Lecture 13 Flashcards
What are the general characteristics of Chlamydiae species?
Gram– cocci | obligate intracellular pathogens (only survive and multiply inside the host) | invasive, nonmotile, smallest bacteria discussed, small genomes, auxotrophic for many amino acids and 3 of 4 nucleotide-triphosphates (cannot produce them)
What is a unique characteristic of Chlamydiae species?
2 cellular forms in developmental cycle = 2 different sizes (one is small and one is larger)
What is the reservoir for Chlamydiae species?
humans and animals (includes birds)
What does it mean when scientists say that Chlamydiae species lack peptidoglycan cell walls?
cell walls are not detected but their genomes contain genes to synthesize peptidoglycan cell walls; don’t know if those genes are being expressed or why we cannot detect the murein
How does the auxotrophic characteristic of Chlamydiae help explain their small genome size?
Chlamydiae species need what they can’t synthesize from the host = have a small genome because they are only limited to what they can synthesize
What is the #1 leading bacteria STI in the US?
chlamydia
How many new cases/year of chlamydia occurs in the US?
2.9million (estimated for the asymptomatic)
What is a nickname of Chlamydiae species and why?
“stealth pathogens” because they hide from the host immune system
Which Chlamydiae species is the best studied?
C. trachomatis
What type of tissues does C. trachomatis typically like to infect?
mucosal areas
What are the 2 genuses of Chlamydiae? What is the difference?
Chlamydia and Chlamydophila; no distinguishing differences, practically the same thing
What are the 4 agents of human chlamydial infections (includes chlamydia)
Chlamydia trachomatis: biovar trachoma serovars A-C, biovar trachoma serovars D-K, and biovar lymphogranuloma venereum and Chlamydia pneumoniae
Which Chlamydia agent causes trachoma?
C. trachomatis biovar trachoma serovar A-C
Which Chlamydia agent causes STI chlamydia?
C. trachomatis biovar trachoma serovar D-K
What does Chlamydia trachomatis biovar lymphogranuloma venereum cause?
invasive STIs = infections that go beyond initial infection, affects other organ systems ; very rare and more serious
Which Chlamydia agent causes pneumonia?
C. pneumoniae
Which agent of animal chlamydial infections causes psittacosis in humans? What animal does it usually infect?
C. psittaci, usually causes respiratory and GI illness in birds
Does Chlamydia cause an old or new world disease?
depends: C. trachomatis causing eye infection is an old world disease but C. trachomatis causing the STI chlamydia is a new world disease
When was STI chlamydia first reported?
1970s
How can a pathogen that causes an eye infection, now cause a sexually transmitted infection?
indirect contact between C. trachomatis infected eye and uninfected genitals
What are 3 facts that STI chlamydia is big and common?
MOST common bacterial STI in US, most commonly reported/notifiable disease in US, C. trachomatis = largest proportion of all STDs reported to CDC
In STI chlamydia, what does C. trachomatis mainly infect? (4)
mucosal epithelial membranes of: cervix, urethra, conjunctiva, throat
Which mucosal epithelial cells does C. trachomatis not infect? Why do you think that is?
vaginal cells may lack the receptor for the bacteria to invade in these cells
What is the 3 modes of transmission of C. trachomatis biovar trachoma serovar D-K?
infected secretions through sexual contact (hetero and gay males, or use of sex toy covered with the secretions) | during birth = mom transfer bacterium to newborn’s eyes = possibility of it developing pneumonia | contact of infected genital secretions to hands to eyes = trachoma
What is trachoma?
a chronic conjunctivitis caused by C. trachomatis serovars A-C
How common is trachoma in the US?
rare
In which regions in the world is trachoma often common?
Sub-Sahara Africa, Middle-East, Asia
What is the leading cause of preventable blindness, globally?
trachoma
After how many years does vision loss usually occur after initial infection?
15-20 years
What are the symptoms of trachoma?
eye discharge, swollen lids, trichiasis (turned-in lashes), bright-light sensitivity, increased HR (heart rate), other complications
What are the antibiotics used to treat trachoma?
azithromycin (Azi) and tetracycline (Tetra) = AziTetra
What are the 2 cellular forms of Chlamydia trachomatis?
elementary bodies (EBs) and reticulate bodies (RBs)
What are the characteristics of elementary bodies?
small (0.25µm) | infectious and invasive | extracellular | metabolically inactive
What are the characteristics of reticulate bodies?
larger (0.6-0.8µm) | intracellular | metabolically active, divides inside host cell
What other “life-cycle” is similar to that of C. trachomatis?
viruses – 2 forms
What is the sequence of events of the C. trachomatis life cycle?
