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Antibiotics and Outpatient Infections

Antibiotic Therapy

· Factors in Choosing an Antibiotic

· Clinical syndrome

· Host characteristics

· Focused history

· Antibiotic characteristics

Assessment of Clinical Syndromes

· Identify predominant symptoms and signs

· Determine the site of infection

· Identify disease process

· Determine likely causative organisms

· Identify likely susceptibility pattern

Host Characteristics

· Age

· Underlying conditions

· Medical devices

· Nutritional status

· Travel

· Exposures

· Immunizations

· Drug abuse

· Sexual activity

Antimicrobial Selection Factors

Spectrum of activity

Absorption

Distribution

Metabolism

Excretion

Adverse Effects

Safety

Routes of administration

Drug-drug interactions

Cost

Palatability

Effect on Resident Flora

Selective Pressure on environment

General Principles of Antibiotic Therapy

· May initiate with broad spectrum awaiting culture results

· Obtain pertinent cultures to narrow therapy

· Use narrowest spectrum as possible

Penicillins

Penicillin - otitis media, pharyngitis, sinusitis Adverse Effects

· Allergic reactions

· Hemolytic anemia

· Interstitial nephritis

· Seizures and hyperkalemia in patients with underlying renal disease

Penicillinase-Resistant Penicillins

Adverse Effects of Penicillinase Resistant Penicillins

· Neutropenia - dose and duration related

· Cholestasis and cholestatic jaundice

· Interstitial nephritis - most common with methicillin

· Poor palatability of oral preparations (dicloxacillin and cloxacillin)

Aminopenicillins