Micro Biology Unit 3 PCC

Prokaryotes
Lack a true membrane-bound nucleus
Include Bacteria.
Eukaryotes
True nucleus and membrane-bound organelles
Opportunistic Infections
Normal flora gone bad
ie. Staph epi
Peptidoglycan
Found only in the cell walls of bacteria.
Transpeptidases link peptidoglycan polymers by amino acid side chains.
PBP
Penicillin binding protein
Transpeptidases that link peptidoglycans
Attachment of penicillin to the PBPs in the cell wall interferes with construction of cell wall.
Gram Positive Cell Walls
Very thick peptidoglycan layer.
Protoplast
Loss of peptidoglycan in a Gram Positive cell results in the formation of a protoplast. Prone to bursting.
Gram Negative Cell Walls
Thin peptidoglycan layer
Has a periplasmic space
Spheroplast
Formed from the loss of peptidoglycan layer in a Gram negative cell.
Periplasmic Space
An active metabolic area. Contains:
1. Digestive enzymes
2. Proteins that facilitate transport of materials into and out of the cell.
3. Buffers that protect the cytoplasm from osmotic flux in the environment.
4. Enzymes (heat shock proteins, chaperones, hydrolases, proteases, etc.
5. Exotoxins and other virulence factors that may be released into the surrounding area.
Outer Membrane
found only in gram negative bacteria
has 2 layers
Inner layer of outer membrane
similar to cell membrane
Outer layer of outer membrane
Part of Gram negative OM that makes it unique from all other organisms because it contains LPS molecules..
LPS
Lippopolysaccharide

