Antibiotics Flashcards
(36 cards)
Penicillin
cell wall inhibitor
b-lactam ring
treats gram +
form of penicillin v and g, amoxicillin, ampicillin
safe in pregnancy
is resistance
no selective toxicity
frequent doeses needed
people can have allergies, decreases effectiveness of birth control
Cephalosporins
cell wall inhibitor
b-lactam ring
treats gram + and -
form of cefotaxime
parental oral administration
2nd choice for gbs, 1st for gonorhea, given before/after surgery
-preg safe
Glycopeptides
cell wall inhibitor
bactericidal form
treats c dif and staphylococcus aureus
form of vancomycin
consider if bactera are b-lactam resistent or allergy
-preg safe
Aminoglycosides
protein synthesis inhibitor
gram - aerobes
form of streptemycin, necmycin, gentamicin
not pregnancy safe
nototoxic and nephrotoxic to baby
administered as intramuscular IV
resistance does exist
-cycline
prevents trna binding
baacteriostatic
treats chlamydia and mycoplasma
form of tetracycline and doxycycline
not pregnancy safe tertatogenic
administered orally
has resistance
avoid use in children younger than 8, can stain teeth, gut alleric reaction
eryhthromycin
prevetns trna release
bacteriostatic
treats uti, chlamydia, mycoplasma
is pregnancy safe
given orally or IV
has resistance
used for PROM
macrolide
azithromycin
prevents trna release
bacteriostatic
treats utis
pregnancy safe
has resistance
no selective toxicity
consider penetrates most tissue and slow release
macrolide
lincosamides
inhibits peptide formation
teats bacterial vaginosis, GBS, chlamydia and gonnorhea
form of clindamycin
pregnancy safe
has resistance
cause diarhea nausea rash colitis
quinolones
inhibit dna
bacteriacidial
treat utis, chlamydia, gonorrhea
not pregnancy safe
given orally
some resistance
cause vommiting, nasuea abdominal pain
sulphonamides
folic acid inhibitor
bacteriostatic
gram -
treats utis
not pregnancy safe
given orally
has resistance
has selective toxicity
not safe for newborn or pregnancy
metronidazole (FLAGYL)
-against anaerobes
-dna inhibitor
treats protozoal infections
preg safe
Ideal antimicrobial:
-hard for pathogen to develop antibiotic resistance to
-broadspectrum (kills all organisms including microbiome) vs target antibiotics (ex. Only gram negative bacteria)
-different administration - needle/IV vs taking a pill
-something that is stable in multiple temperatures (thermostable)
-easily readable and inexpensive
-lethal to pathogen or at least inhibits its growth
-harmless to person
-no allergens or toxicity
-long half life (less frequent dosing)
-low plasma-protein binding (stays in its form, can penetrate, work stronger, does intererfere with other things)
-no interference with other drugs
Antibiotic Resistance:
-not be inhibited or killed by an antibacterial agent
-can happen from the synthesis of new or altered proteins by the microorganism
–Single chromosomal mutation: single amino acid change → lowers affinity (degree of killing) to antibiotic
–Series of mutations: changes on penicillin binding proteins → penicillin resistance
Mechanisms of Resistance:
-Altered target site: Drugs need to bind a particular receptor/site. This lower affinity of the target for the antibacterial. Receptor/site still functions for cell processes
-Altered uptake/increased efflux: Reducing the amount of drug that reaches the target (decreasing cell wall permeability, pumping drug out of cell)
-Drug inactivation:
-Enzymes that modify or destroy the drug
-E.g. Penicillin-β lactamases made be bacteria break down beta lactam ring so it can’t work
Ways HCPs can Prevent Antibiotic Resistance:
-only prescribing when necessary - can sometimes see if infection clears on its own
-making sure people take the full course of antibiotics and not stopping if they feel better
-choosing narrow spectrum antibiotics when possible
-confirm its a bacterial infection before prescribing antibiotics
-make sure people NEVER share antibiotics and never using leftover antibiotics
Ways to Classify Antibiotic
1.Bactericidal or Bacteriostatic
–Bactericidal → Kills a microorganism
–Bacteriostatic → Halts the growth of microorganisms, the immune system can then eliminate them (Not effective if immunity is suppressed)
2.Mechanism of action
3.Chemical structure
–Not of practical use when used alone
–When combined with target site can be useful to organise antimicrobial agents into specific families
Bactericidal vs. Bacteriostatic (1/ways to classify antibacterial agents)
-Bactericidal
–E.g. penicillin can cause holes in the cell walls of bacteria, so they die
-Bacteriostatic
- E.g. tetracycline or erythromycin keep bacteria from dividing further by inhibiting protein synthesis necessary for division
Mechanism of Action (2/ways to classify antibacterial agents)
A) Cell wall synthesis
B) Protein synthesis
C) Nucleic acid synthesis (DNA, Folic acid synthesis inhibition
Antibiotic resistant methods
Efflux Pumps: Bacteria can have pumps that actively remove macrolides from inside the cell, reducing their concentration and effectiveness.
Target Modification: The target of macrolides in bacteria is the ribosome, where they interfere with protein synthesis. Resistance can occur when bacteria modify their ribosomes, making them less sensitive to macrolides.
Antifungal Agents:
-few in number
-selective toxicity is difficult (fungi are eukaryotes, like human cells)
-have ergosterol - a lipid in fungal membranes (humans have cholesterol)
-some times no single antifungal is ideal (ringworm infection of the nails or recurrent vaginal candidiasis are frequently intractable)
-resistance occurs
Azoles or Imidazoles:
-Inhibits cell membrane synthesis (ergosterol)
-Small molecule, easily absorbed
-Clotrimazole (Lotrimin) and miconazole (Monistat) are useful topical preparations
-Fluconazole used increasingly to treat Candida (avoid in 1st trimester especially)*
-Ketoconazole (Nizoral) is the agent of choice for serious infections*
-issues in pregnancy
Polyenes:
-amphotericin B and nystatin (mycostatin)
-inhibit cell membrane function:
-bind to cell membrane and cause leakage of cell products and cell death (breaks ergosterol and not cholesterol)
-selective toxicity because humans do not have the binding site
-used to treat serious systemic fungal infections
-Amphotericin B given IV, orally, or topically
Used to treat serious infections
Side effects: fever, nausea, malaise, chills
*Safe during pregnancy (category B)
-Nystatin topical only (category A)
Used to treat Candida in mouth, mucous membranes (vaginal)
Athlete’s foot (cutaneous mycosis)
Minimal side effects
Vaccines
-active immunisation - the adaptive immune system responds to antigens in the vaccine a produces memory B and T cells.
Antibodies generated by vaccination (or repeated vaccination) are directly available to fight the pathogen when an infection occurs
-Passive immunisation is provided by antiserum or other immunoglobulin (what B cells would normally make) based treatments that provide antibodies to protect from (or treat) infection, but do not induce memory response, and provide only temporary immunity
Basic Types of Approved Vaccines (6 total types- 8 with new COVID Vaccines):
1.Live attenuated
2.Inactivated (primarily good at inducing antibodies)
A) Whole
B) Fractional:
1. Subunit
2. Toxoid
3. Polysaccharide based- Whole/conjugate
3.mRNA *
4.Viral-vectored*
