Antimicrobial Chemotherapy Flashcards
1
Q
What are the 7 principles for prescribing antimicrobials?
A
- Indications for antimicrobials
- Making a clinical diagnosis
- Patient characteristics
- Antimicrobial selection
- Regimen selection
- Liasion with laboratory
- Antimicrobial stewardship
2
Q
What is empiric therapy?
A
Treating without microbiology results
3
Q
What is directed therapy?
A
Treatment based on microbiology results
4
Q
What are the two types of prophylaxis?
A
Primary, e.g. antimalarials, pre-op antibiotics etc.
Secondary (to prevent a second episode)
5
Q
What may involved in assessing the severity of an infection?
A
qSOFA, ?septic shock
6
Q
What patient characteristics may influence antimicrobial choice?
A
- Age
- Renal function
- Liver function
- Immunocompromised
- Pregnancy
Known allergies
7
Q
What should antibiotic selection be based on?
A
The known or most likly causative organism(s)
8
Q
What is the difference between bactericial and bacteriostatic drugs?
A
Bactericidal - kills
Bacteriostatic - prevents replication
9
Q
What features must you consider when selecting an appropriate regimen?
A
- Route of administration
- Dose
- Adverse events
- Duration
- IV to oral switch therapy
- Inpatient/outpatient therapy (OPAT)
- Therapeutic drug monitoring
10
Q
What is involved in antimicrobial stewardship?
A
Making the best use of our current antibiotics
11
Q
Describe the empirical Rx of cellulitis
A
Cellulitis most likely to be strep pyogenes so chose antibiotic effective against that
12
Q
Describe the empirical Rx of pneumonia
A
Most likely to be strep pneumonia (then H. influenzae, staph aureus…)
If have COPD - moraxella catarrhalis
If been in contact with contaminated water - legionella most common
13
Q
Give an example of a bactericical
A
Beta-lactams
14
Q
How do bactericidals work?
A
Act on cell wall
15
Q
What are the indications for bactericidals?
A
- Neutropenia
- Meningitis
- Endocarditis
- Lifethreatening infections
16
Q
Give an example of a bacteriostatic
A
Macrolides
17
Q
How do bacteriostatic drugs work?
A
Inhibit protein synthesis and prevent colony growth
Require host to mop up residual infection
18
Q
When are bacteriostatic drugs most useful?
A
In treating toxin mediated illness as they are able to switch off the proteins that the bacteria use to make toxins
19
Q
Name 2 conditions that require combination antimicrobials
A
HIV and TB
Others: sepsis, mixed organisms
20
Q
A
21
Q
When should you give oral route for antimicrobials?
A
IT is preferred whereever possible if no vomiting, normal GI function, no shock, no organ dysfunction
22
Q
When should you give IV route for antimicrobials?
A
Severe, deep seated infection and when oral route not reliable
23
Q
What are some of the allergic reactions that can occur due to antibiotics?
A
Immediate hypersensitivity (anaphylaxis)
Delayed hypersensitivity (rash, fever, serum sickness, erythema nodosum, SJS)
GI, e.g nausea, vomiting, diarrhoea, C. diff infection
24
Q
Which antibiotics shouldn’t be used in those with renal damage?
A
Vancomycin and gentamicin
25
What antimicrobials are cytotoxic?
Gentamicin and vancomycin
26
What antimicrobial can cause optic neuropathy?
Ethambutol
27
What antimicrobials can cause convulsions and encephalopathy?
Penicillins and cephalosporins
28
What antimicrobials can cause peripheral neuropathy?
Isonazid, metronidazole
29
What antimicrobial can cause megoblastic anaemia and how?
Co-trimaxazole
Poisons DNA synthesis via interrupting foltate metabolism
30
'Reduce the 4 C's and reduce C. diff'
What are the 4 C's?
Ceftriaxone, co-amoxiclav, clindamycin ciprofloxacin
31
What are the classes of antimicrobial?
* Penicillins (beta-lactams)
* Cephalosporins (beta-lactams)
* Aminoglycosides
* Macrolides
* Quinolones
* Glycopeptides
* Others
* Antifungals
* Anti-virals
32
Which antimicrobials work by inhibiting cell wall synthesis?
Beta-lactams (peincillins and cephalosporins)
Glycopeptides (vancomycin and teicoplanin)
33
Which antimicrobials work by inhibiting protein synthesis?
Aminoglycosides (gentamicin)
Macrolides (clarithromycin)
Tetracyclines (doxycycline)
Oxazolidnones (linezolid)
34
Which antimicrobials work by inhibiting nucleic acid synthesis?
