kjcm Korean Journal of Clinical Microbiology Korean J Clin Microbiol 1229-0025 Korean Journal of Clinical Microbiology 10.5145/KJCM.2010.13.3.128 kjcm-13-128 Original Article Aberrant Forms of Escherichia coli in Urine Culture Ma Youngeun Lee Jang Ho Lee Seung-Tae Ki Chang-Seok Lee Nam Yong Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea Correspondence: Nam Yong Lee, Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Korea. (Tel) 82-2-3410-2706, (Fax) 82-2-3410-2719, (E-mail) mi-cro.lee@samsung.com 92010 2192010 133 128131 07022010 13072010 20082010 Copyright © 2010 Korean Journal of Clinical Microbiology 2010 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract

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.

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(A) Small, dry and purple colonies in MacConkey agar plate, 2 days, (B) Comparison with E. coli ATCC 25922, in MacConkey agar plate, 2 days (left: E. coli ATCC 25922).

Unusual shaped large, swollen organisms resembling fungus spore were mixed with a few normal sized bacilli. Long bacilli, filamentous form and elongated bacilli with bulge were also seen (Gram stain, ×1,000).

The organism reverted to normal Gram-negative bacilli. But, some are still larger than normal E. coli (Gram stain, ×1,000).