Molds

Question 1

4 main criteria in identifying molds?

Answer 1

1) growth rate in culture
2) presence of a yeast phase (is it dimorphic?)
3) Colonial and microscopic morphology (appearance) *** MOST IMPORTANT
4) biochemical tests

Question 2

Labs without biological safety cabinets must do what?

Answer 2

NOT work on any mold, except those believed to be dermatophytes

Question 3

Examination of the hyphae enables classification into three groups

Answer 3

1) septate UNPIGMENTED (HYALINE)
^ majority of important molds
2) deptate PIGMENTED (DEMATIACEOUS) 
^ feature brown pigment
3) aseptate wide hyphae (NO SEPTATE) (MUCORALES)
^ lower fungi soemtimes called pin molds

Question 4

1) Hyaline Molds

Answer 4

hyaline - means “like glass”- thats what they look like under microscope

Aspergillus
&
Penicillum

Question 5

What is Aspergillus?

Answer 5

produce smokey gray/green colonies and are important causes of fulminant fungal infections in immunocompromised patients

• causes chronic sinusitisand aspergilloma - fungus ball of mold in immunocompromised patients
• ASPERGILLUS - all movet he same way at the same time **

Question 6

How many species of Aspergillus?

Answer 6

4: fumigatus, niger, flavus, & terreus

Question 7

Species of Aspergillus? (1)

Answer 7

1) fumigatus: has been incriminated in farmer’s lung
- also causes allergic bronchopulmonary aspergillosis in asthmatics and CF patients
looks purple

Question 8

Species of Aspergillus? (2)

Answer 8

2) Niger - commonly causes otomycosis

- black, looks like a dandelion

Question 9

Species of Aspergillus? (3)

Answer 9

3) Flavus - may infect immunocompromised patients and also infects peanuts, producing aflatoxin which is associated with liver carcinoma
- infect peanuts = legumes not actual peanuts
- looks like MEDUSA

Aspergillus FLAvus causes AFLAtoxin***

Question 10

Species of Aspergillus? (4)

Answer 10

4) terreus

Question 11

Penicillum

Answer 11

a rapidly growing greenish colony which you often see on moldy bread

• the source of penicillin: bacteria wouldnt grow close to the mold*
• there is one invasive species called Penicillum Marneffei

Question 12

2) Dermatophytes Molds

Answer 12

• large group of fungi infects the skin, hard and nails and is commonly called tinea or ringworm because of its circular appearance

Question 13

3 species of Dermatophytes

Answer 13

-dermatophytes are commonly associated with human infections - namely Trichophyton (cause superficial skin infections), Microsporum (cigar shaped body) and Epidermophyton (look like antlers)

Question 14

What is a kerion?

Answer 14

A large mat of infection on the head

- large mat of fungi: huge circular scab

Question 15

jock itch is caused by what?

Answer 15

trichophyton mentagrophytes

Question 16

Athletes foot?

Answer 16

• standard - starts between final two toes on foot
• toe jam has anti-fungal in it and not as much as you go from big toe to smallest toe
  = why it normally starts there

Question 17

Tinea Pedis

Answer 17

is athletes foot - 2 types: between toes or ‘mocassin style’ = all over bottom of foot/entire sole of foot
unknown in people who wear shoes = you get it when you’re barefoot but then you put your shoes on and it grows in the moist dark environment of the shoe

Question 18

Tinea Corpis (Ringworm)

Answer 18

• looks like a circle - thicker outer circle colour

Question 19

3) Mucorales

Answer 19

• common in the environment (soil and decaying vegetation and cause MUCOMYOSIS - particularly in immunocompromised patients

Question 20

Where does mucomycosis begin?

Answer 20

in the nose and paranasal sinuses and is one of the most rapidly spreading fungal infections

Question 21

What are the 4 genera most frequently associated with human infections?

Answer 21

Mucor, Rhizopus, Absidia,and Cunninghamella

Question 22

Fungal sinusitis?

Answer 22

in debilitated patients with nasogastric tubes

Question 23

Diagnosis of superficial mold infections

Answer 23

clinical

Question 24

Diagnosis of deep mold infections?

Answer 24

1) initial detection of hyphae in biopsy specimens
2) culture
3) aspergillus is a common contaminant: diagnosis mainly by biopsy and x-ray