Trimethoprim
Sulfonamides (sulfamethoxazole)
Quinolones (ciprofloxacin)
35
How is benzyl penicillin administered?
IV/IM only
36
What is the activity of benzyl penicillin against?
Streptococci, Neisseria, spirochetes
37
What is benzyl penicillin mostly used to Rx?
Soft tissue, pneumococcal, meningococcal, gonorrhoea, syphilis infections
38
What is the activity of amoxicillin against?
Broad spectrum
39
What is amoxicillin mostly used to Rx?
UTI, RTI
40
What is flucloxacillin mostly used to Rx?
S. aureus infections
41
What is co-amoxiclav mostly used to Rx?
UTI, RTI, soft tissue infections, surgical wound infections
42
What is piperacillin/tazobactam mostly used to Rx?
Neutropenic sepsis
43
What is cefradine mostly used to Rx?
UTI, soft tissue infection
44
What is cefuroxime mostly used to Rx?
UTI, RTI, surgical prophylaxis
45
What is ceftriazone/cefotaxime mostly used to Rx?
Hospital infections, e.g. bacteraemia, pneumonia, abdo sepsis
46
What is cefazidine mostly used to Rx?
Pseudomonal infections in hospital and in CF
47
What are gentamicin/amikacin mostly used to Rx?
Serious gram -ve infections, e.g. bacteraemia, endocarditis, neutropenic sepsis
48
What are clarithromycin/erythromycin mostly used to treat?
Respiratory infections, soft tissue infection (if penicillin allergic), STF
49
What is azithromycin mainly used to treat?
Chlamydia
50
What is the main use of ciprofloxacin?
Complicated UTI, complicated HAI, pneumonia, some GI infections
51
What is the main use of levofloxacin/moxifloxacin?
2nd/3rd line for pneumonia
52
What are vancomycin/teicoplanin mostly used for?
MRSA, patients allergic to penicllin, C. diff
53
What is the main use of trimethoprim?
UTI, respiratory infection, MRSA
54
What is the main use of co-trimaxazole?
Respiratory infection, PCP
55
What is the main use of clindamycin?
Soft tissue infection gangrene
56
What is the main use of tetracycline/doxycyline?
Q fever, brucellosis, chlamydia, atypical pneumonia, MRSA
57
What is the main use of rifampicin?
TB, MRSA, meningococcal prophylaxis, complicated staph infections
58
What is the main use of meropenem?
2nd/3rd line for hospital infections
59
What is the main use of linezolid/daptomycin?
2nd line agent for MSSA, MRSA, VRE
60
What is the main use of tigecycline?
2nd line intra-abdominal sepsis, soft tissue infections (last resort)
61
What bacteria does co-amoxiclav have activity against?
Broad spectrum, incl anaerobes
62
What bacteria does piperacillin/tazobactam have activity against?
Broad spectrum, incl anaerobes and pseudomonas
63
What bacteria do the cephalosporins have activity against?
Broad spectrum
64
What bacteria do aminoglycosides have activity against?
Gram negatives
65
What bacteria does clarithromycin/erythromycin have activity against?
Strep, staph, myocplasma, chlamydia, legionella
66
What bacteria does azithromycin have activity against?
Better for gram -ves (incl haemophilus, chlamydia)
67
What bacteria does ciprofloxacin have activity against?
Gram -ve bacilli incl. pseudomonas w. some activity against staph/strep
68
What bacteria does levofloxacin/moxifloxacin have activity against?
Enhanced against staph/strep
Active against pneumococcus, mycoplasma, chlamydia, legionella
69
What bacteria do glycopeptides have activity against?
Gram +ve only (staph, strep)
70
What bacteria does trimethoprim have activity against?
Gram -ve bacilli, some activity against strep and staph
71
What bacteria does co-trimoxazole have activity against?
Broad spectrum, PJP
72
What bacteria does clindamycin have activity against?
Strep, staph, anaerobes
73
What bacteria does tetracycline/doxcycline have activity against?
Strep, staph, chlamydia, ricketassiae, brucella
74
What bacteria does rifampicin have activity against?
Mycobacteria, meningococcus, staph
75
What bacteria does meropenem have activity against?
Broad spectrum antibiotics incl anaerobes, pseudomonas
76
What bacteria does metronidazole have activity against?
Anaerobes, protozoa
77
What bacteria does linezolid/daptomycin have activity against?
Gram +ve bacterial only
78
What bacteria does tigecycline have activity against?
V broad spectrum, e.g. MRSA, ESBL
79
What is the main use of metronidazole?
