Microbiology: Bacteria Background

• Function:
• -rigid support
• -protects against osmotic pressure

• Chemical composition:
• -sugar backbone, cross linked peptide side chains (by transpeptidase)

• -outer layer in GRAM POSITIVE
• -major surface antigen
• -contains lipoteichoic acid (induces TNF and IL1)

• -outer layer in GRAM NEGATIVE
• -Site of endotoxin (LPS)

• -Lipid A: induces TNF and IL1
• -O polysaccharide: antigen
• 

50S and 30S subunits

• -GRAM NEGATIVE
• -space btwn the cytoplasmic membrane and outer membrane
• -contains beta lactamases

• -protects against phagocytosis
• -made of polysaccharides (except B. anthracis, which is made of protein)

• -adherence to cell surface
• -sex pilus during conjugation

-resistant to dehydration, heat and chemicals

-contains genes: abx resistance, enzymes, toxins

• -adherence to surfaces (esp foreign surfaces)
• -polysaccharide

Protein A: binds Fc region of Ig and prevents opsonization and phagocytosis (S. aureus)

• IgA Protease: cleaves IgA to colonize respiratory mucosa
• "SHiN"
• S pneumo
• H influenza
• Neisseria

M protein: helps prevent phagocytosis (Group A strep)

• GRAM POSITIVE ONLY: lipoteichoic acid
• GRAM NEGATIVE ONLY: Endotoxin/LPS, Periplasmic space

• Staphylococcus
• Streptococcus

Neisseria

• Clostridium
• Corynebacterium
• Bacillus
• Listeria
• Mycobacterium (acid fast)
• Gardnerella (Gram variable)

• "CEEK ShYPS"
• Campylobacter
• E. Coli
• Enterobacter
• Klebsiella

• Shigella
• Yersinia
• Proteus
• Salmonella

• Serratia
• Vibrio
• Helicobacter
• Pseudomonas
• Bacteroides

• Haemophilus
• Legionella
• Bordetella

• Francisella
• Brucella
• Pasteurella
• Bartonella

• Actinomyces
• Nocardia

• Rickettsiae
• Chlamydiae

• Spirochetes:
• Leptospira
• Borrelia
• Treponema

Mycoplasma

"These Rascals May Microscopically Lack Color"

• Treponema (thin)
• Rickettsia (intracellular)
• Mycobacteria (high lipid content)
• Mycoplasma (no cell wall)
• Legionella (primarily intracellular)
• Chlamydia (intracellular)

"Certain Bugs Really Try my Patience)

• Chlamydia
• Borrelia
• Rickettsiae
• Trypanosomes
• Plasmodium

"PASs the sugar"

Stains glycogen

Used to diagnose Whipple Disease

Acid fast organisms

• Mycobacterium
• Nocardia

Cryptococcus neoformans

• Fungi (pneumocystis)
• Legionella
• H. pylori

H flu: Chocolate agar (Factors V = NAD+, X = hematin)

Neisseria: Thayer Martin (Vancomycin, Polymyxin, Nystatin)

Bordetella pertussis: Bordet-Gengou (potatoe agar)

C. diphtheriae: Tellurite plate, Loffler's media

M. tuberculosis: Lowenstein-Jensen agar

M. pneumoniae: Eaton's agar

Lactose fermenting enterics: pink on MacConkey's agar

E Coli: EMB agar (green metallic sheen)

Legionella: charcoal yeast agar buffered with cysteine and iron

Fungi: Sabouraud's agar ("Sab's a fun guy!")

"Nagging Pests Must Breathe"

• Nocardia
• Pseudomonas aeruginosa
• Mycobacterium tuberculosis
• Bacillus

"Anaerobes Can't Breathe Air"

• Clostridium
• Bacteriodes
• Actinomyces

• -Lack catalase and/or superoxide dismutase
• -Generally foul smelling
• -difficult to culture
• -produce gas in tissue (CO2, H2)
• -normal flora in GI tract, pathogenic elsewhere

"AminO₂glycosides are ineffective against anaerobes because these abx require O₂ to enter bacterial cell"

"Stay inside when it is Really Cold"

• Rickettsia
• Chlamydia
• (can't make own ATP)

"Some Nasty Bugs May Live FacultativeLY"

• Salmonella
• Neisseria
• Brucella
• Mycobacterium
• Listeria
• Francisella
• Legionella
• Yersinia

• Positive quellung reaction
• "Quellung = capsular swellung"

• "SHiNE SKiS"
• Strep pneumo
• H influenza B
• N. meningitidis
• E coli

• Salmonella
• Klebsiella
• Strep (Group B)

Opsonized then cleared by spleen

Asplenia at increased risk: vaccinate!

