Microbiology Flashcards
THis is a collection of pus (neutrophils) that has accumulated within a tissue because of an inflammatory process.
Abscess
This is an infection of the hair follicle, which may progress to cutaneous tissue, leading to furuncles (boils).
Folliculitis
These are large, painful, raised nodules that contain underlying collections of dead and necrotic cells in cutaneous tissues.
Furuncles (boils)
These are an extension of furuncles into subQ tissues.
Carbuncles
This is a spreading infection that is limited tot he epidermis and presents as a bullous, crusted, or pustular eruption of the skin.
Impetigo
What characteristic color are the lesions in impetigo?
Honey-crusted lesions
This is a spreading infection that involves the blocking of dermal lymphatics and presents as a well-defined, spreading erythematous inflammaton, and often accompanied by pain and fever.
Erysipelas
In which age does a malar (butterfly) bright red rash occur on the face as an erysipelas?
Children
This is a spreading infection where the focus of the infection is in the subQ fat.
Cellulitis
This is the inflammatory response to infection of the soft tissue below the dermis, rapid spread along the fascial planes, disrupting the blood suppy.
Necrotizing fasciitis
Ischemia of the muscle layer can cause this condition, where there is gas resulting from the fermentative metabolism of anaerobic organisms.
Gas Gangene
This is a flat red local inflammation in response to an infiltrating leukocyte (esp their toxins in the dermis).
Macule
This is a raised red inflammation with invasion of neighboring tissues.
Papule
This is a small blister, from a microbe that invades the epithelium (HSV, VZV).
Vesicle
This is the ruptured epithelium from a vesicle, where the microbe is discharged.
Ulder
This is when the microbe grows into the epitheliu, which proliferates, and the microbe sheds with epithelial cells (wart).
Papilloma
What is the most common cause of skin infections?
S. aureus
What are the lab chracteristics of S. aureus?
G+ cocci
Catalase +
Coag +
B-hemolytic
After S. aureus invasion to the skin, what forms within 2-4 days?
Boil
After the boil in the S. aureus forms, it triggers an inflammatory response and the invasion of Neutrophils to cause what to form?
Abscess
What happens to the abscess in S. aureus infections?
Expands and eventually drains.
What is the DOC for bacteria that produce B-lactamase?
Methcillin
What is the DOC for MSSA?
Nafcillin
susceptible
What is the DOC for MRSA?
Vancomycin
Nasal carries of MRSA can be treated with nasal creams, like what drug?
Mupirocin
What does MRSA secrete, which has a lower affinity for B-lactams than normal PBPs, allowing it to continue cell wall synthesis when other PBPs are inhibited.?
PBP2a
What gene codes for PBP2a?
MecA
Vancomycin resistance comes from a ligase producing pentapeptides terminating in what sequence?
D-Ala D-lactate
Which Van genes can be transmitted (chromosomal or plasmid) and inducible?
VanA and VanB can be transmitted and is inducible.
VanD cannot be transmitted (chromosomal) and expressed constitutively
True or False: S. aureus have decreased susceptibility to vancomycin from Van genes.
False
Decreases susceptibility is associated with cell wall composition (↑ thickness) and not a Van gene.
Which Van comes from VRE from a plasmid and has high-level glycopeptide resistance?
VanA gene
Which toxin causes SSSS?
Exfoliatin or SSS toxin
Which ages is SSSS common?
Neonates
What is the manifestations of SSSS?
Large blisters with clear fluid and skin loss, mimics burns.
What is the mechanism of action of the TSST1 to cause TSS?
Superantigen (overstimulation of T cells and macrophages)
What “device” causes young girls to be susceptible to TSS?
Tampons
What are the Sx to TSS?
Fever, hypoTN, diffuse macular erythematous rash followed by desquamation of the skin (esp soles/palms)
What is the main virulence factor for S. pyogenes?
M protein
How does M protein provide resistance from S. pyogenes infections?
Inhibition of opsonization
After 1-2 days, there is an inflammatory response made from S. pyogenes infections, and it spreads using what protein?
Hyaluronidase
What are the superantigens called in S. pyogenes?
SPE’s (A, B, and C)
This is the superficial infection of S. pyogenes.
Impetigo
What is the deeper infection of the dermis called in S. pyogenes, where there can be bacteriemia and death?
Erysipelas
What is the condition from S. pyogenes where there is immune complex deposition on the BM of the glomerulus 2-3 weeks after infection?
PSGN
What is teh condition from S. pyogenes infection that is a mixed infection of anaerobes and faculative anerobes, and there is widespread necrosis of the skin and possible death?
Necrotizing fasciitis
What are the 2 main suspects to Cellulitis?
S. pyogenes
S. aureus
Which bacteria is G+, cocci, catalase -, B hemolytic, bactitracin sensitive, PYR+, and ASO+?
S. pyogenes
What is the source for S. pyogenes cellulitis?
Normal flora –> trauma causes inoculation
Which bacteria is G+, cocci, catalase +, coag +, and mannitol fermenting?
S. aureus
Which VF from S. aureus binds the Fc portion of host IgG?
