What antibiotics are effective against bacterial versus viral infections?

From the Guidelines

Antibiotics are only effective against bacterial infections, and their use in viral infections is not only ineffective but also contributes to antibiotic resistance, making it crucial to differentiate between bacterial and viral causes of infections. When it comes to treating bacterial infections, common antibiotics such as amoxicillin, azithromycin, and ciprofloxacin are used, with dosages and durations varying based on the specific infection and patient factors 1. For instance, for bacterial infections like strep throat, urinary tract infections, or bacterial pneumonia, antibiotics work by killing bacteria or preventing their reproduction. On the other hand, viral infections such as the common cold, flu, or COVID-19 do not respond to antibiotics, and treatment typically focuses on managing symptoms with rest, fluids, and over-the-counter medications like acetaminophen or ibuprofen 1. Some viral infections may be treated with specific antiviral medications when appropriate, such as oseltamivir for influenza A and B 1. It's essential to get a proper diagnosis from a healthcare provider before taking antibiotics, as inappropriate use leads to antibiotic resistance, making serious infections harder to treat in the future 1. Key points to consider include:

• The importance of differentiating between bacterial and viral infections to ensure appropriate treatment and minimize antibiotic resistance.
• The use of clinical signs and symptoms to guide the diagnosis of bacterial infections, such as the presence of fever, purulent nasal discharge, or facial pain in acute rhinosinusitis 1.
• The role of supportive care, including analgesics, antipyretics, and symptomatic relief measures, in managing viral infections and reducing the need for antibiotics 1.
• The need for healthcare providers to reserve antibiotic treatment for patients with clear indications of bacterial infection, such as persistent symptoms or severe disease, and to avoid unnecessary antibiotic use in viral infections 1.

From the FDA Drug Label

Amoxicillin for oral suspension is indicated in the treatment of infections due to susceptible (ONLY β-lactamase–negative) isolates of Streptococcusspecies. (α-and β-hemolytic isolates only), Streptococcus pneumoniae, Staphylococcusspp., or Haemophilus influenzae. Amoxicillin for oral suspension is indicated in the treatment of infections due to susceptible (ONLY β-lactamase–negative) isolates of Escherichia coli, Proteus mirabilis, or Enterococcus faecalis To reduce the development of drug-resistant bacteria and maintain the effectiveness of amoxicillin and other antibacterial drugs, amoxicillin should be used only to treat infections that are proven or strongly suspected to be caused by bacteria

• Amoxicillin is effective against bacterial infections, including those caused by:
  • Streptococcus species
  • Streptococcus pneumoniae
  • Staphylococcus species
  • Haemophilus influenzae
  • Escherichia coli
  • Proteus mirabilis
  • Enterococcus faecalis
• It is not effective against viral infections, as it should only be used to treat infections proven or strongly suspected to be caused by bacteria 2

From the Research

Effective Antibiotics Against Bacterial Infections

• Fluoroquinolones, such as ciprofloxacin, are effective against a wide range of bacterial infections, including respiratory tract infections 3
• Third-generation cephalosporins, such as ceftazidime, are effective against Gram-negative bacteria, including Pseudomonas aeruginosa 3
• Macrolides, such as azithromycin, are effective against Gram-positive bacteria, including Streptococcus pneumoniae 4
• Beta-lactams, such as penicillin, are effective against a wide range of bacterial infections, including respiratory tract infections 3

Effective Antibiotics Against Specific Bacterial Pathogens

• Pseudomonas aeruginosa: ciprofloxacin, ceftazidime, and piperacillin-tazobactam are effective antibiotics 3, 5
• Streptococcus pneumoniae: fluoroquinolones, such as levofloxacin, and macrolides, such as azithromycin, are effective antibiotics 4, 5
• Staphylococcus aureus: fluoroquinolones, such as ciprofloxacin, and beta-lactams, such as oxacillin, are effective antibiotics 3, 5

Antibiotic Resistance and Viral Infections

• Antibiotic resistance is a growing concern, and the overuse of antibiotics can contribute to the development of resistance 6, 7
• Viral infections, such as influenza, should not be treated with antibiotics, as they are ineffective against viral pathogens 6
• The use of antibiotics in patients with viral infections can lead to antibiotic resistance and other adverse effects 6, 7