be higher than that reported in other countries.