From the Guidelines
Cephalexin can be effective against E. coli, but its use should be guided by local resistance patterns and culture and sensitivity testing, especially in complicated infections or areas with high resistance rates. Cephalexin is a first-generation cephalosporin antibiotic that works by inhibiting bacterial cell wall synthesis. For uncomplicated urinary tract infections caused by susceptible E. coli strains, the typical adult dosage is 500 mg orally every 6 hours or 1 gram every 12 hours for 7-14 days, depending on infection severity [ 1 ]. However, resistance to cephalexin among E. coli has been increasing in many regions, with some strains producing extended-spectrum beta-lactamases (ESBLs) that render the medication ineffective [ 1 ].
Some key points to consider when using cephalexin to treat E. coli infections include:
- Local resistance patterns should be taken into account when selecting an antibiotic [ 1 ]
- Culture and sensitivity testing is often recommended before treatment, especially for complicated infections or in areas with high resistance rates [ 1 ]
- Alternative antibiotics may be necessary if the infection involves resistant E. coli strains or if the infection is in a site where cephalexin doesn't achieve adequate concentrations [ 1 ]
- The typical dosage for children is 25-50 mg/kg/day divided into four doses [ 1 ]
It's also important to note that the use of cephalexin to treat asymptomatic bacteriuria in patients with long-term indwelling catheters is not recommended, as it can lead to the emergence of antimicrobial resistance [ 1 ]. In general, the use of cephalexin to treat E. coli infections should be guided by the most recent and highest quality evidence, and should take into account local resistance patterns and the specific clinical context.
From the FDA Drug Label
Aerobes, Gram-negative: Escherichia coli Genitourinary tract infections, including acute prostatitis, caused by Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae
Cephalexin covers E. Coli. It is active against most strains of Escherichia coli and is indicated for the treatment of genitourinary tract infections caused by E. Coli 2 2.
From the Research
Cephalexin Coverage for E. Coli
- Cephalexin is a commonly prescribed antibiotic for urinary tract infections (UTIs) [(3,4,5)].
- Studies have shown that cephalexin has good coverage against E. coli, with susceptibility rates ranging from 91% to 97% [(3,4,5)].
- A study published in 2023 found that cephalexin was effective in treating UTIs caused by E. coli, with a treatment failure rate of 12.7% 3.
- Another study published in 2021 found that cephalexin was prescribed empirically for 53.4% of patients with acute uncomplicated cystitis, and that E. coli was susceptible to cephalexin in 97% of cases 4.
- The susceptibility of E. coli to cephalexin is also supported by a review published in 2020, which concluded that cephalexin has very good early bacteriological and clinical cures in UTIs due to non-extended-spectrum beta-lactamase-producing (ESBL) Enterobacteriaceae 5.
Comparison with Other Antibiotics
- Cephalexin has been compared to other antibiotics, such as nitrofurantoin and ciprofloxacin, in terms of its effectiveness against E. coli [(6,7)].
- A study published in 2008 found that nitrofurantoin had a higher susceptibility rate against E. coli (95.6%) compared to ciprofloxacin (75.6%) 6.
- Another study published in 2014 found that fosfomycin, nitrofurantoin, and temocillin had excellent susceptibility profiles against E. coli, with susceptibility rates ranging from 96.8% to 100% 7.
Clinical Implications
- The effectiveness of cephalexin against E. coli makes it a viable treatment option for UTIs [(3,4,5)].
- Clinicians should consider cephalexin as a fluoroquinolone-sparing alternative for the treatment of UTIs 5.
- The choice of antibiotic should be guided by local resistance patterns and susceptibility testing [(4,5)].