Week Four: Introduction to Microbiology

Introduction to Microbiology

I.               Microbiology

a.     The study of microbes

b.     2 Types

                                               i.     Medical

1.     Host response

2.     Diagnosis

3.     Pathogens

                                              ii.     Non-medical

1.     Animal

2.     Plant

3.     Industrial

c.      Microbes

                                               i.     Bacteria

1.     1-8µ in size

2.     Phenotype classification

a.     External structures

                                                                                                     i.     Flagella

1.     Movement with chemical signals

2.     Highly antigenic

                                                                                                    ii.     Pili

1.     Fimbria

2.     Thin, more numerous, for sticking to stuff

                                                                                                  iii.     Capsule

1.     Very virulent

2.     Non antigenic

3.     No host immune response

b.     Shapes

                                                                                                     i.     Cocci – round

                                                                                                    ii.     Baccili – rod

                                                                                                  iii.     Coccobacilli – very short rods

                                                                                                  iv.     Spirochaetes – spiral or coiled

                                                                                                    v.     Vibrios – commas

c.      Gram staining

                                                                                                     i.     Discovered by Gram

1.     Peptidoglycan – thick in gram +, thin in gram -

a.     Positive=violet

b.     Negative=pink

2.     Acid fast – pink

3.     Non acid fast - green

d.     Culture characteristics

                                                                                                     i.     Hemolysis

                                                                                                    ii.     Pigment

e.     Biotyping

                                                                                                     i.     Biochemical reactions

f.      Serotyping

                                                                                                     i.     Antibody and antigen reactions

g.     Antibiogram

                                                                                                     i.     Antibiotic discs

h.     Phage typing

                                                                                                     i.     Outdated

i.       Genotypic classification

                                                                                                     i.     through genetic differences

                                                                                                    ii.     PCR

                                                                                                  iii.     Rickettsia

1.     Must live in cells

2.     Behave like viruses

3.     Gram negative

                                                                                                  iv.     Genus species- Genus capitalized, species lowercase, all italicized

                                              ii.     Viruses

1.     Needs electron microscopy

a.     Not a cell

b.     May have lipid envelope over protein coat

c.      Strictly intracellular

d.     DNA or RNA

e.     Use cells to replicate

f.      CMI effective

                                            iii.     Protozoa

1.     Single cell

2.     Parasite

3.     Mostly free living

                                            iv.     Helminths

1.     Worms

2.     Macroscopic

                                              v.     Fungi

1.     Yeasts

a.     Oval, round, budding

b.     Rigid cell wall

2.     Molds

a.     Rigid cell wall

b.     Fillamentous

                                            vi.     Microbe Human Host Relationships

1.     Commensals – normal flora

2.     48-72 hours commensals change completely

3.     Short term commensals that become infectious