Aberrant Forms of Escherichia coli in Urine Culture

Bacterial morphology can be altered by various factors, including antibiotics. Unusually shaped, large, swollen organisms were observed in a urine culture obtained from a patient who had no history of antibiotic therapy. The organism was identified as Escherichia coli by the Vitek 2 system and by DNA sequencing of 16S rRNA and gyrB. The patient had no symptoms except fever, which subsided without medication. Microbiology laboratories should be aware of the potential appearance of such bacilli to avoid confusion with fungi and other naturally occurring filamentous organisms. (Korean J Clin Microbiol 2010;13:128-131)