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Pulm > SM_181a: Bacterial Infections > Flashcards

SM_181a: Bacterial Infections Flashcards

1
Q

Streptococcus pneumoniae is a [Gram stain, shape}

A

Streptococcus pneumoniae is a Gram-positive lancet-shaped diplococci (pneumococci)

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2
Q

What are the determinants of pathogenicity of Streptococcus pneumoniae?

A

Streptococcus pneumoniae

  • Capsule: protects bacteria from phagocystosis, antibodies against them are protective in humans, 80 distinct serotypes
  • Pneumolysin: degrades hemoglobin to greenish pigment, may form pores, activates complement
  • Peptidoglycan fragments and teichoic acid: activate complement, leading to intense inflammation and tissue damage
  • IgA protease
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3
Q

Describe the clinical disease caused by Streptococcus pneumoniae

A

Streptococcus pneumoniae

  • Only infects humans
  • Spread person-to-person by small droplets
  • Colonizes oropharynx and nasopharnx of some healthy adults and kids
  • Most common bacterial cause of community-acquired pneumonia
  • Pnuemonia leading to bacteria in the very young and old
  • Pneumonia leading to meningitis
  • Pneumonia in healthy individuals and those with predisposing conditions
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4
Q

Describe the presentation of Streptococcus pneumoniae

A

Streptococcus pneumoniae

  • Fever
  • Cough productive of rusty-colored sputum
  • Pleuritic chest pain
  • Diminished respiratory excursion (splinting): not taking much effort to avoid pain
  • Abrupt onset of symptoms
  • Chest radiographs show lobar infiltrates
  • May cause empyema
  • Frequent cause of otitis media, acute bronchitis, sinusitis
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5
Q

Describe diagnostic testing for Streptococcus pneumoniae

A

Streptococcus pneumoniae

  • Sputum sample: numerous Gram-positive cocci in pairs and chains, many neutrophils, no epithelial cells
  • Culture on blood agar: alpha-hemolytic
  • Catalase-negative
  • Optochin-susceptible
  • Pneumococcal urinary antigen test for urine
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6
Q

Describe the treatment for Streptococcus pneumoniae

A

Streptococcus pneumoniae

  • Penicillin, although now there is significant resistance which is often associated with resistance to other antibiotics as well
  • Vancomycin, cephalosporins, doxycyline, TMP-SMX, macrolides, clindamycin
  • Moxifloxacin effective but cipro is not
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7
Q

Describe prevention of Streptococcus pneumoniae

A

Streptococcus pneumoniae

  • Pneumococcal polysaccharide vaccine (Pneumovax 23)
  • Pneumoccocal polysaccharide-protein conjugate vaccine (Prevnar-13): capsular polysaccharide from 13 serotypes conjugated to protein
  • Vaccination recommended for young children 2-23 months, adults 65 years or older, all others at risk for pneumococcal infections (diabetes mellitus, chronic lung disease, HIV, etc)
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8
Q

Streptococcus pneumomiae is ______-hemolytic

A

Streptococcus pneumomiae is alpha-hemolytic

(partial/green hemolysis)

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9
Q

______ of Streptococcos pneumoniae degrades hemoglobin to a ______ pigment

A

Pneumolysin of Streptococcos pneumoniae degrades hemoglobin to a greenish pigment

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10
Q

Sputum sample shows Gram-positive cocci in pairs and chains along with many neutrophils. The organism is ________

A

Sputum sample shows Gram-positive cocci in pairs and chains along with many neutrophils. The organism is Streptococcus pneumoniae

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11
Q

Most common cause of community-acquired pneumoniae is ______

A

Most common cause of community-acquired pneumoniae is Streptococcus pneumoniae

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12
Q

Pneumonia from Streptococcus pneumoniae can cause _____ in very young and old people

A

Pneumonia from Streptococcus pneumoniae can cause bacteremia in very young and old people

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13
Q

Haemophilus influenzae is a [size, Gram-stain, shape]

A

Haemophilus influenzae is small Gram-negative coccobacilli

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14
Q

What are the determinants of pathogenicity of Haemophilus influenzae?

