Micro Flashcards
1
Q
superficial fungal infections
A
outermost layer of skin and hair pityriasis (tinea) versicola tinea nigra black piedra white piedra
2
Q
causative agent of pityriasis versicolor
A
malassezia furfur
3
Q
characteristics of malassezia furfur
A
dimorphic
lipophilic
opportunistic
interfere with melanin production
4
Q
rash of pityriasis versicolor
A
transient, superficial and scaly
5
Q
diagnosis of pityriasis versicolor
A
KOH
spaghetti and meatball appearance
6
Q
causative agent of tinea nigra
A
hortaea (exophilia) werneckii
infection of stratum corneum
7
Q
rash of tinea nigra
A
asymptomatic well demarcated
slowly expanding brown to black
nonscaly macules with well-defined borders
on palms and soles (from traumatic inoculation)
8
Q
diagnosis of tinea nigra
A
KOH-yeast like cells with hyphal fragments
rule out diagnosis for malignant melanoma
9
Q
cutaneous infections
A
infections that extend deeper into the epidermis, as well as invasive hair and nail diseases
10
Q
favic hair infection
A
inside hair and at the root of the hair shaft
11
Q
extohrix hair infection
A
outside shaft
12
Q
endothrix hair infection
A
inside shaft
13
Q
dermatophytes
A
trichophyton
epidermophyton
microsporum
14
Q
spread of dermatophyte infections
A
anthropophilic-humans
zoophilic-animals
geophilic-soil
15
Q
tinea capitis
A
highly contagious
hair becomes grayish, dull and brittle due to ectothrix invasion of hair
hair breaks near base of shaft
more common in prepubescent children
16
Q
principal agent of tinea capitis
A
t. tonsurans
17
Q
tinea rash and immune response
A
itchy, redness, scaling or fissuring of skin
ring with irregular borders and a cleared central area
no classical humoral or cell protective immunity
DTH hypersensitivity reaction
18
Q
tinea manum
A
contact with another site of infection
direct contact with an infected animal or soil
19
Q
tinea unguium
A
trichophyton rubrum most common cause
rule out candida infections or onichomycosis
20
Q
laboratory diagnosis of cutaneous infections
A
KOH of hair or scalp scrapings
characterized by specific pattern of growth in culture and by production of macro conidia and micro conidia
21
Q
subcutaneous infections
A
involves deeper layers of dermis
associated with some form of trauma (splinter, rose bush thorn, insect bite)
feet, hands, arms and buttocks more prone
produce granuloma
22
Q
examples of subcutaneous infections
A
sporotrichosis
chromoblastomycosis
subcutaenous phaeohyphomycosis
23
Q
lymphocutaneous sporotrichosis
A
travels to lymphatic
“rose gardener’s disease”
24
Q
characteristics of S. schenckii
A
naturally found in soil, hay, sphagnum moss, and rosebushes
usually affects farmers, horticulturists, rose gardeners, plant nursery workers
dimorphic fungus
25
diagnosis of S. schenckii
cigar shaped oval-round yeast cell
| rosette pattern of conidia at 25 C on Sabouraud's agar
26
Asteroid bodies
found in S. schenckii
| asteroid bodies represent host's immune response
27
causative agent for chromoblastomycosis
dermaticeous fungi-fonsecaea pedrosi
28
characteristics of chromoblastomycosis
often seen in workers injured with woods
| colored lesions that start out scaly and become raised, cauliflower-like lesion
29
diagnosis of chromoblastomycosis
presence of pigmented fungi in tissue section or pus
| sclerotic (medlar) bodies
30
causative agents for subcutaneous phaeohyphomycosis
dematiaceous molds-alternaria, bipolaris, curvularia
31
infections in subcutaneous phaeohyphomycosis
abscesses, localized cerebral, subcutaneous, paranasal sinusitis, prosthetic valve endocarditis
32
diagnosis of subcutaneous phaeohyphomycosis
dark hyphae
33
impetigo
superficial skin infections, most frequently in children
