LECTURE - Mycoplasmas, Chlamydia, and Treponema Flashcards
Mycoplasma characteristics
gram neg but no peptidoglycan; very small genomes; pliable shape makes them look like junk; pleomorphic
- require lipids and enriched medium to grow
- live in close association with host cells but on outside (not intracellularly)
- colonies = fried egg appearance
- single cell membrane = cholesterol (From medium or host; don’t synthesise it)
- smallest free-living microorganisms
walking pneumoniae
Mycoplasma pneumonia
- sick but not sick enough to be hospitalaized
- young adults
- X-ray = moth-eaten appearance ; typical pneumonia = compact areas of density with clear edges
cells of Mycoplasma pneumoniae hve:
- unique shape
- show gliding motility
- special attachment organelle
- P1 = main protein involved in adherence
- one end is cytoadherence organelle and the other is gliding end
cell membrane of M. pneumoniae
- asymmetrical
- lipoprotein in outer leaflet cause inflammation like LPS; can possess antigenic differences among different strains
M. pneumoniae pathogenesis
- organisms inhaled
- bind to base of ciliated cells in lung through its cytadherence organelle
- depolarize cells and cause ciliastasis
- lipoprotein of outer leaflet membrane triggers inflammation
- peroxide and other reactive O2 species => ciliated cell death and phospholipase may damage host cells
- big virulence = community-acquired resp disease syndrome (CARDS) toxin
- B cells ad T cells simulated non-specifically = Abs bind to RBCs in cold = cold agglutinins formed
M. pneumoniae pathogenesis
- organisms inhaled
- bind to base of ciliated cells in lung through its cytadherence organelle
- depolarize cells and cause ciliastasis
- lipoprotein of outer leaflet membrane triggers inflammation
- peroxide and other reactive O2 species => ciliated cell death and phospholipase may damage host cells
- big virulence = community-acquired resp disease syndrome (CARDS) toxin
- B cells ad T cells simulated non-specifically = Abs bind to RBCs in cold = cold agglutinins formed
diagnosis of M. pneumoniae
- slow-growing = takes 3-6 wks for positive results
- paired sera in using a commercial serology test can confirm etiology
- PCR available but expensive
treatment for M. pneumoniae
azithromycin (other macrolide)
- resistant strains are making headway in Asia, so tetracyclines or fluoroquinolones are backup
genital mycoplasmas
M. genitalium
M. hominis
Ureaplasma spp.
non gonococcal urethritis and cervicitis
Ureaplasma urealyticum
mechanism of Ureaplasma urealyticum
- E production from hydrolysis on urea
- shapeless mycoplasmas = growth advantage on genital tract
- production of ammonia may contribute to local tissue destruction and pathology
- colonize infant at birth but usually disappear by 2 y/o
- adults acquire bu sexual contact; male exudate is more watery
- women are more commonly colonized than men
- lower socioeconomic groups
- 14 serotypes known
the colonies of this organism shows a fried egg appearance
Ureaplasma urealyticum
an emerging cause of STD in women
Mycoplasma genitalium
this is similar to gonococcal pillin
Mycoplasma genitalium terminal organelle
> MgpB and MgpC = undergo phase and antigenic variation through a reciprocal recombination system similar to gonococcal pillin
This is available for detecting M. genitalium in urine, urethral, and endocervical or vaginal swab
rapid nucleic acid amplification test
M. genitalium is present in the general population at rates between those of __ and ___
Chlamydia trachomatis and Neisseria gonorrhoeae
Chlamydial developmental cycle
- attachment and invasion of elementary body (in aa membrane bound inclusion)
- within inclusion = EBs differentiate into a metabolically active and replicatnig reticulate bodies (RBs); closely interacts with host cell
- end of developmental cycle = RBs go bak to being EBs = released by cell lysis or by extrustion of inclusion and can start a new round of infection
- limited growth conditions and antibiotics = reversible arrest of growth or persiistence with RBs transforming into enlarged aberrant bodies (ABs)
1 cause of STI in NA and leading cause of acquired blindness in world
Chlamydia trachomatis
three possible diseases caused by Chlamydia trachomatis
- trachoma = potentially blinding eye infection
STIs:
- typical chlamydia infection
- Lymphogranuloma Venereum (LGV) = infected lymph nodes (bubos) in groin
type of disease is associated with specific serovars of the organism
LGV more common here than in NA
- tropical countries
- but in NA and Europe there is an increasing incidence of infectious proctitis by LGV strains in MSM with HIV infections
most common of the bacterial STIs
- Chlamydia
- spread by fluids during vaginal and anal intercourse; or from a pregnant woman to her fetus during birth (can happen with gonorrhea too)
- often asymptomatic in females and sometimes males
- asymptomatic doesn’t mean safe!!!!; can cause ascending disease; can infect fallopian tubes = sterility , etc.
chlamydia infection in women
- bleeding between menstrual periods
- vaginal bleeding after intercourse
- abdominal pain
- painful intercourse
- low-grade fever
- painful urination
- uge to urinate ore often
- cervical inflammation
- abnormal vaginal discharge
- mucopurulent cervicitis (yellowish discharge that may have foul discharge
- PID (pelvic inflammatory disease)
- ectopic pregnancy
PID
- infection of fallopian tubes, ovaries, and/or uterus characterized by lower abdominal pain during menstruation, irregular menstruatioon, fever, chills
- scarring may cause infertility by blocking fallopian tubes
ectopic pregnancy
development of fetus in fallopian tube which causes rupture of fallopian tubes