4 Bacterial PNA 1 & 2 Flashcards

1
Q

Pneumonia is defined as …

A

Inflammation of the lung and parenchyma, including the alveoli, respiratory bronchioles, etc

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2
Q

PNA with involvement of the entire lobe

A

Lobar pneumonia

Bronchopneumonia is just the bronchi?

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3
Q

PNA is usually due to an infectious agent, such as…

A

BACTERIA
Fungi
Viruses
Parasites

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4
Q

6th leading cause of death in the US

A

PNA - most common infectious cause of death

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5
Q

How does mortality rate from PNA different in outpatient vs inpatient settings?

A

1% in outpatient

Up to 25% in infections requiring hospital admission

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6
Q

The two major categories of PNA

A

Hospital acquired (nosocomial) - develops within 72 hours of admission

Community acquired (CAP)

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7
Q

Community acquired PNA is further subdivided into what two categories?

A

Typical (usually Strep pneumo, H flu, K pneumo, or Staph aureus)

Atypical (usually Zoonotic, nonzoonotic, or with extrapulmonary involvement)

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8
Q

3 zoonotic pathogens that cause atypical PNA

A
Chlamydia psittaci (psittacosis)
Francisella tularensis (tularemia)
Coli Ella burnetii (Q fever)
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9
Q

3 non-zoonotic pathogens that cause atypical PNA

A

Chlamydia pneumoniae
Mycoplasma pneumoniae
Legionella pneumoniae

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10
Q

Atypical PNA is usually unresponsive to …

A

ß-lactams

Also, difficult to diagnose

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11
Q

Typical or Atypical PNA: Sudden onset

A

Typical

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12
Q

Typical or Atypical PNA: Gradual onset

A

Atypical

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13
Q

Typical or Atypical PNA: Sick appearing, high fever (>103)

A

Typical

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14
Q

Typical or Atypical PNA: Well appearing, lower fever (<103)

A

Atypical

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15
Q

Typical or Atypical PNA: Chills/shaking

A

Typical

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16
Q

Typical or Atypical PNA: Productive cough

A

Typical

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17
Q

Typical or Atypical PNA: Non-productive cough

A

Atypical

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18
Q

Typical or Atypical PNA: Pleurisy

A

Typical

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19
Q

Typical or Atypical PNA: Consolidation (well-defined infiltrates)

