A 5-year-old male was referred to the Riley Hospital for Children for evaluation of limping and refusal to use his right hand. Prior to presentation, he had been intermittently ill for 3 weeks with symptoms that included recurrent fevers (39°C to 41°C), chills, and an erythematous, macular rash on his extremities. Clinical laboratory testing, including serological studies for various infectious and noninfectious etiologies, performed during evaluations by outside facilities were unrevealing. Antibiotics, including azithromycin and doxycycline, were prescribed by separate care providers for treatment of suspected pneumonia and ehrlichiosis. Between courses of antimicrobial chemotherapy, the patient's fever and rash resolved; however, approximately 1 week following completion of each antibiotic regimen, the patient's signs and symptoms reappeared.
Upon presentation to our facility, the patient was overall well appearing and had a fading rash on the plantar surface of both feet. History obtained at that time revealed that the patient had no underlying medical problems, lived with his biological parents and sister, had no recent travel history, had owned a pet rat, and had not sustained any arthropod bites or stings that he or his family could recall. Two sets of blood cultures were collected, and after 2 days of incubation, the aerobic bottles (BD Bactec Plus Aerobic/F; BD Diagnostic Systems) from both sets of blood cultures grew the organism shown in Fig. 1. Subcultures of the blood culture medium grew small, gray, umbonate, and nonhemolytic colonies after 3 days of incubation on sheep and rabbit blood agars incubated at 35°C in 5% CO2. The isolate was oxidase and spot indole negative, and with the exception of arginine dihydrolase and glucose fermentation, the results for all tests using conventional tubed biochemical media, including methyl red testing, Voges-Proskauer testing, citrate utilization, nitrate reduction, amino acid decarboxylation, esculin hydrolysis, and fermentation of lactose, sucrose, and xylose, were negative.
FIG 1.
Gram stain of one positive blood culture bottle showing tangled chains of pleomorphic Gram-negative bacilli. Some of the cells possess central bulbar swelling. Bar, 10 μm.
(For answer and discussion, see page 2213 in this issue [doi:10.1128/JCM.02058-14].)