Antimicrobial Chemotherapy Flashcards
(138 cards)
1
Q
name 10 classes of antimicrobials
A
penicillins (b-lactams) cephalosporins (b-lactams) aminoglycosides gylcopeptides macrolides quinolines others antifungals antivirals immunoglobulins
2
Q
list 6 principles of prescribing for antibiotics
A
indications clinical diagnosis and severity patient characteristics antimicrobial selection regimen selection liaison with lab
3
Q
name 4 mechanisms of resistance
A
alteration of target site to reduce/eliminate binding of drug
destruction or inactivation of antibiotic
blockage of transport into antibiotic into cell
metabolic bypass
4
Q
give 6 examples of hospital bugs with increasing resistance
A
- Methicillin resistant S. aureus (MRSA)
- Methicillin resistant S. epidermidis (MRSE)
- Vancomycin resistant Enterococcus (VRE)
- Vancomycin intermediate S. aureus (VISA / GISA)
- Extended-spectrum (β-lactamase gram negatives (ESBL)
- Multiresistant Tuberculosis
5
Q
give examples of community bugs with increasing resistance
A
- HIV
- Food-borne (Salmonella, Shigella, H pylori)
- Malaria
- Pneumococcus
- Hepatitis B& C
- E coli O157
- Lyme disease
- Legionnaire’s
6
Q
what are the indications for antimicrobials?
A
therapy - empiric/directed
prophylaxis
primary - antimalaria, pre-op, PEP
secondary - to prevent a second episode
7
Q
what are the patient characteristics when selecting an antimicrobial?
A
age renal function liver function immunocompromised pregnancy known allergies
8
Q
what are the factors to consider when selecting an antimicrobial?
A
guideline or individualised therapy likely organism empirical therapy or result based bactericidal vs bacteriostatic drug single or combination potential adverses effects
9
Q
what are the likely pathogens in a soft tissue infection?
A
o Streptococcus pyogenes o Staphylococcus aureus o Streptococcus group C or G o E. Coli o Pseudomonas aeruginosa o Clostridium sp.
10
Q
what are the likely pathogens in pneumonia?
A
o Streptococcus pneumonia o Haemophilus influenzae o Staphylococcus aureus o Klebsiella pneumonia o Moraxella catarrhalis o Mycoplasma pneumonia o Legionella pneumonia o Chlamydia pneumonia
11
Q
what drug class is bactericidal?
A
beta-lactams
12
Q
how do bactericidal drugs work?
A
act on the cell wall to kill the organism
13
Q
indications for bactericidal drugs
A
neutropenia
meningitis
endocarditis
14
Q
what class of drugs are bacteriostatic?
A
macrolides
15
Q
how to bacteriostatic drugs work?
A
inhibit protein synthesis
prevent colony growth
require host immune system to mop up residual indfection
16
Q
when are bacteriostatic drugs useful?
A
in toxic mediated illness
17
Q
what are the advantages of single antimicrobial therapy?
A
simpler
fewer side effects
fewer drug interactions
18
Q
for what would you use combination antimicrobial therapy?
A
HIV and TB
Severe sepsis
Mixed orgnisms
19
Q
when selecting a regimen for antimicrobials what do you need to consider?
A
route of administration dose ADR duration IV vs oral inpatient vs outpatient therapeutic drug monitoring
20
Q
discuss route of administration in regards to antimicrobials
A
Oral bioavailability is the ratio of drug level when given orally compared with level when given IV. It can vary widely e.g. flucloxacillin 50-70% and linezolid 100%. The oral route can be used if not vomiting, normal GI function, no shock, and no organ dysfunction. Use the IV route if there is severe or deep-seated infection, and when the oral route is not reliable
21
Q
name the potential adverse effects of antimicrobials
A
allergy GI Candida liver renal neurological haematological
22
Q
antimicrobial ADR: allergy
A
immediate hypersensitivity - anaphylaxis
delayed hypersensitivity - rash, drug fever, seurm sickness, erythema nodosum, stevens-johnson syndrome
23
Q
what type of antibiotics are people most likely to be allergic to?