A

Typical

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20
Q

Typical or Atypical PNA: Patchy, ill-defined infiltrates

A

Atypical

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21
Q

Typical or Atypical PNA: Chest pain, SOB

A

Typical

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22
Q

Typical or Atypical PNA: Body aches, diarrhea, abdominal pain

A

Atypical

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23
Q

Gram-positive, lancet-shaped diplococcus

A

Streptococcus pneumoniae

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24
Q

Alpha-hemolytic colonies

A

Streptococcus pneumoniae

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25
Green colonies on blood agar
Streptococcus pneumoniae
26
Optochin sensitivity
Streptococcus pneumoniae
27
Encapsulated strains are virulent
Streptococcus pneumoniae
28
_________ increase the risk of pneumococcal pneumonia
Viral infections (more common in colder, wetter months)
29
The major reservoir of Streptococcus pneumoniae infections
Asymptomatic carriers (because it’s an irregular normal flora component)
30
Major virulence factor for Streptococcus pneumoniae
Capsule Basis for serotyping (90 serotypes) and the basis for anti-pneumococcal vaccines Inhibits phagocytosis by interfering with complement activity and preventing C3b opsonization
31
Other protective virulence factors for Streptococcus pneumoniae besides the capsule
IgA Protease - degrades host secretory IgA Hydrogen peroxide —> apoptosis in host cells and elimination of competing bacteria
32
Other binding virulence factors for Streptococcus pneumoniae
Pili - contributes to the colonization of the upper respitatory tract and activates production of large quantities of TNF Surface Proteins - Choline binding proteins (Adhesins that interact with the carbs on the surface of pulmonary epithelial cells)
33
What is the Peptidoglycan-teichoic acid complex?
A Streptococcus pneumoniae virulence factor that illicit a significant immune response and acts as a potent immunomodulator
34
What is Pneumolysin?
Another Streptococcus pneumoniae virulence factor Interacts with target cell membrane to form transmembrane pores —> cell lysis and activation of complement
35
What is Autolysin
Another Streptococcus pneumoniae virulence factor that causes lysis of pneumococcus and results in the release of pneumolysin Released in response to antibiotic therapy and stationary phase Is an attempt by the organism to dampen host immune response
36
What is the pathogenesis of a Streptococcus pneumoniae infection?
Pneumococcus enters respiratory tract through aspiration Multiplies in tissue (stimulates immune response to cellular components) Multiplication results in disease from heightened immune response PNA develops, possibility for hematogenous spread via lymphatic drainage in lungs Fibrinous edema fluid in alveoli —> red cells and leukocytes —> tissue consolidation Resolution occurs with the absorption of fluid and phagocytosis of remaining cells
37
Clinical manifestations of Streptococcus pneumoniae infection
Sudden onset of fever Chills Chest pain Productive cough with purulent RUST COLORED sputum Bacteremia CXR shows consolidation in lungs Confirmed by presence of gram-positive diplococci on sputum
38
Special tests to confirm Streptococcus pneumoniae and rule out others
Optochin sensitivity Bile solubility (bile will lyse Streptococcus pneumoniae but no effecton other alpha-hemolytic strep) Quelling reaction to observe capsules Agglutination tests for capsular polysaccharides Genetic probe test
39
DOC for Streptococcus pneumoniae infection
Penicillin G used in empiric therapy - but resistance is becoming common
40
What is the difference between the two pneumococcal vaccines?
23-valent capsular polysaccharide represents 85-90% of the infections in US - recommended for persons >65 or other predisposing factors 13-valent capsular polysaccharide covers >80% of infections in children 6 years and younger, conjugated to a carrier protein
41
Non-motile, gram-negative bacillus coated by a thick slimy capsule
Klebsiella pneumoniae Can cause both typical CAP and NP
42
Klebsiella pneumoniae is more common in what populations?
Alcoholics and DM Often seen in the homeless population
43
Primary virulence factor for Klebsiella pneumoniae
Polysaccharide capsule (antiphagocytic, prevents MAC-mediated lysis) Also ADHESINS (either fimbrial or non-fimbrial)
44
Aggressive necrotizing CAP with predilection for the upper lobes, causing severe illness with rapid onset high fever
Klebsiella pneumoniae Patients will often have productive cough with a thick, blood tinged sputum (Currant jelly sputum) Often fatal, even with abx treatment
45
Diagnosing Klebsiella pneumoniae
Gram stain/cuture showing mucous capsule Presence of currant jelly sputum Cavitation on CXR
46
Treatment of Klebsiella pneumoniae
