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IBI Test 1 > B3.014 Pulmonary Pathogens > Flashcards

B3.014 Pulmonary Pathogens Flashcards

1
Q

who is susceptible to opportunistic pneumonia?

A

immunocompromised patients

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2
Q

what types of pneumonia are typically caused by bacteria?

A

CAP and HAP

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3
Q

what are the primary bacteria that cause pneumonia?

A

streptococcus pneumoniae
mycoplasma pneumoniae
legionella pneumophila

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4
Q

what types of pneumonia are typically caused by viruses?

A

opportunistic (pediatric/geriatric)

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5
Q

what are the primary viral causes of pneumonia?

A

flu a and b, parainfluenza virus, respiratory syncytial virus (RSV)

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6
Q

what type of pneumonia are typically caused by fungi?

A

opportunistic (immunosuppressed, AIDS, cancer therapy, transplants)

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7
Q

hemolytic properties of s. pneumoniae

A

alpha hemolytic

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8
Q

what type of capsule surrounds s. pneu?

A

carbohydrate

>90 sertoypes

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9
Q

what does it mean to be naturally competent for DNA transformation?

A

has the ability to mutate by taking up DNA from plasmids to make itself more pathogenic

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10
Q

discuss the classification of streptococci

A 
gram +
chains
normal flora of skin and mouth
catalase negative
may produce exotoxins
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11
Q

what types of strep are B hemolytic?

A

group A strep (GAS) : s. pyrogenes

group B strep (GBS) : s. agalactiae

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12
Q

what types of strep are alpha hemolytic?

A

viridans (green) strep: s. mutans

s. pneumoniae

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13
Q

what types of strep are gamma hemolytic?

A

enterococcus (GDS)

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14
Q

who hosts s.p.?

A

humans

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15
Q

where is asymptomatic carriage of s.p. common?

A

nasopharyngeal mucosa
5-75% of population
considered a commensal

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16
Q

how does transmission of s.p.?

A

respiratory droplets

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17
Q

how do most cases of s.p. arise?

A

spread of endogenous organisms

our own natural flora gets into the wrong niches

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18
Q

other than pneumonia, what common illnesses develop as a result of s.p.?

A

sinusitis, otitis media, meningitis

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19
Q

what are predisposing factors for getting s.p?

A

respiratory viral infections

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20
Q

what is pneumonia?

A

aspiration of bacteria and replication in alveolar spaces

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21
Q

how long is the incubation period of pneumonia?

A

1-30 days

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22
Q

what are symptoms of pneumonia?

A

abrupt onset of fever and shaking chills

pleurisy, productive cough, blood tinged sputum

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23
Q

risk factors for pneumonia

A

antecedent viral infection of resp tract, especially influenza
smoking
age <2 or >65
hematological disorders, asplenia, chronic pulmonary disease, diabetes, renal

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24
Q

how can you differentiate typical vs atypical pneumonia?

A 
based on symptoms
atypical "walking" pneumonia:
-slow onset
-moderate fever
-non-productive cough
-headache
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25
Q

key atypical pneumonia pathogens

A 
chlamydia pneumoniae
legionella pneumonia
mycoplasma pneumonia
chlamydia psittaci
coxiella burnetii
some viruses
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26
Q

describe meningitis

A

100% mortality without antibiotic treatment
25% with treatment
inflammation frequently leads to permanent brain damage, blindness, hearing loss, learning disabilities

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27
Q

describe otitis media and sinusitis caused by s.p.

A

50% of middle ear infections
sinusitis occurs in all age groups
can develop into megingitis

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28
Q

virulence factors of s.p.

A

polysaccharide capsule

C polysaccharide

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29
Q

describe the s.p. polysaccharide capsule

A

90 serotypes
essential for pathogenesis
anti phagocyctic
immunogenic

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30
Q

describe the s.p. C polysaccharide

A

complex of phosphorylcholine, peptidoglycan and teichoic acid
common to all serotypes
present in urine and serum during infection

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31
Q

what toxins are associated with s.p.

A

pneumolysin
autolysin
IgA protease

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32
Q

describe pneumolysin

A

cholesterol dependent pore forming toxin
toxic to bronchial epithelial cells
activates classical complement pathway

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33
Q

describe autolysin

A

binds to cell wall
degrades peptidoglycan, resulting in bacterial cell lysis
releases pneumolysin from cell
releases cell wall components that activate the inflamm response
antibodies to autolysin can be protective

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34
Q

describe IgA protease

A

blunts mucosal adaptive immune response

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35
Q

what are other characteristics of s.p. culture other than hemolysis/shape/catalase neg

A

bile solube
optochin-sensitive
Quellung (swelling) reaction: shows capsule on bacteria

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36
Q

where can C polysaccharide be found?

