Survey of Microbes Part I: Important prokaryotes

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Survey of Microbes
Part I: Important prokaryotes
SHAPES:
1. ____________ – spherical, ball shaped
2. ____________ - rod
3. _________________– helical, comma
(vibrio), twisted rod (spirillum, rigid with
lophotrichous flagella), spirochete (flexible with
periplasmic flagella)
Also…
intermediate shapes like coccobacillus
cells can be thin (filamentous)
ButCells
first…
word on(species
shape,
can beapleomorphic
can have >1
form such as Corynebacterium diphtheriae)
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arrangement and size
arrangements of bacteria
Pairs (2 like diplococci, diplobacilli)
Tetrads (4 cells in packet)
Sarcinae (balls or blocks of 8, 16, 32 cells)
Chains (streptococci; streptobacilli)
Clusters (Micrococcus, Staphylococcus)
Palisades arrangement (Corynebacteria)
streptococci
diplobacillus
spirochete
spirillum
size
Bacterial Taxonomy Based on
Bergey’s Manual

Bergey’s Manual of Determinative
Bacteriology – five volume resource covering
all known prokaryotes
◦ Classification based on genetic information –
phylogenetic
◦ Two domains: Archaea and Bacteria
◦ Five major subgroups with 25 different phyla
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Major Taxonomic Groups of Bacteria
Domain ____________ – primitive,
adapted to extreme habitats and modes of
nutrition
 Domain Bacteria:

◦ Phylum Proteobacteria – Gram-negative cell
walls
◦ Phylum Firmicutes – mainly gram-positive with
low G + C content
◦ Phylum Actinobacteria – Gram-positive with high
G + C content
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Figure 4.27 Universal phylogenetic
tree
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IMPORTANT GRAM
POSITIVE BACTERIA
Important Gram positive
bacteria
Soil bacteria:
• Bacillus
• Clostridium (some pathogens)
Lactic acid bacteria: Lactococcus, Lactobacillus, Acidophilus
Several human pathogens:
• Staphylococcus (S. aureus)
• Streptococcus (S. pyogenes, S. pneumoniae)
• Mycobacterium (M. leprae and M. tuberculosis)
• Corynebacterium
• Listeria monocytogenes
Others:
• Propionibacterium
• Streptomyces
• Mycoplasma! (no cell wall, but it’s grouped with G+)
1a.) Gram + cocci
Staphylococcus
Genus: staphylo=“grape clusters”
S. epidermidis – opportunistic pathogen;
no virulence factors; natural flora
 S. aureus – hemolytic, coagulase,
invasive; flora of the nose but still a
pathogen
 Many diseases: endocarditis, pneumonia,
meningitis, arthritis, intoxications such as
______________________ and food
poisoning; more often cuteneous:
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◦ pimples/boils/abscesses/carbuncles, pink eye
◦ scalded skin syndrome,
◦ impetigo.
BOIL
Strep. pyogenes?
IMPETIGO
CARBUNCLE
SCALDED SKIN SYNDROME
Endocarditis
1a.) Gram + cocci
--Staph
Pathogenic effects: mostly associated with ________________________
• Diagnostic marker
• localized clotting
• Kills leukocytes so
that bacteria are
not phagocytosed
Virulence factors of Staph
• Form pus and acne
Prevents
bacteria from
being cleared
from host
Current estimate:
>60% of hospital
acquired S. aureus
infections are MRSA
Many strains are MDR!!
Percentage of Staphylococcus aureus isolates resistant to
methicillin in national surveys, United States, 1999–2004.
TSN, The Surveillance Network (data include hospital infections); NNIS,
National Nosocomial Infections Surveillance System (data include only
intensive care units); SENTRY, includes only skin and soft tissue infections.
(source: Klein et al. 2007. EID)
Hospitalizations and Deaths Caused by Methicillin-Resistant
Staphylococcus aureus, United States, 1999–2005
Figure 1. Estimated methicillin-resistant Staphylococcus aureus (MRSA)–related hospitalization rates,
United States, 1999–2005. Rates are no. MRSA-related discharges/1,000 hospitalizations. Error bars
represent 95% confidence intervals. (source: Klein et al. 2007. EID)
1a.) Gram + cocci
1.

◦
Group A Strep = ____________
Strep throat, pharyngitis
Secondary: Scarlet fever (systemic rash);
Rheumatic fever (heart valves, arthritis)
Cuteneous infections: Impetigo (older
children), pyoderma, acne, Erysipelas –
AKA “St. Anthony’s Fire”; Toxic shock
syndrome

◦
____________ ____________ ; “flesh
eating bacteria”

All are mediated by various virulence
Streptococcus
factors – esp. ____________
1a.) Gram + cocci
--Strep
Strep throat
Strawberry tongue – Scarlet fever

