Mycetoma, Scabies, and Envenomation Flashcards
Pathogenic Agent:
Mycetoma
Bacterial: Nocardia brasiliensis (actinomycetes)
Fungal: Madurella mycetoma (eumycetoma)
Madurella mycetomatis most common in __________
Africa causes fungal infection (black) Madurella mycetoma
Vector:
Mycetoma
Horses, water buffalo, dogs
Distribution:
Mycetoma
Actinomycetoma
Eumycetoma:
Actinomycetoma: Rainfall (SAmerica and Asia)
Eumycetoma: Dry (africa)
Transmission:
Mycetoma
- 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
Where do mycetoma nodules like to form?
Small nodules to
__________ most commonly implicated actinomycetes
Nocardia species (Nocardia brasiliensis)
___________ most common
pathogen in Africa
Madurella mycetomatis
__________ most common etiologic
pathogen in South America
Madurella grisea
Actinomycetomas also more commonly on the _____________
chest, head and abdomen than mycetoma
Clinical Findings:
Mycetoma
- 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
Diagnosis:
Mycetoma
- 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
Treatment:
Mycetoma
Actinomyetoma:
- Bactrim
- Amikam
Eumyetoma:
- Itraconazole/Ketoconazole
- Voriconazole/Scedosporoium
- Posaconazole
Prevention:
Mycetoma
Avoid cuts
Close toed shoes and clothing
Cleaning disinfected wounds
Pathogenic Agent:
Scabies
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
Transmission:
Scabies
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
Clinical Findings:
Scabies
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
Diagnosis:
Scabies
- Clinical recognition
- Microscopy of skin scraping/Dermoscopy
- Between fingers, sides of hands, and writs
Treatment:
Scabies
Topical scabicide
- Permethrin- gold standard
- Ivermectin
- Malathion
- Benzyl benzoate emulsion
- Sulphur ointment
Endemic scabies _______ is the gold standard
oral ivermectin is the gold standard
Prevention:
Scabies
Ivermectin mass drug administration
Or permethrin
_______ is the most common dermatological condition
Scabies
Elapidae species of snakes
Cobras
Death Adders
Kraits
Mambas
(Tropical region - Asia,Africa, Central, South America, Middle East)
Viperidae species of snakes
Adders
Asps
Green Pit Vipers
Rattlesnakes
(Broad distribution but includes Europe and North America)
True or false - Scabes is worse at night
True
Where does scabies not present on body?
Back
- Scalp (except in children)
Nodular Scabies
- Persistent firm,
erythematous, pruritic
dome shaped papules on the groin, genitalia, buttocks
and axillary folds
Crusted Scabies
Usually in immunosuppressed patients if untreated spreads and eventually affect the whole
body. long term
use of corticosteroids
Two ways people get snakebites
- While working
- While sleeping
Clinical Finding:
Envenomation
- Non-speciifc
- Bite wound, swelling
- Tachycardia or shock (hypotension)
Treatment:
Envenomation
- Anticholinesterases (Neostigmine)
- Pressure bandage,
- Antivenoms
- Tetanus Prophylaxis
Types of antivenom
- 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
Envenomation:
Neurotoxins that target presynaptic neurons
Damage the terminal axon at neuromuscular junction and paralysis is not reversible (Kraits and Australian snake)
Envenomation:
Neurotoxins that target postsynaptic neurons
Postsynaptic- long or short chain molecules target acetylcholine and can be reversed with anitvenom
Envenomation:
Myotoxins
- Target skeletal muscles
- Rhabdomyolysis - muscle fiber breakdown
- Systemic hemostasis toxins- interference with blood clotting but can be reversed with antivenom
Envenomation:
Cardiotoxins
Causes bleeding and low blood volume (hypotension) by blocking ACE.
