Elci Lotar Dickel

Isolamento de Salmonella Heidelberg em diferentes pontos da tecnologia de abate de frangos de corte

Bacteria of the genus Salmonella are part of the normal flora of poultry, and its occurrence in poultry products varies with the production management methods and slaughter technology, representing risks to the consumer and difficulties in exports. S. Heidelberg appears to be more invasive and to cause more severe disease than other non-typhoidal serovars. The objective of the present study was to search for Salmonella at different points of the slaughterhouse and to report on the isolation of S. Heidelberg in a slaughterhouse under federal inspection. S. Heidelberg was isolated in poultry soon after feathering-out and in the chiller water, indicating that, although it was not isolated at another sampled points, the bacteria was present in the environment and could contaminate carcasses ready for consumption, with an impact on public health. This concern is underscored by the fact that S. Heidelberg is a proven causative agent of foodborne infections.

Avaliação in vitro de clorexidina, amônia quaternária e ácido peracético frente a amostras de Salmonella Heidelberg isoladas de abatedouro avícola em 2005 e 2009

The objective of this investigation was to evaluate the in vitro sensibility of Salmonella Heidelberg to three commercially available disinfectants used for sanitization in poultry slaughterhouses. A total of 20 S. Heidelberg were tested (14 isolated in 2005 and six in 2009), and as active ingredients were used chlorhexidine (0.5%), quaternary ammonium (0.5 %) and peracetic acid (1%) at contact intervals of 5, 10, 15 e 20 minutes. All isolates were found to be sensitive to peracetic acid at four specific contact intervals. One hundred percent of S. Heidelberg isolated in 2005 was found to be sensitive to quaternary ammonium, while 33% of 2009 isolates were resistant at a 5-minute contact interval and 16.6% at 10-minutes. With respect to chlorhexidine, 25% of the 2005 isolates were resistant at a 5-minute contact interval, 33% of the 2009 isolates were resistant with the same time, and 17% at a 10-minute contact interval. It can be concluded that the highest disinfectant activity in vitro was found to be with peracetic acid for S. Heidelberg isolates in 2005 and 2009, whereas chlorhexidine and quaternary ammonium had a reduced action against 2009 isolates, indicating the progression of bacterial resistance against these sanitizers and the need for periodic evaluation and rotation of active principles for sanitization.

Miniaturized most probable number for the enumeration of Salmonella sp in artificially contaminated chicken meat

Salmonella is traditionally identified by conventional microbiological tests, but the enumeration of this bacterium is not used on a routine basis. Methods such as the most probable number (MPN), which utilize an array of multiple tubes, are time-consuming and expensive, whereas miniaturized most probable number (mMPN) methods, which use microplates, can be adapted for the enumeration of bacteria, saving up time and materials. The aim of the present paper is to assess two mMPN methods for the enumeration of Salmonella sp in artificially-contaminated chicken meat samples. Microplates containing 24 wells (method A) and 96 wells (method B), both with peptone water as pre-enrichment medium and modified semi-solid Rappaport-Vassiliadis (MSRV) as selective enrichment medium, were used. The meat matrix consisted of 25g of autoclaved ground chicken breast contaminated with dilutions of up to 106 of Salmonella Typhimurium (ST) and Escherichia coli (EC). In method A, the dilution 10-5 of Salmonella Typhimurium corresponded to >57 MPN/mL and the dilution 10-6 was equal to 30 MPN/mL. There was a correlation between the counts used for the artificial contamination of the samples and those recovered by mMPN, indicating that the method A was sensitive for the enumeration of different levels of contamination of the meat matrix. In method B, there was no correlation between the inoculated dilutions and the mMPN results.

Effect of Antimicrobials on Salmonella Spp. Strains Isolated from Poultry Processing Plants

The routine use of antimicrobials in animal production for the treatment of infections, disease prevention, or as growth promoters is a predisposing factor for the development and dissemination of antimicrobial resistance. In food industries, sanitizers are used for the control of microbial colonization, and their efficacy depends on contact time and on the dilution of the products used. The present study assessed the effect of 12 antimicrobials and four commercial sanitizers on 18 Salmonella spp. strains isolated from poultry processing plants. None of the evaluated antimicrobials was 100% effective against the tested Salmonella spp. strains; however, 94% of the isolates were susceptible to ciprofloxacin, 77% to amoxicillin + clavulanic acid and to ampicillin, and 72% to enrofloxacin, whereas 100% of the isolates were resistant to penicillin G, 16% to tetracycline, and 11% to sulfonamide. The tested Salmonella spp. strains were 100% inhibited by peracetic acid after five minutes of contact, 0.5% by quaternary ammonium after 15 minutes, and 85.7% by chlorhexidine after 15 minutes. The results indicate the importance of testing of efficacy of antimicrobials used in animal production and in public health to monitor their action and the development of resistance.