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Published on: February 15, 2012
Biofilm characterisation of Mycoplasma bovis co-cultured with Trueperella pyogenes
Koji Nishi1,2, Satoshi Gondaira3, Yuki Hirano4
1Animal Health Unit, Department of Veterinary Science, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
Abstract:
Mycoplasma pneumonia, caused by Mycoplasma bovis (Mycoplasmopsis bovis; M. bovis), is linked with severe inflammatory reactions in the lungs and can be challenging to treat with antibiotics. Biofilms play a significant role in bacterial persistence and contribute to the development of chronic lesions. A recent study has shown that polymicrobial interactions between species are an important factor in biofilm formation, yet the precise mechanism of biofilm formation in M. bovis remains unknown. By assuming multiple pathogen infections in the bovine respiratory disease complex (BRDC), this study examined the characterisation of the polymicrobial relationship between M. bovis and Trueperella pyogenes (T. pyogenes) during biofilm formation. Autopsies were performed on four Holstein calves (two chronic Mycoplasma pneumonia calves and two control calves). Bacterium-like aggregation structures (> 10 μm), which were assumed to be biofilms of M. bovis in vivo, were observed adhering to the cilia in calves with Mycoplasma pneumonia. M. bovis released an extracellular matrix to connect with neighbouring bacteria and form a mature biofilm on the plate. Biofilm formation in the co-culture of M. bovis and T. pyogenes (strain T1: 1 × 105 and 1 × 106 CFU/well) significantly increased (p < 0.05 and p < 0.01; 64.1% and 64.8% increase) compared to that in a single culture of these bacteria. Furthermore, some large aggregates (> 40 μm), composed of M. bovis and T. pyogenes, were observed. The morphological characteristics of this biofilm were similar to those observed in vivo compared to a single culture. In conclusion, the polymicrobial interaction between M. bovis and T. pyogenes induces biofilm formation, which is associated with increased resistance to antimicrobial agents, and this exacerbates the progression of chronic Mycoplasma pneumonia.
Insights
Polymicrobial interactions between Mycoplasma bovis and Trueperella pyogenes significantly enhance biofilm formation. This synergistic effect in bovine respiratory disease complex infections increases antimicrobial resistance and worsens chronic pneumonia.
Area of Science:
- Veterinary Microbiology
- Bacterial Pathogenesis
- Bovine Respiratory Disease
Background:
- Mycoplasma pneumonia, caused by Mycoplasma bovis, leads to severe lung inflammation and is difficult to treat.
- Bacterial biofilms contribute to persistent infections and chronic lesions in Mycoplasma pneumonia.
- Polymicrobial interactions are known to influence biofilm formation, but the mechanism in M. bovis is unclear.
Purpose of the Study:
- To investigate the polymicrobial relationship between Mycoplasma bovis and Trueperella pyogenes in biofilm formation.
- To characterize the in vivo and in vitro biofilm characteristics of M. bovis and T. pyogenes co-infections.
Main Methods:
- Autopsies of Holstein calves with and without chronic Mycoplasma pneumonia.
- In vitro co-culture experiments of M. bovis and T. pyogenes at varying concentrations.
- Microscopic observation of bacterium-like aggregation structures and biofilm morphology.
Main Results:
- In vivo, M. bovis biofilms were observed adhering to cilia in calves with Mycoplasma pneumonia.
- M. bovis released an extracellular matrix to facilitate biofilm formation.
- Co-culture of M. bovis and T. pyogenes significantly increased biofilm formation (64.1–64.8%) compared to single cultures.
- Large aggregates of both bacteria were observed, with biofilm morphology similar to in vivo findings.
Conclusions:
- Polymicrobial interaction between M. bovis and T. pyogenes promotes significant biofilm formation.
- This synergistic biofilm formation is linked to increased antimicrobial resistance.
- The findings suggest a mechanism exacerbating chronic Mycoplasma pneumonia progression in cattle.