Empiric therapy used due to rapid progression of disease Susceptibility testing required as it is ß-lactamase producing Combo treatments with: • Aminoglycosides • 3rd gen cephalosporins • Fluoroquinolones
47
Non-motile, gram-negative coccobacillus that can be either encapsulated or non-encapsulated
Haemophilus influenzae Has ability to lose its capsule (non-typeable H. influenzae) but is still capable of causing disease
48
Contains lipooligosaccharide in cell wall
Haemophilus influenzae Functions as a virulence factor similar to LPS
49
Colonies of this bacterium require factors from RBCs for growth but do not have hemolytic properties
Haemophilus influenzae
50
Most strains of Haemophilus influenzae are classified as ...
Opportunistic pathogens Nontypeable Haemophilus influenzae is part of the normal flora in ~80% of the population
51
Type B of this bacterium can cause pneumonia in infants and young children
Haemophilus influenzae Causes 2-4% of Haemophilus influenzae-related pneumonia’s
52
Haemophilus influenzae virulence factors
Polyribosylribitol phosphate (PRP) capsule*** (renders it resistant to phagocytosis by PMNs Neuraminidase IgA protease Fimbriae (required for successful colonization in the nasopharynx LOS
53
Satellite growths on blood agar
Haemophilus influenzae Only possible in co-infections Colonies of Haemophilus influenzae will appear as convex smooth, pale, grey or transparent colonies
54
Test to detect Haemophilus influenzae other than culture
ID-Latex Particle Agglutination test (LAT) Easier to achieve definitive results than other culture methods Relies on antigen, not viable bacteria Can be used during or following abx treatment***
55
Treatment of Haemophilus influenzae
Treated typically with ß-lactams (ie augmentin) If resistance or highly invasive infections, consider 3rd gen cephalosporins (will also cross BBB) Preventable through the use of one of three different Hib conjugate vaccines
56
Smallest free-living bacteria
Mycoplasma pneumoniae Cause of atypical CAP
57
Due to its lack of cell walls, Mycoplasma pneumoniae is ...
Pleomorphic in shape Has a “fried egg” appearance in culture on many different media
58
Bacteria with plasma membranes containing sterols
Mycoplasma pneumoniae Aerobic and looks like our cholesterol so easily evades immune system
59
SSx of Mycoplasma pneumoniae infection
Non-productive cough that lasts 1-2 months, fever (but not usually in children under 5), crackles, headache and chest pain Relapses common - infection does not produce long lasting immunity
60
Pathogenesis of Mycoplasma pneumoniae infection
Organism adheres to epithelium and releases hydrogen peroxide, resulting in damage to epithelium Prevents clearance of airway and results in colonization of airways Evades immune system by fusing to host cell membrane (via sterols), disguising itself Can also cause otitis, rhinitis, pharyngitis, and tracheobronchitis
61
Mycoplasma pneumoniae generally targets people in what age range?
5-20 years Very common transmission between family members, outbreaks common in crowded conditions Humans are the only reservoir
62
Transmission of Mycoplasma pneumoniae is via...
Respiratory droplets (person-to-person)
63
How is Mycoplasma pneumoniae diagnosed?
Chest X-ray: patchy infiltrates (not lobar consolidation) Culture from sputum COLD AGGLUTININ ASSAY - detects IgM antibodies that bind to the I antigen on the surface of RBCs at 4˚C (not specific though)
64
DOC for Mycoplasma pneumoniae
Azithromycin/Tetracycline
65
Tiny, non-motile, coccoid shaped bacteria that exist as obligate intracellular parasites and cause atypical pneumonia
Chlamydophila pneumoniae They’re gram-negative, in case you were wondering
66
Chlamydophila pneumoniae exists in what two forms?
Elementary bodies (EB) - the infectious form Reticulate bodies (RB) - the intracellular form
67
How does the Chlamydophila pneumoniae life cycle work?
Chlamydophila elementary body enters lung cell Elementary body becomes reticulate body Replication occurs Reticulate body becomes elementary body and is released to reinfect other cells
68
Clinical SSx of Chlamydophila pneumoniae infection are a result of what?
Direct tissue destruction during intercellular bacterial replication, in addition to inflammatory response Possesses at least 2 exotoxins as well Primary response is by neutrophils (immunity not long lasting) Patients may be asymptomatic or present with mild symptoms (persistent non-productive cough and malaise, with UNILATERAL lower lobe involvement)
69
Chlamydophila pneumoniae occurs mostly in ...
Adults 60+ years Transmitted person-to-person via respiratory droplets (humans are the only reservoir)
70
The cell culture for this bacterium is difficult and time consuming
Chlamydophila pneumoniae Dx relies on clinical manifestations and history, along with cell culture and microscopy (looking for inclusions), serology, and PCR
71
DOC for Chlamydophila pneumoniae
Tetracycline/erythromycin
72
How did Legionella pneumophila get its name?
