LRTI Flashcards
acute bronchitis
Acute cough (<3wks) due to inflammation of trachea, lower airways
* Acute cough + preexisting health conditions, exposure hist
* Start in viral upper resp tract infection
- Self-limiting
Differential diagnosis of acute bronchitis
Ensure its viral, not sinister:
* Common cold
* Cough variant asthma
* Acute exacerbation of chronic bronchitis (smoker)
* Acute exacerbation of bronchiectasis
○ Fibrosis in lungs. Smoker damaged lungs caused over-repaired
* Acute rhinosinusitis
* Pneumonia
* Acute asthma
* Exacerbation of COPD
diagnostic testing for bronchitis
Not indicated in absence of other signs and sx of bact infection
treatment for bronchitis
- NO ABX TREATMENT OF ACUTE (regardless of duration of cough)
- Abx only for complication of bacterial infection susp
- Further diagnostic to confirm
*Treat bacterial infection, not the acute bronchitis (does not shorten duration of cough)
- Further diagnostic to confirm
Use of pharm & non-pharm management for acute bronchitis instead
- cough may last >3wks (Abx not hasten resolution)
○ Return to clinic if develop:
§ Fever
§ SOB
§ Chest pain
§ Cough incr extent
§ Cough incr freq
§ Significant cough persist > 3wk
definition of LRTI
- Lower resp tract infection
- Infection of lung parenchyma
- Due to proliferation of microbial pathogens in alveolar level
- Causes:
- Common = BACTERIAL
- Less common = fungi, viral
Top 3 cause of death in SG
pathophysiology for LRTI
1) Aspiration or oropharyngeal secretions
* Bact in oropharyngeal sections enter lungs
2) Inhalation of aerosols
* Inhalation of aerolised droplets containing bacteria
3) Hematogenous spreading
* Bacteremia from extra-pulmonary source
- But bacteremia can also be caused from pneumonia complication
infection of host process
- When exposed to pathogen
a. Inhalation, aspiration, contiguous, hematological mechanism - Susceptible host/ virulent pathogen
a. If have innate defense mechanism, not susceptible. - Proliferation of microbe in lower airways & alveoli
risk factors of LRTI (incr susceptibility of host)
1) Smoking
a. Suppressed neutrophil function
b. Damage lung epithelium
2) COPD, asthma, lung cancer
a. Destroys lung tissue
b. Pathogen more niduses (areas) to multiple and infect
3) Immune suppression (HIV, sepsis, glucocorticoids, chemotherapy)
a.Make host susceptible
1) confirm presence of infection
- sx presentation (localised, systemic) (physical examination)
- objective evidence
radiographic findings, general lab, urinary antigen tests, resp gram stain & culture, blood culture
- sx presentation (localised, systemic) (physical examination)
- Systemic presentation
○ Fever, chills, malaise, change in mental status (elderly), tachycardia, hypotension - Localised sx
○ Cough, chest pain, PLEURITIC CHEST PAIN (chest pain on coughing) SOB, tachypnoea, hypoxia
○ Incr sputum production
§ Innate immunity to protect airways - Physical examination
○ Lung auscultation
§ Diminished breath sounds over affected areas (less O2)
§ Inspiratory crackles during lung expansion
Not as accurate
- Objective evidence
Radiographic findings
Radiographic findings
○ Chest x-rays
○ Lung CT
○ Lung ultrasonography
§ Evidence: new infiltrates, dense consolidations, look for abscess
§ Usually mono-lobe
□ (if both side – likely fluid consolidation, HF)
§ Must be NEW
□Not from TB cavity, infiltrate there alr
General lab findings
○ WBC (4-10x10^9 /L), CRP (normal <10mg/L, infection > 40 mg/L), PROCAL (0.5-1ug/L)
§ Signs of systemic infection
§ Non-specific for pneumonia
Urinary antigen tests
○ Show pt exposure to certain bact (but may not be infected NOW)
§ Remains +ve for days-wks despite Abx treatment
○ what pt was infected with before, cover it (resistance)
○ Esp for CAP pneumo SEVERE/ hosp pts
Resp gram-stain and cultures
○ Sputum
§ Low yield (>50% no yield)
§ Contamination by oropharyngeal secretions
□ High epithelium cells
□ High coloniser bact
○ Lower resp tract samples
§ Invasive sampling
□ Bronchoalveolar lavage (BAL)
□ Requires trained personnel to retrieved the flushed sample from tube
§Less contamination
Blood cultures
○ Rule out bactermia
Only in hosp// complication of pneumo
*** pre treatment: blood and resp gram-stain and cultures
Empiric broad spect first —> narrow in 1-3 days
- hosp: severe CAP
- hosp: risk factors for drug-resistant pathogens (MRSA, psudeo)
○ Being empirically treated
○ Previously infected in last 1year
○ Hosp/ received IV Abx in last 90days
CAP-pneumo classification definition
Onset in comm
<48hrs after hosp admission
* Serious and sig ○ ~10% of pt require admission to ICU ○ ~10% mortality ~50% ICU
HAP-pneumo classification definition
- Onset > 48hrs after hosp admission
- 2nd most common cause of HAI
- Sig healthcare cost
○ Prolong hospitalisation
○ >50% of Abx use - Mortality rate at least 20-30%
(HAP = 18.8%)
VAP-pneumo classification definition
Onset >48hr after mechanical ventilation
* 2nd most common cause of HAI * Sig healthcare cost ○ Prolong hospitalisation ○ >50% of Abx use * Mortality rate at least 20-30% (HAP = 29.3%)
risk factors and ways to prevent CAP
- Risk factors for CAP
○ History of pneumo
○ Smoke, chronic resp disease, immunosupp - Prevention
○ Smoking cessation, immunisation (not 100% but lowers risk)
§ Influenza
§Pneumococcal
outpt CAP pathogen
- Streptococcus pneumoniae
- Haemophilus influenzae
- Atypicals
○ Mycoplasma pneu
○ Chlamydophila pneu
○Legionella pneumophilia
Inpatient (non severe) CAP pathogen
Based on risk factors, MRSA, pseudomonas aeruginosa
- Streptococcus pneumoniae
- Haemophilus influenzae
- Atypicals
○ Mycoplasma pneu
○ Chlamydophila pneu
○Legionella pneumophilia - influenza
inpt severe CAP pathogen
ALLLLL +
- Staphylococcus aureus
- Gram neg:
○ Klebsiella pneumonia
○ Burkholderia pseudomallei
(Pathogen for severe CAP in tropical countries) - Based on risk factors, MRSA, pseudomonas aeruginosa
- influenza considered and tested for all inpt during circulating season
* nov-feb// may-july
CAP inpt non severe MRSA
- MRSA risk factors
- resp isolation of MRSA in last 1 yr
- hosp / IV ABx use in last 90d + MRSA screen +ve
CAP inpt non severe pseudo risk factor
resp isolation of pseudo in last 1 year
CAP inpt severe MRSA cover risk factors:
- MRSA risk factors
- resp isolation of MRSA in last 1 yr
- hosp / IV ABx use in last 90d
