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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
how do you diagnose CAP
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
Tx for S. pneumoniae (in CAP)
empiric = AMOXICILLIN in high dose note that a significant number of isolates are resistant to macrolides and doxycyline
27
what agents cause hospital acquired pneumonia
Enterobacteriaceae--> E. coli, Klebsiella, Serratia S. aureus
28
what agents cause ventilator acquired pneumonia
Pseudomonas aeruginosa +E. coli, Klebsiella, Serratia and S. aureus
29
empiric Tx for HAP
ceftriaxone
30
empiric Tx for VAP
pipercillin/tazobactam
31
what is a lung abcess
microbiological infection causing necrosis of lung parenchyma producing 1 or more cavities
32
what agents tend to cause lung abcesses
mouth flora/oral anaerobes Eikenella corrodens Strep spp
33
Tx for lung abcess
clindamycin or penicillin with metronidazole consider TB/fungal/malignancy if cavitiations without air fluid level
34
what is pleural effusion
fluid in the pleural space
35
what is empyema
infection of fluid in the pleural space
36
risk factors for pleural effusion/empyema
HIV neoplasm pulmonary disease alcoholism
37
what agents cause empyema most commonly
1. if pre-antibiotic: S. PNEUMONIAE (60-70%) S. pyogenes S. aureus 2. if post-antibiotic: anaerobes (bacteroides, fusobacterium, peptostreptococcus) Strep. anginosus enterobacteriaeceae
38
how is empyema diagnosed
drain pleural space and obtain sample to gram stain and determine C & S to guide therapy ultrasound xray
39
clinical presentation of empyema
cough chest pain SOB fever
40
Tx of empyema
empiric = CEFTRIAXONE add metronidazole if chronic
41
what is the global prevalence of TB
30%
42
how is TB passed
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
where in Canada is TB prevalence higher
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
what causes TB
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
TB pathophysiology
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
clinical presentation of TB
``` PULM INFECTION with COUGH, hemoptysis, dyspnea weight loss NIGHT SWEATS low grade fever chest pain ```
47
how do you diagnose TB
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
does a - TB skin test rule out active infection
no
49
how does the TB skin test work
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
Tx for TB
``` isoniazid rifampin ethambutol streptomycin pyrazinamide ``` duration of 6 months to two years

IDMM (29 decks)

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