Micro: Upper Respirator Infections Flashcards by Andrew Gregson

List three normal flora of the URT

Diptheroids (not C.dip)
Alpha and Gamma Streps
Neisseria spp.

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What is the most common infection of the URT seen in ADULTS ?

Sinus infections (chronic sinutsitis)

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What is/are the most common URT infections seen in Children >

Pharyngitis

Acute Otitis Media

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What are the three leading risk factors for children with acute otitis media ?

Daycare
Sibling with otitis media
Parents who smoke

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What are signs of otitis media in children who cannot communicate verbally ?

Crying
Irritability
Anorexia 
Lethargy
TUGGING ON EAR

In older patients:
Vertigo
Fever
tinnitus

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What is the most common bacteria associated with Otitis Media ?

S. pneumo (50%)

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Describe S. pneumo’s profiler pertaining to lab diagnostics and staining

Gram + diplococci
Alpha Hemolytic 
Optochin Sensitive 
Bile Soluble
Encapsulated

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What is the major virulence factor associated with S.pneumo ?

Polysaccharide Capsule

Evasion of host immune system

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PPSV23

Polysaccharide vaccine for S.pneumo

Given to all adults 65 and older
certain risk in younger patients

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PCV7

PCV23

Conjugated (to protein) vaccine for S. pneumo

Given to patients 6 weeks - 71 months. old,
Not recommended for healthy patients
Given to 19 yo + who are IC.

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Haemophilus influenza (non-typeable) is the second leading cause of otitis media. Characterize it based on lab findings and diagnostics.

Gram - Coccobacillus
Grows on Chocolate agar with Factor V and X (NAD and Hemin)

Typicallly encapsulated

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Does the form of H. influenzae which caused otitis media have a capsule ?

NO ! Although the main virulence factor for H.influenzae is the capsule, the strain that causes otitis media does not ! (non-typeable)

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Descrbe the lab findings and diagnostics for Moraxella catarrhalis. ( another cause of Otitis media)

Gram - Diplococci

Betalactamase + ( Major virulence factor break down penicilins etc)

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Most external ear infections are caused by which organism ?

Pseudomonas aeruginosa

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What environmental conditions are associated with higher risk for Pseudomonas infection ?

Hot humid climates
Hot tubs (hot tub folliculitis)
Anywhere in which water is abundant.

Pierced ears can lead to necrotizing infections of the ear

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Describe the lab diagnostics of Pseudomonas aeruginosa

Gram - Rod
Non-fermenter
Grows on MacKonkey (blood and chocolate)
Oxidase +
Green/blue pigment with a grape like smell.

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Describe the epidemiology of Streptococcal Pharyngitis (compare to viral pharyngitis)

Winter/Early Spring
Ages 5-11
Abrupt onset
Fever
Sore throat
ABDOMINAL PAIN, NV

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Describe the epidemiology of Viral Pharyngitis

Year long
All Ages
Cold like symptoms (not such an abrupt onset)
Variable febrile state
Mild sore throat
MYALGIA and ARTHRALGIA

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Describe the lab diagnostics for S.pyogenes

G+ Cocci
Catalase +
Coagulase -
Beta hemolytic

Bacitracin Sensitive.
PYR + (As is enterococcus

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What is the main virulence factor for S.pyogenes in regards to Rheumatic Fever and nephritis ?

M- Protein

Cross reacts with heart, joint and neural tissue –> Rheumatic symptoms
Can form immune complexes leading to acute glomerulonephritis.

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Streptolysin O allows S.pyogenes to lyse what kind of cells ?

RBC’s thus making it beta-hemolytic

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Describe the physical findings of a Streptococcal pharyngitis

Pharyngeal erythema and exudate*
Tender enlarged anterior cervical nodes*
Palatal petechiae*
tonsillar hypertrophy
Scarlett fever
Absence of cough rhinitis hoarseness conjunctivitis and diarrhea

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T or F :Rheumatogenic strains of S.pyogenes can also infect the skin

F. Rheumatogenic strains are associated with ARF

pyodermal strains are more associated with Acute Glomerular Nephritis.

Rheumatic strains of S.pyogenes have tropism for which host antigens ?

Cardiac Myosin
Sarcolemma membrane protein
Synovium
Articular cartilage

Aucte post streptococcal glomerulonephritis occurs how many days after pharyngitis occurs ?

10 (With nephrogenic strains . Can be pyodermal or pharyngitis.

