Pharmacology Chapter 33 Flashcards
Antibacterial Drugs need what to work?
Selective toxicity
Selective Toxicity
selective killing of the invading organism without damaging the host
Why do bacteria invade human tissue?
To replicate they must have a supply of amino acids, sugars, and other substances
Factors of bacterial infection that are harmful
The replicating bacteria compete with the host for essential nutrients
Release of toxins within the host
Signal immune response
In what types of patients are bacterial most severe?
immunocompromised patient or those that are debilitated (ex. AIDS, cancer, transplant patients)
Factors that affect the utilization of antibiotics
Spectrum
Patient Tolerance
Bacterial Resistance
Provider preference
Cidal vs. Static
Cidal- kills or destroys bacteria
Static- halts the progression and allows the body to kill
Mechanism of action: (all in this case have a greater affinity for bacterial components than mammalian or human cellular components)
- Inhibition of cell was synthesis and function
- Inhibition of bacterial protein synthesis
- Inhibition of bacterial DNA/RNA
Cell Wall Synthesis Inhibitors
peptidoglycans makes the bacterial cell wall rigid. Drugs can reduce production of this, thus weaken the cell wall, causing loss of hyperosmotic pressure
bacterial hydrolysis “beta lactam antibiotics”
Most effective and important antibiotics currently available
Penicillins
Penicillins
semisynthetic (broader spectrum); penicillinase resistant (amoxicillin/Clavulanate)
Cephalosporins
1-4th generations- the > the # (generation) to more broad spectrum it becomes (can be used for those allergic to penicillins)
Polymixin: MOA & AE
MOA: Punch holes in the bacteria cell walls via attraction to negatively charges phospholipids in the bacterial cell wall. Like a detergent. (Ex: polymixin B in topical Neosporin creams)
AE: Nephrotoxic (highly kidney damaging) - thus never administered orally
Bacittracin
Activity: Mainly used for topical skin infections broad spectrum activity
Aztreonam
Activity: narrow spectrum; only covers gram negative organisms (Ex. Enterobacter and pseudomonas)
Carbapenems
broad spectrum antibiotics aka “big guns”; activity against gram positive, gram negative, and anaerobic bacteria; reserved for last line use; all administered IV
Three Kinds: Ertapenem, Imipenem, & Meropenem
Ertapenem
broad spectrum; great for intra-abdominal infections; no pseudomonas coverage
Imipenem is given with what? and for what reason?
Given with Cilastatin to prevent breakdown in the kidney
Vancomycin
“Big Gun” antibiotic for severe gram positive infections or in cases of penicillin allergic patients.
Adverse Effects of Cell Wall Synthesis Inhibitors
Hypersensitivity, rash, itching, anaphylaxis, gastrointestinal problems (diarrhea, nausea)
Bacterial Protein Synthesis Inhibitors
Bacterial Protein Synthesis Inhibitors: block bacteria from making life sustaining proteins via binding to bacterial ribosomes.
Aminoglycosides
Activity: mainly target gram negative organisms but have some activity for gram positive and anaerobic bacteria; narrow therapeutic index
AE: Use is limited due to adverse effects: kidney toxicity and ototoxicity (ringing or fullness in ears), and dizziness
Tetracycline
Activity: activity against gram positive, gram negative, and atypical bacteria (rickettsia, spirochetes (lyme disease), chlamydia)
Anti-inflammatory and immunomodulatory effects for use in acne and rheumatoid arthritis
AE: GI distress, hypersensitivity, skin rashes, photosensitivity, teeth discoloration in children; not used in pregnancy
Macrolides
Broad spectrum activity against gram positive and gram negative organisms
Drugs of choice in respiratory infections
“cidal” at high doses
AE: gastrointestinal disorders (azithromycin < clarithromycin < erythromycin) and hypersensitivity reactions (rash, itching)
Chloramphenicol
broad activity against both gram positive and gram negative organisms
Activity:Used last line for severe infections (haemophilus, osteomyelitis, rickettsial infections); only administered IV
AE: blood dyscrasias, thrombocytopenia, and aplastic anemia
Clindamycin
Activity: mainly gram positive and anaerobic activity
AE: Diarrhea, nausea
Linezolid
Activity: mainly works against serious gram positive cocci infections (skin and soft tissue and respiratory)
AE: nausea, diarrhea, blood dyscrasias
Bacterial DNA/RNA Synthesis Inhibitors
inhibit bacterial DNA and RNA and arrest growth and reproduction
Fluoroquinolones
Activity:broad spectrum activity against gram positive and gram negative organisms. Ideal for UTI respiratory, STIs, GI infections, anthrax, & osteomyelitits
AE: **causes tendon pain and inflammation; hold exercise until source of tendinopathy is determined (high risk in patients with kidney impairment, elderly patients, or concomitant steroid use)
Sulfonamides
Activity: broad activity against gram positive and negative organisms
MOA: disrupts folic acid production
UTI, topical skin infections, burns (sulfadiazine, silver nitrate)
Trimethoprim
MOA: Used with sulfonamide for UTI (can’t be used by itself)
Activity: specifically block folate pathway in bacterial cells
Dapsone
Activity: combined with rifampin for leprosy
AE: causes hypersensitivity rxn
Metronidazole
Activity: excellent for anaerobic infections; used for C. Diff
AE: causes neuropathies, GI distress, reactions with alcohol
Ethambutol
Activity: for tuberculosis
AE: causes visual disturbances
Rifampin
Activity: for tuberculosis and leprosy
AE: causes red secretions (pee, cry red)
Mupirocin
Activity: commonly used topical antibiotic for skin infections
AE: may cause skin irritations
Isoniazid
MOA: not fully understood; may possibly interfere with macronutrient metabolism in bacteria
Activity: primary tuberculosis drug
AE: peripheral neuropathy most common side effect
Nitrofurantoin
MOA: produces toxic metabolite that destroys bacteria
Activity: commonly used for UTI; safe to use for those with sulfa allergies
AE: GI distress, headache numbness and fatigue
Selection of an Antibiotic depends on
Organism Location and type of infection Patient factors (age, organ function, allergies) Prior drug exposure (resistance) Culture sensitivity Medication formulary
What are the 4 Bacterial resistance mechanisms
Destruction of antibiotic by enzyme (ex. beta lactamases)
Modification of target receptors (ex. Mutation of penicillin binding protein target site)
Reduced cell penetration (aminoglycosides)
Drug efflux pumps (macrolide antibiotics)