Outbreak at an American Legion Convention in Philadelphia in 1976 There are 48 species and 70+ serogroups in genus Legionella 90%+ of all human infections result from one species (Legionella pneumophila), most are serogroup 1
73
What does Legionella pneumophila look like?
Thin, gram-negative pleomorphic bacillus Also has: • Fimbriae • Single, polar flagellum • ß-lactamase producer
74
Humans are infected with Legionella pneumophila by...
Inhalation of aerosolized contaminated water
75
What is the pathogenesis of Legionella pneumophila?
Bacterial cells are opsonized with C3b, facilitating their phagocytosis, but survive intracellularly by inhibiting phagolysosome fusion Bacterial replication occurs inside phagosome Host cell is killed when phagosome lyses, releasing toxic enzymes Bacteria are released upon cell lysis
76
A self-limited illness resulting from Legionella pneumophila infection with Sx lasting 2-5 days and resolving spontaneously w/o treatment
Pontiac Fever ``` SSx: Fever Chills Malaise Myalgia HA No Sx of PNA ```
77
A severe, acute atypical PNA with a high mortality rate (up to 75% w/o treatment), acquired by inhalation of aerolized bacteria
Legionnaires’ Disease (Legionella pneumophila) 2-10 day incubation period —> abrupt onset of Sx: Fever Chills Dry/nonproductive cough HA GI and Neuro Sx**** differentiates it from other PNAs Death is due to shock or respiratory failure
78
Pathogenesis of Legionnaires’ Disease
Entry of bacilli into macrophages —> multiplication inside macrophage —> death of macrophages —> release of chemotactic factors —> influx of monocytes and PMNs —> increased serum proteins, deposition of fibrin in alveoli, and release of enzymes and cytokines End result? Acute FIBROPURULENT NECROTIZING PNA
79
Where is Legionella pneumophila widespread?
Moist environments Rivers, streams, potable water, sewage, shower heads, cooling towers, other public water supplies In nature, the bacteria survive and replicate within protozoan
80
Risk factors for Legionella pneumophila infection
Presence of a LARGE inoculum (not very virulent) AND ``` Any compromise in pulmonary and/or immune function: • Smoking • Chronic heart disease • Chronic lung disease • Immunosuppression • Elderly • Alcoholics ``` Immunity appears to be long-lasting
81
What medium is used for Legionella pneumophila cultures?
Buffered Charcoal Yeast Extract (BCYE) - it is the only clinical isolate that will grow on it
82
How else is Legionella pneumophila diagnosed if not with a culture?
Rapid test for antigen in the urine (EIA test) High sensitivity, but only detects infections with serotypes 1
83
Treatment for Legionella pneumophila
DOC: Levofloxacin or other fluoroquinolones If <8 years, give em a z-pack Severe disease requires careful management and supportive therapy No treatment necessary for Pontiac fever
84
Describe Pseudomonas aeruginosa
Gram-negative, aerobic, motile bacillus with a single flagellum Clinical isolates possess pili as well Blue-green in color due to Pyoverdin and Pyocyanin
85
Primary bacterium used in bioremediation
Pseudomonas aeruginosa For treatment of sewage, oil spills etc to break down bacteria
86
What is Pyocyanin
“Blue pus” pigment in Pseudomonas aeruginosa Catalyze ROS production —> tissue damage VIRULENCE FACTOR
87
What is Pyoverdin
Green fluorescent pigment found in Pseudomonas aeruginosa Not a virulence factor but gives it a very distinctive appearance
88
What are the virulence factors for Pseudomonas aeruginosa?
Pyocyanin (ROS production) Exotoxin A (A-B toxin —> inhibition of protein synthesis —> ciliastasis and immunosuppression) Elastases (LasA and LasB) - work synergistically to destroy elastin in the lungs (lose ability to expand/contract —> no gas exchange) Alginate (mucous polysaccharide/slime layer) - inhibits mucociliary escalator Pili (attachment to host) LPS (endotoxin) —> fever, shock, DIC, tissue necrosis
89
Where does Pseudomonas aeruginosa come from
Widespread in the environment - inhabits plants, water, and moist soil Frequent or transient carriage on skin and in feces An opportunistic pathogen in the hospital Transmission occurs via fomites, plants, fruits, hands
90
Because Pseudomonas aeruginosa is not very virulent, infection requires what?
A significant break in normal defenses - generally in a immunocompromised host ``` Can cause a variety of infections: UTI PNA (esp after vent) Eye, ear, and skin (from contaminated hot tub, contact lens) Burn patients CF (common cause of death) ```
91
What media support the growth of Pseudomonas aeruginosa
BAP and MacConkey Will produce a water-soluble blue-green pigment Fruity smell Patient may fluoresce or it may tinge sputum/pus
92
Treatment of Pseudomonas aeruginosa
DO SUSCEPTIBILITY TESTING - MDR strains common Synergistic drug combo required for successful treatment Current DOC: Cefepime + Levofloxacin Avoid broad-spectrum abx (b/c they suppress normal flora)