Gram-weird Flashcards
What organisms do not gram stain well?
"These Microbes May Lack Real Color" Treponema Mycobacteria Mycoplasma Legionella Rickettsia Chlamydia
Why don’t treponema gram stain well?
Too small to be visualized
Why don’t mycobacteria gram stain well?
High lipid content in walls – take up carbolfuschin better (acid-fast)
Why don’t mycoplasma gram stain well?
No cell wall.
Why don’t Legionella gram stain well?
Primarily intracellular - silver stain instead
Why don’t Rickettsia gram stain well?
Primarily intracellular
Why don’t Chlamydia gram stain well?
Primarily intracellular, lacks classic peptidoglycan because of low muramic acid
On what kind of culture does Legionella grow?
Charcoal yeast extract with iron and cysteine.
How can legionella be detected?
Urine antigen
Where is legionella found? How is it transmitted?
Ubiquitous in water environments - air conditioning systems/cooling towers. Transmitted via aerosol. No person to person.
What allows legionella to be a facultative intracellular parasite?
- Dot/Icm type IV secretion system inhibits macrophage phagosome-lysosome fusion.
- Cu-Zn superoxide dismutase and catalase-peroxidase protects bacteria from oxidative burst
What are the clinical manfestations of legionella?
Legionnaires Dz: Severe pneumonia, associated with fever, GI and CNS sx.
Pontiac fever: Mild flu-like syndrome, usually self-limiting w/in 1 week.
How is legionella treated?
Macrolide or quinolone.
What is the reservoir of Chlamydia?
Humans.
How is Chlamydia transmitted?
Direct personal contact.
What is the life cycle of Chlamyida?
- Elementary bodies, Enters cells via Endocytosis, is Enfectious.
- Reticulate body Replicates by fission, Reorganizes into elementary bodies.
- larger and more osmotically fragile.
* Chlamydia are OBLIGATE intracellular - steal ATP from host w/ translocator.
How does chlamydia avoid phagosome-lysosome fusion?
Cell wall lacks muramic acid.
What strains of Chlamydia cause atypical pneumonia?
C. pneumoniae and C. psittaci - aerosol tx.
What’s special about C. psittaci’s reservoir?
Avian
What does C. trachomatis cause?
Reactive arthritis (Reithers)
Non-gono urethritis
PID
Follicular conjunctivitis
What do C. trachomatis serotypes, A, B and C cause?
Africa, Blindness (follicular conjunctivitis), Chronic Infection
What do C. trachomatis serotypes L1, L2, and L3 cause?
Lymphogranuloma Venereum: small, painless ulcers on genitals –> swollen, painless inguinal lymph nodes that ulcerate (buboes). Treat w/ doxy.
What do C. trachomatis serotypes D-K cause?
Everything else. Urethritis/PID/neonatal pneumonia w/ staccato cough w/ eosinophilia, neonatal conjunctivitis
How is chlamydia treated?
Azithro (1x) or doxy.
What is chlamydia diagnosed?
cytoplasmic inclusions seen on Giemsa or fluorescent antibody stained smear.
How does gardnerella gram?
Gram variable. Pleomorphic.
How does gardernella vaginalis present?
Bacterial vaginosis: gray vaginal discharge with fishy smell. Non-painful.
What is BV associated with?
Sexual activity. Overgrowth of certain anaerobic bacteria in vagina.
What are clue cells?
Vaginal epithelial cells covered with gardnerella bacteria, giving them a stippled appearance along outer margins.
What is the treatment for BV?
metronidazole or clinda.
How can the odor of BV be enhanced?
Whiff test - mixing discharge w/ 10% KOH
