Escherichia coli
MICROBIOLOGY
- Aerobic, Gram-negative (GN) rod, E. coli is a member of Enterobacteriaceae: human strains may be: (1) commensal bowel flora; (2) intestinal pathogenic (enteric/diarrheagenic); (3) extra-intestinal pathogenic.
- The predominant Gram-negative in the composition of normal human colonic flora.
- Motile, flagellated, non-spore-forming.
- Upon Gram staining, they tend to be plump rods [Fig]
- The predominant Gram-negative in the composition of normal human colonic flora.
- E. coli is easy to grow from sterile specimens.
- Stool cx: only if severe diarrhea (may need reference lab to ID) or suspect O157:H7 (cx all bloody diarrhea) use sorbitol-MacConkey agar or perform Shiga toxin EIA.
- ~ 90% of strains ferment lactose (i.e., lactose-fermenter, D-glucose fermentation produces mixed acids that trigger an indicator such as methyl red)
- Some diarrheagenic E. coli strains, including many of the EIEC strains, are typically lactose-negative.
- Indole testing in all E. coli ~ 99% (+).
- Catalase positive, oxidase negative.
- Major resistance concerns:
- Plasmid-mediated AmpC β-lactamases (e.g., CMY)
- Extended-spectrum β-lactamases (e.g., CTX-M, TEM and SHV β-lactamases)
- A worldwide concern, including community-acquired UTIs and also bloodstream infections
- In some Asian countries, rates of ESBL E. coli have been reported to be as high as 55-79%.
- Rates are lower in North America but rising.
- Most labs judge the presence of ESBL through ceftriaxone non-susceptibility, MIC ≥2 μg/mL.
- A worldwide concern, including community-acquired UTIs and also bloodstream infections
- Carbapenemases (e.g., New Delhi metallo-β-lactamase, Klebsiella pneumonaie carbapenemase and OXA-48)
- Less common than ESBL.
There's more to see -- the rest of this topic is available only to subscribers.
Last updated: September 8, 2024
Citation
Auwaerter, Paul. "Escherichia Coli." Johns Hopkins ABX Guide, The Johns Hopkins University, 2024. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540214/2/Escherichia_coli.
Auwaerter P. Escherichia coli. Johns Hopkins ABX Guide. The Johns Hopkins University; 2024. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540214/2/Escherichia_coli. Accessed December 12, 2024.
Auwaerter, P. (2024). Escherichia coli. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540214/2/Escherichia_coli
Auwaerter P. Escherichia Coli [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2024. [cited 2024 December 12]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540214/2/Escherichia_coli.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Escherichia coli
ID - 540214
A1 - Auwaerter,Paul,M.D.
Y1 - 2024/09/08/
BT - Johns Hopkins ABX Guide
UR - https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540214/2/Escherichia_coli
PB - The Johns Hopkins University
DB - Pediatrics Central
DP - Unbound Medicine
ER -