From the Guidelines
For adults with bacterial infections, the first-line antibiotic therapy should be amoxicillin 1 g three times daily, as it is a strong recommendation with moderate quality of evidence, according to the American Thoracic Society and Infectious Diseases Society of America guidelines 1. When considering the treatment of bacterial infections in adults, it is essential to take into account the patient's comorbidities, risk factors for antibiotic-resistant pathogens, and local resistance patterns.
- For healthy outpatient adults without comorbidities or risk factors, amoxicillin 1 g three times daily is recommended, as well as doxycycline 100 mg twice daily or a macrolide in areas with high pneumococcal resistance to macrolides 1.
- For outpatient adults with comorbidities, combination therapy with amoxicillin/clavulanate and a macrolide or doxycycline is recommended, as well as monotherapy with a respiratory fluoroquinolone, such as levofloxacin 750 mg daily 1. The choice of antibiotic should prioritize effectiveness against the most likely pathogens while minimizing collateral damage to normal flora and reducing the risk of developing antibiotic resistance.
- Patient allergies, pregnancy status, and kidney function should also be considered when selecting an antibiotic.
- Local resistance patterns should be taken into account to ensure the chosen antibiotic is effective against the most common pathogens in the area. It is crucial to note that the guidelines provide recommendations for specific patient populations and infection types, and the choice of antibiotic should be tailored to the individual patient's needs and circumstances, as supported by the American Thoracic Society and Infectious Diseases Society of America guidelines 1.
From the FDA Drug Label
To reduce the development of drug-resistant bacteria and maintain the effectiveness of levofloxacin tablets and other antibacterial drugs, levofloxacin tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria Levofloxacin tablets are indicated for the treatment of adults (≥ 18 years of age) with mild, moderate, and severe infections caused by susceptible isolates of the designated microorganisms in the conditions listed in this section Patients should be counseled that antibacterial drugs, including amoxicillin and clavulanate potassium tablets, should only be used to treat bacterial infections.
The first-line antibiotic therapy for adults with bacterial infections is not explicitly stated in the provided drug labels. However, levofloxacin and amoxicillin-clavulanate are indicated for the treatment of various bacterial infections in adults, including:
- Nosocomial pneumonia
- Community-acquired pneumonia
- Acute bacterial sinusitis
- Acute bacterial exacerbation of chronic bronchitis
- Complicated skin and skin structure infections It is essential to note that the choice of antibiotic therapy should be based on the specific type of infection, the causative organism, and local susceptibility patterns 2, 3.
From the Research
First-Line Antibiotic Therapy for Adults with Bacterial Infections
The first-line antibiotic therapy for adults with bacterial infections varies depending on the type of infection and the causative pathogen.
- For community-acquired pneumonia (CAP), the recommended first-line empiric antibiotic therapy includes:
- A macrolide (e.g., erythromycin, clarithromycin, azithromycin) for outpatient treatment 4, 5
- An intravenous beta-lactam (e.g., cefuroxime, ceftriaxone, cefotaxime) plus a macrolide for inpatient treatment 5
- A fluoroquinolone with improved activity against Streptococcus pneumoniae (e.g., levofloxacin) for adults with CAP, especially for those with a documented infection with highly drug-resistant pneumococci 6, 7, 5
- 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 for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females 8
Considerations for Antibiotic Resistance
- The growing problem of antimicrobial resistance, particularly an increase in macrolide-resistant pneumococcal bacteremia, requires physicians to adopt new approaches to the treatment of CAP 6
- The use of fluoroquinolones should be limited to adults for whom one of the above regimens has already failed, who are allergic to alternative agents, or who have a documented infection with highly drug-resistant pneumococci 5
- The combination of a third-generation cephalosporin and a macrolide may be preferred over fluoroquinolones as first-line therapy of hospitalized patients with CAP to minimize the development of multiresistant nosocomial Gram-negative bacilli 7