VIII- SSTI Bacterial Flashcards
(78 cards)
1
Q
diabetes mellitus associated pathogens
A
- Staph. aureus
- group B strep
- anaerobes
- gram neg bacilli
2
Q
neutropenia associated pathogens
A
pseudomonas aeruginosa
3
Q
hot tub exposure pathogens
A
pseudomonas aeruginosa
4
Q
IV drug abuse
A
MRSA
Pseudomonas aeruginosa
5
Q
non bulous impetigo pathogens
A
- S. pyogenes (GAS)
- S. aureus
6
Q
ecthyma agent
A
S. aureus
7
Q
folliculitis pathogens
A
- S. aureus
- P. aeruginosa (hot tubs)
8
Q
furuncles/carbuncles pathogen
A
S. aureus
9
Q
paronychia pathogens
A
- S. aureus
- S. pyogenes (GAS)
10
Q
erysipelas pathogen
A
S. pyogenes (GAS)
11
Q
cellulitis pathogens
A
- S. pyogenes
- S. aureus
3.
12
Q
necrotizing cellulitis/fascitis, myositis
A
- S pyogenes GAS
- C perfringens
13
Q
osteomyelitis pathogens
A
S. aureus
14
Q
septic arthritis pathogens
A
- S aureus for kids and adults with intraarticular injections in abnormal joints
- N gonorrhoeae in sexually active people
15
Q
staphylococci general features
A
gram pos forms grape clusters
facultative anaerobe
catalase pos
-found on skin and mucus membranes of humans
-transmitted via direct contact or fomite exposure like nasal shedding, environmental surfaces, bed linens
16
Q
Staph aureus culture
A
white or golden colonies
beta hemolytic
17
Q
S. aureus virulence factors
A
- protein A (escape phago, binds IgG Fc domain)
- alpha cytotoxin (pore forming)
- exfoliative toxin (ETA, ETB) split intercellular bridges in epidermis
- coagulase (convert fibrinogen to fibrin to promote abscess form and escape phago)
18
Q
scaled skin syndrome pathogen
A
S aureus
19
Q
MSSA features
A
methicillin sensitive S aureus
so resistant to some beta lactams not all
via efflux pumps, beta lactamases, altered porins
20
Q
MSSA treatment
A
1st penicillin
add beta lactamase inhibitor
21
Q
MRSA features
A
methicillin resistant S aureus
so resistant to all known beta lactamases
-via mecA gene that encodes transpeptidase/PBP with low affintiy for beta lactams
22
Q
S, pyogenes virulence factors
A
- hyaluronic acid capsule
- LTA for adhering to epi surface
- M protein to facilitate invasion
- pyrogenic exotoxins SpeA - superantigen to inc cytokine production esp in scarlet fever, strep toxic shock, necrotizing fasciitis
23
Q
acute poststreptococcal glomerulonephritis def
A
immunologic mediated + nonsuppurative + delayed sequela post pharyngeal or cutaneous GAS infection
24
Q
acute poststrep glomerulonephritis
prez
A
- acute nephritic syndrome so hematuria, edema, hypertension, oliguria
- edema @ facial and orbit
- NO systemic disease
25
diagnosing acute poststrep glomerulonephritis
test for anti-DNase antibodies in sera
-pos = previous exposure
26
strep toxic shock syndrome prez
pain + nonspecific symptoms + shock + multiorgan failure + bacteremic + necrotizing fasciitis
bc exotoxins SpeA and C!!