A

Haemophilus influenzae - polysaccharide capsule

  • Six types (a-f), antiphagocytic
  • Type b caused most serious disease but becoming less common with routine use of vaccination
  • Type specific antibodies are protective
  • Encapsulated H. influenza primarily infects children because most adults have protective antibodies
  • Unencapsulated strains often isolated from adults and children
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15
Q

Describe the clinical disease caused by Haemophilus influenzae

A

Haemophilus influenzae

  • May colonize the upper respiratory tract of healthy individuals
  • Spread by airborne droplets or by direct contact with secretions
  • Frequent cause of otitis media, sinusitis, community-acquired pneumonia, bronchitis, conjunctivitis, meningitis in children under age of 6, septic arthritis in children, may cause life-threatening epiglottitis
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16
Q

_______ may cause life-threatening epiglottitis

A

Haemophilus influenzae may cause life-threatening epiglottitis

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17
Q

_______ is the radiographic sign you would see in a patient with epiglottitis from Haemophilus influenzae

A

Thumb sign is the radiographic sign you would see in a patient with epiglottitis from Haemophilus influenzae

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18
Q

Haemophilus influenzae _____ grow on sheep blood agar

A

Haemophilus influenzae does not grow on sheep blood agar

(needs hemin and NAD which sheep blood agar does not have)

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19
Q

Haemophilus influenzae requires ______ and ______ for growth

A

Haemophilus influenzae requires hemin (X factor) and NAD (V factor) for growth

(can grow on chocolate agar)

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20
Q

Haemophilus influenzae can grow on ______ agar

A

Haemophilus influenzae can grow on chocolate agar

contains hemin (X factor) and NAD (V factor)

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21
Q

Describe treatment of Haemophilus influenzae

A

Haemophilus influenzae

  • Ampicillin, amoxicillin, or penicillin G not effective against beta-lactamase producing strains (25%)
  • Cephalosporins, TMP-SMX, macrolides, amoxicillin/clavulonic acid, and quinolones
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22
Q

Prevention of Haemophilus influenzae involves _______

A

Prevention of Haemophilus influenzae involves Type B capsular conjugate vaccine (Hib)

  • Given to all infants starting at 2 months of age
  • Dramatically reduced incidence of Haemophilus influenzae meningitis in infants and children
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23
Q

Describe Mycoplasma pneumoniae

A

Mycoplasma pneumoniae

  • Extracellular pathogen
  • Lacks cell walls
  • Pleimorphic in shape
  • Smallest organisms that can be free-living in nature and self-replicating on laboratory medium
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24
Q

Mycoplasma pneumoniae is an ______ pathogen and lacks ______

A

Mycoplasma pneumoniae is an extracellular pathogen and lacks cell walls

(pleimorphic in shape)

25
Q

Describe the pathogenesis of Mycoplasma pneumoniae

A

Mycoplasma pneumoniae tightly adheres to respiratory epithelium via protein adhesin P1

26
Q

Mycoplasma pneumoniae tightly adheres to _______ via _______

A

Mycoplasma pneumoniae tightly adheres to respiratory epithelium via protein adhesin P1

27
Q

Describe the clinical disease caused by Mycoplasma pneumoniae

A

Mycoplasma pneumoniae

  • Person to person spread by airborne small droplets
  • May cause pharyngitis, rhinorrhea, acute bronchitis, or community-acquired pneumoniae
  • Causes atypical pneumoniae: gradual onset, cough without sputum, common in young people aged 5-20, usually mild disease (walking pneumoniae), non-lobar on chest radiographs
28
Q

Mycoplasma pneumoniae causes ______ pneumonia

A

Mycoplasma pneumoniae causes atypical pneumoniae

  • Gradual onset
  • Cough without sputum
  • Common in young people ages 5-20 years
  • Usually mild disease (walking pneumonia)
  • Non-lobar infiltrates on chest radiographs
29
Q

