A 9-year-old child is brought to the emergency room with the chief complaint of enlarged, painful axillary lymph nodes. The resident physician also notes a small, inflamed, dime-sized lesion surrounding what appears to be a small scratch on the forearm. The lymph node is aspirated and some pus is sent to the laboratory for examination. A Warthin-Starry silver impregnation stain reveals many highly pleomorphic, rod-shaped bacteria. Which of the following is the most likely cause of this infection?
While the essential information (i.e., the evidence that the child in question was scratched by a cat) is missing, the clinical presentation points to a number of diseases, including cat scratch disease (CSD). Until recently, the etiologic agent of CSD was unknown. Evidence indicated that it was a pleomorphic, rod-shaped bacterium that had been named Afipia. It was best demonstrated in the affected lymph node by a silver impregnation stain. However, it now appears that Afipia causes relatively few cases of CSD and that the small, pleomorphic, gram-negative rods present mainly in the walls of capillaries primarily responsible are Rochalimaea henselae, which has recently been renamed B. henselae. Brucella, Mycobacterium, and Yersinia species have not been shown to have any association with CSD.
Bartonella henselae
Brucella canis
Mycobacterium scrofulaceum
Yersinia enterocolitica
Bacteria