|Headrick, Marcia - FDA - CVM|
Submitted to: National Foundation for Infectious Disease
Publication Type: Proceedings
Publication Acceptance Date: May 10, 2002
Publication Date: June 27, 2002
Citation: Tankson, J.D., Cray, P.J., Jackson, C.R., Gray, J.T., Barrett, J.B., Headrick, M. 2002. DETECTION OF CLASS I INTEGRON AND MARRAB OPERON IN MULTIPLE DRUG RESISTANT SALMONELLA ENTERICA SEROTYPE NIAKHAR. National Foundation for Infectious Disease. P.37 S-10. Technical Abstract: In the United States, Salmonella enterica serotype Niakhar is not frequently isolated. Between 1997 and 2000, the animal arm of the National Antimicrobial Resistance Monitoring System - Enteric Bacteria (NARMS) at USDA-ARS in Athens, GA assayed for antimicrobial resistance a total of 22,383 Salmonella isolates from swine, cattle, chickens, turkeys, exotics, horses, cats, and dogs. Only 5 (0.02%) of these isolates were identified as Niakhar (designated A-E). Of the five, 3 (B - D) were isolated in the Midwest, while A and E were isolated in the Southern United States. Antimicrobial resistance testing indicated that isolates A, B, and E were susceptible to all antimicrobials tested; whereas isolate C was only resistant to one antimicrobial. However, isolate D had resistance to nine antimicrobials. Class I integrons (intI1) in Salmonella are known to harbor multiple resistance genes. Using PCR primers to intI1, a 568-bp fragment was amplified from isolate D. None of the other isolates harbored Class I to Class 4 integrons (intI1, intI2, intI3, and int4) in their genomic DNA. Some Salmonella species are also known to harbor intrinsic mechanisms of resistance such as a multiple antibiotic resistance operon (marRAB). Using PCR primers to marRAB, a 2.3-kb and 0.4-kb fragment was amplified from isolate D (a multi-resistant isolate), and not isolates A and B (isolates susceptible to all antimicrobials tested). This is a first report of a marRAB operon in Salmonella Niakhar.