pneumonia organisms Flashcards
what are the three bacteria that cause atypical pneumonia
mycoplasma pneumoniae
chlamydia pneumoniae
legionella pneumophila
strep pneumo:
gram stain
capsule and shape
appearance on culture
gram positive encapsulated diplococcus (lancet-shaped) alpha-hemolytic=green on blood agar
how can strep pneumo be differentiated from:
strep viridians
staph aureus
other bacteria
optochin sensitive
catalase negative
quellung reaction
what are the three virulence factors of strep pneumo
capsule
IgA protease
lipoteichoic acid
what bacteria are implicated in aspiration pneumonia
strep pneumo
klebsiella
how does pneumonia caused by strep pneumo look on cxr
lobar consolidation
which bacteria does rusty sputum indicate
strep pneumo
how can diagnosis of strep pneumo be confirmed (2 ways)
gram stain and culture
rapid urinary antigen test
staph aureus:
gram stain
capsule
gram positive
encapsulated
how can staph aureus be differentiated from
other staphylococci
other cocci
coagulase positive
catalase positive
which bacteria are most common causes of HAP
staph aureus
pseudomonas
which bacteria are implicated in post-influenza pneumonia?
strep pneumo
staph aureus
which bacteria can cause necrotizing pneumonia and lung abscesses
staph aureus
klebsiella
Nocardia
how does infection with staph aureus appear on cxr
diffuse infiltrates
pseudomonas aeruginosa:
gram stain and shape
2 things on culture
gram negative
bacilli
blue-green with grape-like odor
how do you differentiate pseudomonas from other gram negative bacilli
does not ferment lactose
what two types of pneumonia is pseudomonas especially responsible for
HAP/VAP
CF patients
what are the virulence factors of pseudomonas and their action
endotoxin: causes fever and shock
exotoxin A: blocks protein synthesis
which pneumonia-causing bacteria is often seen in burn wound infections?
pseudomonas
klebsiella pneumoniae:
gram stain and shape
virulence factor
2 common pathology features
gram negative bacilli
capsule
red currant jelly sputum and necrotizing infection
how can klebsiella be differentiated from other gram negative rods
ferments lactose and incapable of growth at 10C
what populations are susceptible to klebsiella
alcoholics
malnourished
which bacteria is cultured on chocolate agar with factors V (NAD) and X (hematin)
haemophilus influenzae
what bacteria are implicated in exarcerbations of COPD
haemophilus influenzae
moraxella catarrhalis
haemophilus influenzae:
gram stain and shape
virulence factor
gram negative coccobacillary
capsule
which especially virulent strain of h. influenzae does the vaccine protect against
capsular type B
moraxella catarrhalis:
gram stain and shape
susceptible population
gram negative coccobacillary
elderly, COPD
which bacteria is never CAP and essentially only seen in ICU/VAP
acinetobacter baumanii
acinetobacter baumanii:
gram stain and shape
susceptible population
gram negative coccobacillary
patients on mechanical ventilation
which bacterial cause of pneumonia lacks cell wall and what does that preclude
mycoplasma pneumoniae
use of vancomycin, penicillins, cephalosporins, etc
and gram stain
what is the most common cause of pneumonia in school aged children and who else?
mycoplasma pneumoniae
military recruits and prisoners
what is the virulence factor of mycoplasma pneumoniae
adhesin:
binds to ciliated epithelial cells and reduces ciliary clearance
what are three diagnostic tests for mycoplasma pneumoniae?
PCR
cold agglutinins
grows on Eaton agar
what other organs can mycoplasma pneumoniae affect
cardiac and CNS (encephalitis) involvement
what causes atypical pneumonia in kids? older adults?
mycoplasma
chlamydia
legionella pneumophila:
gram stain and shape
virulence factors/characteristics
gram negative bacillus
prevent phagolysosome fusion in alveolar macrophage
cell wall endotoxin
what two diseases does legionella cause?
legionnaire’s disease: severe atypical pneumo with diarrhea, confusion
Pontiac fever: mild flu-like syndrome
what organisms can be diagnosed using a urinary antigen test
strep pneumo
legionella
how is legionella diagnosed
grows on charcoal yeast with iron and cystein
urine antigen test
silver stain instead of gram
what organism commonly causes hyponatremia with pneumonia?
legionella
match the genome shape to virus: linear ssRNA helical linear -ssRNA, segmented linear dsDNA pleomorphic linear -ssRNA
parainfluenza and human metapneumovirus
influenza
adenovirus
RSV
how are the following viruses transmitted: influenza RSV adenovirus parainfluenza
influenza: airborne respiratory droplets
respiratory droplets and direct contact
aerosol, fecal-oral, direct contact
respiratory droplets
describe the pathology of influenza
neuraminidase degrades mucus layer and infections causes necrosis of respiratory epithelium
why does influenza cause myalgias
cytokine release from necrosis of respiratory epithelium
which viruses can be diagnosed by RT-PCR
influenza and RSV
what is Reye’s syndrome and which organisms and drug are implicated
influenza/VZV and aspirin
encephalopathy and liver degeneration following the flu
what organism is the most important cause of pneumonia and other LRTI in infants
RSV
what is the virulence factor for RSV? what is the basis for prevention using palvizumab for prevention?