27
non bullous impetigo prez
small pustules crust over 'honey crust' around mouth and nose of kids 2-5
can be confused with HSV or chickenpox
28
bullous impetigo prez
blisters with cloud fluid full of S. aureus rupture = erosions and brown crusting
29
ecthyma prez
non bullous impetigo extends into dermis deeper
-pustules enlarge > ulcerate > crust over and scar
30
treating impetigo and ecthyma
can initiate before ID
-if uncomplicated then soak lesions to get rid of crust, topical antibiotic ointment
-if complicated then use oral antibiotics
31
folliculitis prez
papules/pustules form in hair follicles as crops so apparent erythema
32
furnucle/boil prez
erythematous, tender pustule bc deep hair follicle infection spreads to adjacent tissues
33
carbuncle prez
2+ furuncles that coalesce deeper into subcutaneous tissue
-fever/malaise often present
-systemic spread possible
34
cellulitis prez
1. systemic presentation of fever, chills, malaise
2. local prez of mild erythema > quickly to edema, pain/tender with poorly defined borders + vesicles/bullae/bruising
35
erysipelas prez
abrupt onset of intense pain, erythema, edema so fiery red appearance with sharp demarcation
-subset of cellulitis
36
acute paronychia prez
pain, erythema, edema in nail folds sometimes with abscess esp if chew nails
37
chronic paronychia prez
nail fold infection of 6+ weeks from C. albicans
38
treating furuncle, carbuncle, cellulitis, erysipelas, paronychia
drain abscess if present
-wound care, topical antibiotic oitment
-oral antibiotics in some cases
-severe cases need systemic antibiotics
39
staph scalded skin syndrome prez
1. starts as infection of conjunctiva, nasopharynx, or umbillicus by S. aureus in 0-6 year olds
2. erythema and pain mimick bad sunburn that rapid spreads
3. flaccid bullae appear
4. skin peels off with minimal pressure (nikolsky sign)
5. blisters rupture and superficial skin laters shed in large sheets
6. underlying skin looks scalded
7. after 7-10 days skin returns to normal
40
staph scalded skin syndrome pathogenesis
hematogenous spread of ETA and ETB from infection site so stratum corneum and stratum granulosum of epidermis is shed from cleavage of desmoglein 1 bridge protein
41
why staph scalded skin culture is neg
bullae fluid almost always neg with no evidence of leukocytes bc the production of ETA/ETB is local/elsewhere to the bullae
-systemic spread/manifestation of local disease
42
treating staph scalded skin
1. hospitalization
2. antibiotics
3. supportive care
43
osteomyelitis prez
bone pain + fever + swelling + malaise + erythema
44
risk factors of osteomyelitis
sickle cell anemia, diabetes
injury, foreign bodies, surgery esp bone involvement
IV drug use
45
septic arthritis prez
single painful erythematous joint with limited range of motion and purulent material + fever
-in large joints usually
treat with drainage and antibiotics
46
necrotizing fasciitis prez
rapid necrotizing infection that destroys the muscle fascia and subcut fat
-erythema without distinct margins, edema extends beyond erythema, exquisite pain (more severe than what prez seems), gangrene
-easily progress to multi organ failure
47
necrotizing fasciitis treatment
immediate hospitalization
surgical debridement or amputatin, skin grafting
antibiotics (multiple broad spectrum)
48
pseudomonas aeruginosa features
gram neg aerobic motile rod, oxidase pos
-blue green agar colonies
-soil, vegetation, water
-exotoxin A (EF-2 thru ADP ribosylation blocks protein syn so cell death)
-antibiotic resistance is problematic
49
pseudomonas bacteremia
patients with neutropenia
and extensive burns (bc surface moist and PMNs cant penetrate the wound)
50
ecthyma gangrenosum
fever + systemic illness > erythematous or purpuric macule that rapidly evolves to pustules or bullae > gangrenous ulcer
51
green nail syndrome
pseudomonas growing as a biofilm under nail
-xs hand washing, trauma, hairstylists, dishwashers, healthcare
treat with antibiotic finger soak and treat underlying problem
52
webspace intertrigo
macerated and eroded skin on interdigital toes in xs moisture settings
53
clostridium perfringens
large gram pos non motile, anaerobic, beta hemolytic, spore forming
-in soil, contaminated water, normal GI
-alpha toxin!! disrupts cell membrnes by degrading phospholipids = massive hemolysis and tissue destruction
