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Flashcards in LRTIs (3) Deck (50):
1

list the LRTIs we are expected to know

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

2

epidemiology of influenza

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

3

what causes vaccine mismatches with influenza

antigenic drift

4

what causes influenza

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

5

how does the influenza A virus cause infection and spread

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

6

when does viral shedding of influenza A begin

24-48 hours before symptom onset

7

clinical presentation of influenza

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

8

what is the most common complication of influenza

pneumonia

9

Tx for influenza

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

10

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

oseltamivir (Tamiflu)

needs to be given early to see benefit

11

bacterial causes of acute bronchitis

mycoplasma pneumoniae

chlamydophila pneumoniae

Bordatella pertussis (if cough >3 weeks suspect this)

12

viral causes of acute bronchitis

respiratory viruses :

influenza
coronaviruses
adenovirus
entero/rhinoviruses
RSV
measles

13

is acute bronchitis most often viral or bacterial

viral

14

clinical presentation of acute bronchitis

cough

15

what is one way to distinguish between viral and bacterial causes

procalcitonin levels (>0.25 mcg/L suggest bacterial)

16

what causes AECB

about 50% viral cause

17

how is AECB diagnosed (criteria)

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


18

how is AECB prevented

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

19

what is CAP

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

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

20

how do pathogens reach the lungs to cause infection in CAP

via inhalation, aspiration or by blood

(blood = less common)

21

what are some conditions that may raise your risk for CAP

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

22

causative agents of CAP in neonates

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

23

causative agents of CAP in infants

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

24

causative agents of CAP in adults

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