Anti-infectives Flashcards
What is an antibiotic?
a chemical substance produced for various species of microorganisms that suppress growth or destroys other microorganisms
What 3 things do you need to see in a patient to give an antibiotic?
mucopurulent discharge, diffuse conjunctival injection, potential for corneal compromise
what are the 5 antibacterial drugs that are bactericidal?
Penicillin’s, aminoglycosides, cephalosporins, bacitracin, fluoroquinolones
which 2 bactericidal antibiotics are concentration dependent?
Aminoglycosides and fluoroquinolones
what are 5 antibacterial drugs that are bacteriostatic?
tetracyclines, macrolides, sulfonamides, trimethoprim, chloramphenicol
What does a gram positive bacteria have?
thick peptidoglycan layer
what does a gram negative bacteria have?
thin peptidoglycan layer with lipoprotein and lipopolysaccharide (LPS)
what are the 4 antibacterial drugs that inhibit cell walls?
Penicillins (+>-), cephalosporins (+>-), bacitracin (+), vancomycin (+)
what are the 2 antibacterial drugs that inhibit cell membranes?
polymyxin B (-) and gramicidin(+)
what are 4 antibacterials that inhibit protein synthesis?
aminoglycosides (->+), tetracyclines (+ and -), macrolides (+), and chloramphenicol (+ and -)
what are 3 antibacterials that inhibit cell metabolism?
sulfonamides (+ and -), trimethoprim (+ and -), pyrimethamine (+ and -)
what is 1 antibacterial that inhibits DNA synthesis?
Fluoroquinolones (->+)
What are 3 antibacterials that you should take on an empty stomach?
PAT = penicillins, azithromycin, tetracyclines
what are 2 gram + spherical bacteria arranged in clusters? (most common ocular pathogens = 50% of ocular infections)
staphylococcus aureus and staphylococcus epidermidis
which staphylococcus bacteria, aureus or epidermidis, is more abundant? which is more virulent?
aureus = more virulent epidermidis = more abundant
what is a gram + streptococcus that causes corneal ulcers and pediatric conjunctivitis?
Streptococcus pneumoniae
what is an example of a gram negative cocci?
Neisseria gonorrhoeae = causes gonorrhea (hyperpurulent conjunctivitis)
what is an example of a gram negative rod that causes otitis media and conjunctivitis?
Haemophilus influenzae
what are 4 enteric gram negative rods that are typically found in the intestinal tract and can cause UTIs?
E. coli, serratia marcescens, proteus, pseudomonas aeruginosa
what are 2 water-borne bacteria that affect ocular health?
Serratia marcescens and pseudomonas aeruginosa
what are 2 examples of bacteria that depend on the host to survive?
Chlamydia and treponema pallidum (spirochete)
what is chlamydia trachomatis?
gram negative = transmitted finger/fomite to eye and causes trachoma or by self-contamination from genitals to cause inclusion conjunctivitis
what is treponema pallidum?
gram negative = caused by STD or mother to child (syphilis)
what is the mechanism of action for antibacterials that inhibit cell walls?
inhibit transpeptidases which create peptide x-links between polysaccharide chains that form peptidoglycan in bacteria cell walls
which PCN is acid stable and is a good oral formulation?
Dicloxacillin
what are 2 PCNs that are PCNase sensitive?
PCN V (IV, IM) and PCN G (PO)
what are 3 PCNs that are PCNase resistant?
Methicillin, flucloxacillin, dicloxacillin
what are 2 aminopenicillins?
ampicillin (+/- sulbactam) and amoxicillin (+/- clavulanate)
what are 3 PCNs that have anti-pseudomonal gram negative coverage?
carbenicillin, ticaricillin (+/-clavulanate), and piperacillin
how are PCN typically administered?
need oral therapy - allergy/toxicity is too high risk with topical
what are 4 hypersensitivity reactions seen with PCN?
anaphylaxis, hemolytic anemia, serum sickness, Steven’s Johnson syndrome
what adverse effect can methicillin cause?
interstitial nephritis
what two drugs can have cross reactions with because they have similar chemical structures?
Penicillins and cephalosporins (especially 1st generations)
which antibacterial can cause birth control pills to fail?
PCN (especially Ampicillin)
how are cephalosporins different than PCNs?
have a 6 membered beta-lactam ring (PCNs have a 5 membered ring)
Are cephalosporins susceptible to PCNases?
they are less sensitive but if they are produced by gram negative bacteria they are affected
how are cephalosporins typically administered?
3 out of 4 generations are oral formulations
what is the trend seen with the different generations of cephalosporins?
each generation has increased gram negative coverage
what are the 4 hypersensitivity reactions with cephalosporins?
anaphylaxis, hemolytic anemia, toxic epidermal necrolysis, Steven’s Johnson syndrome
why are vitamin K deficiencies and blood dyscrasia adverse effects of cephalosporins?
cephalosporins destroy normal flora in gut and vitamin K can't be metabolized = deficiency blood dsycrasia (cytopenia) is a reduction in RBCs and without vitamin K to coagulate blood = loose blood if injured
what is a contraindication for cephalosporins?
hemophilia (genetic disorder that impairs ability to control blood clotting)
what is AK-tracin ointment?
bacitracin = narrow gram + spectrum
what is polysporin ointment?
polymyxin B and bacitracin = additional gram negative coverage –> broader spectrum
why is bacitracin only used topically?
due to profound nephrotoxicity
what is the drug of choice for MRSA, MRSE, and bacterial endophthalmitis?
vancomycin (gram + coverage only)
what are 3 adverse reactions for vancomycin?
ototoxicity, nephrotoxicity, red man’s syndrome (IV induced mast cell degranulation)
what is the mechanism for cell membrane inhibitors?
they interact with the phospholipids of the bacterial cell membrane = disrupting the osmotic integrity and increases permeability and causes cell death
what is polymyxin B?
a cationic detergent/surfactant for gram negative bacteria
how is polymyxin B administered?
only topically due to systemic neuro/nephrotoxicity
what is gramicidin?
same mechanism of action as polymyxin B
