Infectious Disease: Streptococcus Pneumoniae (Pneumoccocus)

Front 1

Streptococcus pneumoniae (pneumococcus) is the major bacterial cause of what 4 disease processes?

Back 1

pneumonia, otitis media, acute sinusitis and, absent an outbreak of meningococcal disease, meningitis in all age groups except newborn
(MOPS)

Front 2

What is the major virulence (disease-causing) factor in streptococcus pneumoniae?

Back 2

The capsule is a major virulence (disease-causing) factor because it enables the bacterium to escape ingestion and killing by polymorphonuclear leukocytes (PMN) or alveolar macrophages; organisms then replicate and cause disease. Cell wall contains substantial peptidoglycan and organisms produce pneumolysin both of which stimulate an inflammatory response.

Front 3

Pneumococci colonize _______.

Back 3

nasopharynx (children>>adults)
day care centers are BAD. kids bring home organisms to adults

Front 4

The incidence of pneumococcal pneumonia greater in YOUNG/ELDERLY.

Back 4

elderly

Front 5

What does viral infection generally do?

Back 5

Viral infection increases bacterial adherence and damages clearance. Bacteria proliferate, and disease results.

Front 6

Describe the morphology of pneumococcal pneumonia by microscope exam.

Back 6

1. pairs/chains of elongated cocci
2. gram positive

Front 7

Name the toxin produced by all pneumococci that breaks hemoglobin to a greenish pigment.

Back 7

alpha hemolysin

Front 8

Pneumococci are catalase POSITIVE/NEGATIVE, while staphylococci are catalase POSITIVE/NEGATIVE.

Back 8

pneumococci-NEGATIVE!!!!

staphylococci-positive ("a cat has joined the staff")

Front 9

Define optochin susceptibility as it relates to pneumococci.

Back 9

nearly all pneumococci are susceptible to inhibition by optochin and do not grow around disk that contains this substance (optochin diffuses into the agar). Where the optochin is most concentrated, pneumococci don’t grow.

Front 10

A culture of pneumococci does not grow around: (2)

Back 10

1. optochin
2. bile salts

Front 11

Name the 3 big-picture layers from outside going in of pneumococci

Back 11

capsule, cell wall, cell membrane

Front 12

Why can't organisms, absent Ab's to specific capsular polysaccharide, not be readily ingested by PMNs?

Back 12

capsule is not recognized by receptors on PMN

All humans have IgG to cell wall of pneumococcus. Ig and complement can diffuse through capsule and attach. But capsule prevents PMN receptors from interacting with IgG and Fc.

Front 13

Best bacterial defense against host is ______; our best defense against infection is ______.

Back 13

capsule; Ab to capsule

Front 14

What is teichoic acid? What is the importance of it?

Back 14

it protrudes into the capsule all the way from cell membrane and mediates ATTACHMENT (TLR 2>>4) to cells of innate system and this binding/activation causes inflammation
- contains unique, choline-rich C-polysaccharide of S. pneumoniae
- C reactive protein produced by liver in inflammatory diseases/infections will react with this substance
- there are other important proteins that make pneumococcus virulent that attach to this choline

Front 15

Define virulent

Back 15

disease-causing

Front 16

Importance of choline-binding proteins.

Back 16

choline-binding proteins (ie. PspA, PspC) are important virulence factors that may have anti-phagocytic function. Abs to them may provide some immunity, enabling phagocytosis.

Front 17

What does Choline binding protein D do?

Back 17

lyses pneumococci: cell division and cell wall remodeling

Front 18

Name principal constituent of cell wall.

Back 18

peptidoglycan (alternating glucosamine and muramic acid in long chains)

Front 19

Basic function of peptidoglycan within cell wall of pneumococci.

Back 19

-activate complement (by alternative pathway)
-stimulate inflammatory response. it is analogous to endotoxin (principal cell wall constituent in gram neg bacteria): activate release of TNF, IL 1/6, etc.

Front 20

Name 3 things in pneumococci that produce virulence.

Back 20

teichoic acid, peptidoglycan, pneumolysin

Front 21

What is pneumolysin?

Back 21

major virulence factor w/i pneumococci
- substance (toxin) released that activates complement, stimulating inflammation
- reproduces changes of pneumonia

Front 22

Define autolysin.

Back 22

cell wall hydrolase that lyses pneumococci (normally, for cell cycle and to help it form new organism)
- releases substances like pneumolysin that cause inflammation and damages tissue

Front 23

How is pneumococci spread?

Back 23

intimate facial contact, hand to hand contact or aerosol (sneezing, coughing)

Front 24

Mechanism of pneumococcal entry and pathogenesis.

