BB Ch 12; microbiological quality control Flashcards Preview

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Flashcards in BB Ch 12; microbiological quality control Deck (48)
1

define gnotobiotic

have a completely defined microflora

2

define SPF

free from infection with a defined list of infectious agents

3

what are the characteristics used to distinguish pathogenic bacteria and fungi from commensal and autochthonous (indigenous)

their ability to cross anatomic and biochemical barriers to establish themselves in niches devoid of other microorganisms

4

ls it some common bacterial pathogens found in rodent species

Salmonella, mycoplasma pulmonis, helicobacter hepaticus, clostridium piliforme

5

list some opportunistic bacterial pathogens found in rodent species

Pseudomonas aeruginosa, B hemolytic streptococci, Staphylococcus aureus, and Pneumocystis

6

what does SOPF stand for? why is it significant?

specific opportunistic pathogen free. free of opportunistic as well as primary pathogens

7

what is the most effective "gold standard" for rederivation of mice?

embryo transfer, the zona pellucida that surrounds embryos and oocytes excludes pathogens

8

food is typically heated to what temp during pelleting?

75-80 C

9

gamma radiation of food is performed using what source?

cobalt 60 source

10

UV radiation of supplies is done at what wavelength?

210-328 nm, peak DNA absorption is 260nm

11

limitations of UV radiation

UV light source loses intensity or becomes dirty and by the presence of particles and dissolved organics in water. does not pass through solid objects

12

limitations of radiosensitivity?

correlates with genome volume and the ability of the organism to repair DNA damage. small viruses such as parvoviruses are highly resistant to UV and gamma irradiation, as are bacterial spores, protozoan cysts, and vegetative bacteria with highly efficient DNA repair.

13

give some examples of denaturant disinfectants?

quaternary ammonium compounds
phenolics
alcohols

14

give some examples of reactant disinfectants?

aldehydes
ethylene oxide

15

give some examples of oxidant disinfectants?

halogens (chlorine bleach, chlorine dioxide)
peroxygens (vapor phase H2O2, virkon S)

16

mechanism of action for phenolics and quaternary ammonium compounds

disrupt lipid membranes, potent against lipophilic (paramyxo, corona, arena) viruses than hydrophilic

17

mechanism of action of oxidants?

attack all organic compounds, inactivate hydrophilic (picorna, parvo) as well as lipophilic viruses

18

what tests are traditionally used to screen rodent biologicals for rodent viruses? and how is this test performed?

mouse or rat antibody production tests
SPF rodents are inoculated with the test article orally and parenterally, held in isolation for a month, and tested by serology for antibodies to rodent viruses.

19

define direct health monitoring

testing is performed on specimens from the principle/resident colony

20

define indirect health monitoring

testing is performed on dedicated animals that have been exposed to the principle/resident colony or their bedding or environment

21

what is considered the gold standard for detecting helminth infections?

low power dissecting microscopy of macerated GI tract, ie direct microscopic examination

22

what is the sensitivity of gross and microscopic examination of lesions?

low, lesions must be present at high concentrations to be observed

23

efficacy of transimission of mite infections via soiled bedding?

mites are NOT transmitted well between animals via soiled bedding

24

MacConkey's agar contains what additive, and this additive has what effect?

crystal violet and bile salts, inhibit growth of gram + bacteria while allowing most gram - bacteria to grow

25

what enrichment broth is used to recover salmonella from feces or the intestinal tract?

selenite broth

26

what are the conditions that most cultures are incubated at?

aerobically at 35-37C

27

what are some fastidious lab animal pathogens for which other identification methods are most ideal?

Mycoplasma pulmonis, Helicobacter, Clostridium pilliforme, CAR bacillus, Pneumocystis.
PCR and/or serology are more often used

28

what are two ways to identify a bacterial colony from culture?

create a biochemical profile
PCR

29

what does MALDI-TOF MS stand for

matrix assisted laser desorption ionization time of flight mass spectrometry

30

what does MFIA stand for, how does the test work?

multiplexed fluorometric immunoassay, antigen is covalently coupled to beads of a specific color, antigen-antibody complexes form during serum incubation, incubated with biotinylated anti-species immunoglobulin. Lastly, the complex is incubated with there is a phycoerythrin streptavidin conjugate for color development

31

define sensitivity

the number of known positive samples that are classified correctly

32

define specificity

the number of known negative samples that are classified correctly

33

if you increase the cutoff values what changes about specificty or sensitivity

you increase the specificity (decreases number of false positives, however increase the number of false negatives)

34

if you decrease the cutoff values, what changes about the specificity or sensitivity?

you increase the sensitivity (increase number of false positives)

35

a high specificity test is used to detect pathogens with a high/low prevalence?

low/rare pathogens (avoid false positives)

36

a high sensitivity test is used to detect pathogens with a high/low prevalence?

high/common pathogens (avoid false negatives)

37

define analytical specificity

the ability of an assay to distinguish target from nontarget analytes

38

define a selective assay

one with the capacity to resist matrix-mediated effects, such as sample mediated inhibition of PCR, nonspecific binding of serum antibodies

39

define an inclusive assay

detect related organisms of interest

40

define an exclusive assay

describes a test able to differentiate an infectious agent from others that are closely related

41

what is the component of the assay for a serologic test that determines the analytical specifity of that assay?

the antigen bound to the immunoassay solid phase

42

what is the component of the assay for PCR that determines the analytical specificity of that assay?

the genomic sequence to which the primers anneal

43

formula for positive predictive value

TP/(TP+FP)

44

how do you calculate the KP (number of known positives)

number tested * prevalence

45

how do you calculate the KN (number of known negatives)

#tested- KP or (# tested * (1-prevalence))

46

how do you calculate the number of tested positives

KP*sensitivity

47

how do you calculate the number of false positives

KN* (1-specificity) or KP-true positives

48

how do you calculate the number of tested negatives

KN*specificity