Micro Flashcards
what 4 infections occur almost exclusively in diabetics
Rhinocerebral mucormycosis
necrotizing otitis externa
emphysematous UTIs
emphysematous cholecystitis
in which diabetics is rhinocerebral mucormycosis seen? what organism causes it?
T1DM
Rhizopus oryzae
in which diabetics is necrotizing otitis externa seen? what organism causes it?
T2DM
pseudomonas aeruginosa
What organism is implicated in emphysematous UTIs?
candida albicans
General characteristics of Rhizopus oryzae?
infects diabetics w/ ketoacidosis ubiquitous, found in soil affinity for iron rich, acidic environments tropism for blood vessels not dimorphic
What are the characteristics of the Rhizopus hyphae?
broad irregularly branched aseptate 'ribbonlike' 'moose antlers' fragile have globuse sporangia
What are the rhizopus virulence factors?
avirulent
siderophore rhizoferrin
ketone reductase
transmission and pathogenesis of rhinocerebral mucromycosis
inhalation of spores -> germination in nasal passages -> invasion of blood vessels -> invasion of sinuses, eyes, cranial bones, brain -> infarction, necrosis, thrombosis RAPID!
possible symptoms of rhinocerebral mucromycosis
blood vessel and nerve damage
facial numbness
periorbital edema, proptosis, blindness
black eschars on palate or nose
How do you diagnose rhinocerebral mucromycosis
CT or MRI
gauge sinus involvement
plate and stain on KOH
plate tissue on SDA
treatment of rhinocerebral mucromycosis
debridement + ampho B + control of diabetes
General characteristics of pseudomonas aeruginosa
gr - rod ubiquitous encapsulated oxidase + aerobe salt tolerant growth in water sources iron acquisition
virulence factors of pseudomonas aeruginosa
capsule (alginate) spreading factors exotoxin A biofilm intrinsic and acquired antibiotic resistance pili
What plate do you use to grow Pseudomonas aeruginosa and what does it look like?
MacConkey
mucoid colonies
odor of grapes
blue or green growth
what is the pathogenesis of necrotizing otitis externa
being in EAC -> may invade soft tissue
what are the symptoms of necrotizing otitis externa
severe otalgia, otorrhea
swelling, erythema
temporary hearing loss
diagnosis of necrotizing otitis externa
CT or MRI to determine extent
otherwise on PE
treatment of necrotizing otitis externa
debridement + systemic and topical antibiotics + control of diabetes
what predisposing factors lead to diabetic foot infections
neuropathy
peripheral vascular dz
hyperglycemia
impaired immunity
what is the primary pathogen in a foot infection? and what is the typical number of pathogens present?
s. aureus
5-7 (polymicrobial)
Type I necrotizing fasciitis characteristics
polymicrobial (avg 4.6 isolates)
most often involves feet with rapid extension into legs
Type II necrotizing fasciitis characteristics?
usually strep pyogenes
community acquired
predisposing factors: trauma, infection, drug use, burns, chx pox
What is fournier gangrene?
type I
GI enteric organisms that spread into ant abdominal wall and into scrotum
symptoms of necrotizing fasciitis
pain out of proportion to apparent severity
bullae common
erythema, local warmth, edema, skin induration
treatment of necotizing fasciitis?
debridement + antibiotics + diabetes control + supportive therapy