Describe the findings in Nephritis syndrome :

``` Hematuria (cola-colored) Proteinuria Edema (abdomen, feet, hands) Hypertension Fever NV. ```

Diagnosis of S. progenies pharyngitis can be easily achieved by ..

Rapid strep test (looks for ASO and Anti-DNase B etc) Streptozyme test is all inclusive. No need for culture

What virulence factors of S.pyogenes are responsible for Scarlett Fever ?

Pyrogenic Exotoxins (A,B,C and F --> Strawberry Tongue and Sandpaper rash

Lysogenized strains of S.pyogenes produce two forms or pyrogenic exotoxin that are also super antigens. What are these two ?

A and C

C.diptheria are gram + rods with club like swellings at the ends known to cause diphtheria. However not all C.dip are capable of causing this disease. What must be present for this to occur ?

Presence of the Tox gene. Carried by prophage that infects cells and passes the gene for diphtheria toxin.

C.dip also carry a toxin repressor, DTxR. What is required for this repressor to work ?

Iron Low iron, low repressor ability.

What cells does the diphtheria toxin target and how does it achieve its cytoxic activity ?

Myocytes | It is an AB toxin, the A portion target EF-2 and halts protein transcription.

Describe the signs and symptoms of C.diptheria infection

Sort throat Low grade fever, malaise Pseudomembrane ( white to begin, then grey with patches of green and black necrosis that bleeds upon touching) Cervical Adenopathy (bull neck)

What should you ask when you suspect a patient may have diphtheria ?

Immunized ? | History of travel (or from another country)

What type of media will C.dip grow on >

Loefflers agar or Tellurite Selective Media

Treatment for C.dip includes

Anti-toxin immediately followed by Penicillin or erythromycin. Re-vacinnation !

The vaccine for C.dip produces Ab's for what product of the bacteria ?

``` The toxin ! DTaP--> Children get 5 doses. Tdap--> adolescents. DT--> No pertussis Td --> 10 year booster adolescents and adults ```

Epiglottitis

Acute severe cellulitis of the epiglottis. A TRUE EMERGENCY ! Abrupt onset Acute inflammation Edema and infiltration of PMN's

Causitive agents of Epiglottitis

H.influenzae B S. aureus S. pneumoniae S.pyogenes

Describe the Lab Diagnostics associated with H.influenzae (asked previously just not in as much detail) which causes epiglottitis

Gram - Coccobacilli Grows on Chocolate Agar (Factor V and X) ``` Polysaccharide Capsule ( vaccine if for Type B capsule but now Type C and F are common) Most important virulence factor Others include IgA protease and endotoxin. ```

Which population is most often associated with H. influenza epiglottitis >

Boys age 2-3

Describe H.influenzae epiglottitis

High fever, sitting forward and drooling "Catchers Stance" Cherry Red Epiglottis Tachypnea Stridor and rhonchi on auscultation

What is the main differential difference between epiglottitis due to influenza and parainfluenza ( or pertussis)

Barking cough is usually not present in patients with H. influenzae epiglottitis

PRP-HbOC

Conjugated HiB with nontoxic diphtheria toxin

PRP- OMP

conjugated with outer membrane protein of neisserria meningitidis

PRP-T

conjugated with tetanus toxoid

PRP-D

conjugated with diphtheria toxoid.

What is the causative agent of Whooping Cough ?

Bortadella pertussis (G -, coccobacillus

The B. pertussis virulence factors filamentous hemaglutinin and pert actin allows for binding to which kind of cells ?

Cilliated cells in trachea.

Pertussis toxin causes what to occur within the cell ?

ADP ribosylation of Gi ( inactivates Gi which is usually the break to most Gprotein activities --> increased cAMP production.)

Haemophilus aegyticus (aka Koch-Weeks bacillus) causes what ?

Conjunctivitis

The B.pertussis virulence factor 'adenylate cyclase toxin' causes and increase in which process ?

conversion of ATP -->cAMP

Who is most at risk for contracting pertussis ?

Those who are not immunized (90% of patients) | Infants 3-6 months old.

What is the media that B.pertussis will best grow on ?

Regan Lowe Charcoal Medium | (naspharyngeal aspirate is better than others for this)

What is the DOC for B.pertussis ?

Erythromycin for 14 days.

T or F :Bortadella parapertusis produces pertussis toxin

Bortadella bronchoseptica is also known as ...

``` kennel cough (in dogs) Snuffles (in rabbits ) ``` Rarely affects humans