Antimicrobial resistance profile of Salmonella Heidelberg isolated from a poultry slaughterhouse in 2005 and 2009.

Background: Salmonella spp. is recognized as being one of the most common bacterial causes of food-borne illness spread on poultry production due to easy adaptation to environment and diffi cult to eradicate. In poultry production system antimicrobials are added in feed as growth promoters in continuous and sub-therapeutic doses, inducing a selective pressure and consequent antimicrobial resistance. This management causes public health problems to disseminate resistant pathogens through food chain and reduce the options of treatment of bacterial infections. Materials, Methods & Results: The samples were isolated in a poultry slaughterhouse under Federal Inspection in a monitoring, research and quantifi cation project of Salmonella spp in critical control points in slaughterhouse. Adapted methodology was used for quantifi cation of Salmonella as follows: swabs and cages were placed in 50 mL of peptone water buffered 1% (PW 1%) and incubated at 37oC for 12 h; for the analysis of water 100 mL were inoculated in 50 mL of peptone water buffered in triple concentration and incubated at 37oC for 12 h; the chickens and carcasses were packed in sterile bags with a capacity of 4000 mL, added 150 mL of peptone water buffered 1%, agitated manually for one minute and the rinsing broth incubated by 12 h at 37oC. After hatching were made decimal dilutions Rapapport Vassiliadis broth (RV), inoculated 1 mL in 9 mL of RV broth until 10 dilution and incubation for 12 h at 41°C in a water bath with agitation. After this period 100 μL of RV broth were seeded in Agar Rambach and Agar XLD and the plates incubated at 37oC for 12 h. Salmonella-like growth were placed in Agar Rambach and confi rmed as Salmonella to biochemical tests (TSI, LIA, urea broth) and assayed for polyvalent antiserum to Salmonella. The fi nal identifi cation of the samples was carried out by the Polymerase Chain Reaction (PCR, Premi Test Salmonella DSM). Were selected 20 samples of Salmonella Heidelberg isolated in 2005 (14 samples) and 2009 (6 samples) for antimicrobial susceptibility testing by diffusion in agar front of amoxicillin with clavulanic acid, ampicillin, cephalothin, ciprofl oxacin, chloramphenicol, gentamicin, enrofl oxina, cephalexin, streptomycin, ceftiofur, doxycycline and neomycin. It was observed that 46,1% of the samples isolated in 2005 were resistant to an antimicrobial while 100% of the isolates in 2009 were resistant to at least four antimicrobial. Isolated samples in 2005 were resistant to ceftiofur (38.4%), ampicillin (23.0%), cephalexin (15.3%) and cephalothin (7.6%) while 100% of the isolates in 2009 were resistant to these antimicrobials. It was concluded that samples of Salmonella Heidelberg isolated in 2009 were phenotypically more resistant to antimicrobials tested than isolated samples in 2005. Discussion: S. Heidelberg resistance can be related to the indiscriminate use of antimicrobials in poultry industry. Multiple resistance bacteria like Salmonella can be transferred from animal products to consumers and causes public health problems. Antimicrobial sensitivity tests enable the identifi cation of antimicrobials that have action against pathogenic microorganisms like Salmonella, reinforce the importance of achieving these tests for the defi nition of appropriate programs of use of antimicrobials in livestock production.