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Identification of Pasteurella multocida and Pasteurella haemolytica by API 20E, Minitek, and Oxi/Ferm systems
Abstract:
Fifty serotyped isolates each of Pasteurella multocida and Pasteurella haemolytica were tested on the API 20E strip (Analytab Products, Plainview, N.Y.), the Oxi/Ferm tube (Roche Diagnostics, Nutley, N.J.), and the Minitek system (BBL Microbiology Systems, Cockeysville, Md.). None of the rapid test systems reliable identified these organisms. With the API system, discrepancies between expected and actual results for the oxidase test and nitrate test frequently resulted in misidentification or no identification. The Minitek system misidentified 68% of the P. haemolytica isolates. The Minitek identification of Pasteurella depends on 100% positive xylose reactions, whereas only 56% of the P. haemolytica strains were positive for xylose fermentation. The Oxy/Ferm system, instead of giving a definitive identification, in most instances merely placed Pasteurella in a category of similar organisms.
Insights
Rapid diagnostic systems like API 20E, Oxi/Ferm, and Minitek failed to reliably identify Pasteurella multocida and Pasteurella haemolytica. These systems showed significant discrepancies, leading to misidentification or no identification for these bacterial pathogens.
Area of Science:
- Veterinary Microbiology
- Bacterial Pathogenesis
- Diagnostic Microbiology
Background:
- Accurate identification of bacterial pathogens is crucial for effective treatment and disease control.
- Pasteurella species, including Pasteurella multocida and Pasteurella haemolytica, are significant veterinary pathogens.
- Rapid identification methods are desirable for timely diagnosis in clinical settings.
Purpose of the Study:
- To evaluate the reliability of three commercial rapid identification systems for Pasteurella species.
- To compare the performance of API 20E, Oxi/Ferm, and Minitek systems in identifying Pasteurella multocida and Pasteurella haemolytica.
Main Methods:
- Fifty serotyped isolates of Pasteurella multocida and fifty of Pasteurella haemolytica were tested.
- The API 20E, Oxi/Ferm tube, and Minitek systems were utilized for bacterial identification.
- Biochemical reactions and identification results were recorded and analyzed.
Main Results:
- None of the tested rapid identification systems reliably identified the Pasteurella isolates.
- The API system exhibited discrepancies in oxidase and nitrate tests, causing misidentification.
- The Minitek system misidentified 68% of P. haemolytica, with xylose fermentation being a key issue (56% positive vs. 100% required).
- The Oxi/Ferm system provided only broad categorization, not definitive identification.
Conclusions:
- Current rapid identification systems are inadequate for accurate Pasteurella species diagnosis.
- Further development and validation of diagnostic tools are needed for these important veterinary pathogens.
- Biochemical test limitations, such as xylose fermentation variability, impact the accuracy of automated systems.