3 Parts
Lipid A
Core Polysaccharide
O antigen

Lipid A
Endotoxin!
Endotoxic shock
septic shock
Caused from large release of LPS resulting in an overwhelming immune response. Largely due to Lipid A, often deadly.
20% of patients with septicemia.
Shwartzman Phenomenon
Occurs after a second encounter with large amounts of endotoxin
Results in tissue necrosis and damage.
Mycobacterium
Waxy coat
ie. tubercuulosis, leprae
Mycoplasma species
ie. pneumoniae
lack a cell wall
Flagella
Fillament “tail” providing movement
Monotrichous
Single flagellum
Amphitrichous
Flagella on both ends
Fimbriae
“pili”
Adhere to host tissue
F pili
“sex pili”
Present only on F+ cells
Allows one way cell to cell transfer of DNA.
Capsule
“slime layer”
Allows survival under extreme conditions
Virulence Factor
Adherence to host tissues
Barrier to hydrophobic molecules
Antiphagocytic
Streptococcus pneumoniae
Virulent strains make capsules which protect cells from being phagocytosed and killed by PMN’s
Plasmids
Extrachromosomal circular DNA
Can replicate independently of the Chromosome
Not essential for survival, provides “selective advantage”
Endospores
Bacterial spores
Produced by some Gr+ species
Most resistant life form, able to survive extreme conditions.
Protect chromosomal DNA
Obligate aerobe
Requires O2
Obligate anaerobe
O2 is toxic
Facultative anaerobe
Grow with or without O2
Psychrophile
Prefer cold environments
Psychrotroph
Mesophile that can survive in cold temps
Mesophile
Enjoys moderate temperatures
thermophile
Best in very warm or hot temeratures
Thermoduric
Able to survive in warm/hot temperatures
Lag Phase
First phase of bacterial growth
Occurs when bacteria are first inoculated.
Log phase
Cells are dividing regularly at a constant rate.
Stationary phase
Reproducing at the same rate other cells are dying
Death phase
cells are dying faster than they are being produced.
Transposons
“Jumping Genes”
DNA that can travel from one place on a chromosome to another place.
Sporulation
The making of endospores by G+ species
Germination
Species exiting endospore state
DNA repair mechanism
Bacteria can repair minor damage to DNA
F Plasmid
Fertility factor
Instructions to make F-Pillis and send a copy of plasmid DNA to another bacterial cell
Transposons
Jumping genes
DNA that can travel from one place on a chromosome to another place. Travel to a plasmid and back to the chromosome.
Transformation
Dead cells “naked” DNA picked up by other bacteria and incorporated.
Conjugation
One way transfer directly from one bacteria to another. Uses F pillus (sex pillus)
Transduction
Bacteria infected by a virus.
Bacteriophage
Phage
Virus that targets bacteria.
Lysogenic viruses
Temperate viruses
Replicate with the host chromosome for many generations
Lysogeny
Many bacteria only release harmful toxins after they are lysogenized.
C3a
Inflamation
C3b
Opsinization
C5a
Chemotaxis
Catalase +
Catalase test result indicating staphylococcus
Capsule
Slime layer
associated with virulence, protection, and adherance.
A characteristic of Staff aureus
Protien A
Coats most Staff aureus sstrains.
Prevents antibody-mediated clearance
Repeals macrophages
Binds compllement
Coagulase
Clumping factor
toxins
Associated with Staff aureus
clump together and wall itself off
Staphylococcus epidermidis
Normal flora on skin
Forms biofilm on catheters, shunts, or any other synthetic material in the body
Staphylococcus saprophyticus
Common case of UTI’s (urinary tract infection)
Staphylococcal Scalded Skin Syndrome
SSSS AKA Ritters disease
Caused by toxins
Staphylococcal Food Poisoning
Most Common Food Poisoning
Due to intoxication by an enterotoxin
Heat stable toxin
Coagulase positive staphylococcal infections
due to actual infection by Staphylococcus aureus.
Furuncles, Carbuncles, and wound infections
Bacteremia
Bacteria in blood.
Janeway lesions
Subacute Bacterial Endocarditis
Staphylococcal Pneumonia
Not common!
Empyema
Walled off area of consolidation.
Pus in lung
Osteomyelitis
Infection of the bone
Septic Arthritis
arthritis due to infection
Mechanically abnormal joints
Patients with prosthetic joints
Endocarditis
S. epidermidis may colonize heart valves that are damaged.
Staphylococcus sapropphyticus
UTI especially in sexually active young women.
CA-MRSA
community aquired MRSA. kills white blood cells, more dangerous.
Severe skin and soft tissue infections
Streptococcus
Gram + cocci
Beta hemolysis
complete hemolysis, strep
alpha hemolysis
incomplete hemolysis
Omega hemolysis
no hemolysis
Normal Viridans
Strep mutans
Dental
M proteins
Specific cell-wall protein found in virulent streptococcus
Inhibits phagocytosis
Tampon toxic shock caused by
Staph
C5a peptidase
degrades complement molecule..
Reduces chemotaxis and activation of inflamatory cells
Pharyngitis
strep throat
Streptococcus pyogenes
causes strep throat and scarlet fever
Scarlet fever
complication of streptococcal pharyngitis.
sunburn like rash
Necrotizing fasciitis
streptococcal gangrene
flesh eating bacteria, strains of strepp pyogenes (group A strep)
Streptococcal toxic shock syndrome (TSS)
includes bacterimia and necrotizing fasciitiis
Rheumatic Fever
Aschoff bodies are lesions in Heart Tissue.
Dammage heart valve.
Sydneham’s chorea
involuntary, purposeless contractions of the muscles of the trunk, extremeties, face. Caused by rheumatic fever
Acute glomerulonephritis
Complication of a prior Strep Pyogenes pharyngeal or cutaneous infection elsewehre in body
Group B strep
Cause of puerperal sepsis
Most common cause of meningitis, septicimia, and infectious death in newborns
Viridans streprococci
Not on skin!
Streptococcus pneumoniae
opportunistic
Encapsulated strains produce alpha hemolysis
Nonencapsulated are nonvirulent
Secretory IgA protease
Cleaves IgA found in mucous
gains access to lower respiratory tract.
Strep pneumoniae
found in throat and nasopharynx of normal healthy people.
Non encapsulated
Pneumococcal Meningitis
Strep pneumonia is a major cause in adults and children
Enterococcus
Normal flora of human gut.
Preciously Group D strep
Able to grow in bile
Resistent to all known antibiotics.
Categories: Microbiology