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Choosing an antibiotic depends on the properties of the antibiotic and the nature of the pathogen. The following considerations are important in selecting the proper course of antimicrobial treatment:
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Identification of the pathogen determined with testing
Susceptibility of the organism to a variety of antibiotics
Seriously ill or immunocompromised patients should receive bactericidal rather than bacteriostatic drug
Site of infection (ie, does the blood–brain barrier need to be crossed?)
Patient limitations such as allergy, immunosuppression, hepatic failure, or renal dysfunction
Use of multiple antimicrobials in combination
Route of administration
Duration of treatment
Risk of development of resistant strains
Cost
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In general, narrow-spectrum antibiotics should be chosen before broad-spectrum drugs to avoid disruption of the patient’s normal flora of bacteria. Normal bacterial flora are important as they can compete with pathogens for nutrients, produce antibacterial substances, and combat nosocomial-resistant organisms. The recommended dosing of antibiotics should be strictly followed. Morbidly obese patients may require increased dosing to achieve adequate tissue levels of antibiotics, while patients with hepatic or renal dysfunction may require decreased dosing. A listing of commonly used perioperative antibiotics can be found in Table 70-1.
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