Escherichia coli lobar pneumonia: fatal infection in a patient with mental retardation.

Lobar pneumonia due to Escherichia coli is rare. Most lobar pneumonias are caused by either Streptococcus pneumoniae or Klebsiella pneumoniae, and most E coli pneumonias are bronchopneumonias. We report an acute fulminant course of E coli lobar pneumonia in a 37-year-old patient who was profoundly retarded, institutionalized, and nonimmunosuppressed and who died within 2 days of developing initial symptoms. Antemortem blood and postmortem blood and lung specimens isolated pure cultures of E coli. The source of infection in E coli lobar pneumonia is not clear in this patient or in the few cases that have been reported. We postulate that nasopharyngeal colonization of E coli in those who are institutionalized with mental retardation may predispose these patients to E coli pneumonia. Our case illustrates features of pneumonias that are unique in the institutionalized, mentally retarded patient population (ie, the relatively high prevalence of nasopharyngeal colonization of E coli, a higher incidence of E coli pneumonia than in other institutionalized populations, the often fulminant course of the disease), as well as the need for early, aggressive treatment including antibiotics effective against gram-negative bacteria.