Transcript Survey of Microbes Part I: Important prokaryotes

Survey of Microbes
Part I: Important prokaryotes
Gram negative organisms,
archaea, and others
IMPORTANT GRAM
NEGATIVE
PROTEOBACTERIA
G- cocci
 Neisseria: ________________
 N. gonorrhoeae – _____________ =
________________
 Has fimbriae/pili to attach to genital
epithelium and invade
 Causes infiltration of pus/inflammation
 Fastidious – diagnose on chocolate agar
 N. meningitidis
 Meningococcal meningitis – vaccine
available and highly recommended for
college students (spread by close/direct
contact)
 Penicillin sensitive?
Disease/Treatments
 Adults: genital, urinary, anal infections
posisble
 neonatal eye infection (can prevent
with erythromycin eye drops)
 Men can be asymptomatic
 some show “gleet” (copious purulent
discharge) – see link to images on
supplement site.
 Women: pelvic inflammatory
disease
 Treatment: many antibiotics (e.g.
doxycycline, cipro, z-pack)
 Many are now resistant! (e.g. –
cillins; tetracycline)
PID
 most cases are
associated with
_____________and genital
______________ infections
 Long term infection 
organisms migrate into
uterus, fallopian tubes
 Major cause of infertility
and chronic pelvic pain
 Sexually active
teenagers are more
likely to develop PID
than are older women.
 The more sexual
partners a woman has,
the greater her risk of
developing PID.
See web link: http://www.niaid.nih.gov/factsheets/stdpid.htm
Figure 23. Gonorrhea — Positivity among 15- to 24-year-old women tested in
family planning clinics by state: United States and outlying areas, 2007
Gram negative rods
Enterobacteriaceae – shared
characteristics
Gram - rods
 ____________________; Small rods (4-5
microns long)
Peritrichous flagella (exception: Klebsiella
and Shigella are non motile)
All ferment glucose (produce acid) – used
for ID on differential agar
Have various surface antigens to: avoid
phagocytosis, aid in adherence, SEPTIC
SHOCK (associated with LPS)
_______________ (LPS) – just one antigen on the
outer membrane of Gram-negative bacteria.
Gram - rods
LPS - lipopolysaccharide
 Toxicity is associated with the lipid component
(Lipid A) and immunogenicity is associated with
the polysaccharide components.
 O antigens also are components of LPS.
 LPS elicits a variety of inflammatory responses in
an animal, including fever.
 MOST LPS IS RELEASED ________________
________________________________
Gram - rods
Pathogenesis
 Because of their cell envelope structure:
tolerant to bile salts and toxins in GI tract
Resistant to many antimicrobials produced by
the host
Possibly resistant to phagocytosis
Also – LPS may be involved (along with
pili, fimbrae) in binding host tissue
G- bacilli – Enterobacteriaceae
Gram - rods
 _________(strain O157:H7) – enterohaemorrhagic;
common food poisoning; beef – outbreaks in
hamburger meat
 ___________________ (typhoid fever) –
 ______________________ - common food poisoning
(salmonellosis) ; poultry
 Shigella flexneri, S. dysenteriae – bloody diarrhea;
dysentery; invades mucosa shed lining of intestines
up to 50% of all diarrhea deaths can be attributed to bacillary
dysentery!!
1 M cases/yr (4% death rate)
READ NEWS ARTICLE on Salmonella in peanut butter
Gram - rods
Some toxins produced by enteric
bacteria
 ______________(from ET E. coli, Vibrio) –
lead to secretion of lots of water by intestinal
cells
 ________________ (Shigella and E. coli
O157H7) – destroys host ribosomes 
causes cell death! What is the result?
 ______________ (come E. coli strains) –
destroy RBCs
Invasins (Salmonella, Shigella) – invade
cells (can grow intracellularly)
A quick note on diarrhea…
Traveller’s diarrhea: due to contaminated
water and foods; in developing countries,
risk is 30-50% for travelers (1-2 wk stay)
Food poisoning: can be due to food itself
(bacteria or virus living in that animal or its
waste), poor food preparation (mixing
cooked with uncooked) or due to
unsanitary practices of food handler (fecaloral transmission).
G- bacilli
Other important Enterobacteriaceae
Yersinia pestis (bubonic plague) –
Buboes – large, swolen lymph nodes
killed more people than any other ID (killed ¼
Europe! – 25 M – in the 14th C)
transmitted by ___________during blood meal
MANY virulence factors
Klebsiella pneumoniae – pneumonia; has
___________, evades phagocytosis
G- bacilli (some others)
 ___________________________(whooping cough) –
DPT vaccine – toxin kills ciliated cells
 Pseudomonas aeruginosa (opportunistic
infections – grows everywhere) – slime layers,
fimbrae
 Haemophilus influenzae – MANY diseases!
