Interpretive Criteria for Antimicrobial Susceptibility Testing of Ceftiofur against Bacteria Associated with Swine Respiratory Disease

Abstract

Abstract. Ceftiofur, an extended-spectrum cephalosporin, is active against a variety of animal pathogens, including organisms associated with swine respiratory disease. However, minimum inhibitory concentration (MIC) breakpoint and disk diffusion interpretive criteria have not been established for swine pathogens. Susceptibility tests were performed by broth microdilution MIC and disk diffusion methods on 246 bacterial species that cause swine respiratory disease. Ceftiofur was active against Salmonella sp., Pasteurella multocida, Actinobacillus pleuropneumoniae, Streptococcus suis, and Escherichia coli but was not active against Bordetella bronchiseptica measured by MIC. Based on pharmacokinetic studies of ceftiofur in swine after a single intramuscular injection of 3 or 5 mg/kg body weight of ceftiofur and on the MIC and disk diffusion data, we recommend MIC breakpoints and disk diffusion distances, respectively, of ≤ 2 µg/ml and ≥ 21 mm for susceptible, 4 µg/ml and 18-20 mm for intermediate, and ≥ 8 µg/ml and ≤ 17 mm for resistant classification for swine pathogens. When these breakpoints were applied to data from a previous study using bovine pathogens, only 1 minor interpretive error occurred.Swine respiratory disease is an economically important disease to swine producers 1,13 . The etiology of swine respiratory disease is complex; it may be caused by a variety of organisms, either alone or in combination, but the species commonly implicated include Actinobacillus pleuropneumoniae, Pasteurella multocida, Salmonella choleraesuis, Escherichia coli, Streptococcus suis, and Mycoplasma hyopneumoniae. 1,12,13 Antimicrobial therapy is an important component of programs to reduce both the morbidity and mortality associated with swine respiratory disease. 1,12,13 Ceftiofur is an extended-spectrum cephalosporin that is active against a variety of animal pathogens. 15 It was approved by the Food and Drug Administration in 1988 for use in the treatment of bovine respiratory disease. At that time, minimum inhibitory concentration (MIC) breakpoint and zone interpretive criteria were recommended based upon the microbiology and the pharmacokinetics of ceftiofur in cattle. The MIC breakpoints and zone diameters, respectively, were ≤ 2 µg/ml and ≥ 24 mm for susceptible, 4 µg/ml and 20-23 mm for intermediate, and ≥ 8 µg/ml and ≤ 19 mm for resistant designations. Recently, ceftiofur has also been approved for the treatment of swine respiratory Received for publication September 29, 1995. disease with a dose range of 3-5 mg/kg/day, but MIC breakpoints and zone interpretive criteria have not been established. The purpose of this study was to establish interpretive criteria for swine respiratory disease pathogens based upon the pharmacokinetics of ceftiofur in swine, broth microdilution MIC, and agar disk diffusion data generated for swine pathogens. Materials and methodsBacterial strains. The 246 bacterial isolates used in this study were obtained from Pharmacia and Upjohn (Kalamazoo, MI) and from Lorraine Hoffman at the Vet...

Escherichia coli isolates from sick chickens in China: Changes in antimicrobial resistance between 1993 and 2013

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The influence of antibiotics on B-cell number, percentage, and distribution in the bursa of Fabricius of newly hatched chicks

“…At the same time, broad-spectrum antibiotics, such as ceftiofur, florfenicol, and enrofloxacin are commonly used against many diseases in domestic animals, including the poultry flock (Booker et al, 1997;Burton et al, 1996;el-Banna, 1998;Graham et al, 1988;Ueda and Suenaga, 1995;Vancutsem et al, 1990). Sometimes, they are also administered at the time of vaccination.…”

Ceftiofur Regulates LPS-Induced Production of Cytokines and Improves LPS-Induced Survival Rate in Mice

“…It has been known to have many pharmacological activities, including anti-microbial and anti-inflammatory activities [8]. It has been widely used to treat a broad array of infectious diseases caused by Gram-positive and Gram-negative bacteria, such as pneumonia, peritonitis and mastitis in dairy cattle [8,9]. We have previously shown that ceftiofur can inhibit LPS-stimulated TNF-α, IL-1β and IL-6 secretion in RAW264.7 cells via activation of the NF-κB and MAP-kinase pathways [10].…”