Bacteremia due to Pasteurella pneumotropica occurs infrequently. We report a case of septicemia in a 72-year-old woman who had no underlying illness. The microorganism was isolated from 10 blood cultures and identified by conventional and molecular methods. This is the first reported case of P. pneumotropica septicemia in an immunocompetent patient. The history of P. pneumotropica diseases in animals and humans and their varied clinical features are reviewed.Human systemic infections due to Pasteurella species have been reported in association with exposure to animals, particularly cats and dogs. However, serious systemic infections are rare and generally related to Pasteurella multocida (9). We describe a case of septicemia due to Pasteurella pneumotropica that was confirmed by using molecular identification and which, after a review of the English-language medical literature, we identify as the first documented case occurring in an immunocompetent patient.Case report. A 72-year-old female patient was admitted to the hospital for an 18-day history of fever, chills, night sweats, and asthenia. The patient had a history of rheumatic mitral valvulopathy and had had a Saint-Jude valve transplantation operation in 1982. She underwent a permanent pacemaker implantation procedure in 1999 for sick sinus syndrome. The patient lived in poor social conditions in the company of five cats and one dog. She admitted that she was frequently scratched by the cats. On physical examination the patient was found to be febrile (temperature, 39.5°C) but was not hemodynamically unstable (blood pressure of 150/60 mm of mercury). Skin examination revealed no cutaneous lesion and no visible sign of animal scratch or bite. The white blood cell count was 18.8 ϫ 10 9 /liter, with 91% of cells being polymorphonuclear. Other hematological assessments included the following: hemoglobin, 13.7 g/dl; hematocrit, 41.3%; and platelet count, 112.000/mm 3 . The level of C-reactive protein was 46.1 mg/liter at admission and reached 271.4 mg/liter the next day. Serum electrolyte levels were normal. A transesophageal echography did not reveal any functional anomaly of the mechanical valve and did not show any vegetation. Ten sets of blood cultures were drawn, with seven being drawn on the day of admission and three on the next day. Each of these blood cultures yielded a gram-negative-bacillus pure culture. The other investigations, i.e., urine culture, analysis of cerebrospinal fluid, electrocardiography, chest radiograph, cerebral scanner, and abdominal echography, were normal. The pacemaker was functional and was not replaced.The Gram stain from the culture showed small gram-negative coccobacilli, with some longer bacillary forms. Blood, chocolate, and MacConkey agar plates were inoculated. After 24 h of incubation in 5% CO 2 , small, smooth, white-gray, transparent, nonhemolytic colonies were observed on the plates, but no growth was detected on MacConkey agar. The bacteria were facultatively anaerobic, nonmotile, and nonspore forming. Biochemical t...