Exam 3 review sheet Flashcards
Gram positive cocci (anaerobe)
Peptostreptococcus
Gram negative bacilli (anaerobe)
Bacteriodes
Fusobacterium
Gram positive rods (anaerobes)
Clostridium
Propionibacteria
Aerobes vs. Anaerboes
AEROBES - Uses O₂ as a terminal electron acceptor; have the enzymes Superoxide Dismutase for breaking down harmful Superoxides to H₂O₂, and Catalase, for converting toxic H₂O₂ into water.
ANAEROBES - Obtain energy from fermentation or respiration using SO₄ or NO₃ as terminal electron acceptors
Obligate Anaerobes vs. Microaerophilic Anaerobes
Obligate Anaerobes usually do not have the enzymes Superoxide Dismutase and Catalase, and therefore cannot tolerate being around any amount of O₂.
Microaerophilic Anaerobes can withstand some O₂ but grow better in Anaerobic conditions
Facultative Anaerobes
Can grow in both types of environments; typically do better in O₂ environments but possess Fermentation machinery as well.
Where are anaerobes normal flora
upper respiratory tract
mouth
GI tract
genital
skin
Anaerobes are frequently involved in what type of infections?
polymicrobic infection
**(involving more than one bacterial species)
Often involving both aerobes and anaerobes
Exogenous infections
From an outside source
**Ex: food-borne botulism
**Tetanus
Endogenous infection
*Arise from sources within the body when they move from areas of normal flora into other sites
*Most infections are endogenous, from organisms inside the body
*Examples: surgery, disease, trauma
Anaerobic media Containing a reducing agents
Sodium thioglycollate
Cystine
**They absorb oxygen
Thioglycolate
*Enriched broth with hemin and vitamin K
*Supports growth of most anaerobes
**Grows at bottom of tube
**Used as backup in case plated media fails to grow
Anaerobic media is usually supplemented with what?
Supplemented with hemin, blood, and vitamin K and sodium bicarbonate (source of CO2) for fastidious organisms
Anaerobic-selective media
Anaerobic PEA
Anaerobic KV
Ways to generate anaerobic atmosphere
Gas-generating system within a closed jar or bag
Preferred to collect by needle aspiration instead of swab
*to prevent exposure to O2
Specimens that should not be cultured for anaerobes
Throat or nasopharyngeal swabs
Gingival swabs
Sputum or Bronchial washes
Gastric contents, feces, rectal swab
Characteristics of Anaerobic Infections
Foul-Smelling Discharge
Gas in the Tissues (they produce CO₂ and H₂; i.e. Gas Gangrene)
Abscess Formation - Sets up microenvironment conducive for growth
Infection is in close proximity to a Mucosal Surface
Give a basic morphology of Spirochetes
Long, thin, motile & helical bacteria
NOT seen on Gram stain
Treponema pallidum is associated with what disease?
venereal Syphilis
T pallidum subsp endemicum is associated with what disease?
Endemic syphilis aka Bejel
T.pallidum subsp pertenue is associated with what disease?
Yaws
Borrelia burgdorferi is associated with what disease?
Lyme disease
Borrelia recurrentis is associated with what disease?
Relapsing fever
Leptospira interrogans is associated with what disease?
Leptospirosis
Important categories of Spirochetes are?
Treponema
Borrelia
Leptospira
Spirochetes have corkscrew-like motility due to the possession of?
Endoflagella
Endoflagella consists of
axial filaments
Spirochetes are best visualized via?
Darkfield microscopy
Fluorescent microscopy
How is syphilis spread?
sexual intercourse or transplacentally
What is primary syphilis?
Development of chancre at the site of inoculation
approximately 3 weeks after exposure
The chancre usually heals spontaneously after 4
to 6 weeks
What is secondary syphilis?
Sets in 1-3 months after primary lesion heals
Widespread rash of the skin and mucosa membranes (hands and soles of feet)
lesions are filled with treponemas and considered infectious
“The Great Imitator”
What is tertiary syphilis?
responsible for a majority of the morbidity and mortality associated with the disease
Occurs 5-30 years after primary syphilis
destruction of tissue caused by a response to the presence of treponemal antigens
What are “nontreponemal” tests?
Test for antibodies developed against lipids released from damaged cells during early stage of disease. Screens for syphilis but may be false positive
What are “treponemal” tests?
Test for Ab to treponemal antigens, highly specific
What disease does Borrelia burgdorferi cause?
Lyme disease
How is lyme disease spread?
via bites of Ixodes ticks
Lyme disease stage 1
Erythema Migrans (looks like target)
Flu-like
lasts 1 month
What is stage 2 lyme disease?
Facial palsy
cardiac
migratory pain
fatigue syndrome
What is stage 3 lyme disease?
acute or chronic arthritis
CNS involvement
How do you dx lyme disease?
early: clinical grounds
late: serological-ELISA + Western blot
Which species of Leptospira causes disease?
Leptospira interrogans
Direct transmission of L. interrogans occurs with infected
urine
Indirect transmission of L. interrogans occurs with infected
water
What is the gold standard in diagnosing leptospirosis?
Urine culture
Where is leptospirosis most prevalent?
Rural areas
Leptospirosis is a
zoonotic disease
What cell culture lines are most often used for recovering Chlamydia trachomatis?
-McCoy Cells
Chlamydia infections are most often implicated in
urethritis, conjunctivitis, STDs
Describe the features of Mycobacteria
- Aerobic
- Non-motile, Non-spore forming
- Straight or slightly curved rods
- Distinctive cell wall - has high mycolic acid level
- Fastidious
- Slow growers
Describe the Mycobacteria characteristics
- ‘waxy’ cell wall (lipid-rich)
- Resistance to drying + hydrophobic
- Resistance to antibiotics and disinfectants
- Resistance to acids and alkalis * ‘acid and alcohol fast’
- Impermeable to standard stains
- Survives in macrophages
What stains are used for mycobacterium
- Ziehl-Neelsen / Kinyoun= carbolfuchsin
- Auramine-rhodamine = fluorescent
What is the Runyon classification based on?
based on the rate of growth, production of yellow pigment and whether this pigment was produced in the dark or only after exposure to light.
Runyon classification groups
Group 1- photochromogens
Group 2- Scotochromogens
Group 3- Nonphotochromogens
Group 4- Fast growers
How is mycobacterium diagnosed
Microscopy
Culture (what are the different types of media?)
Molecular = PCR, NAAT, probes (main concepts of tests)
Done in BSL3 facility
