From the Guidelines
For a patient with a sulfa allergy and bacteria resistant to nitrofurantoin, beta-lactam antibiotics like amoxicillin-clavulanate (875/125 mg twice daily for 5-7 days) or cephalexin (500 mg four times daily for 5-7 days) are appropriate antibiotic options, as fluoroquinolones may have a propensity for collateral damage and should be reserved for important uses other than acute cystitis 1. When considering treatment options, it's essential to take into account the patient's allergy to sulfa and the resistance pattern of the bacteria. Given the sulfa allergy, trimethoprim-sulfamethoxazole is not a suitable option. Nitrofurantoin is also not effective due to bacterial resistance.
- Beta-lactam antibiotics, such as amoxicillin-clavulanate or cephalexin, can be used as alternative treatments, despite having inferior efficacy and more adverse effects compared to other UTI antimicrobials 1.
- Fluoroquinolones, like ciprofloxacin or levofloxacin, are highly efficacious but should be reserved for important uses other than acute cystitis due to their propensity for collateral damage 1.
- Fosfomycin trometamol (3 g in a single dose) is another option, but its efficacy is inferior compared to standard short-course regimens 1.
- Pivmecillinam (400 mg bid for 3–7 days) can be considered in regions where it is available, but its efficacy may also be inferior compared to other available therapies 1. It's crucial to obtain culture and sensitivity results to guide targeted therapy, especially in cases of resistant organisms, and to complete the full course of antibiotics even if symptoms improve before completion. Treatment duration may need to be extended for complicated infections. The choice of antibiotic should be guided by the infection site, bacterial susceptibility patterns, and patient factors, as well as the potential for adverse effects and the propensity for collateral damage 1.
From the FDA Drug Label
The mechanism of action of levofloxacin and other fluoroquinolone antimicrobials involves inhibition of bacterial topoisomerase IV and DNA gyrase (both of which are type II topoisomerases), enzymes required for DNA replication, transcription, repair and recombination Fluoroquinolones, including levofloxacin, differ in chemical structure and mode of action from aminoglycosides, macrolides and β-lactam antibiotics, including penicillins Fluoroquinolones may, therefore, be active against bacteria resistant to these antimicrobials.
Levofloxacin can be used to treat a patient with a sulfa allergy and bacteria resistant to nitrofurantoin, as it has a different mechanism of action and may be active against bacteria resistant to other antimicrobials 2.
- Key points:
- Levofloxacin is a fluoroquinolone antimicrobial agent
- It has a different mechanism of action than other antibiotics, such as penicillins and macrolides
- It may be active against bacteria resistant to other antimicrobials
- It does not contain sulfa, making it a potential option for patients with a sulfa allergy.
From the Research
Antibiotic Treatment Options
For a patient with a sulfa allergy and bacteria resistant to nitrofurantoin, several alternative antibiotic treatment options can be considered:
- Fosfomycin tromethamine: a 3-g single dose is recommended as a first-line empiric antibiotic therapy for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females 3
- Pivmecillinam: a 5-day course is recommended as a first-line empiric antibiotic therapy for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females 3
- Oral cephalosporins: such as cephalexin or cefixime, can be used as second-line options 3
- Fluoroquinolones: can be used as second-line options, but their use may be limited due to high rates of resistance 3
- β-lactams: such as amoxicillin-clavulanate, can be used as second-line options 3
Considerations for Patients with Sulfa Allergy
For patients with a sulfa allergy, trimethoprim-sulfamethoxazole (TMP-SMX) should be avoided due to the risk of cross-reactivity 4, 5. Nitrofurantoin may also be contraindicated in some cases, as 16% of women with RUTIs were allergic to nitrofurantoin in one study 5.
Resistance Patterns
Bacteria resistant to nitrofurantoin may also be resistant to other antibiotics, such as fluoroquinolones and TMP-SMX 3, 5. Therefore, it is essential to consider the local susceptibility patterns and the patient's allergy history when selecting an antibiotic treatment option.
Treatment of UTIs Caused by Resistant Bacteria
For UTIs caused by resistant bacteria, such as ESBL-producing Enterobacteriales, carbapenem-resistant Enterobacteriales, or multidrug-resistant Pseudomonas spp., alternative treatment options may include:
- Piperacillin-tazobactam
- Carbapenems, such as meropenem/vaborbactam or imipenem/cilastatin-relebactam
- Ceftazidime-avibactam
- Fosfomycin
- Aminoglycosides, such as plazomicin
- Cefiderocol 3