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MICRO 442 > MICROM 442 ch 8-10 > Flashcards

MICROM 442 ch 8-10 Flashcards

1
Q

-broth microdilution
-disk diffusion
-gradient strips (Etests)

A

phenotypic testing methods

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2
Q

-PCR
-Sequencing

A

genotypic testing methods

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3
Q

-antibody-based detection (lateral low immunochromatographic assays)
-microscopy + machine learning

A

other testing methods

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4
Q

-“gold standard”
-double dilutions of antibiotics in each well + standard inoculum of bacteria into each well
-measure MIC e.g. 2µg/mL

A

broth dilution

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5
Q

-automated, high-output formats for clinical testing
-multiwell can fit many antibiotics
-colorimetric or fluorescent indicators to read bacterial growth
-instruments with automated readers»>

A

Antibiotic susceptibility testing (AST)/phenotypic -> broth microdilution

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6
Q

-bacteria lawn
-nitrocellulose strip with continuous gradient of bacteria
-measure MIC where ellipse of growth inhibition meets the strip
-interpret MIC according to same ranges as broth dilution

A

AST/phenotypic -> gradient strips (Etests)

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7
Q

-bacterial lawn
-paper disks with antibiotic placed on top
-antibiotics diffuse into agar
-standard single concentration used for each antibiotic
-does NOT give MIC
-does give S, I, R

A

AST/phenotypic -> disk diffusion

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8
Q

-for genes with good predictive value ie correlate with phenotypic
-look for presence/abscence of resistant gene
-vanA and vanB for VRE
-mecA for MRSA
-look for presence/absence of mutation associated with resistance e.g. rpoB for rifampin-resistant mycobacterium tuberculosis

A

AST/genotypic -> PCR

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9
Q

genotypic methods struggle more with predicting MIC which is

A

sometimes neeeded for theraputic dosing

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10
Q

sometimes genotype does not easily predict phenotypic resistance in particular

A

GN organisms may harbor multiple, complicated, resistance mechanisms including mutations involving membrane permeability

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11
Q

-to detect PBP2a from staphylococcus aureus
-mecA encodes PBP2a
-PBP2a positive = MRSA
-quick results directly from colony

A

antibody-based detection -> (lateral flow immunochromatographic assays)

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12
Q

-image bacteria challenged with antibiotic
-use machine learning to correlate growth patterns with susceptibility or resistance

A

digital microscopy

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13
Q

standardization for accurate AST determined by:

A

-FDA
-clinical & laboratory standards institute
-European committee on antimicrobial susceptibility testing

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14
Q

Reproducibility between labs and methods

A

-strict quality control standards
-guidelines for variable like media, drug concentration, incubation conditions (metabolism effects)

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15
Q

Ranges determined by many factors:

A

-pharmocokinetic/pharmacodynamic parameters
-site of infection (eliminated/spread differently)
wild-type MIC conditions
-clinical outcome studies (expected survival of patient at certain MIC)
-re-reviewed and revised every so often

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16
Q

site of infection

A

-some drugs [x] in urine
-some drugs inactivated by surfactants in the lungs
-some drugs are better/worse for penetrating the blood brain barrier

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17
Q

treatment considerations

A

-administration
-therapeutic drug monitoring informs dosing
-interxns with other drugs
-toxic side effects
-coverage for infections with multiple organisms
-site of infection
-allergies

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18
Q

administration

A

inhalation, topical, IV, oral

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19
Q

toxic side effects

A

-nephrotoxicity (kidneys)
-ototoxicity (deafness)

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20
Q

empiric therapy

A

broad-spectrum antibiotics

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21
Q

targeted therapy

A

narrow-spectrum antibiotics

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22
Q

meropenem is a

A

broad-spectrum antibiotic

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23
Q

ampicillin is a

A

narrow-spectrum antibiotics

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24
Q

local antibiograms can help

A

guide empiric treatment and are HOSPITAL SPECIFIC

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25
Q

antibiograms track

A

% susceptibility for the most common organisms

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26
Q

other treatment considerations:
SOURCE CONTROL

A

-surgically draining an abscess
-removing infected hardware (prosthetic devices, catheters, central lines, BIOFILMS!!)
-removing infected tissue (necrotic tissue + amputation)

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27
Q

Infections prevention and control

A

major hospitals have formal infection prevention and control programs led by nurses and physicians with certification or special training

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28
Q

tracking hospital-associated infections

A

-hospital environment
-patient to patient or patient to employee
-hospital procedures

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29
Q

standard precautions

A

-hand hygiene, disinfection, PPE

30
Q

transmission-based precautions

A

-isolation and contact precautions
-resistant organism screen
-VRE, MRSA, multi-drug resistant organisms

31
Q

surveillance and public health

A

-tracking and surveillance
-outbreak investigations -> contact tracing and sequencing
-diagnostic testing

32
Q

higher rates of enerobacteriales bacteria in…

A

areas with lower median incomes, lower high school education diplomas, less insurance coverage, limited English proficiency

33
Q

IMP

A

imipenem-resistant metallo-beta-lactamase

34
Q

cefiderocol has a

A

siderophore portion which binds free iron

35
Q

gram positive cocci (GPC)

A

-most form chains
-diplococci
-bullet-shaped/ lancet shaped

36
Q

GPC

A

-aerotolerant anaerobe
-obligate fermenter
-does not respire only ferments

37
Q

catalase negative

A

distinguish from other GPC

38
Q

species differentiation of GPC

A

-hemolysis on blood agar
-cell wall (lancefield) antigens
-biochemical tests, antimicrobial susceptibility, etc.

