Lecture 18 antimicrobial agents Flashcards
Paul ehrlich
german physician and bacteriologist
observed dyes stain in bacterial cells
searched for magic bullet that would kill pathogens without harming human
Salvarsan
Gerhard domagk
Red dye prontosil
used to treat step infections in animal
Chemotherapeutic agents
Salvrsan, red dye prontosil
chemicals used to treat disease
Who discovered penicillin
Fleming
First antibiotic
Penicillin G
Selman waksman purified
Streptomycin
Selective toxicity
Causes greater harm to microbes than human host
Toxicity is relative and expressed as
therapeutic index
Therepeutic index
lowest dose toxic to patient divided by dose used for therapy
Penicillin G has a ______ therapeutic index
high
TI equation
LD50/ED50
Bacteriostatic
chemicals inhibit bacterial growth
Patient’s defense must eliminate pathogen
Bactericidal
chemical kills bacteria
broad-spectrum antimicrobials are important for treating ______ dsiease
acute, life-threatening
Negative side effect of broad-spectrum antibmicrobials
can disrupt microbiome that helps keep out pathogens, dysbiosis
Narrow spectrum antibiotics
affectlimiated range
Narrow spectrum antibiotics requires
identification, susceptibility of pathogen
Half life of medication
time it takes for serum concentration to decrease by 50%
Half life medication dictates
frequency of doses required
adverse effects of antibiotics
allergic reactions, toxic effects, dysbiosis
intrinsic resistance
structural resistance of bacteria, outer membrane of gram negatives block any meds
Bacterial may develop ______ resistance
Acquired
Bacterial processes affected by antibiotics
cell wall synthesis
protein synthesis
nucleic acid synthesis
metabolic pathways
cell membranes
Beta lactam antibiotics have a ______ and ______ therapeutic infex
Beta lactam ring, high
Beta lactam antibiotics competitively inhibit ______
Penicillin binding proteins (PBPs)
PBPs
catalyze formation of peptide bridges between adjacent glycan strands, disrupt cell wall sythesis
PBPs are only effective against
actively growing cells
what does Beta lactam antibiotics do to gram cells
peptidoglycan of gram positives exposed
outer membrane of gram negatives blocked
Penicillinase
inactivates members of penicillin family
______ inactive a wide variety of beta lactam meds
extended spectrum beta lactamase (ESBLs)
gram ______ produce more Beta lactamase than gram ______
Negatives, positives
Extended spectrum penicillins have greater activity against ______ species
enterobacteriaceae, Pseudomonas
ESBLs have reduced activity against gram______
positives
Augmentin
Penicillin + beta lactamase inhibtor added to protect penicillin from being degraded by B-lactamase
Cephalosporins
resistant to B-lactamase
has low affinity for PBPs of gram positives
Glycopeptide antibiotics
bind to amino acid side chain of NAM molecules
Blocks peptidoglycan synthesis