Bacteremia Detected by a Peripheral Blood Smear in a Pediatric Surgical Patient with Thrombocytopenia

Microscopic examination of peripheral blood smear (PBS) for detection of microorganisms is simple method that can be used for doctors to confirm the septicemia more swiftly and to select more specific therapy. But it is unusual to find microorganisms in PBS. We report a case of gram negative bacteremia diagnosed by PBS in a severe thrombocytopenic pediatric surgical patient. A 6-month and 2 week old baby with cyanosis was diagnosed congenital heart diseases such as transposition of great arteries, atrial septal defect, and patent ductus arteriosus. The infant underwent surgical operations and the postoperative platelet count progressively decreased in spite of transfusion of multiple platelet concentrates. We performed routine examination of a PBS for evaluation of severe thrombocytopenia. The PBS revealed severe thrombocytopenia, leukopenia with left shifted and some extracellular bacilli. Toxic granulations, toxic vacuoles and some bacilli were observed in the neutrophils. The bacilli were identified as Pseudomonas aeruginosa and Serratia marcescens in blood culture. To our knowledge, this is the second case of bacteremia diagnosed by PBS before the positive blood culture in Korea. We suggest that a PBS is useful for the rapid detection of organisms in cases of septicemia with severe thrombocytopenic pediatric surgical patient. (Korean J Clin Microbiol 2010;13:182-186)