Week 14 Exam 4

Question 1

Goal of Antimicrobial chemotherapy

Answer 1

administer a drug to an infected person that destroys the infective agent without harming the hosts cell

Question 2

a drug must be able to:

Answer 2

• be easy to administer and able to reach the infectious agent anywhere in the body
• be toxic to the infectious agent and nontoxic to the host
• remain active in the body as long as needed and be safe and easily broken down and excreted

Question 3

prophylaxis

Answer 3

use of a drug to prevent infection of a person at risk

Question 4

antimicrobials

Answer 4

all-inclusive term for any antimicrobial drug

Question 5

antibiotics

Answer 5

inhibit or destroy bacteria

Question 6

semisynthetic drugs

Answer 6

drugs that are chemically modified in the lab

Question 7

synthetic drugs

Answer 7

drugs produced entirely in the lab

Question 8

narrow-spectrum (limited spectrum)

Answer 8

antimicrobials effective against a limited array f microbial types
-a drug effective mainly against gram positive bacteria

Question 9

broad-spectrum (extended spectrum)

Answer 9

antimicrobials effective against a wide variety of microbial types
-a drug effective against both gram positive and negative bacteria

Question 10

what factors must be known before antimicrobial therapy can begin?

Answer 10

• the identity of the microorganism causing the infection
• the degree of the microorganisms susceptibility (or sensitivity) to various drugs
  
  • disc-diffusion test: kirby bauer & E-test
  • tube-diffusion test: MIC

Question 11

Disk Diffusion Test

Answer 11

• surface of an agar plate is spread with test bacterium
• small discs containing a prepared amount of antibiotic are placed on the plate
• zone of inhibition surrounding the discs is measured and compared with a standard for each drug

Question 12

Tube dilution test

Answer 12

• antimircobial is diluted serially in tubes of broth
• each tube is inoculated with a small uniform sample of pure culture, incubated and examined
• minimum inhibitory concentration MIC: smallest concentration (highest dilution) of drug that visibly inhibits growth

Question 13

• broad-spectrum:

- narrow-spectrum:

Answer 13

• broad-spectrum: effective against more than one group of bacteria
• narrow-spectrum: target a specific group

Question 14

how do bacteria in biofilms behave?

Answer 14

• often unaffected by antimicrobials
• antibiotics often cannot penetrate the sticky extracellular material surrounding biofilms
• bacteria in biofilms express a different phenotype and have different antibiotic susceptibility profiles than free living bacteria

Question 15

treating fungal infections

Answer 15

fungal cells are eukaryotic, present special problems in chemotherapy:

• drugs designed to act on bacteria are ineffective against fungi
• similarities between fungal and human cells mean that drugs toxic to fungi will harm human tissues
• only a few agents with special anti fungal properties have been developed

Question 16

treating protozoal infections

Answer 16

• anti-malarial drugs

- ameobicies

Question 17

treating helminth infections

Answer 17

• flukes, tapeworms, and roundworms are larger parasites.
• theri physiology is much more similar to humans
• blocking reproduction doesn’t effect adult worms
• most effective drugs immobilize, disintegrate, or inhibit the metabolism of all stages of the life cycle

Question 18

treating viral infections

Answer 18

• infectious agent relies on a host cell for the vast majority of its metabolic functions
• disrupting viral metabolism requires disruption of cellular metabolism of host
• inhibition of virus entry: receptor/fusion/uncoating
• inhibition of nucleic acid synthesis
• inhibition of viral assembly/release

Question 19

antimicrobial resistance:

Answer 19

-adaptive response in which microorganisms begin to tolerate an amount of drug that would normally be inhibitory

due to genetic versatility & adaptability of microbial populations
microbes become newly resistant to a drug after one of the following occurs:
-spontaneous mutations in critical chromosomal genes
-acquisition of entire new genes or sets of genes via horizontal transfer from another species

Question 20

replacing normal flora terms;

• probiotics:
• prebiotics:
• fecal transplants:

Answer 20

• probiotics: preparations of live microorganisms fed to animals and humans to improve intestinal biota
• prebiotics: nutrients that encourage the growth of beneficial microbes in intestine
• fecal transplants: transfer of feces from a healthy patient via colonoscopy

Question 21

drugs can adversely affect the following organs:

Answer 21

• liver (hepatotoxic)
• kidneys (nephrotoxic)
• GI tract
• respiratory tract
• nervous system (neurotoxic)
• skin
• bones and teeth
• cardiovascular system and blood forming tissues (hemotoxic)

Question 22

Allergic reactions to antimicrobials

Answer 22

• drugs act as an antigen that stimulates an allergic reation
• can be provoked by the intact molecule or by metabolic alteration of the drug
• allergies have been reported for every major drug
• penicillin is most common
• sensitization occurs during the first contact with the drug
• second exposure can lead to hives, respiratory inflammation, or anaphylaxis

Question 23

what should every health care professional be critically aware of?

Answer 23

admirable & utilitarian nature of antimicrobials and of their limitations

Question 24

flu virus

Answer 24

• segmented RNA genome
• orthomyxoviridge
• 3 types: A, B, C
• enveloped with hemagglutinin & neuraminidase glycoproteins

Question 25

flu replication

Answer 25

1. attach to militated epithetical cells via HA protein 2. entry by endocytosis 3. uncoating occurs in endosome &mediated by drop in pH 4. synthesis in nucleus by RNA dependent transcriptase, cap snatching allows for translation by host cell machinery 5. assembly of genome and capsomeres in nucleus 6. release by budding through cytoplasmic membrane

Question 26

flu symptoms and treatment

Answer 26

- fever, muscle aches, lack energy, sore throat, nasal congestion, cough - incubation period 1-2 days - vaccines are 80-90% effective - amantadine and rimantadine prevent type A but no type B, target viral uncoating - neuraminidase inhibitors (zanmivir and aseltamivir) are effective against both A & B

Question 27

flu endemics

Answer 27

- genetic drift: mutation in genes for viral surface proteins, typically HA/Na - makes immunity from previous flu infections less effective: epidemics - antigenetic drifts: reassert of genomes, 2 different strains of flu infect same cell and incorporated into new capsid