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IDMM > LRTIs (3) > Flashcards

LRTIs (3) Flashcards

1
Q

list the LRTIs we are expected to know

A
  1. influenza
  2. acute bronchitis
  3. acute exacerbation of chronic bronchitis (AECB)
  4. community acquired pneumonia (CAP)
  5. nosocomial pneumonia
  6. empyema/lung abcess
  7. TB
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2
Q

epidemiology of influenza

A

distinct outbreaks every year–>typically in winter months

begin abruptly and attack about 10-20% of the population

transmission depends on the virus and the susceptibility of the population

death rates are disproportionately high in elderly and infants

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3
Q

what causes vaccine mismatches with influenza

A

antigenic drift

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4
Q

what causes influenza

A

influenza A virus

3 major subtypes of HEMAGLUTININ (H1, H2, H3)
2 subtypes of NEURAMINIDASE (N1, N2)

have ability to undergo changes in antigenic characteristics of envelope glycoproteins

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5
Q

how does the influenza A virus cause infection and spread

A

HEMAGLUTININ binds to SIALIC ACID on epithelial cell surface to initiate infection

NEURAMINIDASE cleaves the link between progeny and host cell, allowing new virions to escape

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6
Q

when does viral shedding of influenza A begin

A

24-48 hours before symptom onset

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7
Q

clinical presentation of influenza

A

ABRUPT onset

fever, cough, headache, myalgias, malaise, sore throat, rhinorrhea

exam usually unremarkable–> flushing and mild cervical lymphadenopathy in some patients

uncomplicated patients improve in 3-5 days
viral shedding stops after 6-7 days

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8
Q

what is the most common complication of influenza

A

pneumonia

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9
Q

Tx for influenza

A

most cases are self limited and dont require treatment

antivirals are indicated for the severely ill or those at risk of complications

Ab Tx of secondary infection when needed

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10
Q

in a patient with influenza in which antivirals are indicated, what is the medication used

A

oseltamivir (Tamiflu)

needs to be given early to see benefit

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11
Q

bacterial causes of acute bronchitis

A

mycoplasma pneumoniae

chlamydophila pneumoniae

Bordatella pertussis (if cough >3 weeks suspect this)

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12
Q

viral causes of acute bronchitis

A

respiratory viruses :

influenza
coronaviruses
adenovirus
entero/rhinoviruses
RSV
measles
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13
Q

is acute bronchitis most often viral or bacterial

A

viral

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14
Q

clinical presentation of acute bronchitis

A

cough

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15
Q

what is one way to distinguish between viral and bacterial causes

A

procalcitonin levels (>0.25 mcg/L suggest bacterial)

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16
Q

what causes AECB

A

about 50% viral cause

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17
Q

how is AECB diagnosed (criteria)

A

PRODUCTIVE cough for at least 3 months/year for the last 2 consecutive years=chronic bronchitis

criteria for AECB (need at least 2 to diagnose):

  1. increased sputum volume
  2. increased sputum purulence
  3. increased dyspnea
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18
Q

how is AECB prevented

A

COPD patients should receive flu vaccine yearly and pneumococcal vaccine every 6 years

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19
Q

what is CAP

A

pneumonia in a person who is not has not recently been hospitalized

top disease in children worldwide, and among adults in the US

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20
Q

how do pathogens reach the lungs to cause infection in CAP

A

via inhalation, aspiration or by blood

blood = less common

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21
Q

what are some conditions that may raise your risk for CAP

A 
alcoholism
diabetes
CHF
COPD
smoking
aspiration prone
post-influenza
cystic fibrosis
22
Q

causative agents of CAP in neonates

A
  1. GBS
  2. E. Coli
  3. S. aureus
  4. Pseudomonas
  5. C. trachomatis
23
Q

causative agents of CAP in infants

A
  1. RSV
  2. influenza
  3. S. pneumoniae
  4. H. influenzae
  5. S. aureus
24
Q

causative agents of CAP in adults

A

more often bacterial than viral

STREP PNEUMONIAE = most common cause

25
Q

how do you diagnose CAP

A

Hx, physical exam
**CREPITATIONS/RALES (crackles)

