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Microbiology > Exam #4: Bacterial Infections of the URT II > Flashcards

Exam #4: Bacterial Infections of the URT II Flashcards

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Biology 101 flashcards
1
Q

What is conjunctivitis? What are the symptoms of conjunctivitis?

A
  • Pinkeye, or infection of the eye surface/ conjunctiva
  • Increased tears
  • Conjunctival redness
  • Photophobia
  • Eyelid swelling*
  • Significant pus secretion*

These symptoms typically differentiate bacterial conjunctivitis from viral conjunctivitis

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2
Q

What are the causative agents of conjunctivitis?

A
  • Haemophilus influenzae
  • Streptococcus pneumoniae

*Moraxella lacunata, enterobacteria & Neisseria gonorrhoeae can also infect the conjunctiva, but do so to a lesser extent

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3
Q

What are the characteristics of Haemophilus Influenzae?

A
  • Small & hard to see
  • Gram (-)
  • Rod
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4
Q

What other infections can haempphilus influenzae cause?

A
  • Epiglotitis
  • Otitis media
  • Sinusitis
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5
Q

How is conjunctivitis treated?

A
  • Prevention of spread by removal from school or daycare
  • Hand washing, STOP rubbing eyes, don’t use common towels
  • Gentacmicin or ciprofloxacin eye drops
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6
Q

List the characteristics of Streptococcus pneumoniae. What type of hemolysis does streptococcus pneumoniae have?

A
  • Gram +
  • Encapsulated
  • Diplococcus known as a pneumococcus
  • Alpha hemolysis

Remember that Strep. pnemoniae is one of the major groups to have alpha-hemoylsis- green on blood agar.

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7
Q

What is otitis media?

A

Infection of the middle ear–tympanic membrane

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8
Q

What is otitis media commonly caused by?

A
  • Streptococcus pneumoniae (GpC)
  • Haemophilus influenzae (GnR)
  • Moraxella catarrhalis (GnR)
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9
Q

What are the most common agents that cause sinustitis?

A
  • Streptococcus pneumoniae (GpC)
  • Haemophilus influenzae (GnR)
  • Moraxella catarrhalis (GnR)

Same organisms as OM

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10
Q

What is the difference between beta & alpha hemolysis?

A
  • Beta= complete lysis
  • Alpha= incomplete that looks green on the blood agar plate

*Gamma= no lysis
Remember, a-hemolysis= strep. pneumoniae

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11
Q

In commercials for pneumonia vaccines, which bacteria are they targeting?

A

Streptococcus pneumoniae

*Note that this vaccine has decreased not only the annual cases of OM by almost 1 million, it has also decreased the need for pediatric intubation by 20%

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12
Q

In the immunocompromised, what do severe streptococcus pneumoniae infections lead to?

A
  • Sinusitis
  • OM
  • Lobar pneumonia
  • Meningitis
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13
Q

What are the two genera in the family chlamydiaceae?

A
  • Clamydia= trachomatis

- Chlamydophila= psittaci & pneumoniae

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14
Q

What are the characteristics of Chlamydophila?

A
  • V. small
  • Obligate intracellular parasite

*Previously thought to be viruses

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15
Q

What is the difference between an elementary body & a reticulate body?

A

Chlamydia has a unique developmental cycle; they can take on two different forms:

1) Elementary body= metabolically inactive but infectious
2) Reticulate body= metabolically active but non-infectious

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16
Q

What can chlamydia trachomatis cause?

A
  • Trachoma
  • Adult inclusion conjunctivitis
  • Neonatal conjunctivitis
  • Infant pneumonia
  • Urogenital infections
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17
Q

Describe the pathogenesis of Chlamydia Trachomatis.

A
  • Direct destruction of host cells during replication (in the cell, grows, lyses the host cell)
  • Host inflammatory response
18
Q

How do chlamydia trachomatis gain access to the body

A

1) Infectious EB attaches to the susceptible host & is phagocytosed
2) Inhibition of phagolysosome fusion
3) Hours later EB’s reorganize into larger metabolically active RB’s
4) Synthesis of DNA occurs utilizing host energy

19
Q

Does C. trachomatis lead to long-lasting immunity?

A

Not really; rather, infection induces vigorous inflammatory responses to subsequent infection, which can cause vision loss in chronic ocular infection

20
Q

How serious is the disease?