• You need PLACESS for your cats"
• Pseudamonas
• Listeria
• Aspergillus
• Candida
• E Coli
• S. aureus
• Serratia

Catalase degrades H2O2

People with chronic granulomatous disease (NADPH oxidase deficiency) have recurrent infections with these organisms

protein conjugated to polysccharide capsule antigen (allows presentation to T cells --> class switching)

• Pneumovax (no conjugated protein)
• Prevnar (conjugated)
• HIB (conjugated)
• Meningococcal (Conjugated)

"CHuck Norris hates PUNKSS"

• Cryptococcus
• H. pylori
• Proteus
• Ureaplasma
• Nocardia
• Klebsiella
• S. epidermidis
• S. saprophyticus

• Actinomyces israelii: yellow sulfur granules
• "Israel has yellow sand"

• S.aureus: yellow pigment
• "aureus = Latin for gold"

• Pseudomonas aeruginosa: blue-green pigment
• "Aerugula is green"

• Serratia marcescens: red pigment
• "red maraschino cherries"

• -Gram positive and Gram negative bacteria
• -secreted from cell
• -polypeptide
• -genes in plasmid or bacteriophage
• -high toxicity (may be fatal)
• -induces antitoxins (antibodies)
• -toxoids used as vaccines
• -destroyed at 60C (except staph)

EG: tetanus, botulism, diphtheria

• -Gram negative outer cell membrane component
• -Not secreted from cell (released when lysed)
• -LPS
• -genes in bacterial chromosome
• -low toxicity (fatal at very high doses)
• -cause fever and shock
• -induces TNF and IL1
• -poorly antigenic
• -no vaccines
• -stable at 100C for 1 hour

EG: Meningococcemia, sepsis by GN rods

• -Diphtheria toxin (Cornebacterium diphtheria)
• -Exotoxin A (Pseudomonas)
• -Shiga toxin (Shigella)
• -Shiga-like toxin

-exotoxin

-in Corynebacterium diphtheriae

• Mechanism:
• -inactivate EF2

• Presentation:
• -Pharyngitis with pseudomembranes in throat and severe lymphadenopathy (bull neck)

-exotoxin

-in Pseudomonas aeruginosa

• Mechanism:
• -inactivates EF2

• Presentation:
• -Host cell death

-exotoxin

-in Shigella spp

• Mechanism:
• -inactivate 60S ribosome (remove adenine from rRNA)

• Presentation:
• -GI mucosal damage --> dysentery
• -enhance cytokine release --> HUS

-exotoxin

-in EHEC (including O157:H7)

• Mechanism:
• -inactivate 60S ribosome (remove adenine from rRNA)

• Presentation:
• -enhance cytokine release --> HUS

***unlike shigella EHEC doesn't invade host cells

• -Heat-labile toxin (LT)
• -Heat-stabile toxin (ST)
• -Edema factor
• -cholera toxin

-exotoxin

-in ETEC

• Mechanism:
• -overactivates AC --> increased cAMP --> increased Cl- secretion in gut

• Presentation:
• -watery diarrhea

"Labile in the Air (AC), Stable on the Ground (GC)"

-exotoxin

-in ETEC

• Mechanism:
• -overativates GC --> increased cGMP --> decreased resorption of NaCl in gut

• Presentation:
• -watery diarrhea

"Labile in the Air (AC), Stable on the Ground (GC)"

-exotoxin

-Bacillus anthracis

• Mechanism:
• -mimics AC --> increase cAMP

• Presentation:
• -characteristic edematous borders of black eschar in cutaneous anthrax

