Antimicrobial resistance among Escherichia coli isolated from veal calf operations in Pennsylvania

Authors: SALAHEEN, SERAJUS - US Department Of Agriculture (USDA); KIM, SEON-WOO - US Department Of Agriculture (USDA); CAO, HUILIN - US Department Of Agriculture (USDA); WOLFGANG, DAVID - Pennsylvania State University; KARNS, JEFFREY - US Department Of Agriculture (USDA); Haley, Bradd; HOVINGH, ERNEST - Pennsylvania State University; Van Kessel, Jo Ann

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2018
Publication Date: 1/23/2019
Citation: Salaheen, S., Kim, S., Cao, H., Wolfgang, D., Karns, J., Haley, B.J., Hovingh, E., Van Kessel, J.S. 2019. Antimicrobial resistance among Escherichia coli isolated from veal calf operations in Pennsylvania. Foodborne Pathogens and Disease. 16:74-80. https://doi.org/10.1089/fpd.2018.2530.
DOI: https://doi.org/10.1089/fpd.2018.2530

Interpretive Summary: When people are infected by bacteria that are resistant to antibiotics, treatment options are often limited. Antimicrobial resistance is a pressing public health concern, and agricultural operations such as dairy and beef cattle production have been implicated as potential sources of resistant bacteria or the genetic material that leads to resistance. Escherichia coli are ubiquitous in the guts of healthy mammals and can be used as an indicator of the presence of resistance. The purpose of this study was to determine the prevalence or occurance of antimicrobial resistant E. coli in calf manure collected at auction houses and on veal calf operations in Pennsylvania. A total of 1567 generic E. coli isolates were isolated and screened for resistance and resistant E. coli were isolated from all of the auction houses and farms. Incremental prevalence of E. coli resistant to ampicillin, azithromycin, cefoxitin, ceftiofur, ceftriaxone, chloramphenicol, streptomycin, sulfisoxazole, trimethoprim-sulfamethoxazole, and tetracycline in the samples from auction houses and the first and second farms visits were observed ('2 6.98-15.91, p < 0.05). Multidrug resistant (resistant to more than three antimicrobial classes) E. coli were identified in 76.8%, 90.8%, and 100% samples collected from the auction houses, first farms visits, and second farms visits, respectively. The presence of Escherichia coli carrying a specific resistince gene, blaCTX-M, on 11 of the 12 farms presents the possibility of veal production environments being a reservoir for resistant genetic materials that may pose a risk to human health if they are transferred to human pathogens. These results will be used to plan additional research on the impact of various management strategies in veal calf rearing so that recommendations can be made for approaches to reduce the prevalence of resistance.

Technical Abstract: Antimicrobial resistance (AR) is a pressing public health concern, and agricultural operations such as dairy and beef cattle production have been implicated as potential sources of resistant bacteria or genetic elements. This study aimed to determine the prevalence of antimicrobial resistant Escherichia coli from calf pens in six auction houses (56 manure composite samples) and 12 veal calf operations (240 fecal samples in two visits) in Pennsylvania. A total of 1567 generic E. coli isolates were isolated and screened for resistance phenotypes. Resistant E. coli were isolated from all of the auction houses and farms. Based on non-parametric Kruskal-Wallis tests, incremental prevalence of E. coli resistant to ampicillin, azithromycin, cefoxitin, ceftiofur, ceftriaxone, chloramphenicol, streptomycin, sulfisoxazole, trimethoprim-sulfamethoxazole, and tetracycline in the samples from auction houses and the first and second farms visits were observed ('2 6.98-15.91, p < 0.05). Multidrug resistant (resistant to more than three antimicrobial classes) E. coli were identified in 76.8%, 90.8%, and 100% samples collected from the auction houses, first farms visits, and second farms visits, respectively. The presence of blaCTX-M -E. coli on 11 of the 12 farms presents the possibility of veal production environments being a reservoir for resistant genetic materials that may pose a risk to human health if they are transferred to human pathogens. Additional research on the impact of various management strategies in veal calf rearing is needed for a complete scenario of AR in these production environments.