Skin and Soft Tissue infections II Flashcards
1
Q
What is this;
- gram positive BACILLUS
- spore former
- Aerobic and facultative anaerobe
- 200 species
A
Bacillus spp.
2
Q
What are the major 2 types of bacillus spp?
A
B. anthracis -anthrax
B. cereus- misc. infections
3
Q
What does the bacillus spp capsule do?
A
- antiphagocytic
- induces protective immunity
4
Q
What is the capsule of bacillus spp. made of?
A
poly Y D glutamic acid
5
Q
What are the toxins produced in bacillus spp?
A
toxins- AB type toxin
- Protective antigen
- lethal factor
- edema factor
6
Q
What does this:
binds cellular receptors and facilitates uptake of LF or EF
Induces protective immunity
A
Protective antigen
7
Q
What does this:
releases proteases
produces cell death
A
lethal factor (LF)
8
Q
What does this:
release adenylate cyclase
produces edema
A
Edema factor (EF)
9
Q
What is this:
Follows inoculation with spores
Painless papule progresses to ulcer to necrotic black eschar (malignant pustule)
A
Cutaneous anthrax
10
Q
What is this:
Follows ingestion of spores
Local infection that may spread to systemic disease
A
GI anthrax
11
Q
What is this:
Follows inhalation of spores
Lungs → regional lymph nodes → systemic spread
Hypotension, pulmonary edema, massive bacteremia, acute fatal toxic shock
May have prolonged incubation period
Fatal if untreated
A
inhalation anthrax
12
Q
What specimen do you collect to diagnose bacillus anthrax?
A
blood, material from eschar
13
Q
What does a direct examination show if you are looking at bacillus anthrax?
A
gram stain of blood often positive
14
Q
How will you culture bacillus anthrax?
A
blood agar
15
Q
What will the lab identify on bacillus anthrax?
A
Gram-positive bacillus in chains
Capsule by negative stain
Identification by PCR and other specialized tests
Key role for the Laboratory Response Network
16
Q
anthrax is primarily a disease of (blank)
A
herbivores
17
Q
Is anthrax communicable?
A
no (ie not contagious)
18
Q
How are humans normally infected with anthrax?
A
by exposure to animals or animal products e.g. woolsorters disease
19
Q
What is the vaccine for humans with anthrax?
A
AVA (acelluar vaccine adsorbed)
Efficacy is shown in woolsorters disease, many problems
20
Q
How do you vaccinate animals with anthrax?
A
live vaccine
21
Q
How do you treat anthrax?
A
Ciprofloxacin
potential for mAbs to PA
22
Q
How can you prophylacticly treat exposed individuals?
A
ciprofloxacin or doxycycine for 40 days
vaccination with AVA
23
Q
What is this: gram positive bacillus anaerobic spore-formers ubiquitous in soil, water sewage normal flora of GI tract of man and animals prodcue numerous toxins
A
clostridium spp.
24
Q
Does C. perfrigens grow slow or fast?
A
fast in tissue
25
What is the pathogenesis of c. perfringens?
Alpha toxin
| entertoxins
26
What all does the alpha toxin of C. perfringens do?
major lethal toxin of gas gangrene
- lecithinase
- lyses numerous host cells
- massive hemolysis
27
What does C. perfrings release when undergoing sporulation?
enterotoxins
28
What do the enterotoxins of C. perfringins do?
alter membrane permeability-loss of fluids and ions
| superantigen
29
What are the clinical diseases associated with C. perfringins?
```
Soft tissue infection
Food poisoning (relatively common)
Necrotizing enteritis (rare)
```
30
What are the 2 soft tissue infections associated with C. perfringins?
Myonecrosis (gas gangrene)
| cellulitis
31
What is this:
Spores or vegetative cells introduced by trauma or surgery
Intense pain
Muscle necrosis, shock, renal failure
myonecrosis (gas gangrene) caused by C perfringins
32
What is this:
Follows ingestion of contaminated meat
Abdominal cramps, watery diarrhea
Due to enterotoxin production in intestine
Food poisoning-relatively common
33
What is this:
Follows ingestion of contaminated pork with sweet potatoes
Necrotizing destruction of jejunum
Due to beta toxin
necrotizing enteritis
34
where do you get the specimens to diagnose C perfringens?
fluids from site
35
Can you directly exam c perfringins and how?
yes-gram positive rods
36
How can you culture C perfringins?
rapid anaerobic growth on agar or blood culture broth
37
If you have food poisoning, how can you tell if it was caused by c. perfringins?
distinguish infection from colonization
| immunoassay fro enterotoxin in stool
38
Where do you find C. perfringins?
