Garlanda 2

Question 1

what should you consider when giving antimicrobial drugs

Answer 1

• spectrum of action
• growth of microbial populations
• phases of microbial growth

Question 2

susceptibility testing can be done

Answer 2

qualitatively, semiquantitatively, or using nuclei acid based methods

Question 3

what is synergy testing

Answer 3

testing to determine the effect of combining different antimicrobials

Question 4

3 tests for antimicrobial testing

Answer 4

• diffusion susceptibility test (aka kirbey bauer)
• Min inhibitory concentration test
• Min bactericidal concentration test

Question 5

how are results of qualitative tests given

Answer 5

susceptible (S)
intermediate (I)
resistant (R)

Question 6

what influences results of qualitative methods

Answer 6

pharmacokinetic, pharmacodyniamc, clinical and microbiological data

Question 7

Eg of synergism between two antimicrobial agents

Answer 7

amoxillin-clavulanic acid and aztreonam

Question 8

MIC test

Answer 8

is broth dilution test, where a standard amount of microorganisms are incubated with serial diluation of antimicrobial agents. the turbidity indicates bacterial growth

Question 9

How are results of MIC given

Answer 9

sensitive (s)
intermediate (i)
resistant (r)
nonsusceptible

Question 10

what is the Etest

Answer 10

it combines diffusion susceptibility and MIC tests (A plastic strip contains a gradient of the drug of interent). note that multiple antimicrobials can be tested at once on one plate

Question 11

what is MBC test

Answer 11

A semiquantitative space/ Where
samples from clear MIC tubes are tranferred in drug free growth medium. Broth dilution is the godl standard. It is used to discriminate bactericidal from bacteriostatic concentration of a drug

Question 12

nucleic acid based methods are for

Answer 12

detecting known resistance genes.
E.g. mecA and mecC for oxacillin resistant in S. aureus. (if present then its resistant to most B lactam drugs)
- carbapenemase genes in carbapenem resistant enterobactericeae

Question 13

the present of resistant genes means they uniformely confer in vivo resistance T/F

Answer 13

F

Question 14

nucleic acid methods are preferred for diagnosis of MDR TB

Answer 14

t

Question 15

define bacterial persistence

Answer 15

is when persistent cells do not proliferate in the presence of bactericidal agent, they are temporarily in a slow or non growing state, they are tolerant to bactericidal antibiotics. This contributes to the failure to treat chronic and relapsing infections

Question 16

Steps of bacterial persistance

Answer 16

(1) Bacterial persisters can arise stochastically in unstressed bacterial cultures.
(2) Environmental insults (i.e., starvation, oxidative and acid stress, heat shock)
provoke persister cell formation.
(3) Social engagement through quorum sensing promotes persister cell formation.
(4) Heterogeneous and diffusion-limited biofilm microenvironments enhance
persistence.
(5) Host-pathogen interaction also induces formation of persisters.

Question 17

what is cross resistance

Answer 17

it occurs when drugs are similar in structure, and the resistance to one drug confers resistance to a similar drug

Question 18

what are the 3 types of media for culturing viruses

Answer 18

• media with mature organisms
• embryonated eggs
• cell cultures

Question 19

recognition of viral growth in cell culture is done with

Answer 19

• cytopathic effect (morphological changes), inclusion bodies
• hemadsorption

Question 20

explain the cytopathic effect

Answer 20

a syncytium formation can occur in the case of measles virus, or there than be inclusion bodies present in a rabies patient

Question 21

know difference btw hemadsorption and hemagglutination

Answer 21

hemadsorption is when a virus infects cells expressing hemaglutinin and RBC’s attach to it
Hemagglutination is when RBC clump together into a lattice formation

Question 22

which viruses use enzyme immunoassay

Answer 22

EBV, HEPB, HEPE, HIV, human T lymphotropic virus

Question 23

serological tests are for which viruses

Answer 23

hepA and hepD

Question 24

nucleic acid based test are used for which viruses

Answer 24

HIV

Question 25

immunological tests use

Answer 25

antigens or antibodies (note that if the testing is delayed the specimen should be frozen or refrigerated to prevent overgrowth)

Question 26

which antibody rises first

Answer 26

IgM (IgG is the longer lasting one)

Question 27

serological tests are used to

Answer 27

monitor the spread of infection within a population, and establish the diagnosis of a disease

Question 28

spectrum of action definition

Answer 28

the # of different pathogens a drug acts against

Question 29

name a narrow spectrum drug

Answer 29

penicillin

Question 30

name a broad spectrum drug

Answer 30

tetracyclin

Question 31

Steps of binary fission

Answer 31

chromosome replication
cell elongation, chormosomes pushed apart
new cytoplasmic wall/septum
cell separation or cluster

Question 32

phases of microbial growth

Answer 32

lag (adaptation to new environment)
log (is the target for drugs, metabolic rate is high)
Stationary phase (the pop size is constant bc nutrients are depleted and wastes accumulate. Metabolic rate declines)
Death phase (cells die at a faster rate than they are produced)

Question 33

T/F susceptibility tests always predicts tx outcome

Answer 33

F

Question 34

what is synergy testing

Answer 34

testing to determine the effect of combining different antimicrobials

Question 35

MIC explained

Answer 35

same amount of bacteria is given different amount of antimicrobial. And then turbidity is tested to evaluate bacterial growth

Question 36

The major limitation for conventional AST

Answer 36

is the low sensitivity since they sense the change in bacterial pop but measuring optical density

Question 37

MIC is mainly used for

Answer 37

isolates of bacterial, including mycobacteria, anaerobes, fungi esp Candida

Question 38

T/F MIC can tell you the achievable tissue concentration of the free drug

Answer 38

T
Designations of S, I, and R derived from the MIC study correlate
with achievable serum, plasma, or urine concentrations of free
drug.

Question 39

microfluid techniques

Answer 39

microfluidic systems made it possible to
push the time requirements for culture-based ASTs to 1–3 h by
minimizing the bacterial incubation chamber to the single-cell level
and increasing the signal to background ratio in detecting the
variation of proteomes, metabolomes, genomes and/or
transcriptomes.
• The only information needed to determine antibiotic susceptibility
is whether the pathogen is dividing after the antibiotic is added.
• Therefore, some microfluidic-based methods have been developed
to observe bacterial division at early stages.
• The physical confinement of the pathogen in micro-channels allows
rapid ASTs on a time scale comparable to the doubling time of the
bacteria.
Microfluidic technologies for rapid antibiotic susceptibility tests (ASTs) at
the single-cell level, including both phenotypic analysis (microfluidic-based
single bacterial culture) and gene-based antimicrobial resistance (AMR)
detection (droplet digital analysis).