We describe a case of septic arthritis caused by Bordetella holmesii in a 15-year-old boy with chronic haemolytic anaemia. B. holmesii was identified by 16S rRNA gene sequence analysis. The patient outcome was favourable. To our knowledge, this is the first case of B. holmesii septic arthritis in an asplenic patient.
Case reportA 15-year-old male patient with a severe chronic haemolytic anaemia (elliptocytosis) presented to the emergency department of our paediatric hospital (Hôpital ArmandTrousseau) with a fever of 39 u C, a painful left knee lameness and a left thumb oedema since the previous day. Before the boy was 4 years old, an elective splenectomy was first performed in January 1999, and then a total splenectomy in October 2000.At the emergency department (Hôpital Armand-Trousseau), a painful limitation of the knee joint was observed on physical examination, and investigated by aspiration of the knee joint: one aliquot of the aspirate was injected directly into an aerobic broth bottle and analysed using the automated microbial detection system BacT/ALERT (bioMérieux), and additional aliquots were cultured on agar plates (blood agar and chocolate agar) combined with enrichments in two broth bottles (Hemoline; bioMérieux). A blood culture was also performed. The boy was hospitalized, and treated for 24 h with an intravenous antimicrobial combination of cefotaxime (60 mg kg 21 per day) and rifampicin (40 mg kg 21 per day), as well as analgesic drugs. Laboratory findings showed a white blood cell (WBC) count of 23 300 WBCs nl 21 , a C-reactive protein level of 67 mg l 21 and a procalcitonin level of 1.30 ng ml 21 . Afterwards, a left ankle oedema appeared, as well as a generalized jaundice with haemolysis characteristics (haemoglobin58 g dl 21 , reticulocytes5115 000 nl 21 , haptoglobin5low level, and free bilirubin5155 mg l 21 ). A spontaneous decrease of the haemolytic anaemia was subsequently observed. During the hospital stay, on day 1, a synovial biopsy was performed after a surgical knee joint washing, showing a richly vascularized chorion with many neutrophils, and a poor inflammatory response in the aponeurotic tissue resulting in only weakly inflammed tissue. During this operation, two new BacT/ ALERT broth bottles (aerobic/anaerobic) were also directly injected with the joint aspirate specimen. After 24 h, a decrease of the clinical symptoms, such as fever, knee and joint pain, and oedema, was observed, as well as a decrease of the inflammatory syndrome (WBCs513 000 nl 21 , Creactive protein level510 mg l 21 ). The outcome was favourable and the boy was discharged with only an analgesic treatment and the usual penicillin prophylaxis for asplenic patients (2 000 000 IU per day).
Microbiological investigationExamination of the synovial fluid showed 10 6 WBCs nl 21 with 80 % neutrophils but no micro-organism observed by Gram-stained smear. The aerobic joint fluid BacT/ALERT bottle set up whilst the patient was in the emergency department grew in 72 h, showing small, coccoid Gramnegative rods. Subcultur...