EB interact with host cell, invade and enter it via membrane-bound vesicles »_space; once inside = convert to RB form inside their vesicle »_space; RB multiply »_space; convert back to EB-form in order to be released »_space; after conversion = release = infect other cells
When would C. trachomatis ever deviate from its life cycle?
when conditions are not optimal for bacteria to multiply = prevent them from following regular life cycle and stay inside their vesicles where they grow a little more, once conditions are normal = return back to normal size and resume cycle
What conditions would be un-optimal for C. trachomatis to multiply/divide inside the host cell?
temperature, presence of antibiotics, immunoresponse molecules and cells present, interferon-gamma, nutrient limitation
What happens to the host cell when the new generation of EBs are released?
host cell dies
Which secretion system do C. trachomatis utilize?
Type III secretion system
What are the 5 virulence factors of C. trachomatis?
Type-III secretion system, Tarp, CPAF, MOMP, autotransporter proteins
What does “Tarp” stand for and what is it’s role as a virulence factor for C. trachomatis?
translocated actin recruiting protein that interacts with the host cell to recruit actin
What do the C. trachomatis virulence factors CPAF and MOMP stand for?
CPAF = Chlamydia protease-like activity factor | MOMP = major Outer Membrane Protein (probably functions as an adhesin)
How long does it take for STI chlamydia symptoms to appear after infection?
1-3 weeks
What percentage of women are asymptomatic to STI chlamydia?
75%
What percentage of men are asymptomatic to STI chlamydia?
50%
What are the STI chlamydia symptoms seen in women?
pelvic pain and bleeding between periods or after sex
What are the STI chlamydia symptoms seen in men?
redness at penile tip
What are the STI chlamydia symptoms seen in BOTH genders?
discharge, dysuria,
What are the conditions/complications that can develop in women infected with STI chlamydia?
PID, cervicitis, salpingitis, endometritis
What are the conditions/complications that can develop in men infected with STI chlamydia?
Reiter’s syndrome, epididymitis and prostatitis
What are the conditions/complications that can develop in BOTH genders infected with STI chlamydia?
urethritis, proctitis (rectum/anus)
What is the Fitz-Hugh Curtis Syndrome?
(perihepatitis) scar tissue formation around liver from PID and chlamydia infection
What is Bartholinitis?
Bartholin’s glands infected/inflammed
Which women are at risk for contracting STI chlamydia?
unsafe sex, multiple partners who have multiple partners, high risk age group = 15-24yo
Which men are at risk for contracting STI chlamydia?
unsafe sex and partners with cervicitis and PID
What is Salpingitis?
inflammation of fallopian tubes
What are the Bartholin’s glands?
racemous glands posterior of vagina, secretes mucus and lubricates vagina
In what locations of the body would a swab specimen be obtained from? (both genders)
men = urethra; women = cervix
What are the differences in diagnostics between the different sites of infection?
genitals = can do PCR | throat/anal = use of cell-tissue culture methods as Chlamydiae can only survive intracellularly in mucosal epithelial cells
What treatment is available against STI chlamydia?
most antibiotics work as so far no significant antibiotic-resistant strains have surfaced | most antibiotics need to be taken for 7 days
Are there vaccines available for STI chlamydia?
no vaccines are commercially used
What are the prevention methods used against C. trachomatis serovar D-K?
safe sex and condoms
What is one mode of prevention that people believe provides protection against C. trachomatis serovar D-K infection? Is this true?
Nonoxynol-9 = spermicide = does NOT prevent infection
What is Chlamydophylia psittaci?
pathogen causes human psittacosis
What is human psittacosis?
(ornithosis) = zoonotic pneumonia
How many cases/year does psittacosis occur in the US?
100-200
What is a method used to diagnose for the presence of C. psittaci in humans?
blood-based assay (checks for antibody titer) or send specimen to specialized lab for culture
What treatment is available against psittacosis?
most antibiotics work