Describe the clinical presentation of someone with Mycoplasma pneumoniae

A

Mycoplasma pneumoniae

  • Fever
  • Headache
  • Malaise
  • Sore throat
  • Non-productive cough
  • Occasionally pneumonia accompanied by neurologic abnormalities (encephalitis), skin rashes, hemolytic anemia
30
Q

Pneumonia accompanied by hemolytic anemia is caused by ______

A

Pneumonia accompanied by hemolytic anemia is caused by Mycoplasma pneumoniae

31
Q

Classic CXR pattern of someone with ______ is diffuse reticulonodular or interstitital infiltrates

A

Classic CXR pattern of somone with Mycoplasma pneumoniae pneumonia is diffuse reticulonodular or interestitial infiltrates

(but any pattern can be seen)

32
Q

Describe diagnostic testing for Mycoplasma pneumoniae

A

Mycoplasma pneumoniae

  • Cultured from pharynx or sputum - requires sterols for growth
  • Rise in specific antibody titers in the blood
  • Cold hemagglutinins may be seen in 50% of patients: antibodies directed against mature RBCs that cause reversible agglutination at 4ºC
33
Q

_______ may be seen in the diagnostic testing of many Mycoplasma pneumoniae patients

A

Cold hemagglutinins may be seen in the diagnostic testing of many Mycoplasma pneumoniae patients

(antibodies directed against mature RBCs that cause reversible agglutinations at 4ºC)

34
Q

Describe the treatment of Mycoplasma pneumoniae

A

Mycoplasma pneumoniae

  • Macrolides, tetracycline/doxycycline, quinolones
  • Penicillins not active (no cell wall)
35
Q

_____ are not active against Mycoplasma pneumoniae because they do not have a ______

A

Penicillins are not active against Mycoplasma pneumoniae because they do not have a cell wall

36
Q

Describe prevention of Mycoplasma pneumoniae

A

Mycoplasma pneumoniae

  • None (no vaccine)
37
Q

Chlamydia pneumoniae is [location]

A

Chlamydia pneumoniae is obligate intracellular

(closely related species are Chlamydia trachomatis which causes STDs and Chlamydia psittaci which causes pneumonia contracted from birds)

38
Q

Describe the clinical disease caused by Chlamydia pneumoniae

A

Chlamydia pneumoniae

  • Community-acquired pneumonia: atypical pneumonia
  • Relatively common (5-20%) cause of pneumonia in young adults
  • Pneumonia often accompanied by pharyngitis
  • Chest radiographs resemble those of patients with Mycoplasma pneumonia
39
Q

Describe diagnosis of Chlamydia pneumoniae

A

Chlamydia pneumoniae

  • Acute and convalescent antibody titers
40
Q

Describe treatment of Chlamydia pneumoniae

A

Chlamydia pneumoniae

  • Macrolides and tetracycline/doxycycline
41
Q

Describe prevention of Chlamydia pneumoniae

A

Chlamydia pneumoniae

  • None (no vaccine available)
42
Q

Staphylococcus aureus are [Gram-stain, shape, appearance]

A

Staphylococcus aureus are Gram-positive cocci that may have a gold appearance

  • Cause of community-acquired pneumonia and nosocomial pneumonia
  • MRSA
  • Treat with nafcillin/oxacillin (vancomycin or linezolid if MRSA)
43
Q

Legionella pneumophila resembles [Gram-stain] but does not take up Gram-stain

A

Legionella pneumophila resembles Gram-negatives but does not take up gram stain

44
Q

Legionella pneumophila causes ________

A

Legionella pneumophila causes Legionnaire’s disease

  • May be community-acquired or hospital-acquired
  • Considered an atypical pneumonia
  • May be quite severe, with high fevers (greater than 40ºC)
  • Associated with water, air conditioning systems, and cooling towers
  • Treatment: macrolide or fluoroquinolone
45
Q

