What is a good antibiotic for Urinary Tract Infection (UTI) and cellulitis?

From the Guidelines

For both urinary tract infections (UTIs) and cellulitis, the most effective antibiotic choice is often a fluoroquinolone like ciprofloxacin or levofloxacin, but for uncomplicated UTIs, nitrofurantoin (100mg twice daily for 5 days) or trimethoprim-sulfamethoxazole (160/800mg twice daily for 3 days) are recommended as first-line treatments, as per the latest guidelines from the American College of Physicians 1.

Key Considerations for UTI Treatment

• The choice of antibiotic should be based on the severity of the infection, patient allergies, and local resistance patterns.
• Nitrofurantoin and trimethoprim-sulfamethoxazole are preferred for uncomplicated UTIs due to their efficacy and minimal resistance rates, as supported by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases guidelines 1.
• Fluoroquinolones, such as ciprofloxacin or levofloxacin, are highly efficacious but should be reserved for more complex cases or when other options are not suitable due to their potential for adverse effects and resistance development 1.

Cellulitis Treatment Considerations

• For cellulitis, antibiotics that target skin bacteria like Staphylococcus and Streptococcus, such as cephalexin (500mg four times daily for 5-10 days) or dicloxacillin (500mg four times daily for 5-10 days), are commonly prescribed.
• The treatment of cellulitis should be tailored to the severity of the infection and the patient's specific needs, with consideration of local resistance patterns.

General Principles

• Completing the full course of antibiotics is crucial, even if symptoms improve, to ensure the infection is fully cleared.
• Drinking plenty of water can help with UTIs, while elevating the affected area can reduce swelling from cellulitis.
• Proper medical diagnosis is essential before starting treatment, as antibiotic selection should be based on the specific infection and patient factors, as emphasized by the best practice advice from the American College of Physicians 1.

From the FDA Drug Label

To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim tablets and other antibacterial drugs, sulfamethoxazole and trimethoprim tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. Urinary Tract Infections For the treatment of urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis and Proteus vulgaris CLINICAL STUDIES Complicated Urinary Tract Infection and Pyelonephritis – Efficacy in Pediatric Patients: Ciprofloxacin, administered I. V. and/or orally, was compared to a cephalosporin for treatment of complicated urinary tract infections (cUTI) and pyelonephritis in pediatric patients 1 to 17 years of age

Good antibiotics for UTI:

• Trimethoprim-sulfamethoxazole (PO) is effective against susceptible strains of Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris 2
• Ciprofloxacin (PO) is effective against complicated urinary tract infections and pyelonephritis in pediatric patients 3

Good antibiotics for Cellulitis:

• There is no information in the provided drug labels that directly supports the use of these antibiotics for cellulitis.

The FDA drug label does not answer the question about cellulitis.

From the Research

Antibiotic Options for UTI and Cellulitis

• For urinary tract infections (UTIs), the recommended first-line empiric antibiotic therapy includes a 5-day course of nitrofurantoin, a 3-g single dose of fosfomycin tromethamine, or a 5-day course of pivmecillinam 4.
• Second-line options for UTIs include oral cephalosporins such as cephalexin or cefixime, fluoroquinolones, and β-lactams, such as amoxicillin-clavulanate 4.
• For cellulitis, cephalexin plus trimethoprim-sulfamethoxazole or cephalexin alone may be used, with no significant difference in clinical cure rates between the two treatments 5.
• The route of antibiotic administration (oral or intravenous) does not appear to affect clinical outcome for patients with cellulitis of similar severity 6.

Treatment Considerations

• The choice of antibiotic for UTI or cellulitis should be based on local susceptibility patterns and the severity of the infection 4, 7.
• The duration of antibiotic therapy for cellulitis does not appear to affect clinical outcome, with no additional benefit seen with courses longer than 5 days 6.
• Amoxicillin-clavulanate may be a useful alternative therapy for the treatment of ceftriaxone non-susceptible Enterobacterales UTIs 8.

Resistance and Treatment

• The rise of resistant isolates has prompted evaluation of alternative therapies for UTIs and cellulitis 4, 8.
• The use of new antimicrobials should be done wisely to avoid resistance development 4.
• Treatment options for UTIs caused by multidrug-resistant organisms include fluoroquinolones, ceftazidime, cefepime, piperacillin-tazobactam, and carbapenems 4.