-exotoxin

-Vibrio cholerae

• Mechanism:
• -overactivates AC by permanently activating Gs --> increased cAMP --> increased Cl- secretion

• Presentation:
• -voluminous rice water diarrhea

-Pertussis toxin

-exotoxin

-Bordetella pertussis

• Mechanism:
• -overactivates AC by disabling Gi --> impaired phagocytosis

• Presentation:
• -Whooping Cough in children
• -100 day cough in adults

• -Tetanospasm
• -Botulinum Toxin

-exotoxin

-Clostridium tetani

• Mechanism:
• -cleave SNARE protein required for NT release
• -prevents release of inhibitory NTs (GABA and Glycine) in spinal cord

• Presentation:
• -muscle rigidity and "lock jaw"

-exotoxin

-Clostridium botulinum

• Mechanism:
• -cleave SNARE protein required for NT release
• -prevents release of stimulatory (ACh) release at NMJ

• Presentation:
• -Flaccid paralysis
• -floppy baby

• -alpha toxin
• -streptolysin O

-exotoxin

-Clostridium perfringens

• Mechanism:
• -phosophlipase: degrades tissue and cell membranes (PLC)

• Presentation:
• -"gas gangrene" and hemolysis (double zone of hemolysis on blood agar)

-exotoxin

-Strep pyogenes

• Mechanism:
• -protein that degrades cell membrane

• Presentation:
• -lyses RBCs --> beta hemolysis

*** host antibodies against toxin (ASO) used to diagnose rheumatic fever

• -Toxic Shock syndrome toxin 1
• -Exotoxin A'

-exotoxin

-Staph aureus

• Mechanism:
• -bring MHCII and TCR in proximity --> overwhelming release of IFNg and IL2

• Presentation:
• -TSS: fever, rash, shock

• Scalded Skin Syndrome (exfoliative toxin)
• Food Poisoning (enterotoxin)

-exotoxin

-Strep pyogenes

• Mechanism:
• -bring MHCII and TCR in proximity --> overwhelming release of IFNg and IL2

• Presentation:
• -TSS: fever, rash, shock

• -LPS
• -especially Lipid A

• Mechanism:
• 1. Activate macrophages
•      -IL1 (fever)
•      -TNF (fever, hypotension)
•      -NO (hyptension)
• 2. Activate C'
•      -C3a (hypotension, edema)
•      -C5a (NP chemotaxis)
• 3. Activates tissue factor
•      -coagulation cascade (DIC)

• "ENDOTOXIN"
• Edema
• NO
• DIC/Death
• Outer Membrane
• TNFa
• O-antigen
• eXtremely heat stable
• IL1
• Neutrophil chemotaxis

Lag Phase: metabolic activity without division

Exponential/Log Phase: rapid cell division (PCNs and cephalosporins act here)

Stationary Phase: nutrient depletion slows growth, spore formation in some bacteria

Death: prolonged nutrient depletion, waste products lead to death

-take up naked DNA from environment (ie: from lysis)

=competent

• Many bacteria including "SHiN":
• S pneumo
• H influenza
• Neisseria

• F⁺ x F^-
• -F⁺ can replicate (pilus)
• -plasmid (dsDNA) ONLY transferred

• Hfr x F^-
• -F⁺ plasmid incorporated into bacterial chromosome (high frequency recombination cell)
• -may also replicate flanking DNA-transfer of plasmid and chromosomal DNA

• -DNA segment that can "jump" locations
• -can transfer DNA from plasmid to chromosome and vice versa
• -may include flanking chromosomal DNA (potential transfer to another bacterium)

• 1. Generalized:
• -"packaging" event
• -lytic phage can lyse bacterial DNA
• -may be incorporated into viral capsid and be transferred to another bacteria

• 2. Specialized:
• -"excision" event
• -phage infects bacteria and incorporates into its DNA
• -when the virus removes its DNA it may take flanking DNA with it

Genes for 5 bacterial toxins encoded in a lysogenic phage:

"ABCDE"

• ShigA-like toxin
• Botulinum toxin
• Cholera toxin
• Diphtheria toxin
• Erythrogenic toxin (Strep pyogenes)