Microbiology 5

Question 1

what are the environmental control measures used to reduce risk of microbial contamination?

Answer 1

• clean room
• laminar flow cabinets
• isolaters
• air/water controls

Question 2

what are the personnel control measures used to reduce risk of microbial contamination?

Answer 2

• PPE

- hand hygiene (antisepsis)

Question 3

what are the other ways used to reduce risk of microbial contamination?

Answer 3

disinfection/antisepsis
- cleaning/disinfection of working enviro/personnel

sterilisation
- destruction of potential contaminants before release

preservation
- reduces risk of longer term contamination and spoilage

Question 4

how can the risk of contamination be reduced?

Answer 4

use

• bunsen burner
• biosafety cabinets
• laminar flow cabinets
• glovebox/isolator

Question 5

what is a bunsen burner used for?

Answer 5

heat sterilising metal and glass tools on lab bench

Question 6

give examples of how under normal conditions, working area will be constantly contaminated with microorganisms?

Answer 6

• free floating/ carried on dust particles

- personnel

Question 7

grades and C and D?

Answer 7

clean areas for carrying out less critical stages in manufacture of sterile products

Question 8

grade B?

Answer 8

in case of aseptic prep and filling, background enviro for grade A zone

Question 9

grade A?

Answer 9

local zone for high risk operations e.g. filling zone, open ampoules & vials, making aseptic connections

Question 10

which grade is more and less stringent?

Answer 10

grades C and D = less stringent

grade A = more stringent

Question 11

high efficiency particulate air (HEPA) filtration

Answer 11

removal of at least 99.97% of 0.3 micrometers diameter airborne particles

Question 12

what are the 2 standards for water in pharmaceutical manufacturing?

Answer 12

• purified

- water for injection

Question 13

purified water

Answer 13

non-sterile applications

• media prep
• basic prep e.g. cough syrup

Question 14

water for injection (WFI)

Answer 14

sterile applications

• stricter quality guidelines than purified water
• endotoxin levels

Question 15

how long can droplets remain in the air?

Answer 15

up to 2 hours

Question 16

what is the advantage of hand washing?

Answer 16

• reduces risk of transmission of contaminants between hands & products
• reduces risk of transmission to sterile gloves
• alcohol hand gel reduces bacteria number further

Question 17

give examples of protective equipment?

Answer 17

• gloves
• hairnets
• overshoes

Question 18

products sampling/clinical samples

Answer 18

• filtration
• direct inoculation

—> broth/agar

Question 19

environmental sampling

Answer 19

• surface swabbing
• contact plates
• air sampling
• liquid sampling

—> broth/agar

Question 20

serial dilution and plate counts

Answer 20

• only shows viable cells (CFU)

3 diff methods

• pour plate
• spread plate
• drop count

Question 21

optical density (OD) / turbidity

Answer 21

• counts everything

- inaccurate at high and low OD

Question 22

direct microscopy

Answer 22

total number of cells in defined area

Question 23

flow cytometry

Answer 23

uses fluorescence

Question 24

what does total microbial count use?

Answer 24

haemocytometer

Question 25

what does the total microbial coins enable?

Answer 25

counting of bacterial cells in known area
- need multiple fields of viewing

VERY TIME CONSUMING

Question 26

what does the total microbial count show? and what is it good for?

Answer 26

• intact bacterial cells
• good for difficult to culture and polymicrobial
• doesn’t show anything about viability

Question 27

what is the total viable count used for?

Answer 27

bacteria, yeasts and moulds

• can see individual
• count CFU

Question 28

for viruses, you don’t see colonies

what do you count instead?

Answer 28

plaque forming units (PFU)

• absence of growth (plaques)

Question 29

what percentage of human microbiota can be cultures?

Answer 29

1-5%

Question 30

formula to calculate CFU/mL?

Answer 30

number of colonies X (dilution in tubes X no. of aliquots in 1mL)

Question 31

what is the British pharmacopoeia?

Answer 31

• official standards for UK medicinal products & pharmaceutical substances
• specifies acceptable limits for microbial contamination of non-sterile products

Question 32

what do sterile products have to contain?

Answer 32

no microbial contaminants

Question 33

what is spoilage?

Answer 33

chemical and physiochemical deterioration

Question 34

what will the rate of breakdown depend on?

Answer 34

• molecular structure
• environmental conditions
• type and number of microbial contaminant

Question 35

give example of inactivation of a product?

Answer 35

penicillin breakdown by beta-lactamase

Question 36

give example of breakdown of thickening/suspending agents?

Answer 36

starch breakdown by amylase

Question 37

synthetic packing materials (e.g. nylon) are more … than naturally derived materials (e.g. cellophane)

Answer 37

resistant

Question 38

what can you add to resist spoilage?

Answer 38

preservatives

Question 39

the serious responses are from what?

Answer 39

injected products/ immunocompromised patients

Question 40

most serious effects are from contaminated injectable products.

what can this lead to?

Answer 40

• general bacteraemic shock

- death