Relapsed Melioidosis Model in C57BL/6 Mice
Pawana Panomket PhD*, Parichart Wongsana MD*, Surasak Wanram PhD*, Surasakdi Wongratanacheewin PhD**,***, Thanatchaporn Bartpho PhD***
Affiliation : * College of Medicine and Public Health, Ubon Ratchathani University, Ubon Ratchathani, Thailand ** Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand *** Melioidosis Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
Background : Burkholderia pseudomallei are the causative agents of melioidosis, a disease that has a high relapse rate in
endemic areas. The mechanism of relapse is unclear.
Objective : This study aimed to establish relapsed melioidosis in C57BL/6 mice by induction with B. pseudomallei.
Material and Method: Low doses of B. pseudomallei H777 and its biofilm defective mutant (M10) were intra-gastric fed to
C57BL/6 mice. All the infected mice had suppressed immune status by intra-peritoneal injection of hydrocortisone at 2.5 mg
per mouse at day 60 post-infection. Inflammatory response to the infection was investigated by histo-pathological studies and
monitoring bacterial counts in the blood and organs.
Results : All the infected mice were found to have a high infiltration of mononuclear cells at day 60 post-infection. The
results showed high bacterial counts in the blood in both strains post-suppressed immune status after two days. The biofilm
mutant and wild type strains produced relapse in C57BL/6 mice but the latter was responsible for significantly more severe
inflammation than the biofilm mutant.
Conclusion : Low immune status may cause relapsed melioidosis in hosts with chronic inflammation.
Keywords : Burkholderia pseudomallei, Melioidosis, Relapse