A

urine and serum

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37
Q

how is capsular antigen detected?

A

latex agglutination assap

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38
Q

what MIC values are considered susceptible?

A

<2 ug/ml

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39
Q

what MIC values are considered resistant?

A

> 8 ug/ml

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40
Q

DOC for pneumonia

A

penicillin (for sensitive isolates); vancomycin or fluoroquinolone + 3rd gen cephalosporin

41
Q

PPSV23 (Pneumovax)

A

pneumococcal polysaccharide vaccine
covers most bacteremic strains (23)
capsular type-specific antibody is protective
recommended for: adults >65, chronically ill, and immunocompromised kids >2 years

42
Q

PCV7 (Prevnar)

A

pneumococcal conjugate vaccine
capsular antigens from 7 serotypes conjugated to a mutated diphtheria toxin
immunogenic in children and infants
recommended for all children <2 and at risk <6

43
Q

PCV13 (prevnar13)

A

capsular antigens from 13 serotypes conjugated to a mutated diphtheria toxin
children 6-17
adults >50

44
Q

describe the classification of legionella pneumophila

A

gram negative bacillus
does not stain well
motile, catalase positive
fastidious

45
Q

what does l. p. require to grow?

A

L-cysteine
ferric ions
pH 6.9

46
Q

how is l.p. transmitted?

A 
environmental pathogen 
no person to person transmission
found in water and soil
intracellular symbionts of amoebae
inhalation of aerosols containing infection organisms
47
Q

common sources of l.p

A 
air conditioning
cooling towers
medical respiratory equip
showers
whirlpools
humidifiers
48
Q

when are legionella outbreaks most common

A

late summer-fall

49
Q

risk factors for legionella

A 
advanced age
smoking
heavy alcohol use
transplant recipients
immunocompromised (diGeorge)
50
Q

what is l.p.’s mechanism of action

A

infect alveolar macrophages
-MOMP (major outer membrane protein): binds C3 and facilitates entry into macrophages
bacterial replication in phagosomes using T4SS effectors to block acidification/fusion with lysosomes
-“replicative vacuoles” surrounded by ER

51
Q

virulence factors of l.p.

A

hemolysin: tissue degradation, lysis of RBCs
phospholipases: vacuolar escape, surfactant degradation

52
Q

incubation period of l.p.

A

2 to 14 days

53
Q

symptoms of l.p.

A 
moderate fever
headache
slight or non-productive cough
fatigue
anorexia
GI symptoms
hyponatremia
54
Q

l.p mortality rate

A

15-20%

sporadic disease that is frequently misdiagnosed

55
Q

main difference between Pontiac fever and legionella pneumonia

A

Pontiac fever 0% fatality

higher attack rate but hospitalization uncommon

56
Q

gold standard for l.p. identification

A

culture: growth on buffered charcoal year extract (BCYE) agar only
legionella urine antigen: detects only serotype 1 L. pneumophila (majority of infections)

57
Q

antibiotics that achieve high intracellular concentration against l.p.

A

IV fluoroquinolones

IV azithromycin

58
Q

how to prevent legionella

A 
identification of source
increase water temp
hyperchlorination
removal or scale from water tanks
routine monitoring
59
Q

describe the features of mycoplasma

A 
smallest free living organisms
slow growth (1-6 hours)
lack cell walls:
-cell membranes contain sterols
-pleomorphic (different shapes)
60
Q

what diseases results from mycoplasma pneumoniae?

A

atypical pneumonia
tracheobronchitis
mild upper respiratory infections
joint infections

61
Q

m. p. cell shape

A 
intracellular network of protein filaments
cytadhesin organelle (arrow): membrane bound cylindrical extension at one pole that penetrates membrane and binds respiratory epithelial cells
62
Q

spread of m.p

A

respiratory secretions

63
Q

incubation time of m.p.

A

1-3 weeks

64
Q

when are infection rates of m.p. highest?

A

crowded conditions
frats, dorms, schools
older children, adolescents, young adults and HIV patients most susceptible

65
Q

pathogenesis of teacheobronchitis and pneumonia

A
  1. binding of ciliated respiratory epithelial cells
  2. production of phospholipases and peroxides
  3. ciliostasis, leakage of epithelial cells
  4. infection of lower resp tract
  5. IL-1, TNF a
  6. influx of PMNs, T and B cells
66
Q

m.p. symptoms

A 
headache
fever
pharyngitis
dry, nonproductive cough
no elevation of WBCs
bilateral, diffuse infiltrates
skin rash
67
Q

how long does m/p/ last

A

4-6 weeks

68
Q

m. p. culture characteristics

A

medium must contain serum or cholesterol
colony formation in 206 weeks
mulberry/fried egg like colonies

69
Q

m. p. serological tests

A

cold agglutinin assay
complement fixation assay
ELISA for IgM/IgG
PCR- gold standard

70
Q

what antibiotics are mycoplasma resistant to?

