Turicella otitidis in a bacteremic child with acute lymphoblastic leukemia

Abstract

Most infections in neutropenic patients are caused by Pseudomonas aeruginosa, Staphylococcus aureus and Enterobacteriacae [1Verhoef J Prevention of infections in the neutropenic patient.Clin Infect Dis. 1993; 17: S359-S367Crossref PubMed Scopus (48) Google Scholar]. However, other uncommon microorganisms may be isolated from bacteremic infections in patients with hematologic malignancies. We report a case of febrile bacteremia caused by Turicella otitidis in a child with acute lymphoblastic leukemia B (ALL B). A 10-year-old boy had been followed in the hematologic ward for ALL B for 5 months. Chemotherapy was successful, with complete remission (white blood count (WBC): 10 000/mm3). In May, he was admitted to the pediatric unit with febrile neutropenia (temperature of 39 °C) without other symptoms. Physical examination revealed an axillary lymph node and right external otitis. This immunocompromised boy had thrombopenia (platelets: 53 000/mm3) and intense leucopenia: the WBC count was 400/mm3, with 3.5% polymorphonuclear leukocytes and 79.1% lymphocytes. Four aerobic blood cultures and an ear swab were collected, and the child was then treated for 3 days with intravenous cefepime (150 mg/kg/24 h) and vancomycin (40 mg/kg/24 h). After 24 h of incubation, the ear culture yielded a Gram-positive rod in pure culture on blood agar and chocolate agar plates, incubated in CO2. The colonies were non-hemolytic, opaque and creamy. This organism was a Gram-positive pleomorphic bacillus, catalase positive and oxidase negative, suggesting the Corynebacterium family. Two pretreatment blood cultures subsequently grew, after 2 days of incubation, the same Gram-positive rod. Phenotypic identification performed with the API Coryne system (bioMérieux, Marcy l'Etoile, France) revealed only two positive reactions—pyrazinamidase and alkaline phosphatase—without acid production from any sugar and without urease activity. The code number (2100004) gave a result of Corynebacterium group ANF, without discrimination between T. otitidis and C. auris. As described by Funke et al. [2Funke G von Graevenitz A Clarridge JE Bernard KA Clinical microbiology of coryneform bacteria.Clin Microbiol Rev. 1997; 10: 125-159Crossref PubMed Google Scholar], the morphology of colonies (creamy colonies) and the long bacilli were much more like T. otitidis than C. auris (dry colonies). The identification of T. otitidis was confirmed by a positive CAMP test. The antimicrobial agents tested by E test strips exhibited low MICs (amoxicillin < 0.016 mg/L, penicillin G 0.023 mg/L, ciprofloxacin 0.094 mg/L, cefotaxime 0.032 mg/L, vancomycin 0.75 mg/L) for the organism. However, the strain was resistant to erythromycin, the MICs for such strains usually being > 256 mg/L. And the patient was successfully treated with oral amoxicillin (100 mg/kg/day) for 7 days. T. otitidis is a coryneform bacterium usually isolated from middle ear fluids collected by tympanocentesis in immunocompetent patients with otitis media [3Simonet M De Briel D Boucot I Minck R Veron M Coryneform bacteria isolated from middle ear fluid.J Clin Microbiol. 1993; 31: 1667-1668PubMed Google Scholar], but it may also be isolated from ears of healthy persons [4Riegel P Bacteriological and clinical aspects of corynebacterium.Ann Biol Clin. 1998; 56: 285-296PubMed Google Scholar]. Furthermore, this microorganism is often isolated with other pathogens (Streptococcus pneumoniae, Haemophilus influenzae), and its clinical significance in ear specimens remains difficult to define. Systemic infections caused by T. otitidis and reported in the literature are very rare. Only two deep infections have been described: a recent case report identified T. otitidis in a posterior auricular abscess [5Reynold SJ Berh M McDonald J Turicella otitidis as an unusual agent causing a posterior auricular abscess.J Clin Microbiol. 2001; 39: 1672-1673Crossref PubMed Scopus (16) Google Scholar], and another described a case of mastoiditis in a healthy child [6Dana A Fader R Sterken D Turicella otitidis mastoiditis in a healthy child.Pediatr Infect Dis J. 2001; 20: 84-85Crossref PubMed Scopus (11) Google Scholar]. T. otitidis is a relatively newly recognized pathogen [1Verhoef J Prevention of infections in the neutropenic patient.Clin Infect Dis. 1993; 17: S359-S367Crossref PubMed Scopus (48) Google Scholar], probably due to better identification techniques and to the progress in the taxonomy of the Gram-positive bacilli. To our knowledge, it has not been described elsewhere, particularly in patients with hematologic malignancies, and this case is the first reported bacteremia due to T. otitidis.