Salmonella enterica is a ubiquitous enteric pathogen estimated to cause > 1.4 million cases of illness in humans in the United States annually,1 of which 95% are estimated to result from foodborne transmission.2 In addition, the increased incidence of multidrug-resistant infections caused by phage types such as S Enterica serovar Typhimurium DT1043 and the isolation of this strain from swine4 may pose serious health risks to pork consumers.
The addition of antimicrobials to swine diets is a common practice in most parts of the world, including the United States.5 Chlortetracycline is estimated to be the antimicrobial most widely used in feed for the nursery and growth and finishing phases of pork production.6 Feeding of antimicrobials, including chlortetracycline, for growth promotion can decrease fecal shedding of enteric pathogens7 and could serve to improve preharvest food safety by minimizing carcass contamination during processing.
Because of increasing concerns surrounding use of antimicrobials at subtherapeutic concentrations in food animals, the pork industry has funded investigations on alternatives to traditional antimicrobials used as growth or production promoters; those alternatives include herbs, immune modulators, and probiotics. Limited investigations have been conducted on the use of herbal extracts, particularly those containing isoquinolone alkaloids, for their antimicrobial properties.8 An isoquinolone alkaloid, QBA, reportedly has antiinflammatory and antimicrobial properties9–12 and can decrease amino acid degradation, increase feed intake, and promote growth in swine.13,14 In 1 study,15 QBAs significantly decreased damage to the colonic mucosa and mitigated colonic inflammation when included in the feed of rats, which suggests a protective effect of QBAs on the intestinal mucosa. Quaternary benzo(c) phenanthridine alkaloid consists of sanguinarine and chelerythrine extracts. Neither QBAs nor any proprietary formulations have been evaluated for their effects on the antibiogram of foodborne pathogens, the ability to decrease bacterial fecal shedding, or improvement in intestinal wall barrier function. Thus, the purpose of the study reported here was to evaluate the in vitro effects of QBAs on Salmonella isolates and compare the effects of QBAs with those of chlortetracycline on growth performance, feed efficiency, and fecal shedding of Salmonella organisms in nursery-age pigs. Our hypothesis was that Salmonella spp shedding is influenced by feed-grade antimicrobials and that a nonantimicrobial alternative (QBA) could serve as a potential replacement to traditional antimicrobials.
Average daily gain
Most probable number
Quaternary benzo(c)phenanthridine alkaloid
Exede, Pfizer Animal Health, New York, NY.
Difco, Becton Dickinson, Sparks, Md.
Cathra replicator system, Oxoid Ltd, Basingstoke, Hampshire, England.
Excel, Microsoft Corp, Redmond, Wash.
Sangrovit, Phytobiotics GmBH, Eltville, Germany.
Aureomycin, Alpharma, Bridgewater, NJ.
Sensititre veterinary gram-negative MIC plate, TREK Diagnostics, Cleveland, Ohio.
MPN Calculator, build 23, Mike Curiale. Available at: members.ync.net/mcuriale/mpn/index.html. Accessed Feb 24, 2013.
Minitab, version 14, Minitab Inc, State College, Pa.
SAS, version 9.1, SAS Institute Inc, Cary, NC.
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