54
gas gangrene
aka clostridial myonecrosis
-sudden onset of fever and **excruciating** pain, foul smelling wound with thin serosanguineous discharge
-blue or red bullae form
-**crepitus**
-delays in traumatic injury and surgery = inc risk
55
gas gangrene treatment
immediate treatment
radical amputation or numerous surgeries,
high dose antibiotics
56
tetanus toxin
| tetanospasmin
inactivates proteins that control release of inhibitory neurotransmitters so unregulated excitation = spastic paralysis
57
tetanus prez
unexplained sweating, tachycardia > masseter m contraction = trismus/lock jaw
-severe intermittent pain triggered by external stim
-opisthotonos, risus sardonicus
can also present as cephalic if affect cranial nerve (rare) or neonatal if umbilical stump infected
58
tetanus treatment
immediate hospitalization
stop toxin production by wound debridement and antibiotics
-neutralize free toxin by human tetanus immunoglobulin
-vaccinate bc immunity not conferred upon recovery
59
mycobacteria features
in cell wall:
-arabinogalactan
-lipoarabinomannin
-mycolic acids
-mycolic acid associated glycolipids
60
skeletal TB
TB of bones and joints
-Pott's Dz specific to vertebral osteomyelitis
-gibbus deformity
granulomas in biopsy
61
prevention of skeletal TB
-vaccination
-prophylaxis with isoniazid
62
mycobacterium leprae features
-acid fast bacilli but culture not possible
-obligate intracellular pathogens
-reservoirs: human and armadillo
leprosy/hansen's disease
63
M. leprae pathogenesis
1. targets macrophages and Schwann cells
2. proinflammatory cell wall components
3. no classic endo or exotoxins
64
leprosy manifestations
1. tuberculoid: TH1 response and very few bacilli in biopsy. few raised plaques, low infectious
2. borderline tuberculoid
3. midborderline leprosy
4. lepromatous leprosy: TH2 response so hypergammaglobulinemia, multibacillary, chronic dz of dermal macrophages and schwann cells, many lesions and extensive tissue damage, high infectious
65
diagnosing/treat leprosy
NOT culture do full thickness skin biopsy instead of edge of active plaques
treat with antibiotics based on tuberculoid (6 mo) or lepromatous (12 mo)
66
nocardia and actinomyces features
gram pos filamentous bacteria in branches
-resemble hyphae
67
nocardia spp features
aerobic gram pos rod BUT can appear gram neg with internal gram pos beads + catalase and urease pos
-weakly acid fast with mycolic acid in cell wall + branched filaments
-slow growing and fuzzy colonies
| N. brasiliensis only relevant species
68
primary cutaneous nocardiosis
| PCN
in **immunocompetent** hosts
-superficial cellulitis > subcut abscesses > lymphocutaneous infections > mycetoma
-can involve brain and CNS (meningitis)
69
mycetoma
chronic/slowly progress skin and subcut tissue infection after cut/contam with soil or vegetation of Nocardia, actinomyces
-discharging sinuses filled with organism, painless
70
diagnosing nocardia
history of direct exposure thru gardening or farming
-direct exam of specimen thru biopsy
71
actinomyces israelii features
gram pos filamentous bacteria strict anaerobe + catalase and urease neg, not acid fast
-opportunistic so breach in barrier like dental work
| acid fast diffs from nocardia
72
actinomyces israelii infection
pyogenic abscesses connected by sinus tracts
-contain sulfur granules that look like yellow/orange grains of sand
-can progress out as cervicofacial esp if poor dental hygiene, also abdom, pelvic, chest wall
73
acne vulgaris
hair follicle changes = pimples
-follicular epidermal hyperproliferation
-xs sebum production
-inflamm from cutibacterium acnes presence
| not necessarily an infection
74
cutibacterium acnes features
small microaerophillic/anaerobic gram pos rods
-normal microbiota of sebaceous glands, conjuctiva, ear, oropharynx, female genital tract
75
strep mutans
dominant org for dental caries by acid products from biofilm interaction
-acid induced demineralization
76
gingivitis
reversible inflamm of gingiva/gums
77
periodontitis
chronic inflamm dz including gingivitis, irreversible loss of CT and bone support
-more severe
78
periodontal diseases
| aka gingivitis and periodontitis
caused by bacteria in dental plaque that create an inflamm response in gingival tissues and bone
