Mutant prevention and minimum inhibitory concentration drug values for enrofloxacin, ceftiofur, florfenicol, tilmicosin and tulathromycin tested against swine pathogens Actinobacillus pleuropneumoniae, Pasteurella multocida and Streptococcus suis

• Published in: PloS one 2019-01, Vol.14 (1), p.e0210154-e0210154
• Main Authors: Blondeau, Joseph M, Fitch, Shantelle D
• Format: Article
• Language: English
• Subjects: Actinobacillus pleuropneumoniae; Actinobacillus pleuropneumoniae - drug effects; Actinobacillus pleuropneumoniae - genetics; Actinobacillus pleuropneumoniae - isolation & purification; Animal Husbandry; Animals; Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - therapeutic use; Antibiotics; Antiinfectives and antibacterials; Antimicrobial agents; Antimicrobial resistance; Bacteria; Bacterial infections; Biology and Life Sciences; Cephalosporins - pharmacology; Cephalosporins - therapeutic use; Chemotherapy; Clinical outcomes; Complications and side effects; Disaccharides - pharmacology; Disaccharides - therapeutic use; Disease prevention; Dosage and administration; Drug resistance; Drug Resistance, Multiple, Bacterial - drug effects; Drug Resistance, Multiple, Bacterial - genetics; Drug therapy; E coli; Enrofloxacin; Enrofloxacin - pharmacology; Enrofloxacin - therapeutic use; Florfenicol; Heterocyclic Compounds - pharmacology; Heterocyclic Compounds - therapeutic use; Hogs; Hypotheses; Infections; Infectious diseases; Laboratories; Livestock; Medicine and Health Sciences; Microbial drug resistance; Microbial Sensitivity Tests; Microbiology; Minimum inhibitory concentration; Morbidity; Pasteurella multocida; Pasteurella multocida - drug effects; Pasteurella multocida - genetics; Pasteurella multocida - isolation & purification; Pathogenesis; Pathogens; Pneumonia; Prevention; Proteins; Respiratory diseases; Strains (organisms); Streptococcus infections; Streptococcus suis; Streptococcus suis - drug effects; Streptococcus suis - genetics; Streptococcus suis - isolation & purification; Subpopulations; Swine; Swine Diseases - drug therapy; Swine Diseases - microbiology; Thiamphenicol - analogs & derivatives; Thiamphenicol - pharmacology; Thiamphenicol - therapeutic use; Tilmicosin; Tylosin - analogs & derivatives; Tylosin - pharmacology; Tylosin - therapeutic use; Veterinary medicine
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0210154

Actinobacillus pleuropneumoniae, Pasteurella multocida and Streptococcus suis are prevalent bacterial causes of swine infections. Morbidity, mortality and positively impacting the financial burden of infection occurs with appropriate antimicrobial therapy. Increasing antimicrobial resistance complicates drug therapy and resistance prevention is now a necessity to optimize therapy and prolong drug life. Mutant bacterial cells are said to arise spontaneously in bacterial densities of 107-109 or greater colony forming units/ml. Antibiotic drug concentration inhibiting growth of the least susceptible cell in these high density populations has been termed the mutant prevention concentration (MPC). In this study MPC and minimum inhibitory concentration (MIC) values of ceftiofur, enrofloxacin, florfenicol, tilmicosin and tulathromycin were determined against the swine pathogens A. pleuropneumoniae, P.multocida and S. suis. The following MIC90/MPC90 values (mg/L) for 67 A. pleuropneumoniae and 73 P. multocida strains respectively were as follows: A. pleuropneumoniae 0.031/0.5, ≤0.016/0.5, 0.5/2, 4/32, 2/32; P. multocida 0.004/0.25, 0.016/0.125, 0.5/0.5, 8/16, 0.5/1. For 33 S. suis strains, MIC90 values (mg/L) respectively were as follows: 1, 0.25, 4, ≥8 and ≥8. A total of 16 S. suis strains with MIC values of 0.063-0.5 mg/L to ceftiofur and 0.25-0.5 mg/L to enrofloxacin were tested by MPC; MPC values respectively were 0.5 and 1 mg/L respectively. MPC concentrations provide a dosing target which may serve to reduce amplification of bacterial subpopulations with reduced antimicrobial susceptibility. Drug potency based on MIC90 values was ceftiofur > enrofloxacin >florfenicol = tulathromycin > tilmicosin; based on MPC90 values was enrofloxacin > ceftiofur > tulathromycin > florfenicol ≥ tilmicosin.