Chapter 23 - Animal Models of Melioidosis

Abstract

Melioidosis, an infection of humans and animals, is caused by the Gram-negative bacterium Burkholderia pseudomallei. Hamsters are exquisitely sensitive to B. pseudomallei infection, and the infection of hamsters with B. pseudomallei typically results in acute septicemic melioidosis and death within 2–3 days. This animal model of melioidosis has been used to assess the relative virulence of B. pseudomallei clinical and environmental isolates. The infection of infant diabetic rats with B. pseudomallei typically results in acute septicemic melioidosis and death, usually within 7 days. This animal model of melioidosis has been used in passive immunoprophylaxis studies and has been useful in assessing the relative virulence of B. pseudomallei isogenic mutants. No surgical procedures are required in the hamster or infant diabetic rat models of melioidosis. The diluted bacterial culture in the blood collection tube is drawn up into a 1 ml syringe fitted with a 25 G needle, and 100 μl aliquots are injected i.p. into hamsters and infant diabetic rats. The hamster and infant diabetic rat models of melioidosis most closely resemble acute septicemic melioidosis in humans. This form of the disease is the most common clinical presentation in humans and results in 40% mortality, even with vigorous antimicrobial therapy. These animal models of B. pseudomallei infection can help in identifying new antimicrobial agents for use in human cases of acute septicemic melioidosis. On the other hand, these animal models do not resemble other clinical manifestations of human disease, including chronic or latent melioidosis.