- ubiquitous in soil, water, and human GI tract
| - traumatic injury followed by contamination with spores
39
How do you treat soft tissue infections caused by c perfringins?
rapid treatment s critical to outcome-treated mortality is 40-100%
surgical debridement as needed
High dose penicillin and clindamycin
prevent by proper wound care
40
How do you treat food poisoning caused by c. perfrinigns
antibiotics not effective, symptomatic treatment
41
What is this:
weakly gram negative, motile, spirochete.
Complex nutritional requirements; can be grown in culture. Several species can cause disease.
B. burgdorferi (only species in north america)
42
Describe the early localized infection phase of lyme disease
incubation period 3-30 days after bite of hard shelled tick. Characteristic skin lesion (erythema migrans) at site of initia infection -80% of patients
43
Describe the early disseminated disease?
days to weeks after onset of erythema migrans
multiple secondary annular skin lesions
fatigue, arthritis (60%), myalgia, cardiac dysfunction (20%), neurologic signs (10-15%)
44
Describe the late infection
Months after initial infection
Untreated or inadequately treated patients
More extensive arthritis, chronic skin involvement (seen more in Europe), chronic neurological symptoms
45
What is this:
| symptoms similar to chronic fatigue syndrome or fibromyalgia
post-lyme disease syndrome
46
Found in lyme disease,
3-30 day incubation after infection
Most patients with chronic disease never remember lesion
What am I talking about?
erythema migrans
47
What is this:
Bluish-red skin lesions
Late, disseminated disease
More common in Europe
Acrodermatitis chronica atrophicans (also found in lyme disease)
48
What is the pathogenesis of the clinical features of lyme disease?
direct consequence of microbial growth and immune response
49
What is the clinical case definition of lyme disease?
```
Erythema migrans (~5 cm)
At least one late manifestation (musculoskeletal, CNS or cardiovascular) plus laboratory confirmation
```
50
How should you lab test for lyme disease?
antibody detection (elisa first then western blot)
51
When does IgM peak for lyme disease?
after 6-8 weeks
52
When does IgG peak for lyme disease?
after 4-6 months and persists during late disease
53
What is the vector for lyme disease?
hard ticks (Ixodes)- species varies with location
54
What is the most common vector-borne disease in U.S and europe?
hard ticks
55
(blank) stage of hard ticks causes greater than 90% of cases
nymph
56
When do you most commonly get lyme disease?
May-September (when nymph stage is most active)
57
What are the resevoir hosts for lyme disease?
white footed mouse (host larval and nymph forms)
| White-tailed deer-host of adult ticks
58
What are the regional foci for lyme disease?
Northeast and mid-atlantic states, upper midwest and pacific west
59
How do you control lyme disease?
avoid bites
| control resevoir hosts
60
How do you treat early disease form of lyme disease?
doxycycine is drug of choice; alternatives-amoxicillin, cefuroxime or erythromycin
61
How do you treat recurrent arthritis or central or peripheral nervous system disease caused by lyme disease?
IV ceftriaxone; alternatives-cefotaxime or doxycycline
62
How do you treat chronic or post-lyme disease syndrome
no treatment, just treat symptoms
63
What is this:
Gram-negative rods
Aerobic
Obligate intracellular parasites – grow only in cytoplasm of eukaryotic cells
Maintained in animal and arthropod reservoirs and transmitted by arthropod vectors
Humans are accidental hosts
Ricketssia
64
What is the pathogenesis of RMSF?
-replicates in cytoplasma and nucleus of endothelial cells, -vasculitis due to endothelial cell damage and leakage of blood vessels
65
What are the clinical manifestations of the disease?
