L12 Bacterial Pneumonias I Flashcards
2 anatomic types of pneumonias
- lobar pneumonia
2. bronchopenumonia
main cause of pneumonia
- Bacteria*
others: fungi, viruses, parasites
age more likely to get pneumonia
> 65 years
most common infectious cause of death
pneumonia
2 types of pneumonia based on where ya get em
- hospital acquired
2. community acquired
community acquired pneumonia is divided into
- typical
2. atypical
Typical community acquired pneumonia causes
S pneumoniae
H influenzae
K pneumoniae
S aureus
Atypical community acquired pneumonia causes
Zoonotic
Nonzoonotic
Atypical community acquired pneumonia involvement
extrapulmonary/systemic
used for clinical diagnosis
Beta lactams vs pneumonia
not effective against atypical pneumonia
3 zoonotic pathogens that cause pneumonia
- Chlamydia psittaci
- Fracisella tularensis
- Coxiella burnetii
3 non-zoonotic pathogens
- Chlamydia pneumoniae
- Mycoplasma pneumoniae
- Legionella pneumoniae
Chlamydia psittaci
causes psittacosis
zoonotic
Fracisella tularensis
causes tularemia
zoonotic
Coxiella burnetii
causes Q fever
zoonotic
Chlamydia pneumoniae
non-zoonotic
Mycoplasma pneumoniae
non-zoonotic
Legionella pneumoniae
non-zoonotic
typical pneumonia:
onset
appearance
temperature
sudden onset
appear sick
high temps >103
atypical pneumonia:
onset
appearance
temperature
gradual onset
appear well
lower temps <103
typical pneumonia: chills/shaking cough pleurisy CXR other
chills common productive cough frequent pleurisy consolidation on CXR chest pain + SOB
atypical pneumonia: chills/shaking cough pleurisy CXR other
no chills non-productive cough no pleurisy patchy infiltrates, non-defined on CXR body aches, diarrhea, abdominal pain
Strep pneumoniae aka
pneumococcus
Strep pneumonia morphology
G+ Lancet shaped diplococcus Alpha hemolytic: greenish colonies optochin sensitivity encapsulated strains are virulent causes typical community acquired pneumoniae 90 serotypes, only some cause disease
increase risk of pneumococcal pneumonias
viral infections
youth or >65 years
reservoir of strep pneumo
asymptomatic carriers
irregular normal flora component
the serotypes and vaccines forstrep pneumo are based on
its capsule: major virulence factor
the capsule of strep pneumo
inhibits phagocytosis
interferes with complement activity
prevents C3b opsonization of the bacteria
receptor that recognizes C3b and C4b on a phagocytic cell
CR1
Strep pneumo virulence factors for protection
- IgA protease
- Hydrogen peroxide
- causes apoptosis in host cells
- kills competing bacteria
Strep pneumo virulence factors for binding
- Pili
- colonize upper respiratory tract
- activate production of TNF (lots) - Surface proteins
- choline binding proteins: adhesion interact with carbodydrates on the surface of pulmonary epithelial cells
illicits a significant immune response
peptidoglycan teichoic acid complex found on G+ pathogens
Pneumolysin does 2 things
- interacts with target cell membranes to form pores that cause lysis
- activates complement
2 things in red boxes on a picture of strep pneumo
neuraminidase
hyaluronidase
??? idk ???
