Antibiotic Selection Flashcards
Fever
-Temps
-Non infectious causes
-What causes absence of fever with other ssx
Oral temp >38C (100.4 F)
Rectal temp is 0.6C (1 F) higher
Same amount lower for axillary
Malignancy, autoimmune
Drugs
-B lactams, anticonvulsants, allopurinol, amphotericin, hydralazine, nitrofurantoin, sulfonamides, phenothiazides
Antipyretics (can lead to false confirmation of treatment efficacy)
Corticosteroid therapy
Antimicrobial therapy
Overwhelming (hypothermic) infection
Acute phase reactants
ESR (>15M, >20F in infection)
CRP (>0.5 in infection)
-Does not confirm infection but is elevated with inflammation
Procalcitonin- More specific for bacterial infection than ESR/CRP
->10 sepsis/bacterial
-2-10 sepsis specific
Can be used to determine stopping of antibiotics
WBC:
-Normal count
-What increases with infection
What types of infections are associated with:
-Leukocytosis
-Lymphocytosis
-Monocytosis
-Eosinophilia
What causes pyelonephritis (flank pain)
4500-10500
WBC, especially immature neutrophils or bands (left shift)
Bacterial
Viral, TB, Fungal
TB, Lymphoma
Allergic, Allergy, Protozoal, Parasitic
E.coli
For which infections can you delay treatment?
Osteomyelitis
Otitis Media
For empiric therapy, start with ____________, then change to ______ for directed therapy
When to use IV therapy over oral
Broad spectrum
Narrowest effective spectrum, change from IV-PO if improving
CNS infection, endocarditis, staph aureus bacteremia
Bactericidal vs Bacteriostatic:
-Examples of each
-When bactericidal is required
Bactericidal: B-lactams, daptomycin, fluoroquinolones
Bacteriostatic: Macrolides, tetracyclines
Meningitis, Immunocompromised, Osteomyelitis, Endocarditis
Drugs that distribute in extracellular fluid
Which drugs accumulate inside tissue cells
Typical bacteria accumulate _____
B-lactams
Aminoglycosides
Macrolides
Fluoroquinolones
In ECF
Mechanism of antibiotic interactions
Effects with protein binding
Induction/Inhibition of P450 (rifampin, voriconazole)
Complexation and chelation
-Fluoroquinolones and cations
-ZICAMM
Bacteria structures that are relevant to resistance
Plasmids- resistance DNA that can be transferred
Membrane- enzymes, permeability
Cell wall- barrier and contains penicillin binding proteins (most relevant is transpeptidase)
Outer membrane- in gram negatives, porins that won’t permit entry of antibiotics
Periplasmic space- between cytoplasmic membrane and outer membrane of gram negative cell
Intrinsic resistance
Acquired resistance
Organism has always not been affected by an antibiotic
Organism that was once susceptible has now come resistant
Three genetic exchange mechanisms
Conjugation: Sex pili
Transduction: Genes transferred by bacteriophage
Transformation: Free floating DNA taken up and integrated
Four levels of threats from CDC antibiotic resistance report
Urgent
Serious
Concerning
Watchlist
Three primary mechanisms of resistance
Enzymatic inactivation (most common)
Alteration of target site
Altered permeability of bacterial cell
Ambler Classification of Beta-Lactamases
Class A:
Narrow spectrum- Staphylococcal penicillase
Extended spectrum- CTX-M
Serine carbapenemases- KPC
Class B:
-Metallo-B-Lactamases- VIM/IMP/NDM
Class C:
-Cephalosporinases: AMP-C
Class D:
OXA-type
Organisms that have the AmpC gene (Class C)
These are not inhibited by _____
How AmpC induction works
Most potent inducer
Stably derepressed meaning
Which two drugs are best for HECKYESMAAM
ECKSM:
Enterobacter cloacae
Citrobacter freundii
Klebsiella aerogenes
Serratia marcescens
Morganella
Older B-lactamase inhibitors
Repressed, derepressed once drug is introduced, repressed again
Cefoxitin
Consistently de-repressed
Cefepime/Carbapenem