7-day incubation period after tick bite
-high fever, headache, malaise
-macular rash, centripetal spread, evolve to "spotted" or petechial form
-
66
What are complications that can occur with RMSF?
pulmonary, CNS, renal or cardiac abnormalities
67
Death may occur in RMSF within (blank) days- this is a potentially serious infection.
7-15
68
How do you lab diagnose RMSF?
immunofluorescence staining of biopsy tissue
Culture-done in tissue culture or embryonated eggs
antibody detection
69
What are the antibody detection RMSF laboratory tests?
Weil-Felix test
| indirect immunoflourescence
70
What is this:
Detects antibodies that cross-react with a Proteus antigen
No longer recommended – lacks sensitivity and specificity
Weil-Felix test
71
What is this:
Detects antibodies against outer membrane protein and LPS
LPS shared across rickettsial species
Indirect immunofluorescence
72
(blank) are the principle resevoir and vector for RMSF
ticks
73
When do most RMSF infections occur?
april to september when ticks are most active
74
Where do you find RMSF?
throughout US
| mostly south and east
75
What is the treatment for RMSF?
doxycycline is drug of choice
| EARLY TREATMENT is critical. should start treatment if RMSF is even just suspected
76
What are three other rickettsial infections other than ricketssia ricketssi?
Orientia tsutsugamushi
Rickettsia prowazekii
Rickettsia typhi
77
What is this:
Reservoir – mites (chiggers) and wild rodents; vector – mites
Japan, eastern Asia, northern Australia
Abrupt onset, fever, headache, myalgias, maculopapular rash
Orientia tsuttugamushi-scrub typhus
78
What is this:
Reservoir – humans; vector – human body louse
Worldwide distribution; crowded, unsanitary conditions; war, famine
100,000 cases during civil war in 1997 in Burundi
Killed 700,000 of Napoleon’s troops during Russian campaign
Abrupt onset, fever headache, myalgias, macular rash
Ricketssia prowazekki-edemic typhus
79
What is this:
Reservoir – wild rodents; vector – flea
Worldwide distribution
Gradual onset, fever, headache, myalgias, maculopapular rash
Rickettsia typhi (murine endemic typhus)
80
```
What is this:
Gram-negative, facultatively anaerobic rod with bipolar staining
Member of Enterobacteriaceae
Zoonotic disease
Enormous historic importance
```
Y. pestis
81
What is this:
Follows bite by flea; incubation period ≤ 7 days
High fever; painful bubo (inflammatory swelling of lymph nodes)
High mortality if untreated (75%)
Bubonic plague
82
What is this:
Follows aerosol exposure; short incubation period (2-3 days)
Initially, headache, malaise and pulmonary signs
Highly infectious; rapidly fatal if untreated
Pneumonic plague
83
What specimens do you grab for lab diagnosis of Y. pestis?
blood, bubo aspirate, sputum, others
84
How do you diagnose the plague via lab?
lab identification by standard microbiological techniques (easily misidentified by automated ID systems)
85
the plague is (blank) in the US
rare
86
What are the natural hosts for Y. pestis?
rats, squirrels, rabbits, etc.
87
What is the transmission of Y. pestis?
- Flea bite
- direct contact w/ infected tissues
- person to person (pneumonic)
88
How do you prevent plague?
reservoir and vector control
| potential biothreat
89
How do you treat plague?
streptomycin is drug of choice
| doxycycline is best alternative
90
what are these:
| dermatophytosis, sporotrichosis and mycetoma
fungal infections of skin and subcutaneous tissue
91
(blank) are molds that invade stratum corneum of skin or other keratinized tissues
dermatophytes
92
What are the major genera of dermatophytosis?
