Bacterial Pneumonia- Cross Flashcards
Most common cause of pneumonia?
Streptococcus Pneumoniae
Which bugs can cause Community-acquired pneumonia??
Any of them
Criteria for Hospital-acquired pneumonia?
Symptoms appear 48+ hours post-admission; bug cannot be incubating at time of admission
Risk factors for Hospital-acquired pneumonia (there are 5)? Which is highest risk?
1) Mechanical ventilation (highest risk)
2) severe underlying illness
3) immunosuppression
4) prolonged abx therapy
5) IV catheters
Criteria for Healthcare associated pneumonia?
1) Hospitalization of at least 2 days, within the prior 90 days, 2) receiving IV therapy, chemo, or wound care for last 30 days 3) Nursing home or long term care facility resident 4) attend hemodialysis clinic
Physical exam findings in pneumonia?
Crackles (rales), bronchial breath sounds, dullness to percussion, Increased tactile fremitus
What is an empyema?
Spread of infection into the pleural cavity (purulent collection)
2 general criteria of atypical pneumonia?
bug cannot be isolated on normal media;
CXR is atypical (diffuse, unilat/bilat infiltrates), presenting symptoms are atypical
Strep pneumoniae gram stain? shape? capsule?
G+, lancelet shaped, encapsulated diplococcus
Strep pneumoniae hemolysis?
Alpha (incomplete)–> green on blood agar
Strep pneumoniae Quelleng reaction?
+, cells swell due to presence of polysaccharide capsule
Strep pneumoniae virulence factors?
Polysaccharide capsule (most important), IgA protease (enhances colonization of URT), Lipoteichoic Acid
Strep pneumoniae risk factors (5)?
1) EtOH intoxication
2) abnormality of the respiratory tract (obstruction, viral infection)
3) splenectomy
4) sickle cell
5) HIV/immunocompromise
Optochin sensitive bug? Distinguishes it from which other bug?
Strep pneumo, used to distinguish from other alpha-hemolytic bugs (strep viridans)
Strep Pneumo catalase test? Distinguishes it from what other bug?
Catalase -, distinguishes from staph species (catalase +)
Sputum seen with Strep Pneumoniae infection?
Productive cough with RUSTY sputum (pathognomonic)
Strep Pneumonia CXR?
Lobar consolidation
Clinical manifestations of Strep Pneumo?
Rapid onset of fever, shaking chills, cough productive of rusty sputum (BIGGY), SOB, pleuritic pain
Diagnostic tests for Strep pneumoniae?
Gram stain and sputum culture; Rapid urinary antigen test (specific)
Tx guidelines for Strep pneumoniae?
1) PCN is drug of choice if susceptible 2) Vancomycin for severe infection until susceptibilities known 3) Floroquinolones and Azithromycin options with less severe disease
Who should get the pneumovax vacccine?
all persons >65 years of age and those 19-64 that are at increased risk
What is the Strep pneumoniae vaccine for children/infants?
Prevnar
Strep pneumoniae vaccine guidelines for high risk adults?
They get both pneumovax and prevnar sequentially
Staph Aureus gram stain/test characteristics?
G+ cocci in clusters; coagulase+ and catalase+
2 bugs that most commonly cause post-influenza pneumonia?
Strep pneumoniae and staph aureus
Complications of Staph aureus pneumonia?
Necrotizing pneumonia and lung abscess
CXR findings of Staph aureus pneumonia?
Typically a bronchopneumonia (more diffuse findings on CXR)
Tx guidelines for Staph aureus?
Must get susceptibilities; resistance is common
Pseudomonas aeruginosa gram stain/test characteristics?
Aerobic gram(-) bacilli, does not ferment lactose; oxidase (+); Blue-green pigment (Pyocyanin production); Grape-like odor
Patients that Pseudomonas aeruginosa is common in?
Very common in HAP; most common cause of pneumonia in cystic fibrosis patients
Pseudomonas aeruginosa virulence factors?
Endotoxin (elicits shock), Exotoxin A (blocks protein synthesis by inhibiting EF-2 elongation factor). Other hemolysins/proteases
Tx guidelines for Pseudomonas aeruginosa?
Must know antibiogram (highly resistant);
1) Cefepime (4th generation cephalosporin)
2) Meropenem or Imipenenem (carbapenem)
3) Ciprofloxacin (flouroquinolone)
4) Piperacillin/Tazobactam (extended spectrum PCN)
5) Gentamicin (Aminoglycoside)
Klebsiella pneumoniae gram stain/test characteristics?
Gram(-) bacillus; ferments lactose; indole negative
Klebsiella virulence factor?
Capsule
Patients you see Klebsiella in the most?
Alcoholics, malnourished, and those on ventilators/hospitalized
Sputum seen with Klebsiella?
Red “currant jelly” sputum (pathognomonic)
Complications seen in Klebsiella pneumoniae?
Necrotizing pneumonia and lung abscess
Tx guidelines for Klebsiella pneumoniae?
