lesson seven

Question 1

fungi

Answer 1

• nosocomial (hospital acquired) infections and opportunistic infections of immunocompromised

Question 2

ergosterol

Answer 2

• cell walls of fungi:
  1. chitin: stains with calcium-binding agents
  2. ergosterol: in cell membrane

Question 3

amphotericin B

Answer 3

most widely used antifungal drug

Question 4

3 types of fungi

Answer 4

1. molds
2. yeasts
3. thermally dimorphic

Question 5

molds

Answer 5

• body of fungus called thallus
• most molds are aerobic only

Question 6

yeasts

Answer 6

• oval or spherical
• reproduces by budding
• capable of facultative anaerobic growth

Question 7

yeasts: candida albicans

Answer 7

• attach to epithelial cells as a yeast, but invades deeper tissues by means of pseudohyphae

Question 8

yeasts: saccharomyces

Answer 8

• yeast ethanol for wine
  \carbon dioxide for leavening bread dough- nonpathogenic

Question 9

yeasts: cryptococcus neoformans

Answer 9

• produces a polysaccharide capsule

Question 10

thermally dimorphic fungi

Answer 10

• can grow as mold or yeast
• dimorphism: temperature-dependent
• molds: lower temp
  yeasts: body temp
• not infectious from person to person (the mold form is spread by spores in the air)

Question 11

sporothrix

Answer 11

• subcutaneous infection
• dimorphic
• fungal spores introduced into wound after trauma
• lymphangitis (inflammation of the walls of lymphatic vessels) common, causes more ulcers as disease progresses

Question 12

fungal reproduction

Answer 12

• formation of spores
• very different from bacterial endospores

Question 13

fungal nutrition

Answer 13

• less nutritionally demanding than bacteria
• grow better than bacteria in extreme conditions
• most are aerobic and grow best at 25-30 C

Question 14

fungal diseases

Answer 14

• mycoses
  1. superficial
  2. cutaneous
  3. systemic

Question 15

superficial mycoses

Answer 15

• fungal infection along surface of hair shafts and outer layer of skin
  m
• mild infections: black and white piedra, malassezia furfur

Question 16

cutaneous mycoses

Answer 16

• fungal infection of deeper layers of the epidermis (athletes foot or ringworm)
• caused by dermatophytes (degrade and use keratin as carbon source)
• clinical diseases are calles tineas

Question 17

systemic mycoses

Answer 17

• infections in deep tissues
• caused by primary pathogens such as the dimorphic fungi ot opportunistic pathogens such as candida albicans

Question 18

opportunistic fungal pathogens

Answer 18

• fungi are common cause of infections in immunocompromised individuals

Question 19

candidiasis

Answer 19

• causes vulvo-vaginal candidiasis and thrush
  occurs in newborns, immunocompromised, and people who have been treated with broad spectrum antibiotivs
• c.albicans is normal flora in the gut and mouth

Question 20

antiseptic

Answer 20

disinfectant used on the skin

Question 21

aseptic technique

Answer 21

use of methods to exclude microorganisms

Question 22

bactericidal

Answer 22

kills bacteria

Question 23

bacteriostatic

Answer 23

inhibits growth of bacteria, doesn’t kill

Question 24

disinfectant

Answer 24

chemical used to destroy many micro-organisms and viruses

Question 25

fungicide

Answer 25

kills fungi

Question 26

pasteurization

Answer 26

brief heat treatment used to reduce the number of organisms and to kill pathogenic organisms

Question 27

sanitization

Answer 27

reduction of the # of organisms to a level that meets public health standards

Question 28

sterilization

Answer 28

killing of all forms or microorganisms, including inactivating viruses and spores

Question 29

viricide

Answer 29

inactivates viruses

Question 30

ventilation

Answer 30

- ultra clean air - high efficiency particulate air filters - building standards for correct air flows - isolation rooms with air locks

Question 31

positive pressure

Answer 31

air from corridor cannot get into room (immunocompromised)

Question 32

negative pressure

Answer 32

air from room cannot get into corridor (infectious)

Question 33

sterilization may be achieved by

Answer 33

a. heat :hot air for 1-2 hours - autoclaving - test for effective sterilization using bacillus stearothermophilus spores b. irradiation (gamma or UV) c. filtration d. chemicals

Question 34

most important consideration that determines efficiency of sterilization

Answer 34

whether or not the object to be sterilized is free of organic matter

Question 35

spore test

Answer 35

- -based on testing the ability of the autoclaving procedure to totally inactivate bacterial spores -ampule containing nutrient media and spores of a nonpathogenic bacteria are autoclaved with the object to be sterilized. The ampule is then incubated to test for growth. -growth (lack of sterilization) is indicated by a change in the pH of the ampule growth media seen as a colour change as the spore has germinated and the growing or vegetative bacteria is using nutrients in the medium and producing acid or alkali compounds

Question 36

chemical: halogens

Answer 36

- chlorine, iodine - sterilizes

Question 37

chemical: aldehydes

Answer 37

- sterilizes - cidex

Question 38

chemical: ethylene oxide

Answer 38

- gas that sterilizes

Question 39

chemical: peroxygens

Answer 39

- strong oxidizer - sterilizes

Question 40

most used disinfectants in health care

Answer 40

- halogens: iodine and chlorine - halogens can sterilize if appropriate amount of active chemical is sued and prolonged time of exposure

Question 41

alcohols

Answer 41

- kill bacteria and fungi but not endospores and nonenveloped viruses - mechanism is protein denaturation and disruption of the lipid membranes - used for skin “degerming” - not good for treating wounds, as they cause a coagulation of proteins, creating an environment where the bacteria can grow inside the “scab” - optimal conc. ethanol = 70% (denaturation needs water to work) - Isopropanol = rubbing alcohol - is better than ethanol: does not evaporate as fast

Question 42

antisepsis

Answer 42

for skin

Question 43

disinfection

Answer 43

for surfaces