Microbiology - General Bacteriology, Gram Positive , Mycobacteria Flashcards
What structures are unique to gram-positive organisms?
Lipoteichoic acid (combination of lipids and techoic acid)
What structures are unique to gram-negative organisms?
Endotoxin/LPS (outer membane)
Periplasm
Peptidoglycan
gives rigid support, protects against osmotic pressure
composed of sugar backbone with peptide side chains cross-linked by transpeptidase
Cell wall/cell membrane (gram-positives)
major surface antigen.
Peptidoglycan for support. Lipoteichoic acid induces IL-1 and TNF
Outer membrane (gram negatives)
site of endotoxin (lipopolysaccharide [LPS]); major surface antigen
Plasma membrane
site of oxidative and transport enzymes
-made of phospholipid bilayer
Ribosome
protein synthesis
- made up of 50S and 30S subunits
Periplasm
- unique to gram negatives
- space between cytoplasmic membrane and outer membrane in gram-negative bacteria
- contains many hydrolytic enzymes, including B-lactamases
Capsule
protects against phagocytosis
-composed of polysaccharide (except Bacillus anthracis, which contains D-glutamate)
Pilus/fimbria
mediate adherence of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation
- made of glycoprotein
Flagellum
- used for motility
- composed of protein
Spore
resistance to dehydration, heat, and chemicals
- keratin-like coat; dipicolinic acid
peptidoglycan
Plasmid
contains a variety of genes for antibiotic resistance, enzymes, and toxins
Glycocalyx
mediates adherence to surfaces, especially foreign surfaces (e.g. indwelling catheters)
- composed of polysaccharide
Pleomorphic bacteria
Ricksettsiae (Giemsa)
Chlamdyiae (Giemsta)
Branching filamentous bacteria
Actinomyces
Nocardia (weakly acid fast)
Bacteria with no cell wall
Mycoplasma (does not gram stain)
Bacteria with unusual cell membranes/walls
Mycoplasma - contains sterols and have no cell wall
Mycobacteria - contain mycolic acid. High lipid content
Bacteria that don’t Gram stain well
“These Rascals May Microscopically Lack Color”
TREPENOMA (too thin) RICKETTSIA (intracellular parasite) MYCOBACTERIA (high lipid content in cell wall detected carbolfuscin) MYCOPLASMA LEGIONELLA CHLAMYDIA
Culture for H. influenza
Chocolate agar with factors V (NAD+) and X (hematin)
Culture: N. gonorrhoeae, N. meningitidis
Thayer Martin (or VPN) media - Vancomycin inhibits gram positive, Polymixin inhibits gram negative organisms except Neisseria, and Nystatin (inhibits fungi)
Culture for B. pertussis
Bordet-Gengou (potato) agar
Culture for C. diptheriae
Tellurite plate, Loeffler’s media
Culture: M. tuberculosis
Lowenstein-Jensen agar