A
penicillin
cephalosporin
24
Q
antimicrobial ADR: GI
A
nausea, vomiting, diarrhoea
c, diff
25
antimicrobial ADR: candida
broad spectrum penicillins, cephalosporins
26
antimicrobial ADR: liver
all drugs, particularly tetracyclines, TB drugs
| more likely if existing liver disease
27
antimicrobial ADR: renal
gentamicin, vancomycin
| more likely if pre-existing renal disease or nephrotoxic meds
28
antimicrobial ADR: neurological
ototoxicity - gent, vanc
optic neuropathy - ethambutol
convulsions, encephalopathy - penicillins, cephalosporin
peripheral neuropathy - isoniazid, metronidazole
29
antimicrobial ADR: haematological
marrow toxicity
| megaloblastic anaemia - co-triaxazole
30
how must you liaison with the lab in relation to antimicrobials
send appropriate specimens - culture/direct detection/serology
receiving results - preliminary culture results, sensitivity results, final results
monitoring - disease activity, therapeutic drug monitoring
31
what antibiotics inhibit cell wall synthesis?
B-lactams - penicillins and cephalosporins
| gylcopeptides - vanc, teicoplanin
32
what antibiotics inhibit protein synthesis?
aminoglycosides - gent
macrolindes - clarithromycin
tetracyclines - doxy
oxazolidinones - linezoid
33
what antibiotics inhibit nucleic acid synthesis?
trimethoprim
sulphonamides - sulfamthoxazole
quinolones - ciprofloxacin
34
name 5 penicillins
```
benzylpenicillin V
amoxicillin
flucloxacillin
co-amoxiclav
piperacillin with tazobactam
```
35
benzylpenicillin V: acitivity
streptococci
neisseria
spirochetes
36
benzylpenicillin V: main uses
```
soft tissue
pneumococcal
meningococcal
gonorrhoea
syphilis
```
37
amoxicillin: acivity
broad spectrum but resistance common
38
amoxicillin: main uses
UTI
| RTI
39
flucloxacillin: acivity
staphyloccoi
40
flucloxacillin: main uses
S. aureus
41
co-amoxiclav: activity
broad spectrum inc anaerobes
42
co-amoxiclav: main uses
UTRI
RTI
Soft tissue
SSI
43
piperacillin/tazobactam: activity
brad spectrum incl pseudomonas, anaerobes
44
piperacillin/tazobactam: main uses
neutropenic sepsis
45
name 4 cephalosporins
cefradine
cefuroxime
ceftriaxone
ceftazidime
46
cefradine: activity
broad spectrum, resistance
47
cefradine: main uses
UTI
| soft tissue infection
48
cefuroxime: activity
broad spectrum
49
cefuroxime: main uses
UTRI
RTI
surfical prophylaxis
50
ceftriaxone: activity
broad spectrum esp gram -ve bacilli
51
ceftriaxone: main uses
hospital infections e.g. bacteraemia, pneumonia, abdo spesis
52
ceftriaxone: is a risk factor for?
MRSA
C. diff
VRE
53
ceftazidime: activity
broad spectrum esp gram -ve bacilli
| pseudomonas
54
ceftazidime: main uses
pseudomonal infections in hospital and cystic fibrosis
55
ceftazidime: is a risk factor for?
