Lecture - Microbiology Of Pneumonia Flashcards
When is testing for microbiology in pneumonia beneficial?
- more severe cases
- if unusual pathogen is more likely
- sensitivity/specificity
- if results would influence therapy
Less invasive non sterile site for microbiologic diagnosis
- sputum
- urine
- nasopharyngeal aspirate
- nasopharyngeal swab
- nasal washings
More invasive normally sterile site for microbiologic diagnosis
- venepuncture
- bronchoscopy
- lung biopsy
- seldom done: transtracheal aspirate, lung puncture
Test and causative organism for microbiologic diagnosis: bacteria
- strep pneumonia
- others (H. Influenzae, staph aureus)
- Culture: sputum, blood, pleural fluid
Test and causative organisms for microbiologic diagnosis: atypical agents
- Mycoplasma
- legionella
- chlamydia
- Serology, urine antigen detection, PCR
Test and causative organism for microbiologic diagnosis: viruses
- influenza, RSV
- immunofluorescence, PCR
Test and causative organism for microbiologic diagnosis: uncommon
- TB, immune compromised patients
- special procedures and tests
Examination of sputum
- prompt processing
- screen lower airways
- do before antibiotics
Problems in sputum examination
- not available in children under 7-8
- 10-30% adults non productive cough at time of presentation
- 15-30% adults pre treated
- antibiotics - eradicate SP, HI, promote staph, GNB
Specomem collection: Blood
- invasive
- age
- use
- minimally
- all
- culture, serology
Specimen collection: pleural fluid
- invasive
- age
- use
- a bit more invasive
- all
- gram stain, biochemistry, culture
Lung aspirate:
- invasive?
- age
- use
- very
- all
- full spectrum
Lung biopsy
- invasive
- age
- use
- most invasive
- all
- full spectrum and histology
Respiratory specimen collection - uncontaminated sites
- transtracheal aspirate
- bronchoscopy
- urine antigen
- nasopharyngeal swab
- nasopharyngeal aspirate
- Elisa
- PCR
Nasopharyngeal aspirate
- mostly for viruses and pertussis
- mostly in children
- multiplex test
Bronchoalveolar lavage
- PCR especially used for TB but also applicable to fungi and other pathogens
Interpretation of PCR
- multoples tests more common
- false positives can occur
- multiple infections can be identified
Incidence of pneumnia by age
- most common in infancy and old age
- disparity bw indifgenous and non indigenous community. That increases with age
Age specific causes of pneumonia in otherwise healthy children
- less than 2 years
- over two years
- all ages
- less than 2 years: resp virus most important, mycoplasma uncommon
- over 2 years: viruses decrease, mycoplasma increases
- all ages: pneumococcus remains important
Impact of pneumococcal vaccine on pneumonia in Australia
- pneumococcal vaccine reduces rate of pneumonia only in children
- but the vaccine reduces deaths in both age and children
Changes in adult pneumonia between 1980 and 2008
- less pneumococcus
- blood culture down from 13% to 6% positive
- resistant staph emerging
- gram negatives associated with long term care and co morbidities
- mycoplasma associated with
Major pathogens in patients
- S pneumonia
- M pneumonia
- Resp viruses
- C pneumonia
- H influenza
Major pathogens in patients >60 yo or coexisting disease
- S pneumonia
- resp viruses
- H influenza
- Aerobic GNB
- S aureaus
