General Bacteriology

Question 1

cell wall of gram positive

Answer 1

peptidoglycan,
teichoic acid,
Carbohydrates
Proteins
Lipids
waxes

Question 2

Cell wall of gram negative

Answer 2

Peptidoglycans
LPS
porins

Question 3

Cytoplasmic membrane

Answer 3

2/3 protein
1/3 lipids
no sterols
phospholipids
energy prodution, invaginations

Question 4

Nuclear material

Answer 4

single chromosome 1-2mm, superhelix

haploid ring

Question 5

Capsule, components

Answer 5

Polysaccharide, 
hyaluronic acid
polypeptide
in order of commonness 
glycocalyx

Question 6

How do you examin unstained live bacteria?

Answer 6

Hanging drop or wet chamber

Question 7

Why can’t you examine a bacteria unstained?

Answer 7

They have no cell material thus no contrast material, except ribosomes

Question 8

What is simple staining

Answer 8

Staining which reacts with all microbes in an identical fashion, increases contrast

Question 9

Differential staining methods

Answer 9

Gram - blue or pink
Ziehl neelson - red or blue mycobacterium
Koster - red brucella
Stamp - chlamydia chlamydophila

Question 10

Gram staining

Answer 10

Nacl
Crystal violet - 3-5
lugol 1-2
96% alcohol 5-6 drops
fuchsin 0.5-1min

Question 11

Ziehl Neelsen

Answer 11

Strong carbol fuchsin heat three times
wash
sulphuric 5% alcohol 96%
wash methylene blue 1-2min
wash
red is positive blue negative

Question 12

Components of a bacteria

Answer 12

85-90% water
2-15% proteins or minerals
2-40% waxes/lipids
upto 50% carbs, higher in gram negative

Question 13

Things that help move materials across bacterial membranes

Answer 13

Porin protiens
permease
extracellular enzymes

Question 14

Autotrophic bacteria

Answer 14

Utilize INORGANIC C&N
all saprophytes
Phototropic - chloroplasts, upper layer of fresh/salt water
Chemotropic - Oxidates inorganic material, make nitrogen usable for plants, nitrobacter, or found in deep water.

Question 15

Heterotrop bacteria

Answer 15

Majority saprophytes but all pathogenic bacteria are heterotropic
ORGANIC Carbon demand
INORGANIC N, amino acids or proteins

Question 16

What are paratropic bacteria

Answer 16

Cannot be cultured on artificial media need unknown addatives

Question 17

Addatives some bacteria need

Answer 17

NAD, haemophilus/actinocacillus - Vfactor
Haem, haemophillus - Xfactor
Mycobactin, mycobacterium avium ssp. PTB
DNA hydrolisate, Mycoplasm

Question 18

Products of nitrogen metabolism

Answer 18

Amines - histamine, cadaverine, putrescene
Keto- acids
Acids - lactic, acetic, butyric and valeric
NH3, CO2, H2O, H2,H2S idole

Question 19

Detection f nitrate metabolism

Answer 19

Nitrate reduction - illosvay reagent
Urease production - carbamide
Phenylalanine deaminase - phenyl pyruvic acid
H2S production
Indole production - kovacs reagent tryptophan to indole
lysine decarboxylase

Question 20

Aims of culturing

Answer 20

Diagnostic - isolation
Vaccine production
industry - food fermentaion, antibiotics

Question 21

How do you classify media

Answer 21

Aim - common, selective or differential
State - solid, semi solid or liquid
Origin - natural artificial or synthetic

Question 22

What is the difference between selective and differential culture

Answer 22

Selective contains antibiotics or other material to inhibit the growth of unwanted bacteria
Differential is an indicator due to biochemical reactions on the media. often containing fermentable sugars and a PH indicator

Question 23

Name some artificial cultures

Answer 23

Nutrient
Blood - differential 10% ox/ov blood, chocolate 80deg x 20min
MacConkeys - selective, bile salts and crystal violet
Lactose +
Salt Mannitol - 10% NaCl staphylococcus selective

Question 24

Culture additives

Answer 24

C source - saccharides, glycosides, alcohols
N source - anorganic N like ammonium salts or nitrates, AA - peptone or triptone
Native protein
Viatmins - B1/2 lactobacilli
V/X factor haemophilus

Question 25

Demands of a disinfectant

Answer 25

``` Low cost Broad spectrum Not toxic to host or env homogenous, odourless, soluable, stable good penetrance detergent effect not corrosive ```

Question 26

Factors influencing the effectivity of a disinfectant

Answer 26

``` Temperature increases effectivity Duration of contact Concentration of dissinfectant Nature of surface PH Bacterial resistance Amount of bacteria ```

Question 27

Characterisation of disinfectant activity

Answer 27

``` Side effects Species killed Species inactivated Speed Phenol coefficient ```

Question 28

Groups of disinfectants

Answer 28

``` Halogens Aldehydes Oxidative alcohols detergents phenol compounds acids alkalies dyes sterilising gases ```

Question 29

Principles of antibiotic therapy

Answer 29

``` Correct diagnosis Correct dosage duration Correct dose Usage of the most effective antibiotic Exceed ED in the infected tissue ```