Bacteraemic pneumonia caused by Neisseria lactamica with reduced susceptibility to penicillin and ciprofloxacin in an adult with liver cirrhosis

Introduction

Neisseria lactamica is a commensal species colonizing the human upper respiratory tract, and it shares this ecological niche with Neisseria meningitidis (Kremastinou et al., 2003; Saez-Nieto et al., 1985). It frequently colonizes the nasopharynx of young children (Kremastinou et al., 2003; Saez-Nieto et al., 1985). N. lactamica exhibits a higher possibility of colonization in young children than does N. meningitidis, passing more easily from child to child, with a shorter duration of carriage (Kremastinou et al., 2003; Saez-Nieto et al., 1985; Alber et al., 2001). Previous reports of infections (meningitis, bacteraemia and otitis media) caused by N. lactamica have almost exclusively been in young children. The only previous report involving an adult was in a patient who developed meningitis following a skull trauma (Denning & Gill, 1991). None of these infections was caused by isolates with reduced susceptibility to penicillin. To our knowledge, this is the first report of an adult patient with community-acquired pneumonia and bacteraemia due to a penicillin-resistant N. lactamica strain.