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Effects of sub-MICs of antibiotics on cell surface characteristics and virulence of Pasteurella multocida
1Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.
Abstract:
The effects of sub-MICs of certain antibiotics, namely, penicillin G, tetracycline, and trimethoprim-sulfamethoxazole, on the cell surface characteristics and the virulences of two toxigenic isolates of Pasteurella multocida representing capsular types A and D were evaluated. Expression of proteins, in particular, outer membrane proteins and iron-regulated proteins, was not affected by exposure of bacterial cells to low concentrations of antibiotics. However, exposition of surface antigens was modified by sub-MICs of the antibiotics tested. The lipopolysaccharide profile of one isolate (capsular type D) was altered by penicillin G. Sub-MICs of penicillin G and tetracycline diminished the virulence of the capsular type A isolate and adherence to porcine tracheal rings of the capsular type D isolate. Production of dermonecrotic toxin was not affected by sub-MICs of the antibiotics tested. Our results indicate that growth of P. multocida in the presence of low concentrations of antibiotics seems to have, depending on the isolate, profound effects on cell surface characteristics, with concomitant effects on adherence or virulence. Our results also indicate that production of dermonecrotic toxin, an important virulence factor of P. multocida isolates associated with porcine atrophic rhinitis, was not affected by sub-MICs of the antibiotics studied.
Insights
Sub-inhibitory antibiotic concentrations alter Pasteurella multocida surface antigens, affecting virulence and adherence. However, dermonecrotic toxin production remained unaffected in this study.
Area of Science:
- Veterinary Microbiology
- Bacterial Pathogenesis
Background:
- Pasteurella multocida is an important veterinary pathogen causing various diseases.
- Sub-minimum inhibitory concentrations (sub-MICs) of antibiotics can influence bacterial virulence and surface characteristics.
- Understanding these effects is crucial for managing antibiotic resistance and disease control.
Purpose of the Study:
- To investigate the impact of sub-MICs of penicillin G, tetracycline, and trimethoprim-sulfamethoxazole on Pasteurella multocida.
- To evaluate changes in cell surface antigens, protein expression, and virulence factors.
- To assess the effects on adherence to host tissues.
Main Methods:
- Exposure of Pasteurella multocida isolates (capsular types A and D) to sub-MICs of selected antibiotics.
- Analysis of outer membrane proteins and iron-regulated proteins.
- Evaluation of lipopolysaccharide profiles.
- Assessment of bacterial virulence and adherence to porcine tracheal rings.
Main Results:
- Sub-MIC antibiotic exposure modified surface antigen exposition.
- Penicillin G altered the lipopolysaccharide profile of the capsular type D isolate.
- Penicillin G and tetracycline reduced virulence in the capsular type A isolate and adherence in the capsular type D isolate.
- Protein expression, including outer membrane and iron-regulated proteins, was not significantly affected.
Conclusions:
- Sub-MIC antibiotics can profoundly impact Pasteurella multocida cell surface characteristics, influencing virulence and adherence.
- Dermonecrotic toxin production, a key virulence factor, was not affected by the tested sub-MIC antibiotic concentrations.
- These findings highlight the complex interactions between sub-lethal antibiotic levels and bacterial pathogenicity.