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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Two Enrichment Schemes for Qualitative Recovery of Salmonellaserovar Choleraesuis from Rectal Swabs Collected from Neonatal and Early Weaned Pigs

Authors
item Anderson, Robin
item Harvey, Roger
item Genovese, Kenneth
item Stanker, Larry
item Deloach, John - MILK SPECIALTIES
item Nisbet, David

Submitted to: International Symposium on Epidemiology and Control of Salmonella in Pork
Publication Type: Proceedings
Publication Acceptance Date: June 18, 1999
Publication Date: N/A

Technical Abstract: Numerous bacteriological culture methods have been developed for the qualitative recovery of Salmonella from animal sources but none are considered infallible. Presently, we report observations on the recovery of Salmonella Choleraesuis (SC) from rectal swabs cultured via schemes using pre-enrichment in tetrathionate broth (TET-scheme) or GN-Hajna broth (GN-scheme); the latter presumed better for recovering host adapted serotypes. Piglets (n=12) were challenged at 48 hrs of age with 10**7 colony forming units (CFU) of a novobiocin (NO) and nalidixic acid (NA) resistant strain of SC. This NO-NA resistant mutant exhibited no apparent cultural differences from the wildtype parent strain when grown as pure cultures in or on a variety of different media, including those listed below. For the next 21 days post challenge, two rectal swabs were collected daily from each piglet and each was pre-enriched in tetrathionate or GN-Hajna broth and then further enriched in Rappaport- Vassiladias broth. Selective differentiation was accomplished on Brilliant Green agar containing 25 micrograms NO/ml (BGANO) and on BGA supplemented with both 25 micrograms NO/ml and 20 micrograms NA/ml (BGANOV/NAL). Each incubation step was carried out at 37oC for 24 hr. Our marked SC was readily recovered when plated on BGANOV/NAL, although more so (P < 0.10) from swabs cultured via the GN-scheme rather than the TET-scheme (75 and 62%, respectively, of 252 swabs cultured).

Last Modified: 4/18/2014