Check susceptibility, resistance is high
Haemophilus influenzae gram stain/test characteristics?
small gram(-) coccobacilliary rod; pleomorphic; facultative anaerobe; nonmotile
How do you culture Haemophilus influenzae?
chocholate agar with factors V (NAD+) and X (hematin)
Haemophilus influenzae virulence factor?
Capsule
Tx guidelines for Haemophilus influenzae?
Amoxicillin for mild infection, Ceftriaxone (3rd generation) for serious infection
2 bugs that most commonly cause bacterial COPD exacerbation? Which causes it the most?
Haemophilus influenzae (most common) and Moraxella catarrhalis
Acinetobacter baumanii gram stain?
Gram(-) coccabacillary rods
Which bug is almost only seen causing HAP?
Acinetobactor baumanii
Tx guidelines for Acinetobacter baumanii?
Need susceptibility, highly resistant to many abx
Bug you suspect if the CXR looks much worse than the patient?
Mycoplasma pneumoniae
What does Mycoplasma pneumoniae most commonly cause?
atypical “walking pneumonia” (most common cause of atypical pneumonia)
Mycoplasma pneumoniae gram stain?
Can’t gram stain, has no cell wall
Pathogenesis of Mycoplasma pneumoniae?
Adhesins bind to ciliated epithelial cells and reduce mucocilliary clearance
Types of people that most commonly get Mycoplasma pneumoniae?
school-aged children and prison inmates/military personnel
Clinical manifestation of Mycoplasma pneumoniae?
Insidious onset of dry cough, sore throat, myalgias, low-grade fever
Diagnosis of Mycoplasma pneumoniae?
1) PCR on sputum 2) Cold agglutination 3) Will grown on Eaton agar 4) Serology (not great)
Tx guidelines for Mycoplasma pneumoniae?
Macrolide (azithromycin), doxycycline, or flouroquinolones (levofloxacin)
Extrapulmonary manifestations of Mycoplasma pneumoniae?
CNS involvement (encephalitis), Cardiac involvement (rhythm disturbance, CHF, myocarditis)
Chlamydia pneumoniae characteristics?
Obligate intracellular organism (can’t gram stain)
2 bugs that most commonly cause atypical pneumonia? Which is most common?
Mycoplasma pneumoniae (most common) and Chlamydia pneumoniae
Most common cause of atypical pneumonia in adults?
Chlamydia pneumoniae
Tx for Chlamydia pneumoniae?
Doxycycline
Legionella pneumophila gram stain
Gram(-) rod, faculatative intracellular anaerobe
Pathogenesis of Legionella pneumophila?
Avoids phagolysosome fusion and replicates within alveolar macrophages–> decreased clearance
Legionella pneumophila virulence factor?
Endotoxin
Legionella pneumophila transmission?
Aerosol (air-conditioning ducts, outbreaks at conventions or military barracks)
Clinical presentation of Legionella pneumophila?
Legionnaire’s disease: Severe pneumonia with unique symptoms (dry cough, fever, diarrhea, confusion) Pontiac fever: mild flu-like syndrome
CXR of Legionella pneumophila?
Very variable (consolidation, diffuse interstitial infiltrates, pleural effusions)
Growth of Legionella pneumophila on culture plates?
gram stain will only show macrophages/neutrophils; must use silver stain. Grows on charcoal yeast extract, culture with iron and cysteine
What will labs show in someone with Legionella pneumophila?
Hyponatremia
Diagnosis of Legionella pneumophila?
Urine antigen
Treatment of Legionella pneumophila?
Macrolide (azithromycin) or Flouroquinolone (levofloxacin)
Who most commonly gets aspirational pneumonia?
Alcoholics
What are the three bacteria that have capsules and would give a + Quellung reaction?
Strep pneumo, Klebsiella pneumo, Haemophilus influenzae
Which bacteria would stain Gram positive?
Strep pneumo Staph auereus
Which bacteria would stain Gram negative?
Pseudomonas aeruginosa
Klebsiella pneumoniae
Haemophilus influenzae
Acinetobacter baumanii
Moraxella catarrhalis
Which bacteria can’t be stained with Gram stain?
Mycoplasma pneumoniae (lacks cell wall) Chlamydia pneumoniae (intracellular) Legionella pneumophila (intracellular)
Which bacteria cause necrotizing pneumonia with lung abscess?
Staph aureus (Gram +) Klebsiella pneumo (Gram -)
Which bacteria can be diagnosed with urinary antigen?
Strep pneumo (Gram +) Legionella pneumophila (Gram -)
Pseudomonas aeurginosa can cause 5 other diseases besides pneumonia. List them.
Wound infections in burn victims
Sepsis in hospitalized patients
External otitis (esp in diabetics)
UTI
Hot tub folliculitis
Klebsiella normally found where in body?
intestinal flora
Haemophilus influenzae has how many serotypes? All encapsulated or nonecapsulated?
6 serotypes, both encapsulated and nonencapsulated
Most invasive capsular type of Haemophilus influenzae?
Capsular type B
Besides pneumonia, what other diseases are associated with Haemophilus influenzae?
otitis media, epiglottitis, and meningitis. Also common bacteral cause of acute exacerbations of COPD
