The bacteria basics Flashcards
Peptidoglycan
repeating disaccharide base w aa side chains that are cross linked by the enzyme Transpeptidase (blocked by PCN)
- Transpeptidase = “PCN-binding-protein”
- Peptidoglycan cell walls allow bacteria to survive osmotic stres! Give PCNs, cephalosporins, or Vanco to take away this defense - bacteria would disintegrate in hypotonic solution.
Catalase+
You need PLACESS for your CATs
Pseudomonas Listeria Aspergillus Candida E.coli Staph Serratia
Obligate aerobes
Nagging Pests Must Breathe
Nocardia
Pseudomonas aeruginosa
Mycobacterium
Bacillus
Aerobe in burns wounds, diabetes, nosocomial pneumonia, Pneumonia in CF
Pseudomonas Aeruginosa (obligate aerobe)
Capsule of D-glutamate (i.e. made of aa residues)
Bacillus anthracis
unique. Other capsules are made of sugar
Periplasm enzyme
Beta-lactamases
LPS
Gram-negative outer membrane
more inside: Lipid A (induces TNF and IL-1)
Outer: O-polysaccharide (antigen)
Gram + cell wall
Peptidoglycan (support) + Lipotechoic acid (induces TNF and IL-1)
Pilus/fimbria
Mediates adherence of bacteria to cell surface
Sex pilus: connect bacteria during conjugation
-Made of glycoprotein
-E.g. Meningococcal pili - responsible for epithelial attachment to nasopharynx**
Flagella
Motility
-made of protein
Spore
Resistant to dehydration, HEAT, chemicals
- Keratin-like coat*, dipicolinic acid, peptidoglycan
- Spores form when shortage of nutrients –> lie dormant for years
- Kill w STEAM
Bacillus (aer) and Clostridium (anaer)
found in soil
Plasmid
DNA
contains genes for antibiotic resistance, enzymes, toxins
Glycoclayx
Mediates adherence to surface (like pilus) esp foreign ones (catheters!!!)
-made of polysaccharide (like pilus)
Obligate Anaerobes
Can’t Breathe Air
Clostridium
Bacteroides
Actinomyces
Do not gram stain well
These Rascals May Microscopically Lack Color
Treponema (too thin) Rickettisa (intracellular) Mycobacteria (high lipid) Mycoplasma (no cell wall) Legionella pneumophila (intracellular) Chlamydia (intracellular, lacks muramic acid in cell wall)
Silver stain
Legionella, Helicobacter pyloria, Fugni (e.g. Pneumoncystis)
Dark-field microscopy and fluorescent AB staining
Treponema
Giemsa stain
Certain Bugs Really Try my Patience
Chlamydia Borrelia Rickettsia Trypanosomes Plasmodium
PAS stain (periodic acid-schiff)
PASs the SUGAR (glycogen)
Stain glycogen, mucopolysaccharides
-Use to diagnose Whipples (Tropheryma whipplei)
Ziehl-Neelsen (carbolfuchsin**) stain
Acid fast organisms (Nocardia, Mycobacterium)- stains mycolic acid