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.

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.(AU)

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 10(6) 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.

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 10(6) 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.

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 10(6) 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.(AU)