A case of lower respiratory tract infection caused by Neisseria weaveri and review of the literature.

Neisseria weaveri (formerly CDC [Centers for Disease Control and Prevention] group M-5 is part of the normal canine oral flora. Infections in humans are usually associated with dog bite wounds. Very rarely the organism has been isolated from sites other than wounds, or from deep seated infections. A 60-year-old man was admitted to our hospital because of an acute exacerbation of his bronchiectasis. Gram stain of bronchial washings and expectorated sputum showed numerous polymorphs and Gram-negative bacilli. Routine bacterial culture yielded a heavy pure growth of a Gram-negative rod-shaped organism that was strongly oxidase and catalase positive, indole negative, non-motile and did not ferment carbohydrates. The organism was identified as N. weaveri by using 16S rRNA sequencing. The patient was treated with a 3 weeks course of ofloxacin and had a good response. Sputum culture after treatment yielded normal respiratory flora only. To our knowledge, this is the first reported case of lower respiratory tract infection caused by N. weaveri.