Evaluating the interaction and survivability of Chryseobacterium species within Acanthamoeba Castellanii and Human Macrophage

• Main Author: Lim, Wei Gene
• Format: Thesis
• Published: 2020
• Subjects: QR Microbiology; R Medicine (General); RC Internal medicine
• Online Access: http://eprints.sunway.edu.my/2426/

In reason years, Chryseobacterium gleum and Chryseobacterium indologenes frequently reported to be implicated in deadly nosocomial diseases such as bacteremia, pneumonia, and urinary tract infection in individuals with immunodeficiency. The interactions of Chryseobacterium spp. with Acanthamoeba castellanii and THP-1 macrophage cells were unexplored previously. In our study, the co-culturing of C. gleum and C. indologenes with Acanthamoeba castellanii trophozoite and THP-1 macrophage cells were carried out to assess the interactions. Our results reveal that, the bacterial numbers of C. gleum and C. indologenes increased significantly (p < 0.05) within A. castellanii over 24 hours by 8.24 and 4.62-fold respectively, but decreased significantly (p < 0.05) over the next 14 days of incubation. However, 0.09% of C. gleum bacteria cells and no C. indologenes were recovered from THP-1 macrophage cells after an hour of incubation and none of C. indologenes and C. gleum were recovered in intracellular survival assay after 24 hours of incubation. Our results also indicated that C. indologenes and C. gleum exhibited limited cytotoxic effects on THP-1 human macrophages with survivability percentage of approximately 70%-90%. The preliminary observation showed that, the Chryseobacterium spp. interacted and were capable of surviving intracellularly of A. castellanii, but not in THP-1 macrophages. Such observations gave rise to the postulation that A. castellanii may be an environmental host for C. gleum and C. indologenes, and facilitates their transmission to immunodeficiency hosts in healthcare setting, causing nosocomial infections. The failure to survive the interactions with THP-1 macrophage may indicate that C. indologenes and C. gleum use other mechanisms in causing infections to susceptible individuals. For future studies, potentiality of both C. gleum and C. indologenes to survive in cyst and the plausible intracellular survival mechanisms in A. castellanii will be investigated. In addition, the virulence factors of the two bacteria species can be determined as the next step in revealing their ability in causing nosocomial infections in susceptible individuals.