Objectives: To describe an unusual case of fungal infection by Scopulariopsis brevicaulis in a paediatric patient with acute lymphoblastic leukaemia (ALL) and to discuss the challenges in laboratory detection of this organism from blood culture. Case: A 10-year-old girl receiving maintenance chemotherapy after relapse of ALL following bone marrow transplantation was admitted with fever and a dry cough. Her CRP level was 141 mg/L. Blood cultures at this time were negative. A CT scan revealed multiple pulmonary lesions suggestive of fungal pneumonia. AmBisome was added to empirical antibiotic therapy. Bronchial lavage was not performed. Blood cultures collected 10 days later yielded S. brevicaulis. Voriconazole was added but blood cultures remained intermittently positive. Microbiological response and complete resolution of fever was finally achieved after the addition of oral terbinafine. AmBisome was later discontinued and the patient discharged. To date, she remains asymptomatic and apyrexial on oral voriconazole and terbinafine. However, some pulmonary lesions remain. Methods: Inoculated blood culture bottles were processed using the BacTAlert automated system (BioMerieux), which detects growth due to microbial production of CO2. Antifungal MICs were determined at the HPA Mycology Reference Laboratory, Bristol, UK. Results: S. brevicaulis was cultured from blood specimens on 5 occasions (over a period of 4 weeks). However, on 3 of these occasions the inoculated blood culture bottles failed to signal positive. Fortunately, manual observation of the bottles prior to discard revealed several small cream-coloured spherical structures (fungal balls). Culture of the intact fungal balls and the blood culture fluid yielded no growth. However, culture of the disrupted fungal balls yielded S. brevicaulis. Antifungal MICs were: amphotericin 1 mg/L, voriconazole 8 mg/L, itraconazole 16 mg/L, caspofungin 4 mg/L and terbinafine 0.5 mg/L. Conclusions: S. brevicaulis fungaemia is rare and this report reveals that its detection by automated blood culture systems may be problematic. In the present case, laboratory diagnosis relied significantly upon manual examination of the inoculated blood culture bottles. The presence of antifungal agents may reduce the sensitivity of detection of the automated system. In addition, the compact structure of the S. brevicaulis fungal balls may represent a micro-environment from which CO2 is less readily released into the culture medium.
Full conference title:
16th European Congress of Clinical Microbiology and Infectious Diseases
- ECCMID 16th (2006)