A

penicillins
cephalosporins
glycopeptide antibiotics
-all cell wall inhibitors

71
Q

drugs of choice for m.p.

A

tetracyclines
macrolides
fluoroquinolone

72
Q

what causes influenza

A

influenza virus

73
Q

what causes croup

A

parainfluenza virus

74
Q

what causes bronchiolitis

A

RSV

75
Q

what causes bronchopneumonia

A

influenza virus, RSV, adenoviruses

76
Q

main virulence factors of influenza

A 
Hemagglutinin
-18 subtypes
-sialic acid receptor
Neuraminidase
-11 subtypes
-sialidase
M2 ion channel
-sense acidification in the endosome
M1 protein
-structural
NP
NS1
-reprograms host cell to replicate ssRNA
77
Q

symptoms of the flu

A 
acute
febrile
self limited
headache
malaise
myalgias
nasal obstruction
discharge
sore through
cough
78
Q

flu attack rate

A

10-40%

79
Q

when is the flu virus stable

A

low humidity and cool temps

80
Q

what is desquamation of mucus secreting and ciliated cells

A

cilia and mucous are disintegrated resulting in a loss of defense against respiratory infections
likely a cause of secondary infections

81
Q

mediators of flu cytokine storm

A 
IL-6
-fever, acute phase response
-secreted by macrophages
TNF-a
-causes fever and cachexia
IFN a/b
IL-1
-produced by macrophages
-proinflamm and fever inducing
IFN-y
-innate and adaptive immunity
-produced by lymphocytes
82
Q

what cytokines induce the antiviral state

A

IFN a/b

83
Q

what type of genetic mutation results in antigenic drift

A

point mutations in H and N

84
Q

what type of genetic mutation results in antigenic shift

A

major change in H (sometimes N)

genetic reassortment

85
Q

what family do RSV, hMPV, and parainfluenza virus belong to?

A

paramyxoviruses

86
Q

describe paramyxoviruses

A

enveloped
pleomorphic virions
contain non-segmented negative ssRNA
induce syncytia (multinucleated cells)

87
Q

general paramyxoviridae structure

A 
attachment proteins differ between viruses
-parainfluenza/mumps: HN protein
-measles- H glycoprotein
-RSV- G glycoprotein
all have F (fusion) protein
88
Q

where does DNA replication occur for paramyxoviridae?

A

outside of the nucleus

89
Q

when do RSV epidemics occur?

A

winter

90
Q

who is at risk of RSV?

A

1 cause of bronchiolitis and pneumonia in children <1 in the US

-congenital heart disease, bronchopulm dysplasia, immunodeficiency
significant cause of resp disease in older adults
-stem cell transplants, severe heart disease, COPD

91
Q

RSV symptoms

A

fever
chills
cough, congestion, coryza, rhinorrhea, conjunctivitis
bronchiolitis- wheezing, shortness of breath
pneumonia
apnea spells in infants

92
Q

RSV diagnosis

A

rapid antigen detection from aspirates
RT-PCR from bronchial washes
culture difficult and too slow

93
Q

RSV treatment

A 
supportive care
-fluids and resp support
aerosolized ribavirin
-severely immunocompromised
humanized monoclonal anitbodies
-protect at risk infants
no vaccine
94
Q

describe hMPV

A

human metapneumovirus
causes 5-20% of pediatric URIs and LRTIs (serology)
-90% of people have it by 5, 100% by adulthood
clinical symptoms indistinguishable from RSV
supportive treatment

95
Q

parainfluenza virus features

A

5 serotypes
reinfection common
negative ssRNA enveloped virus

96
Q

pathogenesis of parainfluenza

A

cause illness in the large airways of the lower resp tract

  • tropism for ciliated epithelial cells
  • croup, bronchiolitis, also pneumonia
97
Q

immune response to parainfluenza

A 
humoral
-neutralizing antibody to surface proteins
-mucosal IgA can help prevent infection
cellular
-cytotoxic T cells
98
Q

who is susceptible to parainfluenza

A

severe disease in adults and peds w hematopoietic stem cell or solid organ transplants

IBI Test 1 (15 decks)

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