Trichophyton, microsporum and epidermophyton
93
What are the major genera of dermatophytosis?
trichophyton
microsporum
epidermophyton
94
What is this:
itching, cracked skin, scaling between toes
T. rubrum, T. interdigitale, sometimes E. floccosum
Tinea pedis (athletes foot)
95
What is this:
jock itch-groin infection
T. rubrum most common
Tinea cruris
96
What is this:
Infection of arms, legs or trunk
Differential diagnosis – eczema, psoriasis
T. rubrum, M. canis, M. gypseum
Tinea corpis
97
What is this:
- scalp ringworm
- scaling of scalp, itching, hair loss
- numerous species of trichopyton and microsporum
Onchomycosis
98
What is the natural habitat for dermophytosis?
anthropophilic species
zoophilic species
geophilic species
99
Which species of dermatophytes cause this:
| chronic, relatively noninflammatory infections; difficult to cure
anthropophilic
100
What species of dermatophytes cause this:
| profound host reaction, highly inflammatory lesions, respond well to therapy
zoophilic and geographic species
101
How do you diagnose dermatophytes?
direct examianation of scraping or clippings
102
How do you do a scrapings or clippings to diagnose dermatophytes?
take samples from edge of skin lesions or nails or hair
- dissolve tissue with KOH
- examine microscopically for hyphae
103
What do you do with the scrapings of dermatopytes?
culture on mycologic media and it takes 7-28 days
104
How do you treat dermatophytes?
- topicals for localized infection
| - oral agents for more extensive infection or infection of hair or nails
105
What are the topics used for localized infection for dermatophytes?
azoles or terbinafine
106
What are the oral agents used for extensive infection or infection of hair or nails for dermatophytes?
itraconazole, fluconazole, terbinafine, griseofulvin
107
What is the etiology of pityriasis (tinea) versicolor?
Malassezia furfur, budding yeast like cells
108
What are the clinical syndromes associated with pityriasis (tinea) versicolor?
small hypo or hyperpigemented macules
hypo-pigmented in dark skinned individuals; blocks melanin production
light-skinned indivuduals (pale to pale brown)
109
how do you use the lab to diagnose Pityriasis (tinea) versicolor?
KOH mount of skin scrapings
| spaghetti and meatballs appeaerance-yeasts plus hyphal elements
110
What is the epidemiology of pityriasis (tinea) vesicolor?
worldwide
| Most prevalent in tropical or subtropical regions ( may infect up to 60% of population)
111
How do you transmit Pityriasis (tinea) versicolor?
man to man transmission
112
What is the treatment for pityriasis (tinea) versicolor?
- topical azoles or selenium sulfide shampoo
| - oral azoles for more widespread infection
113
What is the fungus that causes lymphocutaneous sporotrichosis?
sporothrix schenckii (dimorphic fungus)
114
What are the clinical features of lymphocutaneous sporotrichosis?
classic infection follows traumatic incoulation of soil or vegetable matter; termed "rose gardener's disease"
- small nodule at site of inoculation; may ulcerate
- secondary nodules along lymphatics that drain primary lesion
115
What is the epidemiology of lymphocutaneous sporotrichosis?
- worldwide distribution
- grows on soil, plants and decaying vegetation
- considered an occupational disease; florists, rose gardeneres, greenhouse workers
116
How do you use the lab to diagnose sporotrichosis?
- culture of infected pus or tissue
| - budding yeast at 35 degrees celcius, mold at 25 degrees celcius
117
How do you treat sporotrichosis?
itraconazole
118
What is the etiology of eumycetoma?
multiple filamentous fungi (curvularia, fusarium, exophiala)
119
What is this:
Localized, chronic, granulomatous process involving cutaneous and subcutaneous tissues
Multiple granulomas and abscesses containing masses of hyphae
Abscesses drain through skin; may extrude granules of hyphae
May destroy muscle and bone locally
Mycetoma
120
How do you use the lab to diagnose mycetoma?
microscopy (demonstrates grains or granules in exudate) and culture
121
What is the epidemiology of mycetoma?
- Tropical areas with low rainfall
- Implantation of fungi from environmental sources
- Specific agents vary by region
122
What is the treatmet for mycetoma?
- poor response to antifungals
| - amputation is only definitive treatment
123
A patient has been exposed to spores of Bacillus anthracis following a deliberate terrorism attack. The patient presents with a “flu-like” illness characterized by low-grade fever, malaise, fatigue and myalgias. What would be the best specimen to confirm a diagnosis of inhalational anthrax?
A) Throat swab
B) Nasopharyngeal swab
C) Blood culture
D) Stool sample and rectal swab
E) Environmental sample at the site of spore release
C) Blood culture
