T1- Infectios Dz of Skin Flashcards
What are the three types of normal flora?
- Diptheroids (Propionbacterium acnes)
- Micrococci (Staphylococcus epidermis)
- Yeast (Candida albicans)
What environmental conditions allow for our Normal flora to survivie?
dry and salty conditions
______ = Bacterial infection, follicle associated lesion… types include comedo, whitehead, blackhead, pustule, and cystic
Acne
What is the most common mode of transmission of acne (Propionibacterium acnes)?
Endogenous
What are the virulence factors associated with acne?
Lipase, inflammatory mediator, other enzymes
What is the treatment for most acne?
Antibiotics (topical or oral), Isotretinoin
What are the two bacteria that cause impetigo?
- Staphylococcus aureus
2. Streptococcus pyogenes
Peeling of the skin =
impetigo
Associated with a number of diseases, including impetigo ; Enzymes = Coagulase, Hyaluronidase, Staphylokinase, Lipases ; Most studied non-spore forming pathogen
Staphylococcus aureus
Impetigo, peeling of the skin, can be caused by Staphylococcus aureus or Streptococcus pyogenes, or may be caused by a mixture of the two. In cases where Impetigo is caused by a mixture of the two, is the onset at the same time? Or one before the other?
S. pyogenes begins is ALL cases of the disease, but LATER S. aureus takes over and produces a bacteriocin that destroys S. pyogenes
What is the mechanism of transmission associated with impetigo?
Transmitted by direct contact, via fomites, and mechanical vectors
When is the peak incidence of Impetigo?
Summer and Fall
______ looks like peeling skin, crusty and flaky scabs, or honey colored crusts
Impetigo
Where is Impetigo most commonly found?
Mouth, Face, and Extremities, but can occur anywhere on the skin
Can a patients symptoms suggest whether the infection is caused by Staph or Strep?
NO
T/F Using SEM (scanning electron micrograph) and colonies of Staphylococcus aureus could confirm the causative agent of impetigo.
true
What is the primary method of identifying Staphylococcus aureus?
Positive coagulase test
_________ = Beta Hemolytic, M protein, and is associated with impetigo
Streptococcus Pyogenes
What is the pathogenesis of Streptococcus pyogenes?
Involves the conversion of plasminogen to plasmin, which can degrade host tissue
What are the virulence factors associated with Impetigo caused by Staphylococcus Aureus?
Exfoliative toxin A, coagulase, other enzymes
What are the virulence factors associated with Impetigo caused by Streptococcus Pyogenes?
Streptokinase, plasminogen-binding ability, hyaluronidase, M protein
What tests would you perform to diagnose Impetigo caused by Staphylococcus aureus?
Routinely based on clinical signs, when necessary, culture and Gram stain, coagulase and catalase tests, multitest systems, PCR
In what age group do you most often see Impetigo caused by Staphylococcus Aureus?
older children or adult
In what age group would you most often find Impetigo caused by Streptococcus pyogenes?
newborns; may have some involvement in all impetigo (preceding S. aureus in staphylococcal impetigo
_______ = Bacterial or Fungal infection of the dermin and subcutaneous tissues; lymphagitis; immunocompromised individuals are at risk
Cellulitis
What are the signs and symptoms of Cellulitis?
- Pain
- tenderness
- swelling
- warmth
Fever and swelling of the lymph nodes in the area may also occur
What is caused by red lines leading away from area that become visible as a result of microbes and inflammatory products being carried by the lymphatic system?
Lymphangitis
What organisms cause cellulitis?
S. aureus
S. pyogenes
What is the most common mode of transmission of cellulitis?
parenteral implantation
What are the virulence factors of Cellulitis caused by S. aureus?
exfoliative toxin A, coagulase & other enzymes
What are the virulence factors of Cellulitis caused by S. pyogenes?
Streptokinase, plasminogen-binding ability, hyaluronidase, M protein
What is the treatment of cellulitis? (for both organisms)
Aggressive treatment with oral or IV antibiotic (cephalexin); surgery sometimes necessary
A 12 week old baby is brought into the ED and presents with bullous lesions and desquamation of the skin. Baleigh suspects which bacterial infection to be the cause of this baby’s condition?
Staphlococcal Scalded Skin Syndrome (SSSS)
What causes the major signs and symptoms of SSSS?
Exofoliative toxins A & B
What is the most common modes of transmission of SSSS?
direct contact and droplet contact
How is SSSS prevented?
by eliminating carriers in contact with neonates
What is the treatment of SSSS?
immediate systemic antibiotics (cloxacillin or cephalexin)
What is the distinguishing feature of SSSS?
split in skin occurs WITHIN epidermis
What are 5 characteristics of Gas Gangrene?
- bacterial infection
- anaerobic
- toxins (Alpha toxin, exotoxins)
- gas formation
- two forms (localized & diffused)
What is the causative organism of gas gangrene?
Clostridium perfringens
What is the most common modes of transmission of gas gangrene?
vehicle (soil), endogenous transfer from skin, GI tract, reproductive tract
Holly was correct in the diagnosis, how can she now prevent the spread of the gas gangrene infection?
clean the wounds
debride dead tissue
Once the wounds have been cleaned what must Holly now prescribe the patient in order to treat gas gangrene?
