Food Safety: Biocides

Front 1

What are the 5 levels of susceptibility?

Back 1

highly susceptible, susceptible, resistant, highly resistant and extremely resistant

Front 2

What microorganisms are highly susceptible to biocides?

Back 2

mycoplasmas

Front 3

What microorganisms are extremely resistant?

Back 3

prions

Front 4

What are disinfectants?

Back 4

antimicrobial agents applied to inanimate objects to destroy microorganisms

Front 5

What are antiseptics?

Back 5

destroy microorganisms on living tissues

Front 6

What are sanitizers?

Back 6

act to reduce the levels of microorganisms to safe levels, must kill 99.9% of all organisms

Front 7

What are the 5 types of disinfectants?

Back 7

alcohols, aldehydes, oxidising agents, phenolics and QACs

Front 8

What are the 10 types of biocides?

Back 8

Antiseptics, germicides, sterilizers, disinfectants, sanitizers, food preservatives, herbicides, pesticides, insecticides, fungicides

Front 9

What is the target of biocides?

Back 9

non-specific

Front 10

What do biocides do?

Back 10

damage cell membrane and react unspecifically with the functional groups of nucleic acids and proteins

Front 11

What are biocides used for in agriculture?

Back 11

part of biosecurity measures in livestock production to prevent outbreaks of disease

Front 12

What 5 biocide agents are often used?

Back 12

QACs, oxidising compounds, acid anionics, hypochloride and chlorine dioxide

Front 13

What 5 cell components are targets for biocides?

Back 13

cell wall, cell membrane, cytoplasm, nucleus and ribosomes

Front 14

What 4 biocides attack DNA?

Back 14

ethylene oxide, formaldehyde, hydrogen peroxide, pancreatic acid

Front 15

What biocide attacks the nucleus outer coat?

Back 15

ozone

Front 16

What 2 biocides attack the cortex, inner membrane and outer membrane?

Back 16

sodium hypochloride and iodine compounds

Front 17

What part of the nucleus does hydrogen peroxide attack?

Back 17

cortex, inner membrane, outer membrane

Front 18

What 4 ways is the nucleus affected by biocides?

Back 18

structural and functional alteration of virus-encoded enzymes and other virus proteins, functional alteration of nucleic acid, structural alteration or denaturation of capsid protein, structural alteration of envelope

Front 19

What does infection with antibiotic resistant organisms lead to?

Back 19

prolonged duration, duration of illness, increased risk of mortality and morbidity and increased economic cost

Front 20

How many antibiotic resistant illnesses are estimated in the US annually?

Back 20

76M, 325,000 hospitalisations, 5,000 deaths

Front 21

What class of integrons are important for horizontal gene transfer?

Back 21

Class 1

Front 22

What causes horizontal gene transfer?

Back 22

plasmids and conjugative transposons

Front 23

What are the 2 mechanisms of biocide resistance?

Back 23

target gene mutations and increase efflux pump activity

Front 24

What 3 ways is resistance transferred?

Back 24

conjugation, transformation and transduction

Front 25

What gene do class 1 integrons contain?

Back 25

qac gene

Front 26

What does chlorhexidine do?

Back 26

denature cytoplasmic proteins and coagulate cell contents

Front 27

What is the efflux pump of E.coli?

Back 27

RND (AcrAB-TolC)

Front 28

What are QACs?

Back 28

quaternary ammonium compounds

Front 29

What do QACs do?

Back 29

physically disrupt and partial solubilise cell and membrane

Front 30

What does triclosan do?

Back 30

act in enoyl-acyl reductase encoded by fab1

Front 31

What efflux pump does triclosan act on?

Back 31

Fab1 enzyme

Front 32

What does selection for biocide resistant mutants result in?

Back 32

cross-resistance to antibiotics

Front 33

What can triclosan select for?

Back 33

MDR P. aeruginosa over-expressing MexCD and MexJK pumps, Salmonella over-expressing AcrAB

Front 34

What can QAC select for?

Back 34

cross-resistance in S. aureus to FQ drugs related to increased expression of norA

Front 35

What is triclosan used in?

Back 35

wide range of personal care products (toothpaste, soap)

Front 36

What does chloroheximide interact with?

Back 36

negatively charged groups on bacterial cell surface

Front 37

What reduces chloroheximide activity?

Back 37

organic matter

Front 38

Why can chloroheximide not be tested using disc diffusion?

Back 38

low diffusion rate

Front 39

What 2 microorganisms have shown to be resistant to chlorohexidine?

Back 39

Pseudomonas aeruginosa and Salmonella enterica

Front 40

What is benzalkonium chloride used for?

Back 40

industrial biocides, topicl antiseptics, soaps, wet wipes, throat lozenges, disinfectants, algaecide and preservative in hygiene products

Front 41

What determines benzalkonium chloride targets?

Back 41

concentration

Front 42

What does benzalkonium chloride do in low conc?

Back 42

membrane active binding to anionic membrane site and disrupts osmoregulation, results in potassium leakage

Front 43

What does benzalkonium chloride do in intermediate conc?

Back 43

perturb membrane physiologies by protein denaturation and disruption of membrane structure

Front 44

What does benzalkonium chloride do in high conc?

Back 44

causes cytoplasmic protein coagulation, denaturation of proteins and inactivation of enzymes in microorganisms and fungi

Front 45

What disinfectant factors cause failure of biocides?

Back 45

selected chemical ineffective against pathogen, too dilute, insufficient contact time, temp too low, relative humidity too low

Front 46

What environmental factors cause failure of biocides?

Back 46

residual organic matter, improper application, lack of contact, biofilm, inactivation by residual soaps and detergents, unclean water

Front 47

What is the EU biocidal product regulation?

Back 47

Biocides must not cause risk