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47 Cards in this Set
- Front
- Back
What are the 5 levels of susceptibility? |
highly susceptible, susceptible, resistant, highly resistant and extremely resistant |
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What microorganisms are highly susceptible to biocides? |
mycoplasmas |
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What microorganisms are extremely resistant? |
prions |
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What are disinfectants? |
antimicrobial agents applied to inanimate objects to destroy microorganisms |
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What are antiseptics? |
destroy microorganisms on living tissues |
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What are sanitizers? |
act to reduce the levels of microorganisms to safe levels, must kill 99.9% of all organisms |
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What are the 5 types of disinfectants? |
alcohols, aldehydes, oxidising agents, phenolics and QACs |
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What are the 10 types of biocides? |
Antiseptics, germicides, sterilizers, disinfectants, sanitizers, food preservatives, herbicides, pesticides, insecticides, fungicides |
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What is the target of biocides? |
non-specific |
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What do biocides do? |
damage cell membrane and react unspecifically with the functional groups of nucleic acids and proteins |
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What are biocides used for in agriculture? |
part of biosecurity measures in livestock production to prevent outbreaks of disease |
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What 5 biocide agents are often used? |
QACs, oxidising compounds, acid anionics, hypochloride and chlorine dioxide |
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What 5 cell components are targets for biocides? |
cell wall, cell membrane, cytoplasm, nucleus and ribosomes |
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What 4 biocides attack DNA? |
ethylene oxide, formaldehyde, hydrogen peroxide, pancreatic acid |
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What biocide attacks the nucleus outer coat? |
ozone |
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What 2 biocides attack the cortex, inner membrane and outer membrane? |
sodium hypochloride and iodine compounds |
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What part of the nucleus does hydrogen peroxide attack? |
cortex, inner membrane, outer membrane |
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What 4 ways is the nucleus affected by biocides? |
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 |
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What does infection with antibiotic resistant organisms lead to? |
prolonged duration, duration of illness, increased risk of mortality and morbidity and increased economic cost |
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How many antibiotic resistant illnesses are estimated in the US annually? |
76M, 325,000 hospitalisations, 5,000 deaths |
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What class of integrons are important for horizontal gene transfer? |
Class 1 |
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What causes horizontal gene transfer? |
plasmids and conjugative transposons |
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What are the 2 mechanisms of biocide resistance? |
target gene mutations and increase efflux pump activity |
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What 3 ways is resistance transferred? |
conjugation, transformation and transduction |
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What gene do class 1 integrons contain? |
qac gene |
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What does chlorhexidine do? |
denature cytoplasmic proteins and coagulate cell contents |
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What is the efflux pump of E.coli? |
RND (AcrAB-TolC) |
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What are QACs? |
quaternary ammonium compounds |
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What do QACs do? |
physically disrupt and partial solubilise cell and membrane |
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What does triclosan do? |
act in enoyl-acyl reductase encoded by fab1 |
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What efflux pump does triclosan act on? |
Fab1 enzyme |
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What does selection for biocide resistant mutants result in? |
cross-resistance to antibiotics |
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What can triclosan select for? |
MDR P. aeruginosa over-expressing MexCD and MexJK pumps, Salmonella over-expressing AcrAB |
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What can QAC select for? |
cross-resistance in S. aureus to FQ drugs related to increased expression of norA |
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What is triclosan used in? |
wide range of personal care products (toothpaste, soap) |
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What does chloroheximide interact with? |
negatively charged groups on bacterial cell surface |
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What reduces chloroheximide activity? |
organic matter |
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Why can chloroheximide not be tested using disc diffusion? |
low diffusion rate |
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What 2 microorganisms have shown to be resistant to chlorohexidine? |
Pseudomonas aeruginosa and Salmonella enterica |
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What is benzalkonium chloride used for? |
industrial biocides, topicl antiseptics, soaps, wet wipes, throat lozenges, disinfectants, algaecide and preservative in hygiene products |
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What determines benzalkonium chloride targets? |
concentration |
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What does benzalkonium chloride do in low conc? |
membrane active binding to anionic membrane site and disrupts osmoregulation, results in potassium leakage |
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What does benzalkonium chloride do in intermediate conc? |
perturb membrane physiologies by protein denaturation and disruption of membrane structure |
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What does benzalkonium chloride do in high conc? |
causes cytoplasmic protein coagulation, denaturation of proteins and inactivation of enzymes in microorganisms and fungi |
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What disinfectant factors cause failure of biocides? |
selected chemical ineffective against pathogen, too dilute, insufficient contact time, temp too low, relative humidity too low |
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What environmental factors cause failure of biocides? |
residual organic matter, improper application, lack of contact, biofilm, inactivation by residual soaps and detergents, unclean water |
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What is the EU biocidal product regulation? |
Biocides must not cause risk |