Exam #4: Bacterial Infections of the URT II Flashcards
What is conjunctivitis? What are the symptoms of conjunctivitis?
- 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
What are the causative agents of conjunctivitis?
- Haemophilus influenzae
- Streptococcus pneumoniae
*Moraxella lacunata, enterobacteria & Neisseria gonorrhoeae can also infect the conjunctiva, but do so to a lesser extent
What are the characteristics of Haemophilus Influenzae?
- Small & hard to see
- Gram (-)
- Rod
What other infections can haempphilus influenzae cause?
- Epiglotitis
- Otitis media
- Sinusitis
How is conjunctivitis treated?
- Prevention of spread by removal from school or daycare
- Hand washing, STOP rubbing eyes, don’t use common towels
- Gentacmicin or ciprofloxacin eye drops
List the characteristics of Streptococcus pneumoniae. What type of hemolysis does streptococcus pneumoniae have?
- 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.
What is otitis media?
Infection of the middle ear–tympanic membrane
What is otitis media commonly caused by?
- Streptococcus pneumoniae (GpC)
- Haemophilus influenzae (GnR)
- Moraxella catarrhalis (GnR)
What are the most common agents that cause sinustitis?
- Streptococcus pneumoniae (GpC)
- Haemophilus influenzae (GnR)
- Moraxella catarrhalis (GnR)
Same organisms as OM
What is the difference between beta & alpha hemolysis?
- Beta= complete lysis
- Alpha= incomplete that looks green on the blood agar plate
*Gamma= no lysis
Remember, a-hemolysis= strep. pneumoniae
In commercials for pneumonia vaccines, which bacteria are they targeting?
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%
In the immunocompromised, what do severe streptococcus pneumoniae infections lead to?
- Sinusitis
- OM
- Lobar pneumonia
- Meningitis
What are the two genera in the family chlamydiaceae?
- Clamydia= trachomatis
- Chlamydophila= psittaci & pneumoniae
What are the characteristics of Chlamydophila?
- V. small
- Obligate intracellular parasite
*Previously thought to be viruses
What is the difference between an elementary body & a reticulate body?
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
What can chlamydia trachomatis cause?
- Trachoma
- Adult inclusion conjunctivitis
- Neonatal conjunctivitis
- Infant pneumonia
- Urogenital infections
Describe the pathogenesis of Chlamydia Trachomatis.
- Direct destruction of host cells during replication (in the cell, grows, lyses the host cell)
- Host inflammatory response
How do chlamydia trachomatis gain access to the body
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
Does C. trachomatis lead to long-lasting immunity?
Not really; rather, infection induces vigorous inflammatory responses to subsequent infection, which can cause vision loss in chronic ocular infection
How serious is the disease?
Can be very serious & lead to blindness if left untreated.
What are the signs of adult inclusion conjuncitivitis?
- Same serovars as genital infections (STD)
- Occurs in sexually active adults
- Mucopurulent discharge
- Keratitis
- Corneal infiltrates
- Some vascularization
What is neonatal conjunctivitis?
Infants exposed to C. trachomatis at birth
- 5-12 days after birth the eyelids swell
- Untreated leads to conjunctival scarring & corneal vascularization
What are the symptoms of infant pneumonia?
Onset 2-3 weeks after birth, caused by C. Trachomatis
- Bronchitis
- Dry cough
- Afebrile
What can Chlamydophila pneumoniae cause?
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
