Mycetoma, Scabies, and Envenomation

Question 1

Pathogenic Agent:

Mycetoma

Answer 1

Bacterial: Nocardia brasiliensis (actinomycetes)
Fungal: Madurella mycetoma (eumycetoma)

Question 2

Madurella mycetomatis most common in __________

Answer 2

Africa causes fungal infection (black) Madurella mycetoma

Question 3

Vector:

Mycetoma

Answer 3

Horses, water buffalo, dogs

Question 4

Distribution:
Mycetoma
Actinomycetoma
Eumycetoma:

Answer 4

Actinomycetoma: Rainfall (SAmerica and Asia)

Eumycetoma: Dry (africa)

Question 5

Transmission:

Mycetoma

Answer 5

• Enter through breaks in skin often on the foot. Requires repeated exposure over long people of time
• Not spread person to person
• DORSAL/top of foot or the hand

Question 6

Where do mycetoma nodules like to form?

Answer 6

Small nodules to

Question 7

__________ most commonly implicated actinomycetes

Answer 7

Nocardia species (Nocardia brasiliensis)

Question 8

___________ most common

pathogen in Africa

Answer 8

Madurella mycetomatis

Question 9

__________ most common etiologic

pathogen in South America

Answer 9

Madurella grisea

Question 10

Actinomycetomas also more commonly on the _____________

Answer 10

chest, head and abdomen than mycetoma

Question 11

Clinical Findings:

Mycetoma

Answer 11

• Painless but firm masses that can spread to the bone
• Multiple sinuses form within the mass with discharge thats sand like (grains) and turns into oozing sore and can eventually destroy underlying muscle and bone
• Gram positive branching filaments within the grain

Question 12

Diagnosis:

Mycetoma

Answer 12

• Evaluation of bioposy or tissue sample to determine if bacterial or fungal
• Culture of draining sinus
• X-ray or ultrasound to see how much damage has been done to muscles and bone

Question 13

Treatment:

Mycetoma

Answer 13

Actinomyetoma:

• Bactrim
• Amikam

Eumyetoma:

• Itraconazole/Ketoconazole
• Voriconazole/Scedosporoium
• Posaconazole

Question 14

Prevention:

Mycetoma

Answer 14

Avoid cuts
Close toed shoes and clothing
Cleaning disinfected wounds

Question 15

Pathogenic Agent:

Scabies

Answer 15

Parasitic infection of Sarcoptes scabiei var hominis
White-brown 8 legged mite.
Female burrows into skin to lay eggs that hatch in 3-4 days and become adult in a week

Question 16

Transmission:

Scabies

Answer 16

Mainly young children and elderly
Person to perosn through close skin contact with infected person (personal items less likely to cause infection)
Transmission can occur before symptoms begin

Question 17

Clinical Findings:

Scabies

Answer 17

Normal symptoms: allerfic reaction to presence of mite proteins and feces usually infected with 10-15 mites
Staph aureus and strep pyogenes infection from stracthing. Causes honey crusted lesions from them

Immunosuprresed(HIV): Norwegian scabies (crusted scarbies) that are hyper infection with millions of mites
High mortality due to sepsis,
Fissure with crusted scabies provides portal of entry for bacteria

Severe itch, linear burrows, vesciles around the hands and wrist, worse at night, not on the scalp (only in children) or on the back Children heavy signs on palms, soles, and scalp

Nodular scabies:
Persistent firm papule on groin, genitalia, butt, and folds of skin

Question 18

Diagnosis:

Scabies

Answer 18

• Clinical recognition
• Microscopy of skin scraping/Dermoscopy
• Between fingers, sides of hands, and writs

Question 19

Treatment:

Scabies

Answer 19

Topical scabicide

• Permethrin- gold standard
• Ivermectin
• Malathion
• Benzyl benzoate emulsion
• Sulphur ointment

Question 20

Endemic scabies _______ is the gold standard

Answer 20

oral ivermectin is the gold standard

Question 21

Prevention:

Scabies

Answer 21

Ivermectin mass drug administration

Or permethrin

Question 22

_______ is the most common dermatological condition

Answer 22

Scabies

Question 23

Elapidae species of snakes

Answer 23

Cobras
Death Adders
Kraits
Mambas

(Tropical region - Asia,Africa, Central, South America, Middle East)

Question 24

Viperidae species of snakes

Answer 24

Adders
Asps
Green Pit Vipers
Rattlesnakes

(Broad distribution but includes Europe and North America)

Question 25

True or false - Scabes is worse at night

Answer 25

True

Question 26

Where does scabies not present on body?

Answer 26

Back

- Scalp (except in children)

Question 27

Nodular Scabies

Answer 27

• Persistent firm,
  erythematous, pruritic
  dome shaped papules on the groin, genitalia, buttocks
  and axillary folds

Question 28

Crusted Scabies

Answer 28

Usually in immunosuppressed patients if untreated spreads and eventually affect the whole
body. long term
use of corticosteroids

Question 29

Two ways people get snakebites

Answer 29

• While working

- While sleeping

Question 30

Clinical Finding:

Envenomation

Answer 30

• Non-speciifc
• Bite wound, swelling
• Tachycardia or shock (hypotension)

Question 31

Treatment:

Envenomation

Answer 31

• Anticholinesterases (Neostigmine)
• Pressure bandage,
• Antivenoms
• Tetanus Prophylaxis

Question 32

Types of antivenom

Answer 32

• Monovalent raised against one species of genus of snake
• Polyvalent from multiple different snakes that share a geographic reasons

Both made in other animals by extracting antivenom from their serum
Given in IV over intramuscular
Pretreat with subcutaneous ephinephine if a high risk for an allergic reaction

Question 33

Envenomation:

Neurotoxins that target presynaptic neurons

Answer 33

Damage the terminal axon at neuromuscular junction and paralysis is not reversible (Kraits and Australian snake)

Question 34

Envenomation:

Neurotoxins that target postsynaptic neurons

Answer 34

Postsynaptic- long or short chain molecules target acetylcholine and can be reversed with anitvenom

Question 35

Envenomation:

Myotoxins

Answer 35

• Target skeletal muscles
• Rhabdomyolysis - muscle fiber breakdown
• Systemic hemostasis toxins- interference with blood clotting but can be reversed with antivenom

Question 36

Envenomation:

Cardiotoxins

Answer 36

Causes bleeding and low blood volume (hypotension) by blocking ACE.