PBL: Respiratory Cultures Flashcards
List the anatomical areas of the respiratory tract
- Upper: Nasal, sinus, nasopharnyx, oropharynx, epiglottis, larynx
- Lower: Trachea, bronchi, alveoli (last 2 are in the lungs)
Which anatomic regions of the respiratory region are sterile?
Lower: trachea, bronchi, alveoli (last 2 are in the lungs)
List the organisms most commonly found as “normal flora” in upper respiratory tract specimens
- Streptococcus Viridans
- S. pneumoniae
- S. pyogenes
- Corynebacterium spp
- Neisseria spp
- CoNS
- Micrococcus spp
- Rothia spp
- Haemophilus spp
- Aggregatibacter aphrophilus
- Moraxella spp
- Anaerobes (Veillonella spp, Fusobacterium spp, Prevotella spp, Porphymonas spp, Parvimonas micra)
List the common general symptoms of pneumonia
- Fever, chills
- Malaise
- Dyspnea
- Thick, purulent sputum
What is pneumonia?
Inflammation of the lungs detected via physical examination of CXR
What are the characteristic signs of pneumonia?
Inflammation → fluid buildup in alveolar sacs
- Physical examination: decreased or abnormal breath sounds (crackles)
- CXR infiltrates: fluid buildup in alveolar sacs
Relationship of positive blood cultures and pneumonia
S. pneumoniae infection occurs w/ 30% positive blood cultures?
Discuss the vaccines which are available for the prevention of respiratory infections
- Pneumococal conjugate vaccine (PCV)
- Pneumococcal polysaccharide vaccine (PPSV23)
List the most common bacterial pathogen in HIV patients
M. avium
List the most common bacterial pathogen(s) in cystic fibrosis patients
- Pseudomonas aeruginosa (most often isolated)
- Burkholderia cepacia
List the most common bacterial pathogen that causes “walking pneumonia” in young adults
Mycoplasma pneumoniae
What are the 3 most common upper respiratory tract pathogens?
- Cryptococcus neoformans
- Streptococcus pneumoniae
- Moraxella catarrhalis
List the most common bacterial pathogen(s) in the throat (pharyngitis)
- Streptococcus pyogenes (Group A/Beta hemolytic)
- Streptococcus pneumoniae
- Neisseria spp (N. gonorrhoeae and N. meningitidis)
- Haemophilus influenzae
List the most common anaerobic pathogen(s) causing aspiration pneumonia
- Fusobacterium spp (GNR)
- Prevotella spp (GNR)
- Porphymonas spp (GNR)
- Veillonella (GNC)
- Peptostreptococcus anaerobius (GPC)
List the common bacterial pathogen(s) that are community acquired
- Streptococcus pneumoniae (most common cause of bacterial pneumonia)
- Haemophilus influenzae
- Legionella pneumophilia
List the most common bacterial pathogen that are nosocomial acquired
Klebsiella pneumoniae
Prevents engulfment and drying out
Polysaccharide capsule
Which organisms have a polysaccharide capsule?
- H. influenzae
- Streptococcus pneumoniae
- Neisseria meningitidis
- Pseudomonas aeruginosa
- Bordetella pertussis
- Klebsiella pneumoniae
- Cryptococcus spp
Which organisms are intracellular?
- Mycobacteirum tuberculosis
- Chlamydophila pneumoniae
Which organisms should be considered agents of bioterrorism if isolated from respiratory culture?
