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Survival of Pseudomonas pseudomallei in human phagocytes
S Pruksachartvuthi1, N Aswapokee, K Thankerngpol
1Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Abstract:
Pseudomonas pseudomallei causes the disease melioidosis, with protean manifestations, protracted clinical course and unpredictable response to antimicrobial treatment. Intracellular location of the organism is suspected to be the cause of these properties. This study was undertaken to examine the intracellular growth of this bacterium. Intracellular growth and survival was assessed at different time intervals, by Gram's stain and electronmicroscopic examination. During the first 5 h, the numbers of P. pseudomallei within phagocytes did not change significantly. By 18-21 h, gram-stained preparations revealed that P. pseudomallei cells completely filled the phagocytes and electronmicroscopy showed evidence of binary fission. During that time the number of cfu of P. pseudomallei growing simultaneously in vitro increased by log10 2-3. The phagocytes remained viable throughout the observation period and retained their capacity to produce an oxidative burst for the first hour of incubation. The ability of P. pseudomallei to survive and multiply in phagocytes shows that it is a facultative intracellular bacterium. This finding is relevant to the selection of antimicrobial regimens, and the management of the disease.
Insights
Pseudomonas pseudomallei, the cause of melioidosis, can survive and multiply inside host cells. This intracellular growth explains the disease's complex nature and challenges in treatment.
Area of Science:
- Microbiology
- Infectious Diseases
- Cell Biology
Background:
- Melioidosis, caused by Pseudomonas pseudomallei, presents with diverse symptoms and unpredictable treatment responses.
- The intracellular lifestyle of P. pseudomallei is a suspected factor in its complex clinical behavior.
Purpose of the Study:
- To investigate the intracellular growth and survival mechanisms of Pseudomonas pseudomallei within host phagocytes.
Main Methods:
- Assessing intracellular P. pseudomallei numbers over time using Gram staining and electron microscopy.
- Monitoring phagocyte viability and oxidative burst capacity during infection.
Main Results:
- P. pseudomallei numbers remained stable within phagocytes for the initial 5 hours.
- Significant intracellular multiplication (binary fission) of P. pseudomallei was observed by 18-21 hours.
- Phagocytes maintained viability and oxidative burst capacity during the early stages of infection.
Conclusions:
- Pseudomonas pseudomallei demonstrates facultative intracellular bacterium characteristics, surviving and multiplying within phagocytes.
- Understanding this intracellular behavior is crucial for selecting effective antimicrobial treatments and managing melioidosis.