First case report of sepsis caused by Rhizobium pusense in Japan.

INTRODUCTION: Species of the genus Rhizobium are opportunistic, usually saprophytic, glucose-non-fermenting, Gram-negative bacilli found in agricultural soil. Rhizobium pusense infections are the least common Rhizobium infections and have low incidence. CASE PRESENTATION: Herein, we report the first case of sepsis with R. pusense in Japan in a 67-year-old Japanese woman with a history of hyperlipidaemia, hypertension, diabetes, hypothyroidism and osteoporosis. She had undergone cerebrovascular treatment because she was diagnosed with a subarachnoid haemorrhage. The results of postoperative blood culture showed oxidase-positive, urease-positive, non-lactose-fermenting Gram-stain-negative rods. Using the Vitek2 system, the isolate was distinctly identified as Rhizobium radiobacter. However, 16S rRNA gene sequencing showed 99.93 % similarity with the type strain of R. pusense and 99.06 % similarity with the type strain of R. radiobacter. Additional gene sequencing analysis using recA (97.2 %) and atpD (96.2 %) also showed that the isolated strain is most closely related to R. pusense. The patient was cured by treatment using intravenous meropenem (3 g/d) for 4 weeks and was discharged safely. CONCLUSION: The definite source of sepsis was unknown. However, the possibility of having been infected through the catheter during the cerebrovascular operation was speculated.

First case report of pulmonary nocardiosis caused by Nocardia mexicana.

INTRODUCTION: Nocardia species usually cause opportunistic infections, and the frequency of these infections is increasing owing to the growing population of immunocompromised hosts. However, Nocardia species may sometimes cause an infection disease in immunocompetent hosts. Nocardia mexicana infections are the least common and are very rare. CASE PRESENTATION: Herein, we report the first case of a pulmonary infection with N. mexicana in a 61-year-old Japanese woman with a history of hyperlipidaemia and bronchiectasis and a 6-month history of non-productive hacking cough. A sample of bronchial lavage fluid obtained by bronchofiberscopy showed filamentous branching gram-positive rods and acid-fast filamentous branching rods, and a colony of suspected Nocardia was cultured. Based on 16S rRNA, gyrB,rpoB, secA1 and hsp65 gene sequence analyses and biochemical and physiological properties, the strain was identified as N. mexicana. The strain was resistant to the antimicrobial agents amoxicillin-clavulanic acid, clarithromycin, minocycline, gentamycin, tobramycin, ciprofloxacin and trimethoprim-sulfamethoxazole. The patient was treated with biapenem followed by intravenous amikacin and oral linezolid. CONCLUSION: Despite its rarity, the species require attention owing to the existence of multidrug-resistant strains.