Antibiotics Flashcards
Empiric therapy
treatment of an infection before specific culture information has been reported or obtained.
Prophylactic therapy
treatment with antibiotics to prevent an infection, as in intraabdominal surgery, exposure to STD, or bacterial endocarditis.
Therapeutic response
Decrease in specific signs and symptoms of infection are noted when compared to baseline findings (fever, elevated WBC, redness, inflammation, drainage, pain)
Subtherapeutic response
Signs and symptoms of infection do not improve either due to the result of incorrect route of administration or dosage, inadequate abscess drainage or bacterial resistance
Bacteriostatic drugs
Inhibition of bacteria but effect reversible if the drug is removed, unless the host defense mechanisms have eradicated the organism
Examples: sulfonamides, erythromycin, and tetracyclines
Bacteriocidal drugs
Antibiotics that kill bacteria
Less dependence on body’s defense mechanisms than bacteriostatic drugs
Examples: penicillins, cephalosporins, and aminoglycosides
Selective Toxicity
Definition: The ability to suppress or kill an infecting microbe without injury to the host
Achievable because:
Specific action on cellular structures of the microorganisms than on host cells
Superinfection
occurs when antibiotics reduce or completely eliminate normal flora
Ex: vaginal yeast infections
Secondary bacterial infection
Antibiotic resistance
caused by inappropriate antibiotic prescription or administration
Common Antibiotic-Resistant Microbes
Methicillin-Resistant Staphylococcus Aureus (MRSA)
Widely resistant to aminoglycosides and antistaphylococcic penicillins
Reduced ability of penicillins to inhibit cell wall synthesis
Also MRSE… Methicillin-Resistant Staphylococcus Epidermidis
Drug of choice: Vancomycin
Penicillin
Bactericidal antibiotics: inhibit cell wall synthesis
Kill a wide variety of gram-positive and some gram-negative bacteria
Also called “β-lactams”
Inside the cell they bind to penicillin-binding protein
Once bound, normal cell wall synthesis is disrupted
Result: bacteria cells die from cell lysis
Penicillins are selectively toxic to bacterial cells and do not kill other cells in the body
Allergic reactions- most serious
rash, fever, wheezing, possible anaphylaxis
GI adverse effects common
Cephalosporins
Bactericidal action - interfere with bacterial cell wall synthesis by binding with PBPs
Broad spectrum: gram-positive, gram-negative and anaerobic bacteria (depends on generation)
Similar to penicillins
N/V/D, anorexia, abdominal pain, flatulence
Hypersensitivity reactions frequent
Maculopapular rash
Psuedomembranous colitis w/ cefazolin
Violent, bloody diarrhea, abd pain
Potential cross-sensitivity with penicillins if allergies exist
Sulfonamides
Bacteriocidal -
Inhibit THF synthesis necessary for thymidine synthesis & DNA synthesis
Only affect organisms that synthesize their own folic acid
Adverse Effects
Blood: Megaloblastic, hemolytic and aplastic anemia, agranulocytosis, thrombocytopenia
Integumentary: Allergic reactions, Photosensitivity, exfoliative dermatitis, Stevens-Johnson syndrome**, Crystalluria
Teach pt to take with a full glass of water
Fluid intake should ↑by 1.5 L/day
Avoid foods & fluids that acidify urine i.e. cranberry juice
Tetracycline
Bacteriostatic —inhibit bacterial growth and inhibit protein synthesis
Stop many essential functions of the bacteria
Dairy products, antacids, and iron
salts reduce oral absorption of tetracyclines
Should not be used in children under age 8 or in pregnant/lactating women because teeth discoloration will occur if the drug binds to the calcium in the teeth
Adverse Effects: Calcium problems, N/V, photosensitivirty, alteration in intestinal flora
Administering on empty stomach with water, not milk, in divided doses around the clock
Continuing drug therapy for at least 7 to 10 days
Backup contraception
