A 4-year-old child living in a slum is bitten by a rat while sleeping. Two days later, the child develops a rash characterized by discrete erythematous 1-4 mm macules on the extremities and face, most obvious on the palms and soles. Which of the following organisms is the most likely cause of this child's disease?

The child has "rat-bite fever." This occurs in two forms with somewhat similar clinical manifestations. The form this child has is the Haverhill fever form, caused by Streptobacillus moniliformis and characterized by a sho (often 1-3 days) incubation period. One of the problems with diagnosing these diseases is that the victims are usually young children, and the bite site may be inapparent by the time the disease becomes severe enough for the child to be taken to a doctor. Borrelia burgdorferi causes Lyme disease, which is characterized by an expanding erythematous rash, ahralgias, and eventual nervous system involvement. Pseudomonas mallei causes glanders, which generally affects horses or humans in close contact with equines. Pseudomonas pseudomallei causes melioidosis, a rare pulmonary disease found mostly in Southeast Asia. Ref: Brooks G.F. (2013). Chapter 22. Legionellae, Baonella, and Unusual Bacterial Pathogens. In G.F. Brooks (Ed), Jawetz, Melnick, & Adelberg's Medical Microbiology, 26e.