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United States Department of Agriculture

Agricultural Research Service

Title: National Antimicrobial Resistance Monitoring System (Narms)

Authors
item Cray, Paula
item Englen, Mark
item Gray, Jeffrey
item Jackson, Charlene
item Headrick, Marcia - FDA-CVM
item Tollefson, Linda - FDA-CVM
item Anandaraman, Neena - USDA-FSIS
item Salamone, Bernard - USDA-FSIS
item Rose, Bonnie - USDA-FSIS
item Dargatz, David - USDA-APHIS

Submitted to: American Veterinary Medical Association Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 19, 2003
Publication Date: July 19, 2003
Citation: Cray, P.J., Englen, M.D., Gray, J.T., Jackson, C.R., Headrick, M.L., Tollefson, L., Anandaraman, N., Salamone, B.P., Rose, B.E., Dargatz, D.A. 2003. National antimicrobial resistance monitoring system (narms). American Veterinary Medical Association Abstract. P. 79.

Interpretive Summary: In 1996, FDA's Center for Veterinary Medicine (CVM) implemented an antimicrobial susceptibility monitoring system for zoonotic enteric pathogens in collaboration with the Centers for Disease Control and Prevention (CDC) and the U.S. Department of Agriculture (USDA). The National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) prospectively monitors changes in antimicrobial susceptibilities of enteric bacteria from human and animal clinical specimens, from carcasses of food animals at slaughter, and from retail meat. NARMS consists of three testing sites (separate arms of the program), which use comparable isolation, identification, and susceptibility testing procedures. The arms are human (CDC), animal (USDA) and retail meats (FDA/CVM). Presentation of data from the animal arm of NARMS has historically summarized the collective number of isolates tested per year. However, detailed analysis indicates that resistance patterns vary by animal source, clinical status, and serotype. Salmonella isolates are received from a number of different studies/sites and are representative of not only the animal species but clinical status of the animal as well. On-farm studies (isolates are referred to as on-farm isolates and are also considered non-diagnostic isolates), veterinary diagnostic laboratories (isolates are referred to as diagnostic isolates) and raw product collected from slaughter and processing plants (isolates are referred to as non-diagnostic isolates) are sources for NARMS Salmonella isolates. On-farm isolates are selected from focused research studies conducted by the USDA or collaborators and usually represent convenience samples. Additional isolates are acquired from the USDA-APHIS National Animal Health Monitoring System (NAHMS) which conducts national studies to gather data and generate descriptive statistics. NAHMS also compiles statistics and information from data collected by other industry sources. Diagnostic isolates originate from two primary sources, the National Veterinary Services Laboratories (NVSL) and Sentinel Sites. Sentinel Sites are State or University Veterinary Diagnostic Laboratories or company associated laboratories. The final source of isolates are slaughter associated which originate from raw product collected from federally inspected slaughter and processing establishments as part of the FSIS program. One of the most critical differences in analysis of resistance data between studies includes accurate description of the serotype(s) involved. Overlap in some serotypes between populations will occur over time. However, significant differences in resistance patterns between serotypes are often observed. Differences within serotypes are often attributed to animal source or clinical status of the animal. Regardless of animal species and clinical status, from 1997 through 2001, 202 different serotypes were identified among the 27,789 Salmonella isolates tested. Numbers of isolates representing a particular serotype ranged from 1 (51/202; 25% of the serotypes) to 2378 for S. Typhimurium var. copenhagen (2378/27789; 8.6% total number of isolates). Forty serotypes each had more than 100 isolates and accounted for 92.6% of the total number of isolates tested between 1997 and 2001. The top 10 serotypes accounted for 58.66% of the total number of isolates tested and included (in decreasing order of frequency) S. Typhimurium var. copenhagen (2378/27789; 8.56%), S. Typhimurium (2310/27789; 8.31%), S. Heidelberg (2241/27789; 8.06%), S. Kentucky (2112/27789; 7.60%), S. Montevideo (1803/27789; 6.49%), S. Derby (1362/27789; 4.90%), S. Anatum (1236/27789; 4.45%), S. Agona (1111/27789; 4.00%), S. Newport (932/27789; 3.35), and S. Hadar (814/27789; 2.93%). Not all serotypes were represented in each of the years. Of the 202 serotypes, yearly increases, defined as a percent of the

