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[Pasteurella multocida pneumonia in a lupus patient: microbial identification with alveolar lavage fluid on blood
E Hazouard1, M Ferrandière, B Cattier
1Service de Réanimation médicale, CHU Bretonneau, Tours.
Background:
Pasteurella multocida pneumonia mainly occurs in immunodepressed patients. Microbiological proof is difficult to obtain.
Case Report:
A 36-year-old woman with systemic lupus erythematosus treated with cyclophosphamide and corticosteroids developed pneumonia. She was given amoxicillin-clavulanate. Bronchioalveolar lavage fluid cultures on gelose were negative but Pasteurella multocida grew on blood culture medium.
Discussion:
Although the direct examination of bronchioalveolar lavage fluid demonstrated Gram negative coccobacilli, gelose cultures were negative, probably because of prior antibiotic therapy. The causal pathogen was only identified when BAL fluid was seeded on blood culture medium, allowing susceptibility tests and subsequent early adaptation of antibiotic therapy. This technique can be helpful in identifying the casual pathogen in microbial pneumonia.
Insights
Diagnosing Pasteurella multocida pneumonia in immunocompromised patients is challenging. Blood culture medium successfully identified the pathogen when standard gelose cultures failed due to prior antibiotic use.
Area of Science:
- Infectious Diseases
- Microbiology
- Pulmonology
Background:
- Pasteurella multocida pneumonia is a rare but serious infection, primarily affecting immunocompromised individuals.
- Accurate and timely diagnosis is crucial for effective treatment, yet microbiological confirmation can be difficult.
Observation:
- A case of Pasteurella multocida pneumonia in a patient with systemic lupus erythematosus undergoing immunosuppressive therapy is presented.
- Initial bronchoalveolar lavage (BAL) fluid cultures on standard gelose media were negative.
- However, Pasteurella multocida was successfully isolated from BAL fluid cultured on blood culture medium.
Findings:
- Direct microscopic examination of BAL fluid revealed Gram-negative coccobacilli, suggesting a bacterial infection.
- The negative gelose cultures were likely due to prior antibiotic administration.
- Blood culture medium proved superior for pathogen isolation in this case, enabling susceptibility testing and targeted therapy.
Implications:
- This case highlights the utility of blood culture medium for identifying Pasteurella multocida in pneumonia, especially after antibiotic treatment.
- Optimizing microbiological techniques is essential for diagnosing challenging infections in immunocompromised patients.
- Early and accurate pathogen identification facilitates prompt adjustment of antibiotic therapy, improving patient outcomes.