Is doxycycline (Doxycycline) a suitable treatment for a urinary tract infection with Escherichia (E. coli) producing Extended-Spectrum Beta-Lactamases (ESBL) that is sensitive to tetracyclines?

From the Guidelines

Doxycycline is not the optimal treatment for a urinary tract infection caused by ESBL-producing bacteria, despite showing sensitivity to tetracyclines in vitro. While doxycycline may appear as an option based on susceptibility testing, it achieves poor urinary concentrations and is not recommended as first-line therapy for complicated UTIs 1. For ESBL-producing organisms, carbapenems (like meropenem or ertapenem) remain the treatment of choice. If carbapenem use is not possible, fosfomycin, nitrofurantoin (for uncomplicated lower UTIs only), or an aminoglycoside might be considered based on susceptibility results. The duration of treatment typically ranges from 7-14 days depending on infection severity. The disconnect between in vitro susceptibility and clinical efficacy occurs because doxycycline is primarily eliminated through non-renal routes and doesn't concentrate well in urine, making it pharmacokinetically unsuitable for urinary tract infections despite laboratory sensitivity results.

Some key points to consider in the treatment of UTIs caused by ESBL-producing bacteria include:

• The importance of choosing an antibiotic that achieves adequate urinary concentrations, such as carbapenems or fosfomycin 1
• The need to consider local resistance patterns and susceptibility results when selecting an antibiotic 1
• The potential for doxycycline to be ineffective in treating UTIs despite in vitro sensitivity, due to its pharmacokinetic properties 1
• The importance of monitoring for signs of treatment failure and adjusting the antibiotic regimen as needed 1

In terms of specific treatment options, carbapenems are generally considered the first-line treatment for UTIs caused by ESBL-producing bacteria, due to their broad spectrum of activity and high efficacy 1. Fosfomycin and nitrofurantoin may also be considered in certain cases, although their use may be limited by resistance patterns and other factors 1. Aminoglycosides may also be used in combination with other antibiotics, although their use is often limited by toxicity concerns 1.

Overall, the treatment of UTIs caused by ESBL-producing bacteria requires careful consideration of the antibiotic regimen and close monitoring for signs of treatment failure. The use of doxycycline is not recommended as a first-line treatment option, due to its poor urinary concentrations and potential for treatment failure.

From the FDA Drug Label

Doxycycline is indicated for treatment of infections caused by the following gram- negative microorganisms, when bacteriologic testing indicates appropriate susceptibility to the drug: Escherichia coli. Because many strains of the following groups of microorganisms have been shown to be resistant to doxycycline, culture and susceptibility testing are recommended When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy.

Doxycycline may be a good treatment option for the urine culture that grew Kendall’s pna cre ESBL and showed sensitivity to tetracyclines, since the drug label indicates that doxycycline is effective against Escherichia coli when bacteriologic testing shows susceptibility to the drug 2. However, it is essential to consider the culture and susceptibility information and the fact that many strains of microorganisms have shown resistance to doxycycline.

• The key points to consider are:
  • Bacteriologic testing indicates susceptibility to doxycycline
  • Escherichia coli is a gram-negative microorganism that doxycycline is effective against
  • Resistance to doxycycline is possible, and culture and susceptibility testing are recommended.

From the Research

Treatment of Urinary Tract Infections with Doxycycline

• Doxycycline can be an effective treatment option for patients with susceptible multidrug-resistant (MDR) urinary tract infections (UTIs) 3.
• The advantages of doxycycline for UTI include its oral formulation, wide spectrum of activity, ability to achieve high concentration in the urine, and low toxicity 3.
• Doxycycline has a long half-life, which makes convenient twice-a-day dosing possible, and it is well absorbed orally even in the presence of food 4.
• Doxycycline displays excellent activity against gram-positive and gram-negative aerobic and anaerobic pathogens, and its tissue penetration is excellent 5.

Sensitivity to Tetracyclines

• If the urine culture shows sensitivity to tetracyclines, doxycycline may be a good treatment option 3.
• Doxycycline remains the preferred tetracycline agent for most indications, including UTIs 4.
• The oral absorption of doxycycline is rapid and virtually complete, and serum concentrations of doxycycline following oral administration are comparable to those following intravenous administration 5.

Clinical Use of Doxycycline

• Doxycycline has been shown to be highly effective in infections of the respiratory tract, skin and soft tissue, genitourinary infection, and intraabdominal infection 5.
• Doxycycline is also effective in the prevention of traveler's diarrhea 5.
• In dermatology, doxycycline is commonly used for the treatment of acne vulgaris, with a long overall favorable track record of effectiveness and safety 6.