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Antimicrobial susceptibility patterns of the A and T types of Pasteurella haemolytica
Abstract:
Minimal concentrations of penicillin, ampicillin, cephalothin, chloramphenicol, tetracycline, erythromycin, nitrofurantoin, kanamycin and gentamicin inhibitory to Pasteurella haemolytica biotypes A and T were determined. They were found to be significantly higher for T than for A type strains in the case of all the antimicrobial drugs tested except the two aminoglycosides kanamycin and gentamicin, for which no differences were observed. In the case of penicillin the differences were so marked that they may be useful as a basis for biotyping P haemolytica isolates. The emergence of antibiotic-resistant strains observed in recent years, however, may limit such application.
Insights
Minimal inhibitory concentrations for Pasteurella haemolytica biotypes A and T were determined for several antibiotics. Biotype T strains generally required higher antibiotic concentrations than biotype A strains, except for kanamycin and gentamicin.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance
- Bacterial Pathogenesis
Background:
- Pasteurella haemolytica is a significant bacterial pathogen in ruminants.
- Understanding antimicrobial susceptibility is crucial for effective treatment and control.
- Biotyping may aid in differentiating strains with varying characteristics.
Purpose of the Study:
- To determine the minimal inhibitory concentrations (MICs) of various antibiotics for Pasteurella haemolytica biotypes A and T.
- To investigate potential differences in antimicrobial susceptibility between the two biotypes.
- To assess the utility of penicillin's differential activity for biotyping P. haemolytica.
Main Methods:
- Determination of minimal inhibitory concentrations (MICs) for penicillin, ampicillin, cephalothin, chloramphenicol, tetracycline, erythromycin, nitrofurantoin, kanamycin, and gentamicin.
- Testing against Pasteurella haemolytica biotypes A and T.
- Comparative analysis of MICs between the two biotypes.
Main Results:
- MICs were significantly higher for biotype T than for biotype A strains for most tested antimicrobials.
- No significant difference in MICs was observed for kanamycin and gentamicin between the biotypes.
- Penicillin demonstrated marked differences in MICs, suggesting potential for biotyping P. haemolytica.
Conclusions:
- Antimicrobial susceptibility varies between Pasteurella haemolytica biotypes A and T.
- Penicillin's differential inhibitory concentrations may serve as a basis for biotyping.
- The emergence of antibiotic-resistant strains could impact the application of these findings.