Exam 2 Lecture 17 Flashcards
True or False: Chlamydia and Rickettsia are genetically similar
False.
The genomes most similar to rickettsia are those encoded by ______.
Mitochondria
Rickettsia are members of the ____-_________. They are able to produce their own ______.
alpha-proteobacteria
ATP
Both chlamydia and rickettsia are ______ _______ bacteria, meaning they need a _______ ____ cell and thus cannot be grown on a plate or liquid culture.
obligate intracellular
eukaryotic host
How many genera and species in the Chlamydiaceae family are pathogenic?
2 genera, 3 species
Name 3 bacteria under the Chlamydiaceae family
- Chlamydia trachomatis
- Chlamydophila pneumoniae
- Chlamydophila psittaci
What infections does Chlamydia trachomatis cause?
Ocular infections, urogenital infections
What infections does Chlamydophila pneumoniae cause?
Respiratory tract infections
What infections does Chlamydophila psittaci cause?
Respiratory tract and systemic infections
What does EB stand for? What does RB stand for?
Elementary body
Reticulate body
Name characteristics of the elementary body (5)
- infectious
- extracellular spore-like form
- metabolically inert
- non-replicating
- stabilized by disulfide crosslinking of outer membrane proteins
Name characteristics of the RB (4)
- non-infectious form
- intracellular replicating form (divide inside inclusion)
- osmotically unstable, can’t survive extracellularly
Describe the life cycle of Chlamydia
- EB binds to a host epithelial cell
- EB induces its own uptake into the cell and resides inside a membrane bound vacuole (inclusion)
- About 8 hours after, the EB differentiates into the RB form
- About 8-18 hours after, RB modifies the inclusion and brings nutrients inside the inclusion so it can replicate
- About 18-24 hours later, the inclusion has grown a lot larger and there’s a mix of Eb and Rb (b/c a signal led to differentiation of Rb back into Eb)
- The cell lyses or forms an extrusion after 48-72 hours. (Rbs do not survive, but Ebs go on to infect new host cells)
Describe the genome size of chlamydia
Small (936 genes)
Why does chlamydia have a small genome?
It has evolved to get a ton of nutrients (amino acids, lipids, nucleotides) from the host cells, so it does not require many biosynthetic pathways
Since chlamydia relies so heavily on the host for nutrients (Amino acids, nucleotides, lipids, etc), most of its genes focus on ……….
interacting and attaching to host cells
What do both EBs and RBs express?
type III secretion systems (T3SS)
More than 5% of the entire genome of Chlamydia encodes for ……..
type 3 secreted effectors
Because Chlamydia infects epithelial cells, it needs to induce its own uptake. When the EBs bind to a host cell using ____, it will inject a protein known as _____
T3SS
Tarp
Tarp is pre-formed by ___, and induces _____ _________ as well as ________ of the ___
RB
actin polymerization
phagocytosis
EB
What do RBs secrete?
- Inc proteins
- CPAF proteases
- Anti-apoptotic factors
Name the function of Inc proteins
- modify the inclusion by the following:
1. chlamydia inserts a SNARE like protein in the inclusion (normally the lysosome interacts w/ the phagosome thru their SNARE proteins). thus, this disables fusion w/ the lysosome
2. the inclusion needs to grow, so it adds membrane by fusing with Golgi vesicles
Name the function of CPAF protease
It degrades TARP. This makes sense because TARP is used to help EBs become phagocytosed. If TARP stays present on host cells, superinfection can occur.
Name the function of Anti-apoptotic factors
Keeps the host cell alive while RBs are maturing into EBs
C. trachomatis infects mucosal epithelial cells, but what areas of the body specifically?
- conjunctiva
- respiratory
- GI tract
- urogenital tracts
True or False: When Chlamydia is taken up by macrophages, most serovars cannot replicate or survive.
True
Infection of C. trachomatis is mostly controlled by the _____-__, which is produced by _ cells.
interferon-gamma
T cells
True or False: Secretory antibodies (IgA) are produced and are associated with disease resolution
False
Unfortunately, the immune response set out by T cells leads to a low level chronic inflammatory response. What does this commonly lead to?
Scar tissue formation
also necrosis, epithelial cell proliferation
True or False: Serovars are based on polymorphic outer membrane proteins
True
What serovars are associated w/ Trachoma (eye infection)?
A, B, Ba, C
What serovars are associated w/ LGV?
L1, L2, L3
Serovars D-K are associated with …..? (3)
- Urethritis/cervicitis
- Perinatal infections
- Inclusion Conjunctivitis
Why are serovars A-K localized while LGV serovars are systemic?
