Comparison of Four Sampling Methods for the Detection of Salmonella in Broiler Litter

Abstract

Experiments were conducted to compare litter sampling methods for the detection of Salmonella. In experiment 1, chicks were challenged orally with a suspension of naladixic acid-resistant Salmonella and wing banded, and additional nonchallenged chicks were placed into each of 2 challenge pens. Nonchallenged chicks were placed into each nonchallenge pen located adjacent to the challenge pens. At 7, 8, 10, and 11 wk of age the litter was sampled using 4 methods: fecal droppings, litter grab, drag swab, and sock. For the challenge pens, Salmonella-positive samples were detected in 3 of 16 fecal samples, 6 of 16 litter grab samples, 7 of 16 drag swabs samples, and 7 of 16 sock samples. Samples from the nonchallenge pens were Salmonella positive in 2 of 16 litter grab samples, 9 of 16 drag swab samples, and 9 of 16 sock samples. In experiment 2, chicks were challenged with Salmonella, and the litter in the challenge and adjacent nonchallenge pens were sampled at 4, 6, and 8 wk of age with broilers remaining in all pens. For the challenge pens, Salmonella was detected in 10 of 36 fecal samples, 20 of 36 litter grab samples, 14 of 36 drag swab samples, and 26 of 36 sock samples. Samples from the adjacent nonchallenge pens were positive for Salmonella in 6 of 36 fecal droppings samples, 4 of 36 litter grab samples, 7 of 36 drag swab samples, and 19 of 36 sock samples. Sock samples had the highest rates of Salmonella detection. In experiment 3, the litter from a Salmonella-challenged flock was sampled at 7, 8, and 9 wk by socks and drag swabs. In addition, comparisons with drag swabs that were stepped on during sampling were made. Both socks (24 of 36, 67%) and drag swabs that were stepped on (25 of 36, 69%) showed significantly more Salmonella-positive samples than the traditional drag swab method (16 of 36, 44%). Drag swabs that were stepped on had comparable Salmonella detection level to that for socks. Litter sampling methods that incorporate stepping on the sample material while in contact with the litter appear to detect Salmonella in greater incidence than traditional sampling methods of dragging swabs over the litter surface.

Salmonella spp. in poultry: a constant challenge and new insights

“…The most convenient methods of taking samples for bacteriological analysis from poultry houses are using boot swabs or the "step on a drag swab" method (Buhr et al, 2007). Official sampling is carried out while birds are in the unit while own checks are carried out not only while livestock is in the unit but also after depopulation.…”

Development and validation of a drag swab method using tampons and different diluents for the detection of members ofSalmonellain broiler houses

“…Several authors have described the use of gauze strips as effective drag swabs (Pope & Cherry, 2000;Buhr et al, 2007;Volkova et al, 2010). However, gauze strips need to be sterilized, either through dry or moist heat, and then transported to the respective farm.…”

An Investigation into the Efficacy of Washing Trucks Following the Transportation of Pigs—ASalmonellaPerspective

“…Despite this finding, visual inspection indicated that washing of trucks had been carried out satisfactorily. This lack of difference before and after cleaning may be attributed to the highly sensitive sampling method employed as the entire surface of the truck compartment was swabbed, and the drag swab method has been shown to have a superior detection level to that of fecal sampling (Buhr et al, 2007). Similarly, a study by Oosterom and Notermans (1983), into the possibility of Salmonella-free slaughter of pigs, indicated a satisfactory visual inspection of trucks following cleaning, despite tests revealing 50% of samples as being positive for Enterobacteriaceae.…”