ARS | Publication request: Changes in the bacterial flora of skin of processed broiler chickens washed in solutions of salicylic acid

Submitted to: International Journal of Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2007
Publication Date: December 31, 2007
Citation: Hinton Jr, A., Cason Jr, J.A. 2007. Changes in the bacterial flora of skin of processed broiler chickens washed in solutions of salicylic acid. International Journal of Poultry Science. 6(12)960-966.

Interpretive Summary: Experiments were performed to determine if washing skin of processed broiler chickens in solutions of salicylic acid (SA) could reduce the number of bacteria on the skin. Skin samples were taken from processed chickens and washed in fresh aliquots of water, 10% SA, or 20% SA for 5 consecutive times. After each washing, the number total bacteria, staphylococci bacteria, intestinal bacteria, lactic acid bacteria, and clostridia bacteria on the skin were determined. Results indicated that washing skin in water for 5 times did not reduce the number of either type of these bacteria on the skin, but washing skin 5 times in 10% SA reduced the number of lactic acid bacteria on the skin. Interestingly, washing skin in 20% SA reduced the number of total bacteria and staphylococci on the skin, and no intestinal bacteria, lactic acid bacteria, or clostridia bacteria were found on skin washed at least 4 times in 20% SA. Additional experiments showed that bacteria isolated from the skin were killed when cultures of the bacteria were mixed in solutions of 20% SA in test tubes. Findings from these experiments showed that SA is able to kill several types of bacteria found on poultry skin and that repeated washing of the skin in SA can reduce the number of bacteria on the skin.

Technical Abstract: Changes in the number of bacteria recovered from the skin of processed broilers after each of five consecutive washings in salicylic acid (SA) solutions was examined. Skin samples from commercially processed broiler carcasses were divided into 3 groups and washed in distilled water (control), 10% SA, or 20% SA by agitating skin in wash solutions in a Stomacher laboratory blender. After each wash, skin was transferred to fresh solutions and washing was repeated to provide samples washed 1 to 5 times in each solution. Washed skin was stomached in Butterfield’s Phosphate Buffer to recover bacteria on the skin. Bacterial flora of the rinsates was enumerated on Plate Count (PC) Agar, Staphylococcus (STA) Agar, Levine Eosin Methylene Blue (EMB) Agar, Lactic Acid Bacteria (LAB) Agar, and Perfringens (PER) Agar with TSC supplement; and then bacterial isolates from each medium were identified. Results indicated that after each of 5 consecutive washes in water, there was no significant difference in the number of bacteria recovered from skin on any of the agar media. Significantly fewer bacteria were recovered on LAB Agar from skin after 5 washes in 10% SA than after 1 wash, but there was no significant decrease in the number of bacteria recovered on any other media after skin was washed in this solution. However, washing skin 4 or 5 times in 20% SA significantly reduced the number of bacteria recovered on PC and STA Agar, while no bacteria were recovered on EMB or LAB Agars from rinsates of skin washed 4 or 5 times in 20% SA or on PER Agar from skin washed 3 or more in the 20% solution. In vitro studies indicated that SA is bactericidal towards bacterial isolates recovered from skin and that resistance to the bactericidal activity of SA in descending order is Staphylococcus simulans > Lactobacillus > Escherichia coli > Clostridium perfringens. Findings indicate that successive washing of skin in SA significantly reduces the number of bacteria recovered from the poultry skin and that the bactericidal activity SA can kill bacteria in vitro and on poultry skin.