Detecção e quantificação de salmonella spp. na tecnologia de abate de frangos de corte

Abstract

Salmonella infections are associated with intensive poultry farming and with outbreaks of clinical salmonellosis. Healthy birds can be contaminated by contact with infected ones or by cross-contamination in abattoirs, where bacterial count varies across different slaughtering processes. Microbiological analyses of samples collected throughout the process (from the broiler farm to the end products) are crucial for estimating microbial load and assessing the effects of control methods used at meat-packing plants, including good manufacturing practices (GMP), sanitation standard operating procedures (SSOP) and hazard analysis and critical control points (HACCP). While contamination of slaughterhouses by Salmonella spp. has been qualitatively assessed by several studies, quantitative research about this species has not been conducted on a regular basis. This occurs because conventional enumeration methods, such as the most probable number (MPN), which use multiple tubes, are time-consuming and costly and require workforce, thus precluding their application in control programs. So, the miniaturized most probable number (mMPN) method has been recommended as a quicker and less burdensome alternative for the enumeration of Salmonella spp. Therefore, the present study aimed to detect and quantify Salmonella spp. in poultry slaughtering procedures using conventional microbiology and mMPN method. Samples were collected in triplicate in three federally-inspected southern Brazilian slaughterhouses and from six collection sites: reception of live birds (cloacal swabs and sponge samples from transport cages before and after sanitation) and carcass processing (after pre-chiller, after dripping, and before primary packaging, frozen at -12oC for 24 h), totaling 108 samples and 240 assays for detection and quantification of Salmonella spp, respectively, including negative (E. coli ATCC 25992) and positive (S. Enteritidis ATCC 13076) controls. Salmonella spp. was detected in three out of the six processing stages and in two of the three sampled slaughterhouses, regardless of the method used, with 5.5% of positive samples, including those obtained from transport cages after sanitation. It was not possible to correlate conventional microbiology and mMPN results or to quantify contamination in the slaughtering processing line, indicating that it is necessary to use a qualitative method in conjunction with a quantitative one whenever Salmonella is found in lower amounts than the proposed mMPN threshold values (0.13 MPN/mL). The following serovars were identified: Typhimurium, Panama, Lexington and Rissen, which are considered paratyphoid organisms and, therefore have a remarkable zoonotic potential, even though these serovars were not isolated from end products, but at the reception of live birds (cloacal swabs and sponge samples from transport cages). The detection of Salmonella spp. in transport cages after sanitation demonstrates the necessity to reassess and adjust the automated washing procedures currently utilized in slaughterhouses