Protracted Cervical Lymphadenitis With Mycobacterium avium and Methylobacterium mesophilicum

Abstract

To the Editors: Methylobacterium mesophilicum has rarely been isolated from specimens of febrile severely immunocompromised hosts1 and in catheter-related infections.2 Hitherto, 5 pediatric patients with bloodstream infection caused by M. mesophilicum have been reported who received intensive anticancer chemotherapy3,4 or who were immunocompromised because of other reasons.5 A 3-year-old white boy was referred to the oncology outpatient unit with an enlarged and obdurate nuchal tumor. The boy used to play and dig in the family’s vegetable garden. Ultrasound examination showed enlarged lymph nodes that measured up to 3 cm in diameter. Mendel-Mantoux and serologic testing for viral pathogens and for Bartonella hensellae yielded negative results. Histologic evaluation of the lymph node revealed epitheloid-cell granulomatous necrotizing lymphadenitis. Aerobic cultures of lymph node tissue on Columbia sheep blood (5%) and chocolate agar yielded a slow-growing pure culture of tiny oxidase-positive colonies; MacConkey agar remained negative. After an incubation time of 4 days at 35°C, 1-mm-diameter colonies were produced, which appeared pink pigmented in incandescent light. Bacteriologic standard procedures resulted in the identification of M. mesophilicum, susceptible in vitro to ceftazidime, ceftriaxone, meropenem, gentamicin, amikacin, and ciprofloxacin. In addition, Mycobacterium avium was cultured from the specimen. The boy was readmitted with high temperatures (39.7°C) and a left-sided tender and warm nuchal swelling with multiple enlarged lymph nodes, and received intravenous ceftazidime and gentamicin (according to the in vitro susceptibility data of M. mesophilicum). After 10 days, the patient was released from hospital in a good condition with oral ciprofloxacin for another week. Four follow-up examinations at 2-week intervals showed a healthy boy with a small residual nuchal induration. To our knowledge, this is the first report of a protracted lymphadenitis yielding growth of Mycobacterium avium and M. mesophilicum in an apparently immunocompetent child. Louria et al5 described an infant and an adolescent with systemic disease and Methylobacterium sp., isolated from blood, lymph node, and bone marrow; both children were severely immunocompromised. In addition, a 5-year-old boy, who received intensive chemotherapy for T-cell lymphoma, had a Hickman catheter-related M. mesophilicum bacteremia. Eventually, the catheter was removed after unsuccessful treatment with ticarcillin-clavulanate and gentamicin.4 Playing and digging in the family’s garden is one possible source of the infection with these 2 ubiquitous opportunistic environmental pathogens in our patient. Tap water used for oral irrigation in patients with mucositis after bone marrow transplantation has been related to an outbreak. Arne Simon, MD Sebastian Völz, MD Department of Pediatric Hematology and Oncology Children’s Hospital Medical Centre University of Bonn Bonn, Germany [email protected] Soo-Mi Reiffert, MD Institute for Medical Microbiology Immunology and Parasitology University of Bonn Bonn, Germany Hans Bölefahr, MD Department of Pediatric Surgery Marienhospital Bonn Bonn, Germany Günter Marklein, MD Institute for Medical Microbiology Immunology and Parasitology University of Bonn Bonn, Germany Reinhard Büttner, MD Institute for Pathology University of Bonn Bonn, Germany Nico Hepping, MD Udo Bode, MD Gudrun Fleischhack, MD Department of Pediatric Hematology and Oncology Children’s Hospital Medical Centre University of Bonn Bonn, Germany