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Antimicrobe Regimen
Antimicrobial Regimen Selection
Question | Answer |
---|---|
How do antimicrobials differ from other drug classes in terms of their effects on individual patients as well as on society as a whole? | Antimicrobials perform their actions on the organism targeted rather than on the host itself. |
Bactericidal | Kills 99.9% (3-log) of a bacterial population. |
Bacteriostatic | Kills less than a bactericidal agent does. |
Post-antibiotic effect (PAE) | |
Normal flora | Bacteria/organisms normally found on/in a particular anatomic location of a patient. |
Pathogen | Disease-causing organism. |
Empiric therapy | General, broad-spectrum therapy used before culture/sensitivity is known. Best-educated guess based on patient- and antimicrobial-specific factors. |
Prophylactic therapy | Therapy given/administered in order to prevent future infections. |
Synergy | Effects of a drug are greater when used concomitantly with another therapy. |
Narrow-spectrum activity | An antimicrobial that kills a few specific species of bacteria. |
Broad-spectrum activity | An antimicrobial that kills several different species of bacteria. Often chosen as empiric therapy. |
Expected normal flora for skin | Staph. aureus Staph. epidermidis micrococci diphtheroids |
Expected normal flora for GI tract | lactobacillus Strep. sp. enterococcus enterobacteriacae diphtheroids few anaerobes peptostreptococcus bacteroides sp. Clostridium sp. Pseudomonas sp. |
Expected normal flora for mouth | oral anaerobes Vridans streptococci |
Gram stain | Gram(-) vs. Gram(+) shape of organism presence of WBCs |
Culture | Information on specific organism Antimicrobial susceptibility (S,I,R) |
CBC | complete blood count |
Left shift | An increased rate of release of neutrophils into blood/tissues in response to infection. |
MIC | Minimum Inhibitory Concentration The lowest concentration of antimicrobial that inhibits visible bacterial growth. Helps to determine level of susceptibility. |
Time-dependent kill/Time above the MIC | Antimicrobial activity based on time above MIC rather than on an increased dose. |
Concentration-dependent kill | Antimicrobial activity based on amount of dose rather than on time above the MIC. |
B-lactamase antibiotic selection | Concentration-independent/Time-dependent Choose dose to maintain blood/tissue concentrations above the MIC in a time-dependent manner. |
Drug-specific considerations in antimicrobial selection | Spectrum of activity Effects on nontargeted microbial flora Appropriate dose Pharmacokinetic properties Pharmacodynamic properties Adverse drug reactions (ADRs) Drug interactions Cose |
Patient-specific considerations in antimicrobial selection | Recent previous antimicrobial exposures ID of anatomic location of infx Hx of drug allergies Organ dysfunction (may affect clearance) Immunosuppression Pregnancy Compliance |
De-escalation | From a broad-spectrum empiric therapy to a narrow-spectrum antimicrobial. |
Common causes of antimicrobial failure | Inadequate Dx Poor initial antimicrobial selection Poor source control Development of a new infx w/resistant organism Non-adherence Insufficient dosing Drug interactions Development of secondary infx/suprainfx |