1a.) Gram + cocci
--Strep
Streptococcal toxic shock syndrome
(STSS), causes blood pressure to drop
rapidly and various organs to fail. About
20% of patients with necrotizing fasciitis
and more than half of those with STSS
will die. Generally, the mortality rate for
other forms of invasive group A
streptococcal disease is 10-15%.
Streptococcus
PYODERMA (S. aureus
or S. pyogenes)
____________
1a.) Gram + cocci
--Strep
: due to secretion of
many enzymes and toxins including:
◦ ____________ : lyse red blood cells
◦ ____________ : breaks down collagen
(cement of connective tissue: helps organism
spread)
Virulence factors of Strep
1a.) Gram + cocci
--Strep
Other pathogenic Streptococci
• ________________________ : causes dental caries (cavities)
• ____________________________ (often called pneumococcus)
•
carried in upper respiratory tract and nasopharynx of humans
15% of children and 5% of adults are “carriers”
•
grow in pairs (NOT in long chains)
•
most common cause of pneumonia and otitis media (middle ear infection)
1b.) Gram + rods
--Clostridium



____________ ____________ (cannot grow
in oxygen)
rod shaped bacteria
contain ____________ : resistant to heat and
chemicals; spores are introduced into injury or
anaerobic wound or ingested (botulism)
◦ spores germinate and active bacteria
multiply
Clostridium
Medically important
species

1b.) Gram + rods
--Clostridium
C. tetani: ____________
◦ neurotoxin: called tetanospasmin (a dot the size of a
period-kills 30!)
◦ blocks muscles relaxation: muscles spasm and contract
◦ contractions: tear muscles/cause compression fraction
of vertebrae
 death from spasms of respiratory muscles
 vaccine (DPT): inactivated toxin used to stimulate antibodies

C. difficile: ____________ ____________


often caused when antibiotic therapy alters microflora in intestines
and allows for growth of this organism

C. perfringens: causes
______________________ (severe tissue
death); also foodborne diarrhea
Medically important species

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C. botulinum: ____________________ .
grows in anaerobic environments (canned foods): discard
bulging cans!
Produces toxin: MOST potent of ALL toxins: specific for nerve
endings (synapses)
Blocks acetylcholine (neurotransmitter): nerve impulses
blocked!
Botulism disease progression:
Initial symptom: blurred vision and nausea flaccid
paralysis: respiratory and cardiac failure
slow recovery: nerve endings regenerate; respiratory
support: antibiotics are of no use!
Prevention: Toxin is destroyed by boiling and nitrites in food
prevent bacterial growth
A word about commercial use of BOTOX:
◦ prevent wrinkles – maybe, BUT…
◦ strasbismus: crossed eyes
◦ blephorospasm: inability to keep eyelids open
Bacillus
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
commonly found in soil
produces ____________
Medically important species of Bacillus
• ____________________ : anthrax disease of cattle, sheep and
humans
Two forms of anthrax:
•____________(skin): transmitted through a break in the skin
cause pustule or lesions: tissue dies, crusts and falls off
systemic (bloodstream): shock/ collapse
•____________(pulmonary): transmitted by inhaling anthrax spores
starts as pneumonia, high fever then septicemia, respiratory
distress, death
•biowarfare agent: spores can be spread in aerosols
•no spread from person to person!
•penicillin effective if given early
Cutaneous anthrax – note BLACK lesions
Anthrax sepsis due to
inhalation anthrax (now
involving eye)
Woman was exposed to
animal hides; Pennsylvania
2006
Inhalation anthrax on x-ray;
Patient died next day.
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1b.) Gram + rods
--Bacillus
Bacillus ____________ : food poisoning often
from starchy food especially rice
Bacillus thuringiensis: insect pathogen
produces delta endotoxin in crystal form insect
eats toxin crystals and dies
◦ sold for plant treatment as pesticide
◦ transgenic plants engineered to produce toxin

Bacillus subtilis: produces bacitracin

Bacillus polymyxa: produce polymixin
Bacillus (cont’d)
Mycobacterium
1b.) Gram + rods
Mycobacterium
__________________________________
__
Acid-fast stain – mycolic acid; Slow growing
1. Leprosy: mainly affects the skin, peripheral
nerves, upper respiratory tract.
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◦
discovered by G.A. Hansen in 1873; first bacterium to be
identified as causing disease in man.
contagious, but not widespread because 95% of the
population have competent immune systems.
TB: causes tubercles in lungs, bones; poor health,
crowding plays a role (communicable);
2.
◦
◦
leading cause of death in the world from a single infectious
disease!
affects 1.7 billion people/year which is equal to one-third of
the entire world population!
TB – cavitation, and calcified tubercle
1b.) Gram + rods
1. ___________________ - --others
C.
diphtheriae: causes diphtheria – DPT
vaccine
-pseudomembrane on tonsils
-strong toxin – can destroy heart
2.
______________________– food
poisoning; outbreak in hot dogs;
intracellular pathogen
Other pathogens
Pseudomembrane:
necrosis, plasma,
fibrin and
bacteria
Pallisades arrangement of
Corynebacterium
Can be pleiomorphic
Nonpathogenic, but important!
Propionibacterium, Brevibacterium swiss cheese, bacterial acne, stinky
feet; propionic acid and sulfur
compounds
2. Streptomyces - antibiotic production:
1.

erythromycin, neomycin, streptomycin,
tetracycline
____________– normal flora in gut
and vagina
3.
◦
found in yogurt, cheeses
(mozzarella, cheddar, provolone)
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naturally lack a cell wall
stabilized by sterols,
resistant to lysis
extremely small (0.1 – 0.5 µm)
range in shape from filamentous to coccus
or doughnut shaped
____________ ____________
Mycoplasma ____________ – atypical
pneumonia in humans (“walking
pneumonia”)
____________

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