Infection Session 2- Infection Model And Antibiotics

Question 1

Describe the basic model of infection

Answer 1

Pathogen and patient -> infection -> management -> outcome

Question 2

What aspects of the patient will affect their infection?

Answer 2

Age
Gender
Physiological state
Pathological state
Social factors
Calendar time
Relative time
Places they've been

Question 3

Name the mechanisms of infection

Answer 3

Contiguous spread
Inoculation
Haematogenous
Ingestion
Inhalation
Vector
Vertical transmission

Question 4

What is the difference between specific and supportive treatment?

Answer 4

Specific treats the infection and supportive make the patient more comfortable- both can be used simultaneously

Question 5

What can be described as supportive treatment?

Answer 5

Symptom relief and physiological restoration

Question 6

What are the examples of specific treatment?

Answer 6

Antimicrobials and surgery

Question 7

What are the 4 different categories of antimicrobials?

Answer 7

Antibacterial
Antifungal
Antiviral
Antiprotozoal

Question 8

What are the different ways tat antibacterial can be classified?

Answer 8

Bactericidal or bacteriostatic
Spectrum- broad/narrow
Target site (mechanism of action)
Chemical structure (antibacterial class)

Question 9

List the ideal features of antimicrobial agents

Answer 9

Selectively toxic
Few adverse effects
Reach site of infection
Oral/IV formulation
Long half life (infrequent dosing)
No interference with other drugs

Question 10

What are the targets for different classes of antibacterials?

Answer 10

Cell was synthesis
Protein synthesis
Cell membrane function
Nucleic acid synthesis

Question 11

How can some microbes become resistant? (Mechanisms)

Answer 11

Drug inactivating enzymes
Altered target- target enzyme has lowered affinity for antibacterial
Altered uptake- decreased permeability or increased efflux

Question 12

How can antibiotic resistance occur genetically?

Answer 12

Chromosome gene mutation

Horizontal gene transfer

Question 13

Name the different penicillins and what they are active against

Answer 13

Penicillin- mainly active against streptococci
Amoxicillin- active against all gram +ve and some gram -ve
Flucloxacillin- active against staphylococci and streptococci
B-lactamase inhibitor combinations:
Co-amoxiclav- all of above and anaerobes and gram -ve
Piperacillin/tazobactam- as above and more gram -ve including pseudomonas

Question 14

What are the properties of cephalosporins?

Answer 14

Broad spectrum but no anaerobe activity- better at treating gram -ve than penicillin (can cause C. Diff)

Question 15

Name a cephalosporin and where is has good activity

Answer 15

Cetriaxone has good activity in the CSF

Question 16

What is an example of a carbapenem and what are its properties?

Answer 16

Meropenem- very broad spectrum, active against most gram -ve

Can generally be used in penicillin allergy

Question 17

What is an example of a glycopeptide and what are its properties?

Answer 17

Vancomycin- active against most gram +ve, some enterococci are resistant, not absorbed, narrow therapeutic margin

Question 18

What are the important clinical points about tetracycline and doxycycline?

Answer 18

Oral only
Broad spectrum- used in penicillin allergy for gram +ve
Active in atypical pathogens in pneumonia
Active against chlamydia and some protozoa
Don’t give to anyone under the age of 12

Question 19

What is the most common aminoglycoside and its clinical relevance?

Answer 19

Gentamicin- profound activity against gram -ve
Good activity in blood/urine
Can be nephrotoxic/ototoxic
Therapeutic drug monitoring required
Reserved for severe gram -ve sepsis

Question 20

Give an example of a macrolide and its properties

Answer 20

Erythromycin- well distributed including intracellular penetration
Alternative to penicillin for mild gram +ve infections
Active against atypical respiratory pathogens

Question 21

Give an example of quinolone and its properties

Answer 21

Ciprofloxacin- inhibit DNA gyrase
Very active against gram -ve and atypical pathogens
Risk of C. Diff

Question 22

How does trimethoprim and sulphonamides work?

Answer 22

Inhibitors of folic acid synthesis

Question 23

What are trimethoprim and sulphonamides used for?

Answer 23

Trimethoprim used alone in uk for UTI

When combined with sulphamethoxazole- used to treat PCP and has activity against MRSA

Question 24

What are the 2 types of antifungals?

Answer 24

Azores- active against yeasts +/- molds

Polyenes

Question 25

How do Azores work and what are they used for?

Answer 25

Inhibit cell membrane synthesis

Fluconazole used to treat candida

Question 26

How do polyenes work and what are they used for?

Answer 26

Inhibit cell membrane function
Nystatin used for topical treatment of candida
Amphotericin for IV treatment of systemic fungal infections

Question 27

Give 2 examples of antivirals and what they are used for

Answer 27

Aciclovir- when phosphorylated inhibits viral DNA polymerase, used for herpes simplex and varicella zoster
Tamiflu- inhibits viral neuraminidase, used for influenza A and B

Question 28

What is metronidazole used for?

Answer 28

Anaerobic bacteria

Protozoa- amoebae, giardiasis and trichomonas