WEEK 16: OBLIGATE INTRACELLULAR ORGANISMS Flashcards
Noninfectious
Reticulate body (RB)
- Infectious
- Major outer membrane protein (MOMP)
- Detected by monoclonal antibodies
Elementary body (EB)
- Urethritis with purulent discharge
- Cervicitis, salpingitis (inflammation of fallopian tubes)
- Eye infections: conjunctivitis and scarring of the eye (mechanical deforming of eyelashes)
- Neonatal: eye infections and pneumonia
trachoma biovar
Three biovars
Trachoma, lymphogranuloma venereum, mouse pneumonitis
Obligate intracellular pathogenic bacteria
Chlamydia trachomatis
- C. trachomatis serovars L1, L2, L2a, L2b, and L3
- LGV
- Also linked to Parinaud oculogladular conjunctivitis
- Survive in mononuclear cells
- Bubo formation then can rupture lymph node
- Uncommon in the United States
- Tropics and subtropical areas abroad
Lymphogranuloma Venereum (LGV)
Urethritis, conjunctivitis, polyarthritis, and mucocutaneous lesions
Reiter syndrome
Incubation period of Chlamydia trachomatis in neonates.
4-5 days
- Formerly Chlamydia sp., strain TWAR
- 10% of world’s pneumonia
- Diseases
- Acute respiratory disease
- Pneumonia
- Pharyngitis and otitis media
- Risk factor for Guillain-Barré syndrome (GBS)
- Also possible relationships
- Sarcoidosis, asthma, and cardiovascular disease
Chlamydophila pneumoniae
Third most common cause of infectious respiratory disease
C. pneumoniae
- Bird chlamydia
- Parakeets, turkey, other psittacine birds
- Parrot fever or psittacosis
- Causes pneumonia in humans
- Usually mild chronic pneumonia
- Can culture
- Not recommended
- Serology
- Current method of choice
Chlamydophila psittaci
- Obligate intracellular bacteria
- Gram-negative bacilli (0.8-2.0 μm by 0.3-0.5 μm)
- Grow in cell lines
- Most are arthropod-borne
- Transmission
- Transovarial transmission in ticks
- Infection through feeding
*Exception
* R. prowazekii
* Humans are reservoir
* Transmitted by body lice
Rickettsiae
Reservoirs include ticks and dogs
Mediterranean spotted fever
- Rash involves the palms and soles of the feet and the body and face
- Taches noires
- Black spots at primary site of infection
Boutonneuse Fever
Primarily in Africa and Central and South America
* Also known as Brill-Zinsser disease
* R. prowazekii
Epidemic louse-borne typhus
Also known as murine typhus
* R. typhi
Endemic typhus
- Vector
- Oriental rat flea: Xenopsylla cheopis
- Cat flea: Ctenocephalides felis
- Reservoir
- Rat and transovarian transmission
- Infection
- Occurs when flea defecates on skin
- Scratching infects the bite.
- Symptoms
- Fever, headache, and rash
Murine Typhus
Human louse
Pediculus humanus
Orchopeas howardii
Squirrel flea
Neohaematopinus sciuriopteri
Squirrel louse
- Reservoir is the common house mouse
- Vector is the mouse mite Liponyssoides sanguineus
- Clinical manifestations
- Papule forms at bite and progresses to a pustule
- Pustule becomes an indurated eschar
- Other symptoms
- Headache, nausea, and chills
- Rash on face, trunk, and extremities but not palms or soles
R. akari
Rickettsialapox
- Causative agent is Orientia tsutsugamushi
- Vector
- Chigger: Leptotrombidium deliensis
- Transovarial transmission between chiggers
- Reservoir
- Rat
- Symptoms
- Tache noire at the site of inoculation
- Fever, headache, and rash that does not involve the palms, the soles of the
feet, or the face
Scrub Typhus
Dogs infected with brown dog ticks died.
* Rickettsial-like inclusions in the monocytes
Ehrlichia
- Many are asymptomatic.
- Fever, headache, malaise, and myalgia but may have nausea, vomiting,
diarrhea, cough, joint pains, confusion, and occasionally rash
Human ehrlichiosis
Trachoma, lymphogranuloma venereum, mouse pneumonitis
Three biovars
- Urethritis with purulent discharge
- Cervicitis, salpingitis (inflammation of fallopian tubes)
- Eye infections: conjunctivitis and scarring of the eye (mechanical
deforming of eyelashes) - Neonatal: eye infections and pneumonia
Symptoms of trachoma biovar
- Human monocytic ehrlichiosis (HME)
- E. ewingii produces indistinguishable disease
- Natural hosts:
- Dogs, deer, and humans
- Primary vector:
- Lone star tick: A. americanum
Ehrlichia chaffeensis
*Anaplasma phagocytophilum
- Incubation period 5 to 11 days with similar symptoms to HME
- Endemic to upper Midwest and Northeast United States
- Rarely have a rash
- Morulae in granulocytes
Reservoirs:
* Deer, rodents, horses, cattle, and humans
Vectors:
* Ixodes scapularis
* Ixodes pacificus
Human Granulocytic Anaplasmosis
- Causative agent of Q fever (Query fever)
- Potential bioterror agent
Coxiella burnetii
Reservoirs:
* Cattle, sheep, goats, dogs, cats, deer, fowl, and humans
* Exposure in vet or animal handlers
* Inhalation of dried birthing fluids or ingestion of unpasteurized milk
Symptoms:
* Only half of infections are symptomatic.
* Acute influenza-like illness
* Prolonged fever, headaches, cough, myalgia, and arthralgia
Coxiella
Laboratory diagnosis:
- DFA of infected tissue
- Nucleic acid amplification testing
- Highly contagious, so culture only in biosafety level 3 (BSL3)
- EIA kits
Coxiella
