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Investigations on the species specificity of Mannheimia (Pasteurella) haemolytica serotyping
O Angen1, M Quirie, W Donachie
1Danish Veterinary Laboratory, Copenhagen. ang@svs.dk
Abstract:
Eleven serotypes (1, 2, 5-9, 12-14 and 16) have been demonstrated within Mannheimia haemolytica. Subsequent serotyping of 166 Mannheimia haemolytica-like strains, genetically and phenotyphically distinct from Mannheimia haemolytica, and isolated from ruminants, pigs, hares and rabbits showed that 13.2% were typeable, 19 of which were serotype 11 representing strains now being classified as M. glucosida. In addition, three strains belonged to serotypes 6, 9 and 16, respectively. Additionally, the serotyping results of 98 (P.) haemolytica-like isolates from non-ruminant sources collected by the UK Veterinary Investigation Centres during the period 1982-1996 were investigated. None of these isolates have been kept, making further genetic characterization impossible. Among these isolates, 25.5% were typeable representing serotypes 1, 2, 3, 5, 6, 9, 10, 13 and 15. Substantial evidence has been reported indicating that M. haemolytica-like isolates from non-ruminant sources represent species different from M. haemolytica. The present investigation underlines that serotyping does not represent a reliable method for the identification of M. haemolytica or M. glucosida. These observations emphasize that extended phenotypic and genetic characterization is necessary for the proper identification of these organisms.
Insights
Serotyping Mannheimia haemolytica and related species is unreliable for accurate identification. Extended phenotypic and genetic characterization are essential for distinguishing these organisms, including M. glucosida.
Area of Science:
- Veterinary Microbiology
- Bacteriology
- Animal Health
Background:
- Mannheimia haemolytica is associated with respiratory disease in ruminants.
- Serotyping has been used to classify M. haemolytica and related bacteria.
- Previous studies suggest M. haemolytica-like isolates from non-ruminants may be distinct species.
Purpose of the Study:
- To evaluate the reliability of serotyping for identifying M. haemolytica and M. glucosida.
- To investigate the serotypes of M. haemolytica-like isolates from various animal sources.
- To determine if serotyping alone is sufficient for accurate bacterial classification.
Main Methods:
- Serological analysis of Mannheimia haemolytica-like strains from ruminants, pigs, hares, and rabbits.
- Investigation of historical serotyping data for (P.) haemolytica-like isolates from UK Veterinary Investigation Centres (1982-1996).
- Comparison of serotyping results with existing knowledge of M. haemolytica and M. glucosida classification.
Main Results:
- Only 13.2% of M. haemolytica-like strains were typeable; 19 were identified as serotype 11 (M. glucosida).
- Historical isolates from non-ruminants showed 25.5% typeability across various serotypes (1, 2, 3, 5, 6, 9, 10, 13, 15).
- Serotyping identified M. glucosida and some M. haemolytica serotypes but failed to definitively classify many isolates.
Conclusions:
- Serotyping is not a reliable method for the definitive identification of M. haemolytica or M. glucosida.
- Significant overlap in serotypes and distinct genetic/phenotypic characteristics suggest separate species.
- Comprehensive phenotypic and genetic characterization are crucial for accurate identification of these bacterial organisms.