Autolysin
causes lysis of pneumococcus and results in release of pneumolysin along with host cell apoptosis
Autolysin is released _______ as an attempt to _________
in response to antibiotic therapy and stationary phase
-trigger: cell lysis
dampen host immune response
local lysis of pneumococcus (ex: abx therapy) results in
the release of virulence factors: autolysin
pneumonia disease results from
heightened immune response to strep pneumo multiplication
pneumonia spreads systemically by
hematogenous spread through lung’s lymph drainage
alveoli fill with
fibrous edema fluid
red cells
leukocytes
resolution of pneumonia
absorption of fluid
phagocytosis of remaining cells
purulent sputum from pneumonia is _______
rust colored
sputum culture of strep pneumo shows
G+ lancet diplococci
significant sign of strep pneumo in many cases
bacteremia
other diseases pneumococcus is responsible for
otitis media
sinusitis
other diseases pneumococcus is responsible for once it disseminates
bacteremia
meningitis
arthritis
peritonitis
on blood agar strep pneumo looks like
small round green, exhibit alpha hemolysis
capsules of strep pneumo on culture
are non-staining
presumptive diagnosis of strep pneumo
optochin sensitivity on culture
confirmation diagnosis of strep pneumo
bile solubility test
bile lyses strep pneumo but doesn’t lyse other alpha hemolytic strep
Quellung reaction
to observe capsules of strep pneumo
mix organism isolated from patient with anti-capsule serum
agglutination tests for
capsular polysaccharides
genetic probe tests look for
strep pneumo specific rRNA
2 strep pneumo vaccines
- 23 valent capusular polyscaccharide vaccine
- for >65 years old or predisposing factors - 13 valent capsular polysaccharide vaccine
- conjugated to a carrier protein –> more immunogenic
- also accounts for penicilline resistant strains
klebsiella pneumoniae causes
typical community or hospital acquired pneumonia
klebsiella pneumoniae morphology
nonmotile
G-
bacillus
slime capsule
klebsiella pneumoniae is found in
normal flora of skin, mouth, intestines
klebsiella pneumoniae causes illness in
alchoholics
DM
homeless
klebsiella pneumoniae can cause
secondary disease in patients with other infections
virulence factors of klebsiella pneumoniae
-
Polysaccharide factor
-antiphagocytic
-prevents MAC mediated lysis - Adhestions
fimbrial or non-fimbrial, have receptor specificity
klebsiella pneumoniae pneumonia is
necrotizing –> alveolar desctruction, inflammation, hemorrhage in lungs
predilection for upper lobes
severe illness with rapid onset
often fatal, even with antimicrobial treatment
klebsiella pneumoniae symptoms
acute onset of high fever
productive cough with thick blood tinged sputum
currant jelly sputum
klebsiella pneumoniae
klebsiella pneumoniae infection can lead to
abcess formation
cavitation
pleuritic chest pain
CXR of klebsiella pneumoniae
cavitation
culture of klebsiella pneumoniae
mucoid capsule
G-
Haemophilus influenzae morphology
G-
nonmotile
coccobacillus
contains LOS in the cell wall
Haemophilus influenzae
LOS
lipooligosaccharide, similar to LPS
Haemophilus influenzae requires _______ for growth
factors from RBCs
but do not have hemolytic properties
Haemophilus influenzae that has lost its capsule is
non-typeable
still capable of causing disease
Haemophilus influenzae that is considered normal flora
non-typeable
Non-typeable Haemophilus influenzae is also prevalent in
debilitated hosts: asthma, COPD, smoking, immunocompromised
considered opportunistic
Haemophilus influenzae that causes pneumonia in infants/children
type B: Hib
Non-typeable Haemophilus influenzae causes infection when
there’s an imbalance of colonization
non-encapsulated Haemophilus influenzae have
adhesions: HAP
- bind to mucins on the ciliated epithelial cells of the respiratory tract
all Haemophilus influenzae causes
loss of cilia, inflammation, sloughing of damaged epithelial cells resulting from secretion of LOS
Haemophilus influenzae culture (general)
difficult due to growth requirements
poor isolation rates
morphology depends on medium
Haemophilus influenzae identification
gram stain
serological testing to determine if encapsulated
Latex particle agglutination test (LAT)
-relies on antigen, not viable bacteria, used during/after abx treatment
-easier than culture
Haemophilus influenzae on chocolate agar
added X (hemin)
added V (NAD)
37 C
enriched CO2 incubator
Haemophilus influenzae on blood agar
only grows as satellite phenomenon around other bacteria
colonies: convex, smooth, pale, gray/transparent