survey of microbes part i: important prokaryotes gram negative organisms, archaea, and others
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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 - PowerPoint PPT PresentationTRANSCRIPT
Survey of MicrobesPart 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
See web link: http://www.niaid.nih.gov/factsheets/stdpid.htm
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.
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
____________________; 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)
Gram - rods
_______________ (LPS) – just one antigen on the outer membrane of Gram-negative bacteria.
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
Gram - rods
G- bacilli – Enterobacteriaceae
_________(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)
Gram - rods
READ NEWS ARTICLE on Salmonella in peanut butter
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)
Gram - rods
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 (fecal-oral transmission).
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
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 flagellaCampylobacter 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
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
Borrelia burgdorferi
Treponema pallidum
Cross section
Syphillis 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
Spirochetes – Treponema pallidum
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
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
CyanobacteriaPhotosyntheticbacteria
Photosynthetic bacteria
CYANOBACTERIA PURPLE SULFUR BACTERIA
filamentous
Colonial (with gelatinous sheath)
Archaea – the “other” prokaryotes
constitute third Domain Archaeamore closely related to Eukarya than to
bacteriaunique genetic sequences - rRNAunique membrane lipids & cell wall
• Halophiles thrive in high salt environments
• Use red pigments for ATP (energy) synthesis
• “Red Sea”
________________ : 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