Anti virals, microbials and fungals

Question 1

Give 4 types of anti herpes drugs

Answer 1

aciclovir, gangciclovir, foscarnet, cidofovir

Question 2

How do aciclovir, gangciclovir, foscarnet and cidofovir work?

Answer 2

All inhibit viral DNA polymerase, most by acting as guanosine analogue, except forscarnet which acts as a pyrophosphate analogue

Question 3

Which virus is aciclovir used to treat?

Answer 3

HSV1 and 2 and VZV

Question 4

How can you get resistance to aciclovir?

Answer 4

reduction/ removal of the TK enzyme which activates aciclovir

Question 5

Give 3 ADRs of aciclovir and gangciclovir?

Answer 5

• nephrotoxic

- headache, confusion, behaviour change, psychosis, seizures, coma

Question 6

Describe the order of drugs used to treat CMV

Answer 6

gangciclovir, then foscarnet, then cidofovir

Question 7

Describe how resistance can arise to gangciclovir, foscarnet and cidofovir

Answer 7

foscarnet= resistance can arise from RT or polymerase mutations but are rare
Cidofovir and gangciclovir= DNA polymerase mutations (esp UL54)

Question 8

What can cidofovir be used to treat?

Answer 8

CMV, adenovirus, EBV, polymavirus etc

Question 9

Give 3 ADRs of cidofovir and foscarnet

Answer 9

• nephrotoxic
• myelosurpression
• CNS effects (headache, n+v, coma, seizures etc)
• diarrhoea
• fever
• anxiety
• fatigue

Question 10

How is hepatitis B treated?

Answer 10

Lamivudine, adefovir, entacavir

Question 11

How does lamivudine work?

Answer 11

Cystidine analogue- false substrate and chain terminator of reverse transcriptase enzyme.

Question 12

Give an ADR of lamivudine

Answer 12

raised LFTs, otherwise well tolerated

Question 13

Give one drug which may be used for treatment of hep C?

Answer 13

Ribavirin, also interferons. Sofosburvir is new drug with good data.

Question 14

How does sofosbuvir work?

Answer 14

Inhibits HCV polymerase to inhibit replication of virus

Question 15

How does ribavirin work?

Answer 15

Guanosine analongue, so inhibits RNA/mRNA synthesis and nucleoside stores

Question 16

Name 2 antivirals to treat influenza

Answer 16

oseltamivir, zanamivir. Note: these can be used a prophylaxis, are not that effective and yearly vaccines are the preffered approach

Question 17

How do oseltamivir (tamiflu) and zanamivir work?

Answer 17

inhibit neuraminidase, which prevents newly made virus leaving the host cell

Question 18

How does resistance to anti- influenza drugs occur?

Answer 18

neuraminidase enzyme mutations,

Question 19

Give 4 classes of drugs to treat HIV

Answer 19

• NRTIs (nucleoside RT inhibitors causing chain termination- lamivudine)
• NNRTIs (direct (non- nucleoside) RT inhibitors - neviapine)
• protease inhibitors (neviapine)
• fusion inhibitors (enfurvirtide)
• Integrase inhibitors
• CD4 receptor inhibitors

Question 20

Give 2 ADRs of NRTIs such as zidovudine (AZT)

Answer 20

• hyperlactataemia
• lactic acidosis
• hepatomegaly
• steatosis

Question 21

Why is anti- viral resistance monitoring important?

Answer 21

• optimises clinical outcomes and care of the pt
• reduce costs and ADRs of using ineffective therapy
• reducing spread of resistant viruses

Question 22

When is viral resistance testing done?

Answer 22

when the treatment is not working, need to see if due to resistance, poor compliance or high baseline of viral load

Question 23

how is viral resistance testing done?

Answer 23

By phenotype- intubate virus with varying concentrations of the drug and culture to see if virus can grow
By genotype- gene sequencing, PCR etc

Question 24

What is an unfit virus? When do they often occur

Answer 24

A virus which has mutated to become resistant to an antiviral, but as a result has become less effective at replicating. The drug which the virus is resistant to is still given as it keeps replicating power of the virus low. This is common in lamivudine

Question 25

When may anti- biotics be given for prophylaxis?

