Basic Principles of Anti-infective Pharmacology

Question 1

Pathogens

Answer 1

microbes that can cause disease

Question 2

Pathogenicity

Answer 2

qualitative ability of organism to cause disease, to infect organisms and to evade host defences

Question 3

Virulence

Answer 3

quantitative measure of organism’s pathogenicity

Question 4

Invasiveness

Answer 4

ability to grow rapidly and to cause damage to surrounding tissue

Question 5

Production of toxins

Answer 5

toxins stimulate development of disease, main elements of pathogenicity

Question 6

Exotoxins

Answer 6

proteins released by bacteria that inactivate or kill host cells

Question 7

Endotoxins

Answer 7

non-protein released from cell wall of Gram-negative bacteria that elicit immune responses (cause macrophages to release cytokines leading to fever, inflammation and chills)

Question 8

Classifying Bacteria: By staining properties

Answer 8

• gram positive - stay positive

- gram negative

Question 9

Classifying Bacteria: by shape

Answer 9

• rod-shaped - bacillus
• spherical - coccus
• spiral

Question 10

Classifying Bacteria: by ability to use oxygen

Answer 10

• Aerobic - thrive in O2 rich environment

- Anaerobic - do not require O2 to survive

Question 11

Anti-Infectives

Answer 11

Drug that is effective against pathogens

Question 12

Classification of Anti-Infectives

Answer 12

• susceptible organism (antibiotic, antiviral, antifungal, antiprotozoan)
• chemical structure of drug
• mechanism (bacteriocidal, bacteriostatic - inhibiting the bacterial protein synthesis pathways)

Question 13

Mechanisms of Antibacterial Agents

Answer 13

• drugs that damage bacterial cell wall (beta-lactam antibiotics synthesis of bacterial cell wall; tend to be bacteriocidal)
• drugs that damage cell membrane
• drugs that inhibit protein synthesis
• Drugs that inhibit DNA replication or bacterial cell division

Question 14

Acquired Resistance

Answer 14

• ability of organism to become insensitive to effects of anti-infective
• major clinical problem, worsened by improper use or anti-infectives

Question 15

Mechanisms of Resistane

Answer 15

• pathogen destroys drug
• pathogen prevents drug entry or pumps drug out of itself
• pathogen alters target site of drug or undergoes mutation or adapts to drug

Question 16

Bacteria change physiology to become resistant by:

Answer 16

• replicating rapidly
• mutating spontaneously and randomly
• acquiring resistance and promoting resistance to other bacteria via conjugation (transfer of small pieces of DNA called plasmids that contain resistance promoting gene)

Question 17

Guidelines to help prevent resistant strains from developing

Answer 17

1. preventing infections when possible
2. diagnosing and treating the infection properly and specifically by identifying the bacteria
3. limiting use of antibiotics where possible
4. preventing the transmission of infections

Question 18

Four main sources for spreading of HAIs

Answer 18

1. patients flora
2. invasive devices (catheters or endoscopes)
3. medical personnel
4. medical environment

Question 19

Methicillin-resistant Staphylococcus aureus (MRSA)

Answer 19

• resistant to certain antibiotics
• at least 60% of MRSA infections resistant to penicillin
• most often acquired in hospital
• usually occurs in patients with weakened immune systems
• therapy options are limited

Question 20

Vancomycin-resistant Enterococci (VRE)

Answer 20

• found in wounds and pressure ulcers in hospitals and nursing homes
• patients with weakened immune systems at most risk

Question 21

use of correct antibiotic is key to effective treatment

Answer 21

• where possible, use testing culture and sensitivity to identify the organism, and then the appropriate antibiotic
• if not possible to do C&S begin with broad spectrum antibiotic then use a narrow-spectrum antibiotic

Question 22

Guidelines for Antibiotic Therapy

Answer 22

• anitbiotics should not be used for viral infections or for cough
• if infection caused by one microbe, treatment with a single drug is usually best (combining antibiotics can decrease their effectiveness and promote resistant strains)
• Antibiotics are sometimes given (to prevent secondary infections, prophylactically for some surgeries, for patients with damaged heart valves)

Question 23

Patient factors affect choice of anti-infective

Answer 23

1. determine the hosts defences and immune system status
2. local tissue conditions
3. knowing patients allergy history and drug hypersensitivity
4. pregnancy, age, and genetics

Question 24

Superinfections

Answer 24

develop when host flora is damaged by antibiotic as nutrients and space become available for pathogens to grow