What are the smallest free living microbes
Mycoplasmas
What are three significant structures that most bacterial organisms have, but mycoplasmas do not
cytochromes
enzymes of the krebs cycle
cell walls
What is necessary for the groth of mycoplasmas
cholesterol (sterols)
Where do you usually find colonized mycoplasmas in the human body
the mucus membranes or respiratory and urinary tracts
What is the mycoplasma that causes walking pneumonia
mycoplasma pneumonia
what is another name for walking pneumonia
primary atypical pneumonia
Where does mycoplasma pneumonia attach
to receptors at the bases of cilia on respiratory epithelial cells
What is different about walking pneumonia (primary atypical pneumonia) caused by mycoplasma pneumoniae
it causes a fever, headache, and sore throat those aren’t typically pneumonia symptoms
how is walking pneumonia spread
by nasal secretions among people in close contact
how serious is walking pneumonia
it is usually not severe enough to require hospitalization and death
Why is diagnosis difficult for mycoplasma pneumoniae
because they are small and slow growing
why is treatment of walking pneumonia difficult
because patients can be infected for a long time without signs or symptoms
how big is rickettsias
Extremely small
what is the cell wall of rickettsias like
it has such a small amount of peptidoglycan that it appears almost wall less
Rickettsias are OBLIGATE INTRACELLULAR PARASITES, what is unusual about them?
it is unusual that an obligate intracellular parasite has functional genes for:
protein synthesis
ATP production
and reproduction
What are the four genera of rickettsia that cause disease in humans
Rickettsia
Orienta
Ehrlichia
Anaplasma
What causes rocky mountain spotted fever
Rickettsia Rickettsii
How is Rocky mountain spotted fever (Rickettsia Rickettsii) transmitted
it is transmitted by infected wood ticks (hard ticks)
What causes epidemic typhus
Rickettsia Prowazekii
What is the primary host of rickettsia prowazekii
humans
how is Rickettsia Prowazekii transmitted
by infected lice (when their feces is rubbed into a bite)
what is the mortality rate of epidemic typhus without treatments
70%
What is it called when epidemic typhus occurs many years later
Brill-Zinsser disease
What is the structure of chlamydial cell walls
Two membranes without any peptidoglycan between them
Chlamydias are obligate intracellular parasites, but where inside the cell do chlamydias grow
only within the vesicles of host cells
What is unique about Chlamydia’s developmental cycle
it involves two forms Elementary Bodies (EB) and Reticulate Bodies (RB).
- EBs enter the cell via endocytosis
- EB converts into RB
- RB rapidly divides
- Most RBs convert back into EBs
- EBs are released from the host cell
how is chlamydia diagnosed
with a direct fluorescent Ab test
What is the bacteria that causes a sexually Transmitted disease and Trachoma
Chlamydia Trachomatis
What is the problem associated with the chlamydia STD
Lymphogranuloma veneruem
what strain of chlamydia trachomatis causes lymphogranuloma veneruem
the LGV strand of chlamydia trachomatis
how is the infection of men and women with the LGV strain of C. trachomatis different
it is mostly in women, but most are asymptomatic (85%)
most of the men who are infected have symptoms (75%)
What is Trachoma
the leading cause of non-traumatic blindness in humans in which the bacteria multiplying in conjuctival cells results in scarring, this causes the eyelashes to turn inward and abrade the eye.
How is the trachoma transmitted
either to children at birth, or from genital C. Trachomatis bacteria infecting the eye
What are spirochetes
thin, tightly coiled, helically shaped bacteria
what must you do to see spirochetes
you must use dark-field to see them
What are the cell walls of spirochetes like
they are gram negative walls, but they have flagella located in the periplasmic space
What are the spirochete flagella called
endoflagella or axial filaments
how do spirochetes move
in a corkscrew fashion, the pathogenic ones can burrow through their hosts tissues
what are the three genera of spirochetes that are pathogenic to humans, in order of most tightly coiled to most loosely coiled
Leptospira (tight coils)
Treponema (8-20 coils)
Borrelia (3-10 coils)
Where is the only place that treponema palliidum pallidum lives naturally
in humans (obligate parasite)
What causes syphilis
treponema pallidum pallidum
what is almost the only way that syphilis is transmitted
via sexual contact, but it can be spread from infected mother to fetus
what occurs when a fetus is infected with syphilis
death, mental retardation, or malformations
What are the three stages of a syphilis infection
Primary: Chancre at contact site (3-6 weeks)
Secondary: Rash and chondyloma lata (grey, flat, wart-like lesions(6 weeks))
Tertiary: Gummas and neurologic symptoms (years later)
What are the two diseases caused by borrelia
lyme disease and relapsing fever
What is the bacteria that causes Lyme disease
borrelia borgdorferi
how is lyme disease spread
by ticks (deer tick) (and potentially sexually)
How is lyme disease treated
with penicillin or tetracycline
What are the three phases of lymes disease in untreated patients
- An expanding bulls-eye rash
- neurological symptoms and cardiac dysfunction
- severe arthritis that can last for years
Are cases of lyme’s disease increasing or decreasing
increasing due to living proximity between humans and deer ticks
how successful are treatments of lymes disease
they are pretty sucessful if done in the first stage of lyme disease, they are less successful after because at that point the damage is mostly done by the immune system
how is lyme’s disease prevented
avoiding ticks
Where is leptospira interrogans normally found
in wild and domestic animals (causes leptospirosis)
how is leptospira interrogans transmitted to humans
via direct contact with infected animal’s urine, or via contact of contaminated streams, lakes, or moist soil
how does leptospira interrogans enter the body
via invisible cuts and abraisions in the skin and mucus membranes
once leptospira interrogans enters the body how does it move
via the bloodstream
What typically happens with a leptospira interrogans infection
the bacteremia resolves itself and the bacteria are only found in the kidneys and in excreted urine
what is the most widespread zoonotic disease
leptospirosis
What causes cholera
vibrio cholerae, but there must be a large inoculum because the acidity in the stomach can kill them
what is the most important virulence factor of vibrio cholerae
cholera toxin
what does cholera cause
firehose diarrhea
What is the mechanism of cholera causing diarrhea
- cholera binds to the epithelial cells
- portion of toxin (A1) enters the cell
- A1 stimulates adenylate cyclase
- cAMP is synthesized
- cAMP stimulates the cell to release Cl-, Na+ and other electrolytes
- this draws water into the lumen = firehose diarrhea
Are all cholera infections severe
no, some are asymptomatic, others only cause slight diarrhea
What are the symptoms of a severe cholera infection
- watery diarrhea (rice-water stool)
- vomiting
- severe dehydration and electrolyte loss
- dramatic weight loss
How is cholera treated
fluid and electrolyte replacement
What is likely the most common cause of gastroenteritis in the US
campylobacter jejuni
how do humans become infected with campylobacter jejuni
consumption of contaminated food, milk, water, and poultry (poultry is the most common)
how is campylobacter jejuni prevented
proper food handling and preparation
what are the symptoms of a campylobacter jejuni infection
self-limiting bloody and frequent diarrhea
What is the bacteria that is implicated with 90% of stomach and duodenal ulcers
helicobacter pylori
What leads to a higher incidence of uclers
type O blood, the helicobacter pylori uses the O antigen on gastric cells as a receptor
what does helicobacter pylori do that allows it to live in the stomach
it produces a potent urease the produces ammonia and bicarbonate
how does helicobacter pylori cause ulcers
by causing the mucus layer in the stomach to become thin and go away. This allows the stomach acid to destroy tissue