MRSA
c. diff
VRE
56
name an aminoglycoside
gentamicin
57
gentamicin: activity
gram -ve bacilli
58
gentamicin: main uses
serious gram -ve infections e.g. bacteraemia, endocarditis, neutropenic sepsis
59
gentamicin: ADR
renal toxicity
| ototoxicity
60
name 3 macrolides
clarithromycin
erythromycin
azithromycin
61
clarithromycin: activity
```
streptococci
staphylococci
mycoplasma
chlamydia
legionella
```
62
clarithromycin: main uses
RTI
soft tissue infection if penicillin allergic
STD
63
erythromycin: activity
```
streptococci
staphylococci
mycoplasma
chlamydia
legionella
```
64
erythromycin: main uses
RTI
soft tissue infection if penicillin allergic
STD
65
erythromycin: SE
Gi intolerance
66
azithromycin: activity
better for gram -ve e.g. haemophilus, chlamydia
67
azithromycin: main uses
chlamydia
68
name 3 quinolones
ciprofloxacin
levofloxacin
moxifloxacin
69
ciprofloxacin: activity
gram -ve bacilli inc pseudomonas
| some activity against staph and strep
70
ciprofloxacin: main uses
complicated UTI
complicated hospital acquired pneumonia
some GI infections
71
ciprofloxacin: ADR
c. diff
| may affect growing cartilage
72
levofloxacin/moxifloxacin: activity
```
enhanced activity against staph and strep, less against pseudomonas
pneumococcus
mycoplasma
chlamydia
legionella
```
73
levofloxacin/moxifloxacin: main uses
2nd/3rd line for pneumonia
74
name 2 glycopeptires
vancomycin
| teicoplanin
75
vancomycin/teicoplanin: activity
gram +ve bacteria only (strep/staph)
76
vancomycin/teicoplanin: main uses
MRSA
penicillin allergy
oral - c.diff
77
vancomycin/teicoplanin: SE
nephrotoxicity
78
trimethoprim: activity
gram -ve bacilli
| some activity against strep and staph
79
trimethoprim: main uses
UTI
RTI
MRSA
80
co-trimoxazole (trimethoprim-sulphamethoxazole): activity
broad spectrum
pneumocystis
jiroveci
81
co-trimoxazole (trimethoprim-sulphamethoxazole): main uses
RTI
| PCP
82
co-trimoxazole (trimethoprim-sulphamethoxazole): SE
rash
83
clindamycin: activity
strep
staph
anaerobes
84
clindamycin: main uses
soft tissue infection
| gangrene
85
tetracycline/doxycycline: activity
```
strep
staph
chlamydia
rickettsiae
brucella
```
86
tetracycline/doxycycline: main uses
```
Q fever
brucellosis
chlamydia
atypical pneumonia
MRSA
```
87
when is tetracycline/doxycycline contraindicated?
pregnancy and childhood
88
rifampicin: activity
mycobacteria
meningococcus
stapg
89
rifampicin: main uses
TB
MRSA
meningococcal prophylaxis
stap
90
meropenem: activity
broad spectrum incl anaerobes, pseudomonas
91
meropenem: main uses
2nd/3rd line for hospital infections
92
metronidazole: activity
anaerobes
| protozoa e.g. giardia
93
metronidazole: main uses
SSR
giardiasis
amoebiasis
trichomonal infections
94
metronidazole: reacts with what?
alcohol
95
linezolid: activity
gram +ve bacteria only
| strep, staph, enterococci
96
linezolid: main uses
2nd line for MSSA, MRSA, VRE
97
linezolid: SE
blood and optic neuropathy
98
daptomycin: activity
gram +Ve bacteria only
99
daptomycin: main uses
2nd line for MSSA, MRSA< VRE
100
when is daptomycin inactive?
lung myositis
101
tigecycline: activity
very broad spectrum, inc MRSA, ESBL, anaerobes
102
tigecycline: main uses
3rd line in intraabdo sepsis, soft tissue infection
103
IV tigecycline is ineffective against?
Pseudomonas
104
give 3 examples of azole antifungals
fluconazole
itraconazole
voriconazole
105
what is fluconazole active against?
candida
106
what is itraconazole active against?
candida + aspergillus
107
what is voriconazole active against?
candida + aspergillus
108
name 2 polyene antifungals
amphotericin
| nystatin
109
what is amphotericin active against?
candida + aspergillus
110
what is nystatin active against?
candida
111
name 3 echinocandin antifungal
caspofungin
anidulafungin
micafungin
112
what are the echinocandin antifungals active against?
candida + aspergillus
113
what is terbinafine active against?
tinea
114
all antiviral drugs are? (virustatic or virucidal)
virustatic
115
how do viruses replicate?
obligate intracellular parasites
| utilise host cell enzymes in order to replicate
116
what makes it hard to develop antivirals?
limited viral proteins that are potential targets
117
most drugs target what stages in virus replication?