Technical Abstract: In 1996, FDA's Center for Veterinary Medicine (CVM) implemented an antimicrobial susceptibility monitoring system for zoonotic enteric pathogens in collaboration with the Centers for Disease Control and Prevention (CDC) and the U.S. Department of Agriculture (USDA). The National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) prospectively monitors changes in antimicrobial susceptibilities of enteric bacteria from human and animal clinical specimens, from carcasses of food animals at slaughter, and from retail meat. NARMS consists of three testing sites (separate arms of the program), which use comparable isolation, identification, and susceptibility testing procedures. The arms are human (CDC), animal (USDA) and retail meats (FDA/CVM). Presentation of data from the animal arm of NARMS has historically summarized the collective number of isolates tested per year. However, detailed analysis indicates that resistance patterns vary by animal source, clinical status, and serotype. Salmonella isolates are received from a number of different studies/sites and are representative of not only the animal species but clinical status of the animal as well. On-farm studies (isolates are referred to as on-farm isolates and are also considered non-diagnostic isolates), veterinary diagnostic laboratories (isolates are referred to as diagnostic isolates) and raw product collected from slaughter and processing plants (isolates are referred to as non-diagnostic isolates) are sources for NARMS Salmonella isolates. On-farm isolates are selected from focused research studies conducted by the USDA or collaborators and usually represent convenience samples. Additional isolates are acquired from the USDA-APHIS National Animal Health Monitoring System (NAHMS) which conducts national studies to gather data and generate descriptive statistics. NAHMS also compiles statistics and information from data collected by other industry sources. Diagnostic isolates originate from two primary sources, the National Veterinary Services Laboratories (NVSL) and Sentinel Sites. Sentinel Sites are State or University Veterinary Diagnostic Laboratories or company associated laboratories. The final source of isolates are slaughter associated which originate from raw product collected from federally inspected slaughter and processing establishments as part of the FSIS program. One of the most critical differences in analysis of resistance data between studies includes accurate description of the serotype(s) involved. Overlap in some serotypes between populations will occur over time. However, significant differences in resistance patterns between serotypes are often observed. Differences within serotypes are often attributed to animal source or clinical status of the animal. Regardless of animal species and clinical status, from 1997 through 2001, 202 different serotypes were identified among the 27,789 Salmonella isolates tested. Numbers of isolates representing a particular serotype ranged from 1 (51/202; 25% of the serotypes) to 2378 for S. Typhimurium var. copenhagen (2378/27789; 8.6% total number of isolates). Forty serotypes each had more than 100 isolates and accounted for 92.6% of the total number of isolates tested between 1997 and 2001. The top 10 serotypes accounted for 58.66% of the total number of isolates tested and included (in decreasing order of frequency) S. Typhimurium var. copenhagen (2378/27789; 8.56%), S. Typhimurium (2310/27789; 8.31%), S. Heidelberg (2241/27789; 8.06%), S. Kentucky (2112/27789; 7.60%), S. Montevideo (1803/27789; 6.49%), S. Derby (1362/27789; 4.90%), S. Anatum (1236/27789; 4.45%), S. Agona (1111/27789; 4.00%), S. Newport (932/27789; 3.35), and S. Hadar (814/27789; 2.93%). Not all serotypes were represented in each of the years. Of the 202 serotypes, yearly increases, defined as a percent of the total number of isolates tested per year, were only observed for four serotypes: S. choleraesuis (0.33% of the total number of isolates in 1997 to 4.76% in 2001), S. Heidelberg (6.11% in 1997 to 10.98% in 2001), S. Newport (0.75% in 1997 to 7.93% in 2001), and S. Uganda (0.08% in 1997 to 0.89% in 2001). Diagnostic sources accounted for the majority of the isolates from 1997-2001 for S. Choleraesuis (445 diagnostic isolates/465 total S. Choleraesuis isolates; 95.7%), S. Newport (518 diagnostic isolates/932 total S. Newport isolates; 55.58%) and S. Uganda (80 diagnostic isolates/173 total S. Uganda isolates; 46.24%) while non-diagnostic sources accounted for the majority of the S. Heidelberg isolates from 1997-2001 (1716 non-diagnostic isolates/2241 total S. Heidelberg isolates; 76.57%). Other serotypes either fluctuated (both positively and negatively) in percent of total number of isolates over the five years, or were not isolated for one or more years. Historically, resistance to more antimicrobials is observed for isolates originating from diagnostic sources rather than non-diagnostic or on-farm sources. This is not unexpected since it is likely that animals would have received treatment as a result of the clinical illness which resulted in the submission to the diagnostic laboratories. NARMS data describing antimicrobial resistance trends among Salmonella isolates collected from cattle, chicken, swine and turkey, including differentiation by serotype and clinical status, will be presented.

Last Modified: 10/20/2014