- Bacillus anthracis
- Yersinia pestis (plague)
- Francisella tularensis
- Mycobacterium tuberculosis (mult-drug resistant)
Which specimens should avoid exposure to usual flora of the upper respiratory tract (*should be sterile)
- Transtracheal
- Lung biopsy
- FIne needle aspirate
Strep screens
- Specimen type
- Throat swab of tonsillar areas
- Posterior pharynx
Strep screens
- Media to set up
BAP
Routine lower respiratory specimens
- Specimen type
- Expectorated and induced sputum
- Endotracheal aspirate
- BAL
- Bronchial washings
- Bronch brushes
Routine lower respiratory specimens
- Media to set up
- BAP
- CHOC
- MAC
- CNA
- Direct smear
Sterile respiratory specimens
- Specimen type
- Transtracheal aspirates
- Lung aspirates
Sterile respiratory specimens
- Media to set up
- ABAP
- PEA
- BAP
- CHOC
- MAC
- CNA
- Direct smear
Legionella cultures
- Specimen type
- Biopsy/autopsy tissues
- Pleural fluids
- Transtracheal aspirations
- Sputum or other respiratory specimens
- Blood
Legionella cultures
- Media to set up
- Buffered charcoal yeast extract agar (BCYE)
- Buffered charcoal yeast extract agar w/ cephalothin, colistin, vancomycin, cycloheximide (BCYE selective)
- 5% SBAP
Bordetella pertussis cultures
- Specimen type
Swab of posterior nasopharynx
- NOTE: no cotton swabs!
Bordetella pertussis cultures
- Media to set up
- BAP
- Regan-Lowe
- Charcoal agar (Bordet-Gengou)
- Possible Gram stain or use of FA reagents
C. diphtheriae cultures
- Specimen type for respiratory infections
Throat and nose, preferably posterior nasopharynx specimens
C. diphtheriae cultures
- Specimen type for cutaneous infections
Culture skin area as well as nose and throat
C. diphtheriae cultures
- Media to set up
- BAP
- CHOC
- Tinsdale (black colonies)
- Gram stain
- Catalase
- CHOs
- Nitrate broth
- Urea agar
Actinomyces
- Specimen type
Various (slow grower → 2 weeks)
Actinomyces
- Media to set up
ABAP
Cystic fibrosis patient w/ B. cepacia
- Specimen type
Sputum
Cystic fibrosis patient w/ B. cepacia
- Media to set up
- PC (used specifically for B. cepacia)
- MSA (some strains can oxidize mannitol)
- BAP
- CHOC
- MAC
- CNA
- Direct Gram stain by request
MRSA
- Specimen type
Nasal swab
MRSA
- Media to set up
- Oxacillin screening plates (Growth vs. No growth)
- MSA
- CHROM agar (MRSA selective)
Significance of Rapid Ag testing in diagnosis of strep throat
POC test that uses enzyme immunoassays or latex agglutination to identify group A strep Ags
- HIGH specificity
- LOW sensitivity
Discuss the reasoning for quantitation of organisms in respiratory tract specimens
- Quantitation of fresh sputum is indicative of probable pathogens based on how much bacteria is found
- Pathogens are usually found in higher quantities than oropharyngeal flora
- Proper collection and quantitation of culture is very helpful in providing information that would aid in the physician helping the patient, such as recognizing superinfections, or preforming antimicrobial susceptibility testing
What indicates a good collection of a respiratory specimen?
- Dust macrophages
- Ciliated epithelium
- — If found in URT, indicates contamination
- WBCs (indicates infection)
Evaluation of Gram-stained direct smears of sputum
- Bartlett’s method
Assign + and - values; +2 if > 25 WBC; +1 if 10-25 WBCs; +1 if mucus seen; -2 if > 25 epis; -1 if 10-25 epis
Evaluation of Gram-stained direct smears of sputum
- Bartlett’s criteria for acceptability
Any positive score (sum of + and - values assigned)
Evaluation of Gram-stained direct smears of sputum
- Murray and Washington’s method
Average number of epi/LPF
Evaluation of Gram-stained direct smears of sputum
- Murray and Washington’s criteria for acceptability
< 10 EPI/LPF
List the bacteria that cause aspiration pneumonia
Mouth flora
Epiglottis is caused by…
Haemophilus influenzae
Ear/sinus infections is caused by…
Moraxella catarrhalis
