A 17-year-old woman with cystic fibrosis, and with diabetes and persistent colonization of the respiratory tract with
Staphylococcus aureus since childhood was admitted in October 2006 to our specialized centre for a respiratory infection with dark sputum, asthenia, fever (38.5°C) and a loss of weight of 4.5 kg. On examination, the patient had shortness of breath and diffuse crepitations in both lungs. The oxygen saturation on air was 92% and her chest X-ray showed a diffuse bronchitis syndrome with bronchial distension in the right lung apex and left lung base. There was no pleural effusion. Relevant laboratory findings included a white blood cell (WBC) count of 18,380/mm
3 with 82.8% polymorphonuclear cells (PMNs), a platelet count of 618,000/mm
3, C-reactive protein (CRP) of 57 mg/litre, fibrinogen of 5.17 g/litre and whole blood glucose of 9 mmol/litre. An admission sputum sample was plated onto Columbia colistin-nalidixic acid (CNA) agar, chocolate Poly ViteX agar, MacConKey agar (bioMérieux, Marcy l'Etoile, France), CEPACIA agar, and SABOURAUD agar (AES laboratory, Combourg, France). Direct Gram staining of the sputa showed numerous PMNs (>25 cells/field), Gram-positive cocci, and infrequent epithelial cells (<10 cells/field). Apart from 10
7 CFU/ml methicillin-susceptible
S. aureus, two different Gram-negative rods (oxidase and catalase positive) were isolated from CEPACIA agar at 10
3 CFU/ml after 3 days of incubation. Using API 20NE (bioMérieux, Marcy l'Etoile, France), two isolates initially identified as
Weeksella virosa /
Empedobacter brevis (Code 0010014, 84.5% probability) and
Ochrobactrum anthropi (code 1641344, 98.9% probability) were definitively identified as
B. diminuta (100% homology with
B. diminuta strain DSM 1635, GenBank accession number X87274) and
O. anthropi (100% homology with
O. anthropi strain W24, GenBank accession number EF198140), respectively, after amplification and sequencing of the 16S rRNA gene as previously described [
4]. Although there is neither clear consensus nor guidelines for antibiotic susceptibility testing (AST) of these two bacteria, AST was performed using VITEK 2 Auto system (bioMérieux, Marcy l'Etoile, France) and disc diffusion methods. The
B. diminuta was resistant to amoxicillin, amoxicillin/clavulanic acid, ceftazidime, ciprofloxacin, trimethoprim/sulphamethoxazole and colistin but remained susceptible to ceftriaxone, ticarcillin, ticarcillin/clavulanic acid, imipenem, amikacin, tobramycin, gentamicin, isepamicin, rifampicin, and piperacillin/tazobactam. The
O. anthropi was resistant to amoxicillin, amoxicillin/clavulanic acid, ticarcillin, ticarcillin/clavulanic acid, ceftazidime, ceftriaxone, piperacillin/tazobactam and colistin but remained susceptible to ciprofloxacin, imipenem, amikacin, tobramycin, gentamicin, isepamicin, trimethoprim/sulphamethoxazole and rifampicin. The patient was initially treated with ceftazidime (2 g 4 times/day) and nebulized tobramycin (300 mg/day) for 2 weeks. The treatment was switched to intravenous imipenem (4 g/day) and tobramycin (320 mg/day) for 2 weeks with dramatic improvement. Two weeks later, the patient was clinically well and sputum culture yielded a mixed oral population.
B. diminuta and
O. anthropi were not cultured again in 5 sputa investigated during 7 months of follow-up.