| staph and strep
34
folliculitis
pyogenic infection in the hair follicles
| staph and pseudomonas
35
furuncles (boils)
extension of filliculitis (stye)
| staph
36
carbuncles
infection extends to deeper subcutaneous tissue (chills and fever due to systemic spread) with a single inflammatory mass
staph
37
spreading infections
impetigo when in epidermis, erysipelas when involving dermal lymphatics, and cellulitis when subcutaneous fat layer
38
abscess formation
folliculitis, boils, carbuncles
39
necrotizing infections
fasciitis and gas gangrene (myonecrosis)
40
pustuble
most neutrophils with serous fluids within or beneath epidermis
41
bulla
collection of serous fluid and small number of inflammatory cells
42
common causes of impetigo
strep pyogenes
| staph aureus
43
common causes of erysipela
strep pyogenes
44
common causes of necrotizing fasciitis
anaerobes and microaerophiles
| usually mixed infections
45
common causes of myonecrosis gangrene
clostridium perfringens
46
enteric fever
rose spots containing bacteria
| caused by salmonella
47
septicemia
ecthyma gangrenosum
| caused by pseudomonas aeruginosa
48
scarlet fever
```
erythematous rash (toxin)
caused by strep pyogenes
```
49
toxic shock syndrome
rash and desquamation (toxin)
| caused by staph aureus
50
characteristics of staph aureus
```
gram positive
resistant
nonmotile
facultative anaerobe
catalase +, coagulase +
NaCl for growth
```
51
clinical manifestations of staph aureus
abscesses
systemic diseases
food poisoning
toxic shock syndrome
52
staph aureus virulence factors
staphylococcal toxins (alpha, beta, gamma, PV)
exfoliative toxins
enterotoxins
toxic shock syndrome toxins
enzymes-coagulase, catalase, hyaluronidase, fibrinolysin, lipases, nucleases
53
characteristics of strep pyogenes
```
gram + arranged in chains
avoid phagocytosis by capsule, M proteins, C5a peptidase
non-motile
facultative anaerobe
need blood or serum for isolation
```
54
virulence factors of strep pyogenes
C carbohydrate
M protein
streptolysin O and S
hyaluronidase, DNAse
55
risk factors of abscesses, furuncles, and carbuncles
all related to hair follicle-pus within the dermis and deeper skin tissues
diabetic, immunologic abnormalities, skin breaches
56
treatment of abscesses, furuncles, and carbuncles
small-warm compresses to help drainage
| incision and drainage
57
impetigo characteristics
superficial infection, contagious
seen primarily in children, poor personal hygiene
purulent with crusting
commonly caused by strep pyogenes
58
non-bullous impetigo
papules to vesicles surrounded by erythema
ages 2-5
GAS and staph aureus
59
risk factors for non-bullous impetigo
poverty, crowding, poor hygiene, scabies
60
pustular impetigo
intraepidermal vesicles filled with exudate (pus)
GAS or staph aureus
seen in exposed areas of body during warm, moist weather
61
bullous impetigo
```
localized staph scalded skin syndrome
caused by staph aureus of phage group II (toxin A-no cell adhesion)
happens in newborns and young children
no Nikolsky sign
highly communicable
```
62
clinical erysipelas
tender, superficial erythematous and edematous lesions
infection spreads in upper dermis and superficial lymphatics
mainly affected young and elders
caused by GAS
63
clinical cellulitis
redness, induration, heat and tenderness
accompanied by inflammation of draining lymph nodes
GAS and S. aureus
in unimmunized (h. flu type B)
associated with bites or scratches from cats or dogs (P. multocida)
64
clinical necrotizing infections of skin and fascia
extensive tissue destruction, thrombosis of blood vessels, bacteria spreading along fascial planes
destruction of fascia and fat but may spare skin
65