It has to do with differential release of infectious EBs from epithelial cells
In serovars A-K, bacteria (EBs) are released to the ______ side of the epithelial cells
apical
In LGV serovars, bacteria (EBs) are released to ______ side of epithelial cells
basolateral
True or False: LGV serovars of Chlamydia can survive and replicate in macrophages
True :’(
True or False: Chlamydia is the most common STI in the world
True
What is the age group most severely affected by Chlamydia?
ages 15-24
In men, what is urethritis is characterized by:
-dysuria with discharge (less discharge than gonorrhea)
What is a common complication of urethritis?
Epididymitis
Similar to men, women also gets _____
Dysuria
True or False: With chlamydia trachomatis, there is an absence of white blood cells in the urine
True
Women can get cervicitis from C. trachomatis, where most women are _____
asymptomatic (this often leads to more scar tissue formation)
C. trrachomatis can also lead to PID, including:
- endometriosis
- salpingitis
- peritonitis
Persistant/repeated infections of C. trachomatis can lead to ???
- Ectopic pregnancies
- Tubal infertility
- Chronic pelvic pain syndrome
Symptoms of PID are usually asymptomatic, but about ____-____% of women have symptomatic PID
10-15%
Neonatal infections commonly lead to … but can also lead ….
inclusion conjunctivitis (30% of infants from infected mothers w/ genital serovars) -or pneumonia (15% of infants from infected moms)
Chlamydia can be diagnosed via two techniques. What are they?
- Nucleic acid amplification techniques (NAAT)
2. Screening
How is LGV acquired?
Sexual contact
LGV is capable of regional and ______ dissemination
systemic
What are the 3 stages of LGV?
- Primary stage: small ulcer on genital mucosa
- Inguinal lymphadenopathy, fever, headache..can lead to scarring
- Procto-colitis (inflammation of the rectum/colon), swelling of genitals
Ocular serovars (A-C) can lead to chronic follicular conjunctivitis, which can eventually lead to _____ and that results in loss of vision
trichiasis
Highest prevalence of C. trachomatis is in _________ ____ and _______ ____
Sub-saharan Africa
Southeast Asia
True or False: Chlamydophila pneumoniae can spread from respiratory droplets
True
T or F: C. pneumoniae is distinguishable from other cases of pneumonia
False
C. pneumoniae infects and multiplies in a variety of cells, including _____
Macrophages
Interestingly, C. pneumoniae is associated with _________
atherosclerosis
Why can C. pneumoniae exacerbate inflammation in plaque?
Because macrophages w/ C. pneuomoniae go to sites of infection like atherosclerotic plaques on blood vessels. Since the macrophages are infected, they increase inflammation in the plaques, thus worsening them
C. psittaci is usually acquired from ____ via inhalation
birds
C. psittaci has a ___% mortality rate when untreated
20%
The antibiotic ______ is used for treating all types of Chlamydia
Doxycycline
For neonates, doxycycline is too strong, so it is recommended to give drops of _______ in the eyes
erythromycin
Rickettsia is a ____-______ bacteria that is also an obligate intracellular bacteria
gram negative
How is rickettsia transmitted?
Arthropods
What are typical symptoms of Rickettsia?
Fever, rash, headache
T or F: Rickettsia Rickettsi is transmitted by ticks, and it usually infects dogs and mice, but it can accidentally infect humans
True
Rickettsia rickettsi is able to enter the circulation via the bite, and attach to ____ epithelial cells
vascular
Unlike chlamydia, rickettsia is capable of independent ______ despite having a ????
metabolism
small genome
Rickettsia rickettsi can spread from cell-to-cell using ____-based motility, which leads to host cell injury and _____ blood flow due to formation of “holes” in blood vessels
actin
increased
Rickettsia rickettsi has a characteristic ________ ____
maculopapular rash
If untreated, rickettsia rickettsi has a ____ mortality rate, b/c it can affect organ systems
30%
How can rickettsia rickettsi be prevented/treated?
removal of ticks
doxycycline (even in children)
R. prowazekii and R. felis are transmitted by human ____ ____
body lice
For R. felis, ____ fleas are the most common vector in the US but dogs are probably the primary reservoir
Cats
T or F: Ehrlichiosis is caused by either anaplasma phagocytophilum or ehrlichia chaffeensis
True
Anaplasma infects ____, while ehrlicia infects ____
neutrophils
monocytes
Therapy for ehrlichiosis includes ______
doxycycline
Similar to chlamydia, Ehrlichia species grow within an _____ and are able to replicate in there. IT can also inhibit ______ fusion
inclusion
lysosomal
