What is the Real issue with MDR?

Authors: ZHAO, SHAOHUA - FDA-CVM; Cray, Paula; WHICHARD, JEAN - CDC; THRELFALL, JOHN - HEALTH PROTECTION AGENCY

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 4/4/2008
Publication Date: 8/3/2008
Citation: Zhao, S., Cray, P.J., Whichard, J., Threlfall, J. 2008. What is the Real issue with MDR? [abstract]. International Association for Food Protection. P. 11-12.

Interpretive Summary:

Technical Abstract: Since the early 1990s there has been increasing awareness and concern regarding the development of antimicrobial resistance among bacteria of public health significance. Reports targeting zoonotic bacteria, and in particular Salmonella species, suggest that multiple drug resistant (MDR) is trending upward. In the UK, MDR Salmonella Typhimurium DT104 exploded and reached epidemic proportions. DT104 was unique in that it exhibited a penta-resistant pattern of resistance to Ampicillin, Chloramphenicol, Streptomycin, Sulfamethoxazole, and Tetracycline (ACSSuT) which was chromosomally integrated. Cattle appeared to be the primary reservoir in animals although a wide-range of animals presented with DT104. Contaminated foodstuffs were responsible for severe outbreaks and increased morbidity and mortality. In the US, DT104 also emerged, but has been primarily concentrated in cattle from the Pacific Northwest. Although attributed to several outbreaks, DT104 in the US has never been associated with the extent of morbidity and mortality observed in the UK. However, starting in 2000, the emergence of multiple drug resistant (MDR) Salmonella Newport was the focus of much research. Like DT104, S. Newport is often isolated from cattle although in recent years an increase in isolation from chickens has been observed. Unlike DT104, resistance is plasmid mediated and has been associated with a number of foodborne outbreaks. Interestingly, in recent years both DT104 and Newport have decreased in incidence while other MDR serotypes such as Agona, Reading, and Heidelberg appear to be increasing. Further, MDR is not only confined to Salmonella as MDR is also observed in other foodborne pathogens including Campylobacter as well as the commensal bacteria E.coli and enterococci. The purpose of this symposium is to present the current knowledge and status of MDR both here and abroad. The speakers will present the mechanism of MDR, describe the ease of which MDR can spread, and provide an update on the MDR plasmid that is increasing in prevalence. An update on MDR in foodborne and commensal bacteria in the US will focus on the status in animals and humans and the complement will be presented from ‘across the pond’. Finally, the speakers will reconvene as a panel to engage the audience. Following this symposium, attendees will have a better perspective on what drives MDR as well as the status of MDR in foodborne bacteria both here and abroad.