type 1 necrotizing fasciitis
mixed infection by aerobic and anaerobic bacteria and occurs most commonly after surgical procedures and in patients with diabetes and peripheral vascular disease
66
type 2 necrotizing fasciitis
mono-microbial infection caused by GAS or MRSA (mostly GAS)
67
V. vulnificus necrotizing fasciitis
rapidly progressive wound infections after exposure to contaminated seawater
development of vesicles or bullae and eventual tissue necrosis
50% mortality
68
myonecrosis clinical manifestation
due to c. perfringens, c. septicum, c. histolyticum, c. sordellii
associated with local trauma
gas found in skin (fascia and deep muscle spared)
nonclostridial-mixed anaerobic and aerobic (diabetes with foul odor)
most by GAS
69
staphylococcal scalded skin syndrome
perioral eryhtema covers entire body
positive Nikolsky sign-large blister with clear fluid, no organism, no leukocytes
exfoliative toxin destroys intracellular connections in the skin
70
toxic shock syndrome
cutaneous and soft tissue involvement
| associated with use of tampons
71
characteristics of pseudomonas aeruginosa
```
gram negative
aerobic
rod shaped
motile (pili and flagella)
grape like odor
environmental bacterium
simple growth requirement
```
72
pseudomonas folliculitis
resulting from immersion in contaminated water (hot tubs, whirlpools, swimming pools)
secondary infection in people who have acne or shave their legs
fingernail infection
73
characteristics of mycobacterium leprae
obligately aerobic rod with gram+ like cell wall
mostly infects through aerosols
animal models-armadillo and mice footpads
74
locations of best growth for m. leprae
skin histiocytes, endothelial cells and schwann cells of peripheral nerves
75
tuberculoid leprosy
red blotchy lesions with anesthetic areas
| Th1 mediated; low infectivity
76
lepromatous leprosy
diffuse skin lesions
cell mediated immunity is deficient (Th2)
highly infective
nonreactive to lepromin
77
treatment of leprosy
lepromatous-dapsone, ribiospfampin, clofazimine for 2 yrs
| tuberculoid-dapsone and rifampin for 6 months
78
characteristics of bacillus antrhacis
gram positive
spore forming
capsule (D glutamic acid)
exotoxin-edema factor, lethal factor, protective antigen
79
virulence factors for anthracis
edema factor+protective=edema toxin
lethal factor+protective=lethal toxin
typical AB type binary toxin
80
edema factor mechanism
```
adenylate cyclase (similar to pertussis)
activated by calmodulin
increase cAMP (impaired flow of ions and water)
```
81
lethal factor mechanism
protease induces macrophage to produce high levels of cytokines that trigger shock
82
protective antigen
promotes entry of EF into phagocytic cells
83
inhalation antrhax
aerosolized spores
mediastinal widening
replication occurs within the lung with local exotoxin release
death within 3 days of initial symptoms
84
cutaneous anthrax
```
most common
painless papule at site of inoculation
progress to ulcer surrounding vesicles
necrotic eschar
localized tissue necrosis
round black lesion with a rim of edema-malignant pustule
```
85
diagnosis of anthax
no spores in clinical specimen
serpentine chain of bacilli
culture-non hemolytic, sticky colonies
86
protection and therapy for anthrax
inactivated cell free product as vaccine
live attenuated also available
teatment-60 days with penicillin, cipro, doxy
87
characteristics of rickettsia
weakly gram negative bacilli
obligate intracellular
replicate in cytoplasm of cells
Giemsa and Gimenez stains
88
beta lactams for rickettsia
dont work
peptidoglycan is minimal
LPS weak endotoxin
89
R. rickettsii characteristics
RMSF
Omp A pathogenic factor for endothelial adherence
replication in cytoplasm and nucleus results in vasculitis
