Persistence of L. pneumophila in monospecies biofilms formed by K. pneumoniae, Flavobacterium sp., P. aeruginosa, or P. fluorescens.

A base biofilm of either K. pneumoniae strain DMDS 92-08-28a (□) (A), Flavobacterium sp. strain CDC-65 (Δ) (B), P. aeruginosa ATCC strain 7700 (◊) (C), or P. fluorescens ATCC strain 17569 (Δ) (D) pre-formed on stainless steel coupons was exposed to L. pneumophila strain 130b (▪) on day 3 and flow of 1∶100 R2A began at 1–2 ml/min. Each data point represents the averages and standard deviations of CFU obtained from the coupons within a single rod. The experiments shown are representative of four experiments for (A) and at least two for (B–D). In a repeat of the experiment using P. aeruginosa base biofilms, no legionellae were recovered at the initial sampling point.