A

Can be very serious & lead to blindness if left untreated.

21
Q

What are the signs of adult inclusion conjuncitivitis?

A
  • Same serovars as genital infections (STD)
  • Occurs in sexually active adults
  • Mucopurulent discharge
  • Keratitis
  • Corneal infiltrates
  • Some vascularization
22
Q

What is neonatal conjunctivitis?

A

Infants exposed to C. trachomatis at birth

  • 5-12 days after birth the eyelids swell
  • Untreated leads to conjunctival scarring & corneal vascularization
23
Q

What are the symptoms of infant pneumonia?

A

Onset 2-3 weeks after birth, caused by C. Trachomatis

  • Bronchitis
  • Dry cough
  • Afebrile
24
Q

What can Chlamydophila pneumoniae cause?

A

This is also known as the TWAR pathogen (Taiwan acute respiratory agent)

  • Pneumonia- most severe infections involve only one lobe
  • Bronchitis
  • Sinusitis

most common in adults & most

25
Q

What pathogens is Chlamydophilia pneumoniae difficult to differentiate between?

A

Mycoplasma pneumoniae
Legionella pneumophila
Respiratory viruses

Thus, treat BOTH Mycoplasma pneumoniae

26
Q

How do you differentiate chlamydia?

A

PCR- nucleic acid amplification

Complement fixation test

27
Q

What is Chlamydophila psittaci associated with?

A

Psittacine birds- parrots, parakeets…etc.

28
Q

Describe the pathogenicity of Chlamydophilia psittaci.

A
  • Infection by respiratory tract
  • Bacteria spread to reticuloendothelial cells
  • Seeded due to hematogenous spread
  • Lymphocytic inflammatory response on the alveolar & interstitial spaces
29
Q

Describe the infectious process in OM.

A

1) OM begins with infection of the nasal chamber & nasopharynx
2) Infection spreads upwards trough the eustachian tube to the middle ear
3) Infection damages ciliated cells, resulting in inflammation & swelling
4) Damaged Eustachian tube cannot move secretions–>pressure from pus & fluid build-up

30
Q

How is OM caused by streptococcus pneumoniae or H. influenzae treated?

A

Ampicillin

31
Q

List the characteristics of Haemophilus influenzae.

A
  • Small
  • Pleomorphic
  • Gram (-)
  • Rods or coccobacilli
32
Q

What is Diptheria? What are the symptoms?

A

Diptheria is a deadly toxin mediated disease. Symptoms include:

  • Mild sore throat
  • Slight fever
  • High fatigue
  • Malaise
  • Dramatic neck swelling (cervical lymphadenopathy)
  • Whitish/ gray mucous membranes
33
Q

How is Diptheria controlled?

A

Toxoid vaccine i.e. a vaccine against the toxin that diptheria produces

34
Q

What organism causes Diptheria?

A

Corynebacterium

35
Q

List the characteristics of Corynebacterium.

A
  • Gram (+) rod that looks like Chinese letters
  • Variable shape
  • Non-motile
  • Non-spore forming
36
Q

What is the major virulence factor of Diptheria?

A

Diptheria exotoxin

*Note that diptheria did not originally have this, it was lysogenized by a bacteriophage

37
Q

Describe the pathogenesis of Diptheria.

A
  • Not an invasive pathogen
  • Stays on the surface & releases toxin that diffuses and absorbs into the bloodstream
  • Causes a classic gray-white membrane of clotted blood, epithelial cells of the mucous membrane, & leukocyte infiltrate
38
Q

What is the Diptheria toxin? What is its mechanism of action?

A

AB subunit

  • A= inactivation of elongation factor-2 (EF-2) to stop protein synthesis & induce cell death (enzyme)
  • B= binding
39
Q

Where is severe damage seen in individuals that survive Diptheria?

A
  • Heart
  • Kidneys
  • Nerve cells
40
Q

Describe the progression of conjunctivitis caused by C. Trachomatis.

A

1) Follicular conjunctivitis i.e. diffuse inflammation of the conjunctiva
2) Conjunctiva scarring–eyelids turn inward
3) Turned in eyelids abrade the cornea

–>Blindness

41
Q

How do you treat all Chlamydia infections?

A

Macrolides

  • Erythromycin
  • Azithromycin

Tetracycline
Levofloxacin

Microbiology (49 decks)

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