Bacteremia by Chryseobacterium oranimense, A Colistin-Resistant Gram-Negative Bacilli, in an Immunocompetent Pediatric Patient

Le résumé fourni par la source

To the Editors: We report the case of a 6-year-old girl, with autism spectrum disorder, who attended the emergency department because of an episode of decreased level of consciousness without paroxysmal movements, lasting 3 minutes, with fever the last few hours. She showed somnolence, lethargy and incomprehensible sounds, without neck stiffness, meningeal or focal signs. A blood sample was taken with normal results except C-reactive protein 74 mg/L, and lumbar puncture was performed (cerebrospinal fluid : glucose 53 mg/dL; proteins 25,5 mg/dL, 1 leucocyte/mm3). The patient was admitted and treated with intravenous acyclovir and cefotaxime. On the third day, the blood culture showed the isolation of Chryseobacterium oranimense. No other samples were taken for further cultures. Polymerase chain reaction in cerebrospinal fluid for herpes simplex, varicella zoster and enterovirus yielded negative results. The blood culture was incubated in a Bactec-FX instrument (Becton Dickinson). Bacterial growth was detected within 17.07 hours of incubation. The isolate was identified using MALDI-TOF (Brucker, Germany) mass spectrometer, where no other bacteria were isolated. Results were confirmed in the Centro Nacional de Microbiología by means of 16s recombinant DNA sequence analysis using a previously reported method.1 Antibiotic susceptibility testing was performed by automated broth microdilution (MicroScan; Becman-Coulter), and minimal inhibitory concentration results were interpreted by using European Committee on Antimicrobial Susceptibility Testing (EUCAST) interpretive criteria for Pseudomonas species. The isolate was susceptible to the following antibiotics: ciprofloxacin, trimethoprim-sulfamethoxazole, minocycline and piperacillin-tazobactam and resistant to colistin, second- and third-generation cephalosporins and carbapenems. With the diagnosis of bacteremia by C. oranimense, antibiotic treatment was changed to ciprofloxacin. Fever disappeared in 24 hours, as expected from the antibiotic susceptibility test, and the patient was discharged 7 days after admittance. She received 7 days of acyclovir and 2 weeks of antibiotics: initially ciprofloxacin followed by oral trimethoprim-sulfamethoxazole. Four weeks after discharge, the patient remained asymptomatic. Immunoglobulins and lymphocyte subsets were analyzed, with normal results. C. oranimense is a Gram-negative, aerobic, nonmotile rod, catalase and oxidase-positive.2 It was isolated from raw cow’s milk in Israel in April 20043. The genus Chryseobacterium contains around 80 species, widely distributed in aquatic and soil environments, and some species are pathogenic to humans and animals.2 Members of the genus Chryseobacterium have been documented as opportunistic pathogens associated with nosocomial infections in infants and immunocompromised patients of all age groups.4 The most common species causing human disease are C. meningosepticum and C. indologenes. To the authors’ knowledge, this is the first case of invasive disease caused by C. oranimense in an immunocompetent patient. There is a single published case of isolation of this bacterium, in the sputum of a 26-month-old child, previously diagnosed of cystic fibrosis. The patient was coinfected with Stenotrophomonas maltophilia and Pseudomona aeruginosa and had received a prolonged treatment with colistin prior the isolation of C. oranimense. The authors consider that colistin therapy could lead to the selection of the colistin-resistant bacterium and conclude that C. oranimense could be considered an opportunistic human pathogen in immunocompromised patients.5 Even more, the only published data on isolation of Chryseobacterium species in human infections are recorded in immunosuppressed patients or during a prolonged broad spectrum antibiotic therapy.4 None of these risk factors were present in this case. Nevertheless, the patient’s parents report usual ingestions of inorganic substances (soil or grass) because of her behavioral alterations, which may be interesting to study as a possible route of acquisition. Serena Villaverde González, MDPediatric Infectious Diseases UnitHospital Universitario Puerta de Hierro MajadahondaMadrid, Spain Feia Eugenieva Marinova, MDDepartment of MicrobiologyHospital Universitario Puerta de Hierro MajadahondaMadrid, Spain Alejandro Rasines Rodríguez, MDPediatric Infectious Diseases UnitHospital Universitario Puerta de Hierro MajadahondaMadrid, Spain Beatriz Orden Martínez, MD, PhDDepartment of MicrobiologyHospital Universitario Puerta de Hierro MajadahondaMadrid, Spain Luz Golmayo Gaztelu, MDPediatric Infectious Diseases UnitHospital Universitario Puerta de Hierro MajadahondaMadrid, Spain Juan Antonio Saez Nieto, MD, PhDArea of Bacteriology, mycology and parasitologyCentro Nacional de MicrobiologíaInstituto de Salud Carlos IIIMadrid, Spain M. José Cilleruelo Ortega, MD, PhDPediatric Infectious Diseases UnitHospital Universitario Puerta de Hierro MajadahondaMadrid, Spain

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.