intracellular growth protects from immune clearance
90
R. rickettsii epidemiology
most common Rickettsia in USA
| April-September
91
vector R. rickettsii
```
ticks from Ixodeae family
dermacentor andersoni (Rocky mountain states)
dermacentor variabilis (SE US)
```
92
states with highest incidence of R. rickettsii
Arkansas, Delaware, Missouri, North Carolina, Oklahoma, Tennessee
93
reservoir R. rickettsii
ticks via transovarian transmission
94
transmission R. rickettsii
tick bite
6-10 hrs dormant, avirulent bacteria activated by warm blood meal
translocation of bacteria from salivary glands to human bloodstream
95
RMSF clinical manifestations
incubation 2-14 days
fever, chills, headaches, myalgias
centripetal, palms and soles=rash after 3-5 days
abdominal pain, vomiting, hepatitis
respiratory failure, encephalitis, renal failure, hypotension, myocarditis
fatal in 20% of cases if untreated
96
RMSF lab findings
```
thrombocytopenia, coagulopathy
anemia
normal WBC
hyponatremia
transaminitis
```
97
diagnosis of RMSF
PCR and immunohistochemical in acute phase (notify CDC)
serology but Ab may not be present in initial samples
fourfold change in IgG in paired serum (1st week and 2-4 weeks later)
98
Rickettsia akari characteristics
causes rickettsialpox
cosmopolitan
huamns infected by mites
99
transmission R. akari
transmitted by infected mites
| reservoir is rodent (common house mouse)
100
clinical presentation of rickettsialpox
biphasic presentation
first week-papule to ulcer to eschar
incubation for 7-24 days, systemic spread
second phase-fever, headache, photophobia, papulo-vesicular rash, pox like progression (milder than RMSF)
101
characteristics of R. prowazekii
```
epidemic (louse borne) typhus
humans-reservoir
pediculus humanus (body louse)
disasters, war, famine outside of US
squirrels in US
```
102
transmission of R. prowazekii
louse defecates at site of feeding
may be introduced into abraded or injured skin or mucous membranes by scratching or hand contamination
infectious for as long as 100 days
103
clinical manifestations of R. prowazekii
```
acute-potentially severe vasculitis (7-14 days) with fever, centrifugal maculopapular rash, CNS symptoms
recrudescent form (Brill-Zinsser disease) 10-50 years after primary infection (flu-like symptoms)
```
104
diagnosis of R. prowazekii
serology (MIF test)
105
characteristics of R. parkeri
mainly southern US
American Boutonneuse fever/Tidewater spotted fever
eschars and rash on PE, fever, headaches, myalgias
106
vector of R. parkeri
amblyomma maculatum (Gulf coast tick)
107
diagnosis of R. parkeri
serology, PCR, culture from skin biopsy
108
treatment for R. parkeri
doxycycline
109
characteristics of r. typhi
endemic typhus
| humans are infected by inoculation of infective flea feces in bite wounds
110
vector r. typhi
xenopsylla cheopis (rat flea)
111
reservoir r. typhi
rodents
112
clinical manifestations r. typhi
non-specific symptoms
fever, headache, chills, myalgias
rash
113
diagnosis r. typhi
serology by IFA
114
characteristics of orientia tsutsugamushi
scrub typhus
| endemic in Asia Pacific rim
115
reservoir and vector for orientia
mites
larval mites (chiggers) via transovarian
feed once in a lifetime
116
clinical for orientia
severe headache, fever, myalgias
maculopapular rash, spreads centrifugally
CNS complications, heart failure
117
diagnosis for orientia
serology IFA
118
treatment of rickettsial and orientia
doxycycline
chloramphenicol or fluoroquinolone as alternatives
do not wait for confirmatory serology
119
RMSF in pediatrics treatment
doxycycline is drug of choice regardless of age
120
characteristics of erlichia and anaplasma
obligate intracellular bacteria
