Skip to main content
ARS Home » Research » Publications at this Location » Publication #290627
Title: Phenotypic and genotypic characterization of Salmonella enterica serovar Dublin isolates from cattle and humans

Author
item Abley, Melanie
item Cray, Paula
item LINDSEY, REBECCA - Former ARS Employee
item FOLSTER, JASON - Centers For Disease Control And Prevention (CDC) - United States
item WHICHARD, JEAN - Centers For Disease Control And Prevention (CDC) - United States

Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2013
Publication Date: 7/28/2013
Citation: Abley, M.J., Cray, P.J., Lindsey, R., Folster, J., Whichard, J. 2013. Phenotypic and genotypic characterization of Salmonella enterica serovar Dublin isolates from cattle and humans. International Association for Food Protection Proceedings. July 28-31, 2013. Charlotte, North Carolina.

Interpretive Summary:

Technical Abstract: Introduction: Antimicrobial resistance (AR), particularly multi-drug resistance (MDR), is of global concern. Salmonella causes approximately 93.8 million human infections worldwide/year including 1.2 million cases in the US. An increase in both AR and MDR among some serotypes has been observed. Salmonella Dublin is the second most common serotype isolated from cattle (2007 to 2011; animal arm of the National Antimicrobial Resistance Monitoring System (NARMS)) and an increase in MDR has been observed. Purpose: Determine AR, the presence of integrons and replicon types of plasmids in Dublin isolated from cattle and humans submitted to NARMS (1999-2011). Methods: AR was determined to 15 antimicrobials using a semi-automated broth micro-dilution system (Sensitire®, Trek Diagnostic Systems, Inc., Cleveland, Ohio) for 272 cattle (C) and 69 human (H) isolates. Resistance was determined using Clinical and Laboratory Standards Institute breakpoints, when available. Isolates were screened for integrons (class 1, 2 and 4) and incompatible (Inc) replicon types using standard PCR protocols. Results: Percent resistance was observed most often to: Ampicillin (63% C; 41% H), Chloramphenicol (60% C; 43% H), Kanamycin (51% C; 39% H), Streptomycin (69% C, 43% H), Sulfa antimicrobials (65% C; 49% H), and Tetracycline (67%C; 46% H). No resistance to Amikacin or Ciprofloxacin was observed. MDR (>5 antimicrobials) was observed in both 43% of cattle and humans isolates. The most common MDR pattern in cattle (n=27) was Amoxicillin – Clavulanic Acid/Ampicillin/Cefoxitin/Ceftiofur/Cefriaxone/Chloramphenicol/Kanamycin/Streptomycin/Sulfa/Tetracyline (n=27) and Ampicillin/Chloramphenicol/Kanamycin/Streptomycin/Sulfa/Tetracycline (n=11) in humans. Only class 1 integrons were identified in 30% (n=82) and 25% (n=17) of the cattle and human isolates, respectively. The replicon types identified were: FIIS (80% C; 91% H), A/C (52% C; 29% H), H1 (17% C; 16% H), FIA (17% C; 3% H), I1 (7% C; 1% H), FIB (6% C; 3% H), P (3% C; 1% H) and N (1% C; 0% H ). Significance: The presence of integrons and the “epidemic resistance plasmids” Inc FIIS, Inc A/C, Inc I1 and Inc N are important when studying the transmission of resistance genes and developing mitigation strategies.