Treatment for E. coli Infections
The treatment for Escherichia coli infections should be tailored to the specific type of infection, with antimicrobial selection guided by the site of infection, severity, and local resistance patterns. 1
Treatment Based on Infection Type
Gastrointestinal E. coli Infections
- For enterotoxigenic E. coli (ETEC): Trimethoprim-sulfamethoxazole (TMP-SMZ) 160/800 mg twice daily for 3 days (if susceptible) or fluoroquinolones such as ciprofloxacin 500 mg twice daily for 3 days 2
- For enteropathogenic E. coli (EPEC): Similar treatment as ETEC with TMP-SMZ or fluoroquinolones 2
- For enteroinvasive E. coli (EIEC): TMP-SMZ or fluoroquinolones for 3 days 2
- For enteroaggregative E. coli (EAEC): Consider fluoroquinolone treatment, though optimal therapy is not well established 2
- For enterohemorrhagic E. coli (EHEC/STEC): Antibiotics should be avoided as they may increase the risk of hemolytic uremic syndrome (HUS) 2, 1, 3
- For traveler's diarrhea caused by noninvasive E. coli: Rifaximin 200 mg three times daily for 3 days 4
Urinary Tract Infections
- For uncomplicated UTIs: TMP-SMZ 160/800 mg twice daily for 3 days if local resistance is <20% 1
- For pyelonephritis: Fluoroquinolones for 7 days if local resistance is <10% 1
- For hospitalized patients with pyelonephritis: Initial IV therapy with fluoroquinolones, aminoglycosides, extended-spectrum cephalosporins, or carbapenems 1
Severe/Invasive Infections
- For bacteremia or severe infections: Extended-spectrum penicillin or extended-spectrum cephalosporin combined with an aminoglycoside for at least 6 weeks 1
- For non-typhi Salmonella: Not routinely recommended, but if severe or patient is <6 months or >50 years old or has prostheses, valvular heart disease, severe atherosclerosis, malignancy, or uremia, TMP-SMZ (if susceptible) or fluoroquinolone for 5-7 days 2
Special Considerations
Antimicrobial Resistance
- Local antimicrobial susceptibility patterns should guide empiric therapy, as E. coli resistance varies considerably between regions 1
- Resistance rates >20% are common for ampicillin and TMP-SMZ in many regions 1
- If there is significant resistance (10-20% of isolates) to an antimicrobial regimen in local use, routine culture and susceptibility studies should be obtained 2
Pediatric Considerations
- Fluoroquinolones may be justified in special circumstances after careful assessment of risks and benefits 2
- Appropriate pediatric uses include: urinary tract infections caused by multidrug-resistant bacteria, chronic suppurative otitis media caused by P. aeruginosa, and Gram-negative bacterial infections in immunocompromised hosts 2
Treatment Duration
- Uncomplicated UTIs: 3 days 1
- Pyelonephritis: 7-14 days 1
- Bacteremia or severe infections: Minimum of 6 weeks 1
- Traveler's diarrhea: 3 days 4
Common Pitfalls and Caveats
- Using antibiotics for EHEC/STEC infections may worsen outcomes by increasing Shiga toxin production 2, 1
- Failure to obtain appropriate cultures before starting antibiotics can lead to suboptimal therapy 1
- For severe infections, combination therapy is recommended until susceptibility results are available 1
- Increasing antimicrobial resistance necessitates knowledge of local susceptibility patterns 1, 5
- Aminoglycoside-containing regimens have been a cornerstone of antimicrobial therapy for enterococcal IE but should be used cautiously in elderly or debilitated patients due to nephrotoxicity 2