no peptidoglycan or LPS
grow on hematopoietic cells
replicate in phagosomes of host cells
121
morula
microcolony of erlichiae within a vacuole
122
ehrlichia chafeensis
human monocytic ehrlichiosis
| rashless RMSF
123
anaplasma phagocytophilum
human granulocytic anaplasmosis
124
reservoir ehrlichia
deer, dogs
125
vector ehrlichia
ticks (Ambylomma americanum)
126
clinical ehrlichia
flu like 1-3 weeks after tick bite
| rash (spares hands and feet)
127
diagnosis of ehrlichia
serology by IFA
PCR
peripheral blood (Giemsa) to see morulae in monocytes is insensitive
128
reservoir anaplasma
deer, sheep, rodents
129
vector anaplasma
hard-shelled ticks (Ixodes scapularis and pacificus)
130
location anaplasma
northeast/north central states and N. Cali
131
clinical anaplasma
1-3 weeks after tick bite-flu like
| rash spares hands and feet
132
diagnosis of anaplasma
serology by IFA
PCR
PB Giemsa is insensitive
133
laboratory findings for anaplasma and ehrlichia
leukopenia
lymphopenia
thrombocytopenia
elevated liver enzymes
134
DOC ehrlichia and anaplasma
doxycycline
135
borrelia characteristics
weakly staining, gram negative spirochetes
motile (flagella)
difficult to cultivate
136
B. burgdorferi locations
NE, Minnesota, Wisconsin
137
vector B. burgdorferi
Ixodes scapularis and pacificus
138
reservoir B. burgdorferi
white footed mouse and white tailed deer
139
transmission B. burgdorferi
transmitted in tick's saliva during prolonged period
140
clinical manifestations of Lyme disease
incubation up to 1 month
early-EM
early disseminated-facial nerve palsy
late-arthritis, carditis, meningitis
141
diagnosis lyme
Ig not detectable within 1st 4 weeks
EIA or IFA (sensitive)
Western (specific)
142
treatment of Lyme
amoxicillin or cefuroxime for children
doxy for over 8
ceftriaxone for CNS, carditis or recurrent arthritis
143
STARI characteristics
Southern
rash of EM and flu-like in non-Lyme endemic areas
associated with bite of Lone Star tick (A. americanum)
144
reservoir STARI
white tailed deer
145
diff STARI and Lyme
STARI does not have arthritis, neurologic disease, or chronic symptoms
less likely to have multiple skin lesions in STARI
146
B recurrentis characteristics
```
louse borne (epidemic)
natural disasters, unsanitary conditions
```
147
endemic tick borne
ticks feed nocturnally and contaminate the wound with saliva and feces
148
reservoir for endemic tick borne borrelia
rodents, small mammals
149
relapsing fever clinical syndrome
incubation for 1 week
biphasic-fever, chills, headaches, hepatosplenomegaly
afebrile for 1 week
return of symptoms
150
diagnosis relapsing fever
Giemsa on PB during febrile episode
| serology is not useful due to antigenic phase variation
151
treatment relapsing fever
doxy
| penicillin and erythromycin in pregnant and children under 8
152
characteristics babesia
protazoa
| sporozoite (ticks) trophozoite to merozoite to gamete
153
most common babesia species
babesia microti
154
reservoir babesia
white footed mouse
155
vector babesia
ixodes tick
156
life cycle babesia
blood meal-introduces sporozoites into human host
enter eryhtrocytes and undergo asexual replication
multiplication of blood stage responsible for clinical manifestations
157
clinical babesia
hemolytic anemia
influenza like symptoms
splenomegaly, hepatomegaly, jaundice
158
risk factors for babesia
asplenia, advanced age, impaired immune function (HIV, malignancy, corticosteroid)
159
diagnosis babesia
maltese cross on blood smears
PCR for low levels of parasites
serology not helpful (cannot distinguish between acute or old infection)
160
treatment of babesiosis
combination
mild-atovaquone and azithromycin
severe-clindamycin and quinine
