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Title: 2000 NARMS REPORT OF SALMONELLA NEWPORT SLAUGHTER AND ON-FARM ISOLATES

Author
item Tankson, Jeanetta
item Cray, Paula
item HEADRICK, MARCIA - USDA-CVM

Submitted to: Interscience Conference on Antimicrobial Agents & Chemotherapy Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2000
Publication Date: 9/14/2000
Citation: TANKSON, J.D., CRAY, P.J., HEADRICK, M. 2000 NARMS REPORT OF SALMONELLA NEWPORT SLAUGHTER AND ON-FARM ISOLATES. INTERSCIENCE CONFERENCE ON ANTIMICROBIAL AGENTS & CHEMOTHERAPY PROCEEDINGS.SESSION 91 , C2-865 P.126

Interpretive Summary: Background: Salmonella is ubiquitous and has been recovered from nearly all vertebrates. Even though most Salmonella serotypes remain susceptible to most antimicrobials encountered through either therapeutic or sub-therapeutic uses, there are exceptions. Salmonella Newport is one of these exceptions, exhibiting a rapid increase in multi-drug resistance (MDR). In 2000, the animal arm of the National Antimicrobial Resistance Monitoring System - Enteric Bacteria (NARMS) reported a total of 121 S. Newport isolates obtained from raw product collected from federally inspected slaughter and processing plants (SI) and 62 on-farm study isolates (OFI). Methods: The Sensititre **TM semi-automated system (TREK Diagnostics, Cleveland, OH) was used for susceptibility testing. Antimicrobials were configured in custom made panels. NCCLS guidelines, where applicable, were followed for interpretation of results. Results: All SI (121) were susceptible to amikacin, apramycin, ciprofloxacin, and nalidixic acid. All OFI (62) were susceptible to amikacin, apramycin, ciprofloxacin, gentamicin, kanamycin, and nalidixic acid. Thirty-one (26%) S. Newport SI were pan-susceptible, 1 (0.8%) was resistant to only one antimicrobial, and 89 (74%) were MDR (defined as resistance to 2 or more antimicrobials). Of the 31 pan-susceptible isolates, 21 (68%) were from cattle, 4 (13%) were from chicken, 5 (16%) were from turkey, and 1 (3%) was from swine. Of the 89 MDR isolates, 86 (97%) were from cattle, 1 (1%) was from chicken, 1 (1%) was from turkey, and 1 (1%) was from swine. Five (8.1%) S. Newport OFI were pan-susceptible, while 57 (92%) were MDR. Of the 5 pan-susceptible isolates, 3 (60%) were from cattle, and 2 (40%) were from swine. All MDR isolates were from cattle. Molecular analyses (PFGE, plasmid profiling, and probing) indicate a high/low degree of hetero or homogeneity among isolates. Conclusion: Compared to previous years, increase of MDR S. Newport suggests that resistant genes are readily acquired and clonal spread of S. Newport has occurred throughout the U.S.

Technical Abstract: Background: Salmonella is ubiquitous and has been recovered from nearly all vertebrates. Even though most Salmonella serotypes remain susceptible to most antimicrobials encountered through either therapeutic or sub-therapeutic uses, there are exceptions. Salmonella Newport is one of these exceptions, exhibiting a rapid increase in multi-drug resistance (MDR). In 2000, the animal arm of the National Antimicrobial Resistance Monitoring System - Enteric Bacteria (NARMS) reported a total of 121 S. Newport isolates obtained from raw product collected from federally inspected slaughter and processing plants (SI) and 62 on-farm study isolates (OFI). Methods: The Sensititre **TM semi-automated system (TREK Diagnostics, Cleveland, OH) was used for susceptibility testing. Antimicrobials were configured in custom made panels. NCCLS guidelines, where applicable, were followed for interpretation of results. Results: All SI (121) were susceptible to amikacin, apramycin, ciprofloxacin, and nalidixic acid. All OFI (62) were susceptible to amikacin, apramycin, ciprofloxacin, gentamicin, kanamycin, and nalidixic acid. Thirty-one (26%) S. Newport SI were pan-susceptible, 1 (0.8%) was resistant to only one antimicrobial, and 89 (74%) were MDR (defined as resistance to 2 or more antimicrobials). Of the 31 pan-susceptible isolates, 21 (68%) were from cattle, 4 (13%) were from chicken, 5 (16%) were from turkey, and 1 (3%) was from swine. Of the 89 MDR isolates, 86 (97%) were from cattle, 1 (1%) was from chicken, 1 (1%) was from turkey, and 1 (1%) was from swine. Five (8.1%) S. Newport OFI were pan-susceptible, while 57 (92%) were MDR. Of the 5 pan-susceptible isolates, 3 (60%) were from cattle, and 2 (40%) were from swine. All MDR isolates were from cattle. Molecular analyses (PFGE, plasmid profiling, and probing) indicate a high/low degree of hetero or homogeneity among isolates. Conclusion: Compared to previous years, increase of MDR S. Newport suggests that resistant genes are readily acquired and clonal spread of S. Newport has occurred throughout the U.S.