surface spikes: cause respiratory epithelium cells to fuse forming syncytium
palvizumab: antibody against F protein, neutralizes infectivity of virus in premies
how does RSV infection present in adults
mild, self-resolving URT infection
what are two diagnostic tests for RSV
RT-PCR
rapid antigen test
how does RSV present in adults
mild URTI
what sometimes follows RSV pneumo in infants
asthma
adenovirus commonly causes viral pneumonia in which population?
military recruits
what virus can cause atypical pneumonia with diarrhea and vomiting
adenovirus
what other illnesses can adenovirus cause?
febrile pharyngitis
conjunctivitis
hemorrhagic cystitis
gastroenteritis
what commonly follows pneumo caused by adenovirus
bronchiectasis or bronchiolitis obliterans
military recruits get vaccinated against which organism that no one else does? what serotypes are covered?
adenovirus
serotypes 4 and 7
what are the virulence factors of parainfluenza virus
F protein
neuraminidase
hemagluttinin
what illnesses do the 4 strains of parainfluenza cause
HPIV-1,2: croup
HPIV-3: croup and pneumonia and bronchiolitis
HPIV-4: common cold
what is croup? what organisms can cause it
URTI with seal-like barking cough and stridor
HPIV-1,2,3, influenza, RSV, HMPV
what is infection by human metapneumovirus often mistaken for
RSV, influenza, HPIV
where is SARS endemic to and what are distinctive pathologic features?
east asia
leukopenia and thrombocytopenia
affects middle and lower lobes
what is distinctive about the pathology of MERS?
pneumonia and ARDS with hemoptysis
AKI common
how does histo show up under microscope?
macros filled with oval yeasts
what are 2 pathologic characteristics of histo?
pancytopenia
mouth/GI ulcers
what’s the most common pathologic feature of blasto? what else happens?
ulcerated, wart-like lesions
-bone, GU, CNS involvement
what does blasto look like under microscope?
big, broad-based buds
what does coccidioides look like under microscope?
spherules filled with endospores
what is a common pathologic feature of coccidioides?
eosinophilia
what are 2 common pathologic features of paracoccidioides?
submandibular lymphadenopathy
facial, ulcerated, nodular leasions
how does paracoccidioides look under microscope?
pilot wheel configuration: multiple buds
what are 3 common pathologic manifestations of aspergillus?
hemoptysis
fungus balls
allergic aspergillosis: IgE response with expectoration of brownish bronchial plugs
how does aspergillus look under microscope?
septate hyphae with acute angle branching
-and radiating conidia
what are 2 common pathologic findings in mucormycosis?
frontal lobe abscesses
rhinocerebral sinusitis
what 4 conditions is mucormycosis associated with
immunosuppression
diabetes
iron overload
burns
how does mucormycosis look under microscope?
non-septate right angle branching hyphae
how does pneumocystis appear on microscope (2 things)?
alveoli filled with foamy exudate from cysts
helmet-like cysts on silver stain
how is pneumocystis stained?
silver or Giemsa
what disease does cryptococcus in immunosuppressed/AIDS
meningitis
how does cryptococus appear under microscope?
single narrow-based bud with capsule around it
nocardia:
gram stain
other stain for it
appearance on microscope
gram positive
weakly acid fast
thin branching filaments: fungal appearance
what three diseases/pathologies is nocardia responsible for?
- PNA
- lung abscesses/empyema
- brain abscesses
rhinovirus:
2 distinct characteristics about growth
virulence factor
- won’t replicate below 33C
- acid labile
- binds ICAM-1 on epithelial cells
what is the difference between rhinovirus and coronavirus?
corona can cause GI illness
bordetella pertussis:
gram stain and structure
virulence factor
common pathologic feature
gram negative coccobacillus
AB toxin: increases cAMP
lymphocytosis
3 stages of infection with pertussis
catarrhal: 2 weeks of mild URTI
paroxysmal: 2-3 months of whooping cough
convalescent: 1-2 weeks of reduction in cough
corynebacterium diphtheriae:
gram stain and shape
appearance on microscope
virulence factor
gram positive bacillus
arranged in palisades
AB toxin: blocks EF-2/protein synthesis
diphtheriae: 3 common pathologic features (besides pseudomembrane)
bull neck: cervical lymphadenopathy
cardiac toxicity
neurotoxicity
how is diphtheria cultured and stained?
Loeffler medium or tellurite plate
methylene blue
what three organisms cause otitis media and sinusitis?
- strep pneumo
- H flu
- moraxella
what are 2 virulence factors of TB
- cord factor: inhibits macro maturation, induces TNF-alpha release
- sulfatides: inhibits phagolysosome fusion (assisted by PKnG protein)
how is TB cultured?
lowenstein-jensen agar
