Chapter 9 Flashcards
1
Q
chemotherapy
A
the use of any chemical/drug to treat any disease/condition
2
Q
chemotherapeutic agent
A
any drug used to treat any condition/disease
3
Q
antimicrobial agent
A
- any chemical/drug use to treat infectious diseases
- either by inhibiting action or by killing pathogens in vivo
- some antimicrobial agents are antibiotics
4
Q
drugs used to treat bacterial diseases
A
antibacterial agents
5
Q
drugs used to treat fungal diseases
A
anti fungal agents
6
Q
drugs used to treat protozoal diseases
A
antiprotozoal agents
7
Q
drugs used to treat viral diseases
A
antiviral agents
8
Q
antibiotic
A
- a subtended produced by a microorganism that kills or inhibits growth of other microorganisms
- another microbe creates it
9
Q
semisynthetic antibiotics
A
- antibiotics that have been chemically modified to kill a wider variety of pathogens or reduce side effects
- ex: semisynthetic penicillin like ampicillin and carbenicillin
10
Q
Alexander flemming
A
- discovered penicillin and antibiotics
- had a staph colony growing well in one are of plate and poorly growing in another due to an antibiotic being produced by a colony of mold
11
Q
characteristics of an ideal antimicrobial agent (6)
A
- kill or inhibit the growth of pathogens
- cause no damage to host
- cause no allergic reactions
- be stable when stores in liquid or solid form
- remain in specific tissues in body long enough to be effective
- kill pathogen before they mutate and become resistant
12
Q
5 most common mechanisms of action of antimicrobial agents
A
- inhibition of cell wall synthesis
- damage to cell membranes
- inhibition of nucleic acid (DNA or RNA)
- inhibition of protein synthesis
- inhibition of enzyme activity
13
Q
bacteriostatic drugs
A
inhibit growth of bacteria
14
Q
bactericidal drugs
A
kill bacteria
15
Q
folic acid
A
some bacteria require folic acid to produce certain essential proteins, without it they will die
16
Q
sulphonamide drugs
A
- inhibit production of folic acid in bacteria that require p-aminobenzoic acid (PABA) to synthesize folic acid
- they are competitive inhibitors
- bacteriostatic
- competes the PABA because there is more of sulfa/metabolite
17
Q
mechanism of action of penicillin
A
- in most gram + bacteria pen interferes with the synthesis and cross-linking of peptidoglycan (cell wall)
- pen destroys bacteria by inhibiting cell wall synthesis
18
Q
narrow spectrum antibiotics
A
- colistin and nalidixic acid destroy only gram - bacteria
- vancomycin selectively kills gram +
19
Q
broad spectrum antibiotics
A
- destructive to both gram + and - bacteria
20
Q
multidrug therapy
A
- when two or more drugs are used simultaneously
- treatment of TB
21
Q
synergism
A
- when 2 antimicrobial agents are used together to produce a degree of pathogen killing that is greater than that achieved by either drug alone
22
Q
antagonism
A
- when 2 drugs work against each other
- extent of pathogen killing is less than that achieved by either drug alone
23
Q
major categories of antibacterial agents
A
- penicillins - bactericidal
- cephalosporins - bactericidal
- tetracyclines - bacteriostatic
- aminoglycosides - bactericidal
- macrolides - bacteriostatic at low dose; bactericidal at high dose
- fluroquinolones - bactericidal
24
Q
major categories of antibacterial agents and their mechanism of action
A
- penicillins - cell wall synthesis
- cephalosporins - cell wall synthesis
- tetracyclines - protein synthesis
- ahminoglycosides - protein synthesis
- macrocodes - protein synthesis
- fluroquinolones - DNA synthesis
25
anti fungal agents 3 possible mechanisms of action
1) binding with cell membrane sterols
2) interfering with sterol synthesis
3) blocking mitosis or nucleic acid synthesis
26
antiprotozoal agents mechanisms of action
1) interfering with DNA and RNA synthesis
| 2) interfering with protozoal metabolism
27
why are antiprotozoal and anti fungal agents more toxic to host
- because the drugs are eukaryotic organisms, like the infected host
- same structures of own cell