Answer 25

before surgery, meningitis contact, asplenia, immuno deficiency

Question 26

What factors are taken into consideration when giving empirical antibiotics?

Answer 26

- likely organism (age, date, PMH, occupation, travel, duration and site of infection) - likely susceptibility and consequences of wrong choice - safety (age, allergies, interactions, toxcicity, cost, administration, pregnancy)

Question 27

Give 3 general ADRs of anti- biotics?

Answer 27

- N+ V - Most are neuro, nephro and hepatotoxic - many may cause idiosyncratic reactions (dunno cause/ how it happens) - ecological effects on microbiota (C. diff) - drug interactions

Question 28

How does vancomycin work? When is it used?

Answer 28

inhibits cell wall synthesis via phospholipids and peptidoglycan inhibition at a site earlier than penicillins . it is generally reserved for mutli drug resistant organisms (mainly gram+)

Question 29

Which anti- microbials are most likely to cause C. diff?

Answer 29

- cephalosporins - co- amoxiclav - clindamycin - fluoroquinolones

Question 30

Give one ADR specific to tetracyline?

Answer 30

turns teeth yellow if given to children

Question 31

Which drug would be given to treat cellulitis?

Answer 31

Flucoxacillin

Question 32

What drug should be used to treat c. diff?

Answer 32

Metronidazole

Question 33

What drug should be used to treat UTIs?

Answer 33

Trimethoprim or nitrofurantion

Question 34

What drug should be used to treat neisseria meningitisis?

Answer 34

ceftriaxone

Question 35

What drug should be used to treat gram + sepsis?

Answer 35

vancomycin

Question 36

What drug should be used to treat uncomplicated community acquired pneumonia?

Answer 36

amoxicillin or doxycylin

Question 37

What drug should be used to treat complicated community acquired pneumonia?

Answer 37

macrolides or tetracyline

Question 38

What drug should be used to treat hospital acquired pneumonia?

Answer 38

co- amoxiclav

Question 39

What drug should be used to treat severe, bacterial gastroenteritis (campylobacter, enterotoxic E. coli, shigella dysenteriae)

Answer 39

ciprofloxacin (if used in salmonella, may make you worse)

Question 40

What drugs should be used severe giardia, entamoeba, cyclospora and cyptosporidium infections?

Answer 40

Giardia and entamoeba= metronidazole Cyclospora= trimethoprim cyptosporisium= nitazoxanide

Question 41

How are trachomatis vaginalis, thrush and bacterial vaginosis treated?

Answer 41

TV and BV= metronidazole | thrush= fluconazole

Question 42

How is syphilis treated?

Answer 42

IM benzathine penicillin G

Question 43

How is gonorrhoea treated?

Answer 43

IM ceftriaxone and oral azithromycin

Question 44

How is chlamydia trachomatis treated?

Answer 44

doxycycline

Question 45

How is pyelonephritis treated?

Answer 45

trimethoprim, not nitrofurantoin as not systemic

Question 46

What is the minimum inhibitory concentration?

Answer 46

The minimum concentration of antibiotics needed to inhibit growth of a bacteria in vitro to a specific single isolate and antibiotic

Question 47

What is the difference between time and concentration dependant killing?

Answer 47

One theory is that successful treatment needs prolonged antibiotic prescence at a infection, but concentration doesnt matter as long as >MIC Conc dependant killing is that time doesnt matter as much as concentration

Question 48

How does carbapenem resistance occur?

Answer 48

- decreased permeability - increased efflux - carbepenemase production

Question 49

State the 3 categories of antimicrobial stewardship and for each give an example

Answer 49

- persuasive: education, consensus, opinion leaders, reminders, audit, feedback - restrictive: formulary restriction, automatic stop orders - structural: computerised records, rapid lab tests, expert systems, quality monitoring

Question 50

What 4 drugs are needed to treat TB?

Answer 50

- rifampicin (6 months) - isoniazid (6 months) - pyrazinamide (2 months) - ethambutol (2 months)

Question 51

Give 4 ADRs for drugs to treat TB?

Answer 51

- all hepatotoxic - many nephrotoxic - GI upset - psychosis - epilepsy - anaphylaxis - optic neuritis, colourblindness (ethambutol)