Avaliação da resistência antimicrobiana em sorovares de Salmonella caracterizados em carcaças de frango congeladas e resfriadas, provenientes de diferentes regiões do Brasil

Abstract

Salmonella ssp. is recognized, among pathogens of zoonotic nature, for its high incidence in food borne diseases around the world. It currently receives special interest because of resistance to antimicrobials since this feature might compromise the effectiveness of treatments in human infections. The aims of the present study were to detect the Salmonella serotypes isolated from poultry carcasses, evaluate the emergence of antimicrobial resistant strains and recognize the mechanisms involved in the spread of resistant clones, mainly in last generation drugs, used in human and veterinary medicine. From 2009 to 2011, 243 Salmonella spp., isolated from frozen (n=84) and refrigerated (n=159) poultry carcasses commercialized in Brazil were received by LRNEB for antigenic characterization. Nine serogroups were identified, being O:4 (B) in refrigerated carcasses (32.7%) and O:4 (B), O:7 (C1), O:8 (C2-C3) with similar percentual in frozen carcasses (≈20%). Thirty-three Salmonella serotypes have been recognized and, Salmonella ser. Mbandaka (10.3%), Minnesota (7.4%), Enteritidis (7.4%), Typhimurium (7.0%) and Infantis (6.2%) the five most prevalent. The antimicrobial susceptibility evaluated in 194 strains showed 70% resistance up to seven antimicrobial drugs, with 57 distinct patterns. From 2009 to 2011 increase the resistance to 3rd generation cephalosporins (from 7% to 20%) in refrigerated carcasses while in frozen, was observed from 2011 in 22.2% of strains. Percentages for quinolones resistance were similar in both sources (13 to 15%). Particularly for fluoroquinolones this was only detected in refrigerated carcasses in 7% of strains (2009) and 1% (2011). Percentages detected to aminoglycosides varied between 9 to 15%. Discontinued drugs (MAPA resolution, 1998 and 2003) showed that decreased resistance to nitrofurans (from 37% in 2009 to 4% in 2011). Resistance to tetracyclines and phenicols was observed in 3 and 9% during the period. All strains were sensitive to carbapenens. The genes blaCMY were detected by PCR in strains resistant to beta-lactams isolated from refrigerated and frozen carcasses (50%) and from 2.9% strains which showed reduced susceptibility zone diameter isolated from frozen. The gene blaCTX-M was obtained in 21.2% and 9% of Salmonella strains isolated from both sources. Among strains resistant to quinolones, qnrB was observed in 13% and, aac(3’)IIa and integrase was characterized in 2% and 18%, respectively. The occurrences of food-borne diseases represent an important public health problem, and continuous surveillance to assess the risk of different pathogens and implement actions for its control it is necessary to monitor, act by the prevention in the entry or export of pathogenic microorganisms.