CAP AND HCAP Flashcards
What are some risk factors for pneumonia?
- chronic disease
- immunologic deficiency
- leukopenia/ immunosuppression
Impaired local defense mechanisms is a big reason why pneumonia can occur. What are some situations in which local defenses might become impaired?
- alcohol suppressing cough reflex
- cystic fibrosis
- pulmonary edema
- alcohol and tobacco inhibiting alveolar macrophages
What is the most common cause of pneumonia worldwide?
Strep pneumo (most of the time the causative organism is not ID’d though)
What (basically) happens in pneumonia?
bacteria invade lung parenchyma causing alveoli to be filled with inflammatory exudate, causing consolidation of the pulmonary tissue
What patients have the greatest risk of HAP?
ventilated patients
What is healthcare associated pneumonia?
Hospitalization of at least 2 days within the prior 90 days, or
has been receiving IV therapy, chemo or wound care in past 30 days, or
resident of nursing home or attends hemodialysis clinic or hospital
What are the physical findings of pneumonia?
- crackles
- bronchial breath sounds
- dullness to percussion
- tactile fremitus
What are crackles (rales)?
scratchy sounds caused by accumulation of fluid/white cells/bacteria in alveolar spaces
Why are bronchial sounds heard?
dense consolidation of lung parenchyma results in transmission of large airway noises to the periphery
What are some complications of pneumonia?
- tissue destruction and necrosis leading to abscess
- spread into pleural cavity causing an empyema (pus in a cavity)
- dissemination
What organisms cause typical pneumonia?
- Strep pneumo
- Staph aureus
- Pseudomonas aeruginosa
- Klebsiella
- Haemophilus influenzae
- Moraxells catarrhalis
- Acentobacter baumanii
What organisms cause atypical pneumonia?
- mycoplasma pneumoniae
- chlamydophila pneumoniae
- Legionella pneumophila
Difference between typical and atypical pneumonia
CXR and symptoms are different and causative organism cannot be isolated on normal media
Describe Strep pneumo
- Gram positive, lancet shaped, encapsulated diplococcus
- alpha hemolysis
- catalase neg
- Optochin sensitive
Strep pneumo undergoes the Quellung reaction. What is this?
With type specific anti-serum the capsule swells
What virulence factors does Strep pneumo use?
- Polysaccharide capsule
- IgA protease
- Lipoteichoic acid
What does lipoteichoic acid do?
activates complemtn/induces cytokine production
What are the risk factors for S. pneumo?
- Alcohol/drug
- Pulmonary congestion/CHF
- Splenectomy
- SCD (auto-splenectomy)- S. pneumo has a capsule
- HIV (most common infection in HIV)
How does Strep pneumoniae present?
SUDDENT onset of fever, shaking chills, RUSTY sputum, SOB, pleuritic pain
How is Strep pneumo diagnosed?
gram stain and culture sputum (blood cultures will be positive in 15-25% of people), or
rapid urinary antigen test
What will CXR show in Strep pneumo?
lobar consolidation
Treatment of Strep pneumo?
- Penicillin if susceptible
- Vanco empirically if severe
-Ceftriaxone, Fluoro, Amoxicillin, Azithro are options
What are the vaccine options for S. pneumo?
Polyvalent (23-type) polysaccharide vaccine (PPSV23 or Pneumovax) provides 5 yr protection
Prevnar (PCV13)
Pneumovax is recommended for what patients?
all persons 65+ you and those 19-64 at increased risk
Prevnar is recommended for what patients?
children and infants and HIV patients
What else can Strep pneumo cause?
- Meningitis
- Otitis media
- Sinusitis
Describe staph aureus
gram + cocci in clusters
- coagulase and catalase +
- commensal
T or F. Antibiotic resistance to staph aureus is common
T. Susceptibilities must be known before treating
What are the complications of Staph aureus?
- necrotizing PNA
- lung abscess
Staph aureus typically cause a bronchopneumonia. What does this mean?
more diffuse findings on CXR causes by a cute inflammatory infiltrates from bronchioles into adjacent alveoli usually patchy and involving more than 1 lobe
Describe Pseudomonas aeruginosa
Aerobic gram neg bacilli that is oxidase positive and does NOT ferment lactose
Why does Pseudomonas aeruginosa appear blue-green?
procyanin production
Pseudomonas aeruginosa gives a characteristic smell on BAP. What is it?
grape-like
Pseudomonas aeruginosa is a very common cause of pneumonia in what patients?
Cystic fibrosis
Virulence factors of Pseudomonas aeruginosa
- endotoxin (fever and shock)
- Exotoxin A
- elastase, leucocidin, hemolysins, proteases
What does exotoxin A do?
blocks protein synthesis by inactivating elongation factor EF-2 by ADP ribosylation.
T or F. Pseudomonas aeruginosa is a highly resistant organism
T. Must get antibiotic susceptibilities and know the antibiogram of the institution
Treatment of Pseudomonas aeruginosa
- Cefepime
- Meropenem or Imipenem
- Cipro
Ceftriaxone will NOT treat pseudomonas
What other diseases does Pseudomonas aeruginosa cause?
- wound infections in burn victims
- sepsis in hospitalized patients
- external otitis in diabetics
- UTI
- Hot tub folliculitis
Describe Klebsiella pneumoniae
encapsulated, commensal gram - bacillus that DOES ferment lactose and is indole NEGATIVE
T or F. Klebsiella pneumoniae can grow at 10C
F.
Klebsiella pneumoniae is an important cause of pneumonia in which patients?
alcoholics and malnourished
What is Klebsiella pneumoniae characterized on sputum culture
red ‘currant jelly’ sputum (produced very mucoid colonies by its capsule)
What are the compliations of Klebsiella pneumoniae?
abscess and necrotizing pneumonia
T or F. Klebsiella pneumoniae resistance is common
T.
Describe Haemophilus influenzae
gram- neg non-motile, pleomorphic rods
Is Haemophilus influenzae aerobic or anaerobic?
facultative anaerobic
Culture of Haemophilus influenzae on chocolate agar requires what for growth?
factors V (NAD+) and X (hematin)
Some serotypes of Haemophilus influenzae are encapsulated and others are not. What serotype is the most invasive?
capsular type B (vaccines incorporate the capsular polysaccharide b)
What other diseases can Haemophilus influenzae cause?
- otitis media
- epiglottitis
- meningitis
- exacerbations of COPD
How is Haemophilus influenzae treated?
Amoxicillin for mild infection and ceftriaxone for more severe
Describe Moraxella catarrhalis
gram negative coccobacillary rods that commonly causes pneumonia in the ELDERLY
Moraxella catarrhalis is the 2nd most common bacterial cause of what?
acute exacerbations of COPD
Moraxella catarrhalis also causes what diseases?
- otitis media (common cause)
- sinusitis
Describe Acinetobacter baumanii
opportunistic (so not really a CAP cause) gram-neg coccabacillary rods found in water and soil
When is Acinetobacter baumanii pneumonia common?
Hospital settings, especially associated with respiratory equipment
What diseases does Acinetobacter baumanii cause?
-VAP/HAP, sepsis, line infections, UTIs
T or F. Resistance is high in Acinetobacter baumanii
T.
What are two common secondary bacterial infections following a H. flu infection?
Strep pneumo and staph aureus
What kinds of bacteria produce endotoxins?
gram negatives