Meningitis, ear infection, sinusitis, pneumonia,
septicemia, arthritis, epiglottitis (life threatening) –
some strains have capsule; vaccine available
 Bacteroides – major constituent of gut flora;
usually commensalistic but can grow elsewhere
and cause problems (resistant to Abt)
G- curved
________________, the cause of
Asiatic cholera.
 Watery, profuse diarrhea  dehydration
 shock  renal failure  death
 Spread by contamination (fecal/oral esp.
travel to endemic countries) and by
seafood (other Vibrio spp.)
 uses glycocalyx to anchor to epithelium
 Produces cholera-toxin (enterotoxin)
READ NEWS ARTICLE on cholera outbreak in Zimbabwe
G- Spiral shaped
Have a rigid cell wall and polar flagella
Campylobacter jejuni -- bacterial
diarrhea, especially in children.
undercooked poultry or shellfish, or untreated
drinking water.
 _________________________– peptic ulcers;
colonizes gastric mucosal cells of humans
Mode of transmission uncertain
Dx – gastric biopsy and urease test
>80% ulcers are Hp!
Rickettsias
 Very tiny!
 Most are pathogens (vector borne = spread by
arthropods)
 ________________ ________________ parasites
 Rickettsia rickettsii – Rocky Mtn. Spotted
Fever – ticks
 Rickettsia typhi – endemic typhus (lice)
 Coxiella burnetti – Q fever
(http://www.cdc.gov/ncidod/dvrd/qfever/)
Spots due to small
hemorrhages
Other phyla of prokaryotes
Chlammydias, Spirochetes,
Photosynthetic bacteria, Archaea
(extremophiles)
Spirochetes
Cross
section
Borrelia
burgdorferi
Treponema
pallidum
phylogenetically distinct group very thin,
flexible, spiral-shaped
move by means of axial filaments
(periplasmic flagella).
Most spirochetes are free living or
harmless; a few are pathogens of animals
 _____________________– Lyme disease –
humans + dogs
 _____________________– syphillis – hook to
embed in host cell
Syphillis
Spirochetes – Treponema pallidum
 Sores occur mainly on the external genitals, vagina,
anus, or in the rectum. (also on lips and in mouth)
 Transmitted by direct contact (Also congenitally)
 first stage - small sore disappears in 2 to 8 weeks.
 second and third stages -- progressively worse
eventually lead to brain, heart, and blood vessel
damage if not diagnosed and treated.
 syphilis is 100% curable with penicillin, yet there
is now more syphilis than since the late 1940s, and
it is spreading rapidly.
 Rising rapidly in white, homosexual male
demographic
Chlammydias
Obligate intracellular parasites (cannot
survive without host cell)
 VERY, very tiny (thought to be viruses!)
Chlammydia trachomatis – trachoma
(severe eye infection) and STD
Most frequently reported ID in the US – Georgia
in top 5! (15 – 24 year old women)
C. pneumoniae – pneumonia
Photosynthetic bacteria
Green and Purple photosynthetic
bacteria – do not produce O2; have
bacteriochlorophyll; anaerobic; use H2S or
S in their metbolism
Cyanobacteria. Chlorophyll a and other
pigments; thylakoids to increase surface
area; blue-green pigment is phycocyanin
great ecological importance in the global
carbon, oxygen and nitrogen cycles
Photosynthetic
bacteria
Cyanobacteria
Oscillatoria
Nostoc
Anabaena with
heterocyst, a
specialized cell for
nitrogen fixation.
The large bright cell
in the filament is a
type of spore called
an akinete
Synechococcus
–marine; 25%
of primary
production
Photosynthetic bacteria
Colonial (with
gelatinous
sheath)
filamentous
CYANOBACTERIA
PURPLE SULFUR BACTERIA
Archaea – the “other” prokaryotes
constitute third Domain Archaea
more closely related to Eukarya than to
bacteria
unique genetic sequences - rRNA
unique membrane lipids & cell wall
 ________________ :
 Based on their
physiology, the Archaea
can be organized into
three types:
 ________________ --
prokaryotes that produce
methane; obligate
anaerobes
extreme ____________-live at very high
concentrations of salt
(NaCl)
extreme (hyper)
________________ -- live at
very high temperatures
• Halophiles thrive in high
salt environments
• Use red pigments for ATP
(energy) synthesis
• “Red Sea”