intracellular
118
most antivirals are have what mechanism of action?
nucleoside analogues - inhibit nucleic acid synthesis
119
antivirals may be used for:
prophylaxis
pre-emptive therapy
overt disease
suppressive therapy
120
antivirals in prophylaxis
to prevent infection
| acyclovir - herpes
121
antivirals in pre-emptive therapy
when evidence of infection detected but before symptoms
| interferon/ribavirin - HCV
122
antivirals in overt disease
aciclovir
| oseltamivir
123
antivirals in suppressive therapy
to keep viral replication below the rate that causes tissue damage in asymptomatic infected patient
antiretrovirals
124
why may suppressive antiviral treatment be needed after successful treatment?
do not eradicate virus from latently infected cells
125
when may you use antivirals for HSV?
mucocutaneous - oral ,genital, eye, skin
encephalitis
immunocompromised
126
when may you use antivirals for chicken pox?
neonate
immunocompromised
pregnant
127
when may you use antivirals for shingles?
only in first 72 hours of onset of symptoms to decrease post-herpetic neuralgia
128
what antivirals and route may you use for HSV and VSV?
o Acyclovir – oral, IV, eye ointment, cream
o Valaciclovir – oral
o Famciclovir – oral
o Foscarnet – IV
o Aciclovir like drugs are only active in herpes infected cells
129
describe the mechanism of action of aciclovir
Aciclovir is converted by viral thymidine kinase to ACVMP. ACVMP then converted by host cell kinases to ACV-TP. ACV-TP, in turn, competitively inhibits and inactivates HSV-specific DNA polymerase preventing further viral DNA synthesis without affecting the normal cellular processes
130
why is there a lack of cellular toxicity with aciclovir?
1. Initial phosphorylation takes place only in virus-infected cells.
2. Aciclovir triphosphate inhibits viral (not cellular) DNA polymerase.
131
discuss antivirals and CMV
```
All available drugs have significant toxicity. Only treat life or sight threatening CMV infections e.g. HIV patients: CMV retinitis, colitis, transplant recipients: pneumonitis. They may also be used to treat neonates with symptomatic congenital CMV infection.
• Ganciclovir – IV, ocular implant
• Valganciclovir – oral
• Cidofovir – IV
• Foscarnet – IV
```
132
discuss antivirals and HIV
This is a fast-changing specialist area for which UK treatment guidelines exist. Combination antiretroviral
therapy (cART), also called highly active antiretroviral therapy (HARRT), uses combinations of antiretrovirals to effectively reduce viral load. This has transformed HIV care with:
1. Restoration of immune function in AIDS
2. Decrease in opportunistic infections
133
discuss antivirals and chronic hep B
```
• Pegylated interferon alpha (SC)
• Nucleoside/tide analogues
o Tenofovir
o Adefovir
o Entecavir
o Lamivudine
o Emtricitabine
o Telbivudine
```
134
discuss antivirals and chronic hep C
• Often 12-48weeks
• Current therapies
o Pegylated interferon alpha and ribavirin
o As above plus protease inhibitor – telaprevir or boceprevir
• New directly acting antivirals in combination
o Daclatasvir
o Sofosbuvir
o Simeprevir
135
discuss antivirals and respiratory infections
```
• Influenza A or B
o Oseltamivir, zanamivir
o Role in both treatment and prophylaxis
o Not always indicated, but if used, start within 48 hrs of onset/contact
• RSV
o Ribavirin
o Rarely indicated
```
136
when should you suspect resistance to herpes virus in immunocompromised patients?
no response to appropriate doses within 7 daus
137
if HSV and CMV are resistant to acyclovir, what is usually effective?
foscarnet
138
name the 9 components of the antibiotic paradox
1. Antibiotics initially led to poorer hygiene
2. Antibiotics increase infections
3. Antibiotics can increase severity of infection
4. Antibiotics increase infections and mortality in uninfected patients
5. Are new antibiotics really the answer?
6. Antibiotics are too cheap – even when new and branded – this encourages inappropriate use
7. There are many similarities to global warming
8. Non-human use is greatest
9. The global village