Protein A
What cause of cellulitis is a G+ rod, catalase-, non-spore forming, and nonmotile?
Erysipelothrix rhusiopathiae
What is the host for Erysipelothrix rhusiopathiae infections?
Pigs
What is the cause of cellulitis that is G- rod, comma shaped, lactose non-fermenter, oxidase +, and motile?
Vibrio vulnificus
Vibrio algionlyticus
Where can u get vibrio?
Marine invironments
Which bug can cause gas gangrene from the soil and feces?
C. perfringens
What does the Lecithinase (alpha toxin) cleave on the host cell membranes, leading to cell lysis and death?
Phospholipids
What are the 2 risk factors for gas gangrene?
Ischemic vascular disease
Peripheral arteriosclerosis
Which specialized agar differentiates C. perfrinegens from other bacteria?
+ Nagler rxn (egg yolk agar)
These are greasy plugs of keratin, sebum, and bacteria, capped by a layer of melanin.
Comedones (black heads)
What is the main cause of comedones, which an aerotolerant anaerobic G+ rod?
Proprionibacterium acnes
What hormones ↑ in the body to ↑ sebum and keratinization/desquamation in pilosebaceous ducts to cause acne/comedones?
Androgenic H’s
These are acid fast rods that stain with Ziehl-Neelsen or auramine stain.
M. leprae
Which 2 cells does M. leprae grow in?
Skin histiocytes
Schwann cells
True or False: like TB, M. leprae can be grown in vitro.
FALSE
Where can u find M. leprae in infected individuals?
Nasal secretions
How long is the incubation period for M. leprae?
Years
This is the form of leprosy where there is a vegrous CMI response, leading to phagocytic destruction of bacteria and exaggerated allergic response.
Tuberculoid leprosy
What is a common Sx of Tuberculoid leprosy?
Local anethesia from thickening of peripheal nerves
What is the CMI response to M. leprae to cause Lepromatous leprosy?
Weak CMI response
Which is worse, Lepromatous leprosy or Tuberculoid?
Lepromatous leprosy
What are the Sx to Lepromatous leprosy?
Loss of eyebrows
Thickening and enlargement of nostrils, ears, and cheeks
Lion-like face
Lose nasal septum
Which form of Leprosy (L or T) will have numerous organisms on staining?
Lepromatous leprosy
Which mycobacterium do u associate with fish tanks?
M. marinum
What usually happens to you to allow M. marinum into your skin?
Some sort of trauma
What is the initial lesion of M. marinum after 2-8 weeks?
Small papules –> enlarge and may ulcerate.
What are Mycobacterium genus that causes chronic, relatively painless cutaneous “buruli” ulcers?
M. ulcerans
Where can u find M. ulcerans?
Africa and Australia
Which form of fungi (yeast or mold) are unicellular, reproduce by budding, and can form pseudohyphae?
Yeast
So we can guess that molds are multicellular and have hyphae, but what are hyphae?
Elongated tubes of cells attached end to end
What are the form of hyphae that have membranes separating individual cells?
Septate hyphae
What are the 4 dimorphic fungi?
C. immitis
H. capsulatum
B. dermatidis
S. schenkii
Tinea pedis and vaginal candidiasis are of what type of mycoses infection?
Superficial
What is involved in subcutaneous mycoses?
Nails and deeper layers of the skin
What is it called when there are mycoses of the internal organs?
Systemic/Deep mycoses
Malassezia furfur- conditions
Pityriasis or Tinea versicolor
Malassezia furfur- lesion morphology
Hypo or Hyperpigmented macules that coalesce to form scaling plaques.
Malassezia furfur- Sx
Itchy lesions, resolve spontaneously
Malassezia furfur- findings on KOH prep
Spaghetti and meatballs
Malassezia furfur- Tx
Miconazole, selenium sulfide
This is is a common label for a group of 3 types of fungus that common causes skin disease in animals and humans.
Dermatophytes
What contacts the skin to cause dermatophytes?
Anthospores
What are the most common cause of dermatophyte infections, where the anthrospores are spread shed from human skin scales and hair?
Antropohphilic
What is the most common dermatophyte from animals?
Zoophilic
Where do the following Zoophilic dermatophytes come from?
Trichophyton verrucosum
T. mentagrophytes
Microsporum canis
Trichophyton verrucosum- cows
T. mentagrophytes- rodents
Microsporum canis- dogs and cats
What are the type of dermatophytes from soil, and includes species like Microsporum gypseum?
Geophilic
Which epidermal protein do the tinea spp like to infect?
Keratin (skin, hair, nails)
What is the typical lesion morphology in tinea infections?
Serpentine scaling patch with raised margin
Which tinea spp infects the hair and scalp, leading to hair loss?
Capitis
Which tinea spp infects the body?
Corporis
Which tinea spp infects the crotch?
Cruris
Which tinea spp infects the feet?
Manuum and Pedis
Which tinea spp infects the nails?
Unguium
these names are freakin weird
What are the 3 genera responsible for dermatophytoses?
Microsporum
Epidermophyton
Trichophyton