bacteria and antibiotics

what do antibiotics do?

• disrupt cell membrane (phospholipid bilayer) function

• inhibit cell wall synthesis (petidoglycan)

• inhibit RNA and DNA synthesis

• inhibit metabolic activity (disrupt critical metabolic reactions inside the bacterial cell)

which ones disrupt the cell membrane function?

polymixins and polyenes-antifungal

which ones inhibit cell wall synthesis?

penicillins and cephalosporins

which ones inhibit RNA and DNA synthesis?

fluoroquinolones and metronidazole

which ones inhibit protein synthesis

erythromycin, tetracycline, streptomycin, and gentamicin

which ones inhibit metabolic activity?

sulfonamides and trimethoprim

antimicrobial treatment categories: definitive

used when specific pathogen susceptibility is identified

antimicrobial treatment categories: prophylactic

used to prevent infection in high risk situation (surgical procedure, likely exposure)

antimicrobial treatment categories: empiric

• infection source

• pathogen is unknown but patient needs to be treated

• treatment selection based on judgement of most probable causative organism and susceptibility

what are anti-infectives/antimicorbials?

• drugs that prevent or treat a broad range of infections

  • bacterial

  • viral

  • fungal

  • protozoal

antimicrobials are effective in the treatment of infections due to…

selective toxcity

what is selective toxicity ?

• ability to injure or kill an invading microogranism without harming the cells of the host

what are antibiotics?

used to treat infections caused by bacteria

what is the goal of antibiotics?

to decrease invading bacteria and have the human immune system effectively deal with invaders

why do antibiotics only work on bacteria and not viral infections?

• leads to antibiotic resistance

• lowers options for future antibiotic treatments

• risk of side effects and extra costs

beta lactam antibiotics

• inhibits bacterial wall biosynthesis

• includes the penicillins, cephalosporins, and carbapenems

• most commonly prescribed drug

• active against many gram-positive, gram0negative, and anaerobic organisms

penicillin (PCN)

• bactericidal

• used PO, IM, IV

• examples: ampicillin, amoxicillin, dicloxacillin

B-lactamase (resistant bacteria)

• enzyme produced by some bacteria to break chemical bond of beta lactam structure

  • makes antibiotics ineffective

cephalosporin

• bactericidal

• less susceptible to Beta- lactamase

• PO, IM, IV

• could indicate: strep throat, UTIs, otitis media

• can cause PCN allergies

carbapenems

• bactericidal

• broadest antibacterial action

• used for moderate to life-threatening bacterial infetions

• Injectable ONLY

sulfamides (“Sulfa“)

• bacteriostatic

• broad spectrum

• indications: UTIs, MRSA, pneumonia, ear infections, toxoplasmosis

• PO or IV

• should be taken on empty stomach and lots of water

adverse effects of Sulfa

• hepto or renal toxicity

• CNS effects — dizziness

• kidney tubule damage

• hypersensitivity effect of Toxic Epidermal Necrosis

• should monitor urine output, RBC (anemia), and platelets (thrombocytopenia)

tetracyclines

• bacteriostatic — inhibit protein synthesis

• indications: acne, chlamydia, lyme disease, pneumonia

• take on empty stomach if tolerated

• dont take with calcium, milk, antacid, or iron supplements

• do not give to pregnant (teratogenic)

• beware of photosenitivity

• PO

aminoglycosides

• bactericidal

• highly potent

• indications: septicemia, prophlyaxis, eye infections

• nephrotoxic — toxic to kidneys —> decreased urine output

• ototoxic — toxic to hearing

• IV or eye drops

adverse effects of aminoglycosides

• nephrotoxicity (acute renal failure)

• ototoxicity (hearing loss)

• can block ACH

• can cause motor changes