28
antiviral agents
- newest weapon
- difficult to develop because viruses are produced within host cell
- some drugs developed to kill certain viral infections
- work by inhibiting viral replication within cells
29
cocktail drugs
- when several antiviral drugs are administered simultaneously
- to treat HIV
30
superbugs
- microbes, mostly bacteria, that have become resistant to one or more antimicrobial agents
- infections are difficult to treat
31
examples of bacterial superbugs (8)
- methicillin-resistant staphylococcus aureus (MRSA)
- vancomycin-resistant enterococcus (VRE)
- multidrug-resistant mycobacterium TB (MDRTB)
- e coli
- klebsiella
- salmonella
- shigella
- n. gonorrhoeae
32
why do hospitals produce a lot of resistant microbes
- because they are cleaning all the time and a lot of bacteria is introduced into hospitals
33
intrinsic resistance
- bacteria that are naturally resistant because they lack the specific target site for the drug
- or drug is unable to cross organisms cell wall or membrane and can't reach site of action
34
acquired resistance
when a bacteria was once susceptible to a particular drug becomes resistant
35
acquired resistance involving chromosomal mutations
- causes change in structure of binding site preventing drug from binding to cell
- causes change in cell membrane permeability preventing the drug from crossing it and entering cell
36
acquired resistance involving acquisition of a gene
- enables bacteria to produce an enzyme that destroys/inactivates drug resulting in drug being destroyed or inactivated by enzyme
- enables bacteria to produce a multi-drug resistant (MDR) pump that pumps the drug out of the cell before it can act
37
acquisition of a gene to create resistance by...
- transduction, transformation, and conjugation
| - most commonly conjugation
38
penicillin resistance
- many bacteria have become resistant to it because they have acquired the gene for penicillinase production
- penicillinase kills penicillin
39
resistance factor (R-factor)
- a plasmid that contain multiple genes for a drug resistance
40
B-lactam ring
- every penicillin and cephalosporin molecule contain double ringed structure referred to as "house and garage"
- "garage" is known as B-lactam ring
41
B-lactamases
- some bacteria produce B-lactamases that destroy B-lactam ring
- when ring is destroyed the drug no longer works
- drug companies have developed drugs that combine B-lactam antibiotic with B-lactamase inhibitor
42
2 types of b-lactamases
- penicillinases and cephalosporinases
- some bacteria produce both
- these enzymes kill the drugs
43
strategies in war against drug resistance (8)
- education of HCP and pts
- its should stop demanding antibiotics when they are sick
- physicians should not be pressured to prescribed antibiotics by its
- clinicians should prescribe narrow-spectrum drug if lab indicates that it kills the pathogen
- pts should destroy excess/outdated meds
- antibiotics should not be used prophylactically
- HCP should practice good infection control
- pts should take drugs as directed
44
empiric therapy
- when drug therapy is initiated before lab results are available
- sometimes necessary to save life
- clinicians make educated guess based on experience
- multiple factors to consider before prescribing
45
factors to be considered in empiric therapy (11)
- use pocket chart of antimicrobial susceptibility test data if pathogen identity is known
- pt allergies
- pt age
- pregnant pt
- inpatient or outpatient
- is drug the hospital formulary
- where is site of infection
- other meds of pt
- pt medical problems
- pt WBC count or immunocomprimisation
- cots of drug
46
undesirable effects of antimicrobial agents
- organisms susceptible to agent will die but resistant ones will survive, which is selecting for resistant organisms
- pt may become allergic to agent
- many agents are toxic or very toxic to humans
- broad-spectrum may destroy normal flora resulting in overgrown bacteria known as superinfection with prolonged use