Back 24

-Attaches by adhering to epithelial cells (through lipoteichoic acid, protruding through capsule to surface of bacterium, interacting with epithelial cell surface of nasopharynx)
- next, 1 or 2 things could happen: 1) pneumococci carried by secretions to space where clearance is poor (bc of damage to clearance mechanisms) or obstruction - bacteria get where they don't belong -like alveoli
2)local invasion through respiratory epithelial cell layers with organisms going directly to blood stream or lymphatics (ie. direct to CNS - meningitis; spread bodywide in blood) ==> less common
- evade phagocytosis (due to capsule), replicate, spread from one alveolus to another
- cause activation of inflammatory response (virulent)

Basic property of pneumococcal disease: organisms get where they do not belong; clearance is damaged; they induce inflammation, disease results. Much of the disease is the inflammatory response

Front 25

T or F. Most common infectious diseases are caused by organisms that normally colonize humans.

Back 25

T. they make disease by getting where they don't belong in absence of protective immunity

Front 26

Pneumonia results from what 2 things of adherent bacteria?

Back 26

aspiration (back flow from mouth into trachea during sleep-- more important way esp in elderly) or inhalation

Front 27

What could cause apirated or inhaled material to not be expelled like normally - leading to bacteria being able to reach distal bronchioles or alveoli?

Back 27

1. Alcohol, codeine, morphine suppress cough
2. Smoking increases mucus production and causes inflammation, diminishing clearance
3. Inflammation, e.g. due to smoking or viral infection, or direct effect of viral infection damages ciliary clearance (viruses predisposes to pneumonia)

Front 28

Pneumoccocus activates inflammatory response. Name three ways it does this.

Back 28

1. alternative complement pathway - mostly by peptidoglycan and also pneumolysin (generating C5a)
2. classical pathway - form Ab's to cell wall
3. Taken up by dendritic cells and macrophages, activating TLRs

Front 29

What do these 5 things have in common: alcohol/opiates, smoking, viral respiratory infection, pollution and asthma.

Back 29

they all contribute to a decreased pulmonary clearance

Front 30

What do these 5 things have in common: diabetes mellitus, glucocorticosteroids, renal insufficiency, cirrhosis, alcohol ingestion.

Back 30

all lead to diminished neutrophil function
-poor migration of PMN to an infected area; and once they get there, they don’t ingest bacteria as well; once they ingest them, they don’t kill them so well (will make you much more susceptible to pneumonia and bacterial infections)

Front 31

List some ways to get defective IgG production (3)

Back 31

-congenital
-acquired: myeloma, lymphoma, CVID
- HIV infection (AIDS pts 50-100x more likely to get pneumococcal infection)

Front 32

What is the most common cause of adult pneumonia either outpatient or leading to hospitalization?

Back 32

pneumococcus

Front 33

Name 5 clinical manifestations of pneumococcal infection.

Back 33

1. often preceded by viral illness
2. sometimes sudden onset shaking cill and fever (this is actually uncommon)
3. cough, fever, sputum production, chest pain (some patients, esp elderly, may be asymptomatic)
4. patient "looks sick"
5. abnormal chest exam - dull percussion, wheezing, rales (BUT NOT ENOUGH TO DIAGNOSE)

Front 34

What is the only proper way to diagnose pneumonia?

Back 34

CHEST X-RAY!!!

Front 35

Name some lab findings consistent with pneumonia.

Back 35

- PMN count usually elevated with band forms present. 2/3 chance of dying if it is reduced below 6,000 (indicates overwhelming infection)
- chest x-ray: fluid accumulation in costo-phrenic angle)

Front 36

Name urine test to detect cell wall pneumococcal polysaccharide.

Back 36

Binax test - detects c-polysaccharide of pneumococcus (can't use this test on kids bc of high rate of false pos)

Front 37

Parapneumonic effusion vs. empyema

Back 37

Parapneumonic effusion - collection of fluid in pleural space that's uninfected and spontaneously resolves (in 30-40% of patients)

Empyema - collection of fluid in pleural space that's infected with bacteria; most common complication of pneumonia and requires surgery (in 5% of patients)

Front 38

What does pneumococcus do by proliferation in respiratory tract?

Back 38

otitis media (not seen much in adults), sinusitis, acute exacerbation of chronic bronchitis, pneumonia

Front 39

T or F. Antibiotic will need to be given to patients with acute bronchitis.

Back 39

F. Pneumococcus doesn't cause acute bronchitis - it is viral and therefore antibiotics don't do anything. Pneumoccocus only exacerbates chronic bronchitis (most commonly caused by cigarette smoking)

Front 40

Who is least likely to have pneumococcal disease? young adult with cough, fever chest pain; 3 year old child with fever, earache; 3 yr old with no symptoms but high fever and pos blood culture; school teacher with sudden onset severe sore throat fever

Back 40

school teacher with sudden onset of sore throat; acute onset of sore throat w/o any other symptoms is not streptococcal!!

Front 41

Name current vaccine for pneumococcus and how it works.

Back 41

Pneumovax. Capsular polysaccharide of 23 serotypes. Level of protection best in healthier, younger adults, worse in diseased and elderly who need it most. Antibody probably lost in 5-10 years
- Polysaccharides largely stimulate T cell independent immune reaction.

Front 42

What type of vaccine do kids under 2 need to get for pneumococcus?

Back 42

Prevnar. protein-conjugated vaccine, which alters mode of presentation, enhancing antigenicity, perhaps by invoking different sets of T helper cells