B3-054 Ear Infection Pathogens Flashcards
primary otalgia
abnormal ear exam
do the inner ear structures cause pain in primary otalgia?
no
secondary otalgia
normal ear exam
do the inner ear structures cause pain in secondary otalgia?
yes, referred pain
causes of otitis media
recent UTRI-winter
red/cloudy and immobile tympanic membrane
causes of otitis externa
swimmer’s ear-summer
ear bud use
white discharge
common causes of secondary otalgia
dental caries, periodontal abscessess
pharyngitis, tonsilits
what characterizes malignant (necrotizing) otitis externa?
painful, granulation tissue
what characterizes malignant (necrotizing) otitis externa?
painful, granulation tissue
what characterizes malignant (necrotizing) otitis externa?
painful, granulation tissue
what population is concerning for malignant (necrotizing) otitis externa?
diabetes, elderly, immunocompromised
ramsay hunt is caused by
herpes zoster oticus
vesicular rash
vertigo, hearing loss, tinnitus
ramsay hunt
similar to otitis media, but no tympanic membrane bulging
viral myringitis
common pathogens causing otitis media
S. pneumoniae
H. influenzae
M. catarrhalis
S. pyogenes
common pathogens causing otitis externa
S. epidermis
P. aeruginosa
S. aureus
H. influenzae is gram _______
negative
shape of H. influenzae
coccobacilli
What strain of H. flu is the most virulent?
type B (HiB)
NTHi _______ cause invasive disease
rarely
Hib colonizes the
oropharynx
Virulence factors Hib
fimbriae
IgA protease
LPS
Hib capsule is made of
polyribosylribitol phosphate (PRP)
Hib vaccine is a conjugate vaccine consisting of _______
PRP
PRP allows H flu to spread to
joints
meninges, CNS
LPS from Hib causes
disseminated disease (meningitis)
Hib vaccine is purified PRP conjugated to
carrier proteins
Hib vaccine is purified PRP conjugated to
carrier proteins
combination vaccines for Hib
DTap-Hib and Hepatitis B-Hib
the Hib vaccine contain _______ antigens
t cell dependent
the Hib vaccines is given at what ages?
2-18 months
**prior to two months, maternal antibodies are protective
the Hib vaccine is not recommended >5 years of age. What are the exceptions?
sickle cell, aspenia, immunodeficiency, HIV infections
Hib can be diagnosed via a gram stain of ______
CSF or synovial fluid
Hib can be diagnosed via antigen detection for
PRP
Hib is grown on _____ agar
chocolate
Hib requires media containing
NAD (factor V)
Hemattin (factor X)
Hib can be grown on blood agar with ________ due to its ____ hemolytic properties
S. aureus; beta
NTHi lacks
a capsule
NTHi is a common cause of [3 diseases]
otitis media
sinusitis
pneumonia
NTHi causes a _______ spread
localized
is penicillin a good treatment for H. Flu?
no, growing resistance
treatment for invasive H. flu (menigitis)
ceftriaxone
pseudomonas is gram
negative
is pseudomonas motile?
yes
what is the oxygen dependency of pseudomonas?
obligate aerobes
where is pseudomonas found?
everywhere; ubiquitous
common nosocomial pathogen
psuedomonas
pseudomonas commonly infects [4]
skin, pulmonary, outer ear, eye
capsule of pseudomonas aeruginosa is called
alginate
what contributes to the antibiotic resistance of . aeruginosa?
alginate capsule
antiphagocytic and adhesive
alginate is made of
polymer of mannuronic and glucuronic acid
in virtro p. aeruginosa is
smooth and pigmented
Flagella +, pilli +, alginate negative
in a CF lung, P. aeruginosa is
mucoid colonies of highly encapsulated bacteria
Flagella-, Pili-, Alginate+
production of alginate is
highly regulated, environmental
alginate is produced at high levels
in CF lungs
P. aeruginosa: Exotoxin A
ADP ribosylates EF-2 affecting protein synthesis
AB toxin
P. aeruginosa: Exotoxin S
T3SS, blocks phagocytosis
P. aeruginosa: Exotoxin U
cytotoxic to macrophages
P. aeruginosa elastase
degrades elastin
regulated by quorum sensing
P. aeruginosa: infections in otherwise healthy
hot tub folliculitis
otitis externa “swimmer’s ear”
eye infection related trauma
default treatment of P. aeruginosa
ear drops
if the TM is ruptured
no neomycin eardrops
P. aeruginosa otitis externa prevention
alcohol ear drops
in diabetic, P. aeruginosa can cause _________ which spreads to surrounding tissues
malignant otitis externa
when would you expect to see pseudomonas colonize a wound in a burn patient?
> 2 weeks later
P. aeruginosa is extremely prevalent in what patient population?
Cystic fibrosis
P. aeruginosa can form a ________
biofilm
CF antibiotic therapies select for
highly resistant organisms
80-90% of CF patients are colonized with P.A by age
3
symptoms of P.A. pneumonia
fever, chills, dyspnea, cyanosis, productive cough
What patient populations are most as risk for P.A. pneumonia?
ICU patients and nursing home residents
P.A. is catalase
positive
P.A is oxidase
positive
what color colonies are associated with P.A?
blue-gree
what is the blue antibiotic pigment in P.A.
pyocyanin
**cytotoxic, causes oxidative stress
P.A.: Fluroscein is what color
yellow
fruity smell (grapes, tortillas)
P.A.
Pyocyanin causes
low ATP
low NADPH
because pyocyanin causes oxidative stress, it greatly affects what cell type
neutrophils
initial empiric combination treatment for P.A
antipseudomonal B-lactam + B-lactamase inhibitor + aminoglycoside
(ex. piperacillin, tazobactam, and tobramycin)
P.A. monotherapy is based on
local susceptibility patterns
last resort for P.A.
colistin (solubilizes bacterial membrane)