Cephalosporin (surgical removal & oxygen therapy may also be needed)
What are 5 characteristics of Gas Gangrene?
- bacterial infection
- anaerobic
- toxins (Alpha toxin, exotoxins)
- gas formation
- two forms (localized & diffused)
What is the causative organism of gas gangrene?
Clostridium perfringens
Holly has a patient she suspects has gas gangrene, what cultures/tests can she perform to determine the diagnosis?
Gram stain, CT scans (for abdominal infections), X-ray, clinical picture
Steph’s diagnosis of leprosy has been confirmed, what should she do to treat this patient’s condition?
use multidrug treatment including rifampin and dapsone; varies with form of leprosy
What is the causative organism of Hansen’s disease (Leprosy)?
Mycobacterium leprae
What is the most common modes of transmission of Leprosy?
not clear, possibly direct or droplet contact; or caused by some mechanical vector.
What are the virulence factors of leprosy?
binding to Schwann cells, ability to survive within macrophages.
Chickenpox re-emerges as____; due to stress, x-ray treatments, drug therapy, or a developing malignancy.
shingles
elevated lesions filled with fluid = ______.
vesicular rash diseases
What are 2 viral infections that are vesicular rash diseases?
chickenpox
smallpox
What is a common, benign vesicular rash disease that affect a dermatome? It can be life-threatening for immunocompromised individuals.
Chickenpox
Chickenpox is a result of _____.
varicella-zoster virus infection
What epidemic vesicular rash disease has been considered a bioterrorism agent and has been eliminated due to world-wide vaccine program?
smallpox
Causative organism for Chickenpox
Human Herpesvirus 3 (varicella-zoster virus)
Most common modes of transmission of chickenpox
droplet contact, inhalation of aersolized lesions fluid
Virulence factor for chickenpox
ability to fuse cells, ability to remain latent in gangia
Diagnosis of chickenpox is based largely on ___
clinically appearance
Prevention of chickenpox
live attenuated vaccine
Treatment of chickenpox
NONE
Causative Organism of Smallpox
Variola virus
Most common Mode of transmission of small pox
droplet contact or indirect contact
Virulance factor of smallpox
Ability to dampen, avoid immune system
Diagnosis of small pox is based on ___
clinical appearance
Prevention of smallpox
live virus vaccine
What are examples of maculopapular rash diseases - flat to slightly raised colored bump
Measles or rubeola
Rubella
Fifth disease
Roseola
Viral infection, Vaccine avaibable but the disease still exists, Koplik’s spots
Measles
Whats a complication of Measles infection?
Subacute sclerosing panencephalitis (SSPE)
viral infection, vaccine available in MMR, mild, serious for a fetus
Rubella
Teratogenic for a fetus, disrupts fetus development
rubella
viral infection, erythema infectiosum, mild and no vaccine
fifths disease
viral infection, latent period that reactivates as mononucleosis like or hepatitis-like sysmptoms, immunocompromised individuals are at risk
roseola
Causative organism for Measles and most common mode of transmission
measles virus
droplet contact
virulence factor and preventation of measles
syncytium formation, ability to suppress CMI
Live attenuated vaccine MMR
Causative organism of rubella and most common mode of transmission
rubella virus
droplet contact
virulence factor and preventation of rubella
in fetuses: inhibition of mitosis, induction of apoptosis and damage to vascular endothelium ** read that again! thats important
MMR vaccine
Causative organism of fifth disease and most common mode of transmission
parvovirus B19
droplet contact and direct contact
causative organism of roseola
human herpesvirus 6 or 7
Distinguishing feature of measles
starts on head, spreads to whole body and lasts over a week
distinguishing feature of rubella
milder red rash, lasts approximately 3 days
distinguishing feature of fifth disease
“slapped face” rash first, spreads to limbs and trunk, tends to be confluent rather than distinct bumps
distinguishing feature of roseola
high fever precedes rash stage - rash not always present
two agents that cause warts
papillomas and molluscum contagiosum
viral infection, benign, nearly everyone is infected
papillomas
types of virus that causes plantar warts
hpv-1
type of virus that causes flat warts
hpv-3
hpv-10
hpv-28
hpv-49
virual infection, distributed world-wide, spread by contact, and inclusion bodies contain viruses
molluscum contagiosum
causative organism of warts
hpv
most common mode of transmission for warts
direct contact, autoinoculation and indirect contact
diagnosis of warts is by __ and preventation
clinical diagnosis, PCR
avoid contact
most common modes of transmission of molluscum contagiosum
direct contact, including sexual contact, autoinoculation
large skin lesions can be due to - - - -
Leishmaniasis
Cutaneous anthrax
Ringworm
Superficial mycoses
Protozoan infection (cutaneous/mucocutanous or systemic) zoonosis and no vaccine
leichmaniasis
bacterial infection, endosporulation and germination, untreated cases can be fatal and vaccine is available
cutaneous anthrax
Fungal infections caused by dermatophyte
Mycosis, Ringworm.
Tinea Capitus (head) Tinea barbae (beard) Tinea corporis (body) Tinea cruris (groin) Tinea Pedis (foot) Tinea poris (hand) Tinea unguium (nail)
What is a type of superficial mycosis infection that has cosmetic effects without inflammation?
Tinea Versicolor
What are two types of superficial mycosis infections?
Yeast infection
Tinea Versicolor