Diagnostic testing–> sputum (gram stain), bronchoscopy/lung biopsy/thoracentesis, CBC/procalcitonin/blood cultures/serology/urine antigen, diagnostic imaging

CXR–> location and nature of infiltrates, cavitation, volume loss, pleural fluid, mediastinal adenopathy

26
Q

Tx for S. pneumoniae (in CAP)

A

empiric = AMOXICILLIN in high dose

note that a significant number of isolates are resistant to macrolides and doxycyline

27
Q

what agents cause hospital acquired pneumonia

A

Enterobacteriaceae–> E. coli, Klebsiella, Serratia

S. aureus

28
Q

what agents cause ventilator acquired pneumonia

A

Pseudomonas aeruginosa

+E. coli, Klebsiella, Serratia and S. aureus

29
Q

empiric Tx for HAP

A

ceftriaxone

30
Q

empiric Tx for VAP

A

pipercillin/tazobactam

31
Q

what is a lung abcess

A

microbiological infection causing necrosis of lung parenchyma

producing 1 or more cavities

32
Q

what agents tend to cause lung abcesses

A

mouth flora/oral anaerobes

Eikenella corrodens

Strep spp

33
Q

Tx for lung abcess

A

clindamycin

or penicillin with metronidazole

consider TB/fungal/malignancy if cavitiations without air fluid level

34
Q

what is pleural effusion

A

fluid in the pleural space

35
Q

what is empyema

A

infection of fluid in the pleural space

36
Q

risk factors for pleural effusion/empyema

A

HIV
neoplasm
pulmonary disease
alcoholism

37
Q

what agents cause empyema most commonly

A
  1. if pre-antibiotic:
    S. PNEUMONIAE (60-70%)
    S. pyogenes
    S. aureus
  2. if post-antibiotic:
    anaerobes (bacteroides, fusobacterium, peptostreptococcus)
    Strep. anginosus
    enterobacteriaeceae
38
Q

how is empyema diagnosed

A

drain pleural space and obtain sample to gram stain and determine C & S to guide therapy

ultrasound

xray

39
Q

clinical presentation of empyema

A

cough
chest pain
SOB
fever

40
Q

Tx of empyema

A

empiric = CEFTRIAXONE

add metronidazole if chronic

41
Q

what is the global prevalence of TB

A

30%

42
Q

how is TB passed

A

it is carried in AIRBORNE particles and then inhaled

inhalation can result in 3 outcomes

  1. immediate clearance
  2. primary active disease
  3. latent infection with possibility of active disease later in life
43
Q

where in Canada is TB prevalence higher

A
  1. in medically underserved communities
  2. urban poor, homeless
  3. prison inmates
  4. alcoholics and IV drug users
  5. elderly
  6. foreign-born
  7. contacts of active cases
44
Q

what causes TB

A

mycobacterium

acid fast bacilli
strictly aerobic
slow growing (2-6 weeks)

pathogenic: M. tuberculosis, M. bovis, M. ulcerans

potentially pathogenic: M. kansasii, M. avium compex

45
Q

TB pathophysiology

A

M. tuberculosis organisms are inhaled and then engulfed by macrophages, which forms a cavitation

host immune response typically limits spread but bacilli can remain dormant for years

46
Q

clinical presentation of TB

A 
PULM INFECTION with COUGH, hemoptysis, dyspnea
weight loss
NIGHT SWEATS
low grade fever
chest pain
47
Q

how do you diagnose TB

A

most commonly through MICROSCOPY–ZIEHL-NEELSON stain for acid fast bacilli

culture or molecular probe is necessary to distinguish from nontuberculous mycobacteria (NTM)

culture necessary to test drug susceptibility

TB skin test–MANTOUX

48
Q

does a - TB skin test rule out active infection

A

no

49
Q

how does the TB skin test work

A

interferon gamma release assays (IGRA)

measures cell mediated immune response

T cells in patients blood bind to TB antigen and release IFN-gamma

increased IFN-gamma expected in those who have been exposed

50
Q

Tx for TB

A 
isoniazid
rifampin
ethambutol
streptomycin
pyrazinamide

duration of 6 months to two years

IDMM (29 decks)

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