Pseudomonas aeruginosa is an opportunistic pathogen often associated with chronic lung infections in individuals with the genetic disease cystic fibrosis (CF). Previous work from our laboratory revealed that five genes predicted to be important for catabolism of N-acetylglucosamine (GlcNAc) are induced during in vitro growth in CF lung secretions (sputum). Here, we demonstrate that these genes comprise an operon (referred to as the nag operon) and that NagE, a putative component of the GlcNAc phosphotransferase system, is required for growth on and uptake of GlcNAc. Using primer extension analysis, the promoter of the nag operon was mapped and shown to be inducible by GlcNAc and regulated by the transcriptional regulator NagR. Transcriptome analysis revealed that in addition to induction of the nag operon, several P. aeruginosa genes encoding factors critical for extracellular antimicrobial production are also induced by GlcNAc. Finally, we show that the GlcNAc-containing polymer peptidoglycan induces production of the antimicrobial pyocyanin. Based on this data, we propose a model in which P. aeruginosa senses surrounding bacteria by monitoring exogenous peptidoglycan and responds to this cue through enhanced production of an antimicrobial.