39
Q

streptococcus

A

alpha-hemolysis -> GREEN
-viridans group streptococci common normal oral microbiota occasional opportunists
-streptococcus pneumoniae

40
Q

group A streptococcus (GAS)

A

-beta-hemolysis
-streptococcus pyogenes
-YELLOW

41
Q

Other streptococci (S. bovis group)

A

NO HEMOLYSIS

42
Q

Cell wall (lancefield) antigens

A

-species specific carboydrate antigens
-GAS vs GBS

43
Q

GBS

A

streptococcus agalactiae

44
Q

streptococcus pneumoniae

A

-GP cocci
-alpha hemolytic on blood agar
-polysaccharide capsule -> MAJOR VIRULENCE FACTOR
-100 different serotypes

45
Q

Viriddans group streptococci (VGS)

A

-GP cocci in pairs/short chains
-can be alpha, beta or non-hemolytic
-bad taxonomy!
-S. MUTANS GROUP WHAT WE CONCENTRATE ON

46
Q

catalse test used to

A

distinguish streptococci from other species

47
Q

pneumococcal disease

A

refers to disease caused by streptococcus pneumoniae or pneumococcus

48
Q

pneumococcal disease causes a range of diseases like

A

-mild: ear infections, sinusitis
-serious: pneumonia, meningitis, bloodstream infections

49
Q

pneumococcal pneumoniae

A

most common cause of community-acquired (CA) pneumonia in older adults; infants at risk

50
Q

pneumococcal pneumoniae symptoms

A

cough, fatigue, fever, chills, sweats, shortness of breath

51
Q

symptoms of PP worse for smokers, people with asthma, respiratory issues and

A

often follows viral respiratory infections e.g. influenza

52
Q

transient (bacteremia)

A

immune system not working so bacteria overcomes it

53
Q

transient (bacteremia)

A

sepsis, septic shock

54
Q

pneumococcal disease causes

A

-bacteremia
-meningitis

55
Q

meningitis

A

-swelling in protective lining around brain and spinal cord
-children and elderly more susceptible

56
Q

streptococcus pneumoniae is what type of anaerobe

A

aerotolerant

57
Q

streptococcus pneumoniae has a polysaccharide capsule and

A

100 antigetically distinct serotypes

58
Q

streptococcus pneumoniae is naturally

A

COMPETENT, takes up DNA from environment

59
Q

streptococcus pneumoniae THIN capsule when

A

binding to host cells (colonizes in the nasopharynx mucosal surfaces)

60
Q

streptococcus pneumoniae THICK capsule when

A

breaking through capsule of nasal epithelium

61
Q

pneumolysin (Ply)

A

-produced as soluble toxin monomer -> binds to membrane cholesterol -> forms large pores by oligomerization of up to 50 monomers (30nm)
-kills cells directly
-can induce an inflammatory response

62
Q

s. pneumoniae is extracellular or intercellular pathogen?

A

EXTRACELLULAR

63
Q

disease occurs when

A

bacteria gain access to sterile sites

64
Q

s. pneumoniae transmission

A

-direct: respiratory droplets, aerosols, coughing, sneezing
-indirectly via fomite -> objects
-increased mucus production e.g. during viral infections and allergies

65
Q

s. pneumoniae role of pneumolysin

A

induces inflammation in nasopharynx -> inc. in mucus production

66
Q

s. pneumoniae capsule is required for

A

-invasion -> prevents phagocytosis by INHIBITING OPSONIZATION
-prevents complement and Fc from interacting with receptors of phagocytic cells ie evading host defenses

67
Q

s. pneumoniae role of pneumolysin in pathogenesis

A

-damages mucociliary escalator -> inhibits cilia beating -> holes
-disrupts alveolar epithelium and adema fluid accumulates in alveolar space -> fluid build up
-recruitment of inflammatory cells
-damages cells in BBB -> meningitis

68
Q

s.pneumoniae diagnosis

A

-gram stain
-antimicrobial susceptibility
-blood agar (alpha-hemolytic)
-blood, CSF, sputum, etc.
-urine antigen test detects C polysaccharide (present in all serotypes)

69
Q

viridan group streptococci -> s. mutans and s. sorbinus are

A

-early colonizers of oral cavity, main contributors to dental caries (cavities)
-uses sucrose to produce glucans (EXC polysacchar.) which enhances attachment to tooth enamel
-grow well in low pH

70
Q

infective endocarditis parthenogenesis

A

-pathogens gain access to bloodstream
-rapidly adhere to injured or inflamed valve surface
-pathogens grow on/in endothelium -> vegetation forms on valve
-vegetation can embolize/move elsewhere and colonize other parts of body

MICRO 442 (25 decks)

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