Describe aspiration pneumonia

A

Aspiration pneumonia

  • Seen in patients with depressed gag reflex: elderly patients, seizures, alcoholic blackouts
  • Clinical presentation: cough, fever, malaise, foul-smelling sputum
  • CXR: consolidation on dependent lung fields
  • Causative organisms are pharyngeal flora: Prevotella, Fusobacterium, anaerobic cocci
  • May evolve into lung abscesses or empyema
46
Q

Patient has pneumonia with pleuritic chest pain. The causative organism is ________

A

Patient has pneumonia with pleuritic chest pain. The causative organism is Streptococcus pneumoniae

47
Q

Gram-negative rod that is oxidase positive is ________

A

Gram-negative rod that is oxidase positive is Pseudomonas aeruginosa

48
Q

Which organisms can cause ventilator-associated pneumonia?

A

Ventilator-associated pneumonia

  • Staphylococcus aureus
  • Enterobacteriaeceae (Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Serratia spp.)
  • Legionella pneumophila
  • Pseudomonas aeruginosa
  • Acinetobacter baumannii
  • Mixed anaerobic bacteria
  • Aspiration pneumonia
49
Q

Describe the Enterobacteriaeceae (Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Serratia spp.)

A

Enterobacteriaeceae (Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Serratia spp.)

  • Gram-negative rods
  • Oxidase negative
  • Many inhabit the human GI tract
  • May colonize the oropharynx in hospitalized patients -> HAP or VAP
  • Hospital-acquired organisms tend to be resistant to multiple antibiotics
50
Q

Describe Pseudomonas aeruginosa

A

Pseudomonas aeruginosa

  • Gram-negative, aerobic bacilli
  • Common cause of HAP and VAP
  • Resistant to many antibiotics: must check susceptibilities for definitive treatment regimen
51
Q

Describe Acinetobacter baumannii

A

Acinetobacter baumannii

  • Gram-negative, aerobic bacillus or coccobacillus
  • Causes HAP or VAP
  • Resistant to many antibiotics
  • 50% of isolates may be resistant to carbapenems
52
Q

Which organisms caise acute bronchitis/tracheitis?

A

Acute bronchitis/tracheitis

  • Streptococcus pneumoniae
  • Haemophilus influenza
  • Mycoplasma pneumoniae
  • Chlamydia pneumoniae
  • Bordetella pertussis
53
Q

Describe Bordetella pertussis

A

Bordetella pertussis

  • Tiny gram-negative coccobacilli, strict aerobe
  • Cause of whooping cough
  • Secretes pertussis toxin
  • Historically a disease of children but recently outbreaks among adults have been repoted
54
Q

Describe Corynebacterium diphtheria

A

Corynebacterium diphtheria

  • Gram-positive bacilli, club-shape
  • Diphtheria toxin (DT): ADP-ribosylating EF-2
  • Causes diphtheria: patients (historically children) present with sore throat and fever, difficulty swallowing, cough, hoarseness, rhinorrhea - oropharyngeal pseudomembrane may lead to airway obstruction
55
Q

Oropharyngeal ______ is characteristic of CCorynebacterium diphtheria infection

A

Oropharyngeal pseudomembrane is characteristic of Corynebacterium diphtheria infection

(may lead to airway obstruction)

56
Q

Gram-positive cocci causing alpha-hemolysis: ________

A

Gram-positive cocci causing alpha-hemolysis: Streptococcus pneumoniae

57
Q

Atypical pneumonia, hemolytic anemia, neutrophils and no growth on sputum: _______

A

Atypical pneumonia, hemolytic anemia, neutrophils and no growth on sputum: Mycoplasma pneumoniae

58
Q

Air conditioner repair man, high fever, CXR shows bilateral patchy infiltrates, no growth on culture: _______

A

Air conditioner repair man, high fever, CXR shows bilateral patchy infiltrates, no growth on culture: Legionella pneumophila

59
Q

Homeless, blood-tinged sputum, weight loss, right upper lobe rhonchi: _________

A

Homeless, blood-tinged sputum, weight loss, right upper lobe rhonchi: Mycobacterium tuberculosis

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