Surgical infections, giardiasis, amoebiasis, trichomonal infections
80
Which antibiotics are in the penicillins group?
* Benzylpenicillin penicillin V
* Amoxicillin
* Flucloxacillin
* Co-amoxiclav
* Piperacillin/tazobactam
81
What antibiotics are in the cephalosporin group?
* Cefradine (1st)
* Cefuroxime (2nd)
* Ceftriazone/cefotaxime (3rd)
* Cefazidine
82
What antibiotics are aminoglycosides?
* Gentamicin
* Amikacin
83
What antibiotics are macrolides?
* Clarithromycin
* Erythromycin
* Azithromycin
84
What antibiotics are quinolones?
* Ciprofloxacin
* Levofloxacin/moxifloxacin
85
What antibiotics are glycopeptides?
* Vancomycin
* Teicoplanin
86
What are the four types of antifungal therapy?
Azoles
Polyenes
Echinocandins
Terbinafine
87
What are the azole drugs and what fungi are they active against?
* Fluconazole: candida, some resistance
* Itraconazole: candida, aspergillus
* Voriconazole: candida, aspergillus
88
What are the polyenes and what are the active against?
* Amphotericin: candida, aspergillus
* Nystatin: candida
89
What are the endocandins and what are the active against?
Caspofungin, anidulafungin, micafungin: candida, aspergillus
90
What is terbafine mostly used for?
Tinea or fungal nail infections
91
Delete as appropriate:
All antivirals are viruostatic/virucidal
Viruostatic
## Footnote
Viruses require host cell enzymes to replicate & therefore antivirals target viral proteins that do this
92
How do most antivirals work?
Most are nucleoside analogues
They work by inhibiting nucleic acid synthesis
93
What is a big problem with antivirals?
Toxicity to the host cell may lead to side effects
Only used in minority of cases because of this
94
What are the types of antiviral treatment?
* Prophylaxis (preventing infection)
* Pre-emptive (evidence of infection detected but before symptoms apparent)
* Overt disease
* Suppressive therapy (keep viral replication below rate that causes tissue damage in asymptomatic infected patients, e.g. antiretrovirals
95
When are antivirals indicated in herpes infections?
* Mucocutaneous: oral, genital, eye, skin
* Encephalitis
* Immunocompromised
96
What antivirals can used to treat herpes infection?
Aciclovir, famciclovir, ganciclovir
Usually use foscarnet if aciclovir resistant
97
What antivirals can be used to treat HCV?
Pegylated nterferon alpha (s/c)/ribavirin + protease inhibitor (e.g. telaprevir/boceprevir)
98
When are antivirals indicated for chickenpox?
* In those at increased risk of complications
* Neonates
* Immunocompromised
* Pregnant
* Immunocomponent adult (only if begun within 24 hours of onset of rash)
99
The treatment of shingles with antivirals only decreases the risk of ___________ in the immuncompetent if begun within \_\_\_hours of onset of symptoms
post-herpetic neuralgia
72
100
What is the mode of action of aciclovir?
Acyclovir is converted by viral thymidine kinase to AVCMP
ACVMP then converted by host cell kinases to ACV-TP via phosphorylation
ACV-TP (aciclovir triphosphate) competes for the viral DNA polymerase, becomes incorporated into the viral DNA chain and inhibits further DNA polymerase activity
Aciclovir lacks a 3’-hydroxyl group on its acyclic side-chain, and therefore cannot form a phosphodiester bond with the next nucleotide due to be added to the growing herpes DNA chain, which is terminated prematurely
This prevents further viral DNA synthesis without affecting normal cellular processes
101
What antiviral may be used in the treatment of respiratory syntical virus?
Ribavirin (rarely indicated)
102
What are the two ways to test for resistance to antivirals?
* Phenotypic – can virus grow in presence of compound
* Genotypic – sequence genome and identify resistance-associated mutations
103
What 3 points are included in the UK 5 Year Antimicrobial Resistance Strategy?
* Improve knowledge and understanding of AMR
* Converse and steward the effectiveness of existing treatments
* Stimulate the development of new antibiotics, diagnostics and novel therapies
104
What is the role of the Scottish Antimicrobial Prescribing Group (SAPG)?
Coordinates and delivers a national framework for antimicrobial stewardship to enhance the quality of antimicrobial prescribing and management in Scotland
105
What is IVOST?
IV to Oral Switch Therapy
Consider switching patients from IV to oral antibiotics after 48 hours, provided that patient improving clinically & able to tolerate oral formulation (can swallow, normal vital signs etc.)
