Give examples of antibiotic overuse, misuse, and underuse, such as prescribing amoxicillin to a healthy 30‑year‑old with a viral upper respiratory infection, using ciprofloxacin for a non‑pregnant woman with an uncomplicated urinary tract infection, and failing to initiate cefazolin for a 65‑year‑old diabetic patient with cellulitis.

Examples of Suboptimal Antibiotic Use

Suboptimal antibiotic use encompasses three distinct categories: overuse (prescribing antibiotics when not needed), misuse (selecting the wrong antibiotic or incorrect dosing), and underuse (failing to prescribe antibiotics when clearly indicated).

Antibiotic Overuse

Overuse occurs when antibiotics are prescribed despite no bacterial infection being present or when the infection is self-limited and does not require treatment.

Classic Examples of Overuse:

• Prescribing amoxicillin for viral upper respiratory tract infections (URTIs) in otherwise healthy adults, such as a 30-year-old with the common cold, acute bronchitis, or viral pharyngitis 1
• Treating acute laryngitis with antibiotics, which is predominantly viral and self-limited, with most patients improving within 7-10 days regardless of treatment 1
• Prescribing antibiotics for dysphonia (hoarseness) when the underlying cause is acute viral laryngitis rather than bacterial infection 1
• Treating asymptomatic bacteriuria in non-pregnant women, which represents colonization rather than infection and does not require treatment 1

Scope of the Problem:

• At least 30% of antibiotics prescribed in US outpatient settings are unnecessary, with some estimates reaching 50% 1, 2
• In the European Union, 67% of non-prescription antibiotics supplied by pharmacies are for URTIs, predominantly penicillins (amoxicillin, amoxicillin-clavulanic acid) and macrolides (azithromycin) 1
• Approximately 41% of all antibiotic prescriptions in the US are for respiratory conditions, many of which are viral 1

Antibiotic Misuse

Misuse involves prescribing antibiotics when they may be indicated, but selecting the wrong agent, using inappropriate dosing, or prescribing excessive duration.

Classic Examples of Misuse:

• Using ciprofloxacin (a fluoroquinolone) for uncomplicated urinary tract infections in non-pregnant women when first-line agents (nitrofurantoin, trimethoprim-sulfamethoxazole) are recommended 3
• Prescribing broad-spectrum antibiotics when narrow-spectrum agents would suffice, which was the main reason for inappropriate antimicrobial treatment in hospital settings 4
• Excessive duration of antibiotic therapy after hospital discharge, with 63.1% of overuse days for pneumonia due to excess duration beyond what is needed 5
• Incomplete antibiotic courses or skipping doses, which creates subtherapeutic drug levels and promotes resistance development 6

The Fluoroquinolone Problem:

• Fluoroquinolones remain the most commonly prescribed antibiotics for uncomplicated UTIs (36.4% of prescriptions) despite guideline recommendations against their use as first-line therapy 3
• The FDA has issued multiple black box warnings about fluoroquinolones due to serious adverse events and antibiotic resistance concerns 7, 3
• Guideline concordance for UTI treatment improved from 48.2% in 2015 to 64.6% in 2019, but 35.4% of prescriptions still represent misuse 3

Consequences of Misuse:

• Inappropriate antibiotic selection and dosing increases antimicrobial resistance, particularly with broad-spectrum agents 1
• Subtherapeutic drug levels from missed doses allow bacteria to survive and develop resistance 6
• Treatment failure from poor adherence doubles antibiotic exposure unnecessarily, requiring retreatment with different regimens 6

Antibiotic Underuse

Underuse occurs when antibiotics are clearly indicated for bacterial infection but are not prescribed, leading to preventable morbidity and mortality.

Classic Examples of Underuse:

• Failing to initiate cefazolin for a 65-year-old diabetic patient with cellulitis, where prompt antibiotic therapy is essential to prevent progression to deeper tissue infection or sepsis 8
• Not providing prophylactic antibiotics for high-risk procedures when indicated, such as failing to give ceftriaxone or ampicillin/sulbactam before pyloric stent placement in appropriate patients 9
• Withholding antibiotics from immunocompromised patients with bacterial infections due to concerns about resistance, when treatment is clearly warranted 1
• Inadequate treatment of confirmed bacterial infections in older patients due to concerns about polypharmacy, when the infection poses greater risk than the medication 10

High-Risk Populations for Underuse:

• Immunocompromised patients (transplant recipients, HIV-positive patients, those on immunosuppressive therapy) who develop bacterial infections 1
• Diabetic patients with skin and soft tissue infections requiring prompt antibiotic therapy 8
• Patients with confirmed bacterial infections who have multiple comorbidities, where concerns about drug interactions may lead to withholding necessary treatment 10

Common Pitfalls Across All Categories

Prescriber-Related Factors:

• Assuming partial treatment is better than none is false—incomplete therapy promotes resistance without achieving cure 6
• Prescribing antibiotics "just in case" for viral infections exposes patients to adverse events (occurring in 5-25% of patients) without benefit 1
• Specialty variation in prescribing: obstetricians-gynecologists and urologists show 3.5-fold higher guideline concordance compared to family medicine and internal medicine physicians 3

System-Level Issues:

• Hospital-level antibiotic overuse after discharge varies 5-fold (from 15.9% to 80.6%), suggesting that prescribing culture and organizational processes drive inappropriate use 5
• Non-prescription antibiotic supply reaches 62% globally, with 78% supplied upon patient request, leading to widespread self-medication for viral URTIs 1

Patient Safety Concerns:

• One in five patients taking antibiotics will experience an adverse event requiring medical attention 1
• Clostridium difficile infection causes 29,300 deaths annually in the US, predominantly from antibiotic exposure 1
• Antimicrobial resistance caused 1.3 million deaths globally in 2019, driven largely by inappropriate antibiotic use 11