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Medical Microbiology > Day 5: Introduction Bacteriology and Diagnosis > Flashcards

Day 5: Introduction Bacteriology and Diagnosis Flashcards

HC12, 13

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1
Q

HC12: Microbiome

A

Human-associated microorganisms
> 4* 10^13
> 500-1000 different species

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2
Q

There are different microbiota on different parts of the body, why?

A
  • Temperature
  • Moisture
  • more location specific factors
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3
Q

Microbiota as source health and disease

A
  • Nutrition and metabolism of foods
    > breakdown of indigestivle polysaccharides
    > Production vitamin B and K
  • Maturation and instruction of immune system: and tolerance
  • Colonization resistance: protection against invaders
  • Potenital disease causing: risk infection
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4
Q

Balance microbiota should be towards…

A

Commensals and not pathogens

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5
Q

Pathogen

A

Microorganism causing disease

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6
Q

Commensal

A

Microorganism in symbiotic relationship with host

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7
Q

Commensialism

A

Presence microorganisms multiplying in host without damage and reaction from the host (no advantage or disadvantage for host)

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8
Q

Infection

A

Presence (invasion) of microorganisms multiplying in the host, with damage to and reaction of the host

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9
Q

Name 4 types of opportunistic commensals

A
  • Neisseria meningitidis: meningococcus
  • Streptococcus pneumoniae: causing pneumonia
  • Staphylococcus aureus: normally harmless in skin, can get into bloodstream when invasion
  • Group A Streptococcus: infection of throat which can get into blood: sepsis
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10
Q

Carrier

A

Host that harbors potential pathogen without disease

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11
Q

Pathogenicity

A

Ability to produce disease in host organism

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12
Q

Virulence

A

The degree of pathogenicity of the microbe

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13
Q

Virulence factor

A

Microbial component that contributes to disease-making ability

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14
Q

Different clinical pictures for infection S. aureus

A
  • Different factors of bacterium
  • Scalded skin syndrome
  • Food poisoning by the excreted toxins
    > bacteria can be killed by cooking food but toxins survive
  • same causative agent
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15
Q

Course of infection is determined by
1: Route of contamination and invasion of host
> name entries for S. aureus

A
  • Skin or mucous membrane > SSSS (staphylococcus scalded skin syndrome)
  • Transcutaneous: vectors, insects
  • Directly in bloodstream: needles
  • Airways > SSSS
  • Gastrointestinal > food poisoning
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16
Q

Pathogenicity: invasiveness and toxigenesis

A
  • Invasiveness
    > ability to invade tissues
    > colonization, bypass host defense
  • Toxigenesis
    > ability to produce toxins
    > exotoxins, endotoxins

> > Virulence factors

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17
Q

Course of infection determined by
1 Route of contamination and invasion of host
2 Properties of the microorganism
> name virulence factors

A
  • Adhesins
  • Invasins
  • Capsule (polysaccharide): prevent phagocytosis or decrease complement activation
  • Toxins
  • Enzymes
  • Pili: protein strands which point out for attachment
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18
Q

Different toxins in SSSS and S. aureus food poisoning

A

SSSS
> S. aureus secretes exfoliative toxins A and B
> disrupt desmosomes by binding them and unstick epithelial cells of skin
> bacteria from local infection
Food poisoning
> S. aureus enterotoxin A
> potent gastrointestinal exotoxins

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19
Q

Tropism types

A

Cellular, tissue and host tropism

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20
Q

Virulence factors S. aureus: toxins

A
  • Cytolytic toxins: tissue destruction/abscess formation
  • Enterotoxins (A-E): toxicity
  • Exfoliative toxin: blistering: loss of desmosomes
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21
Q

Virulence factors S. aureus: enzymes

A
  • Coagulase: blood clotting
    > reacts with prothrombin in blood > complex: staphylothrombin > enables enzyme to act as protease and convert fibrinogen to fibrin > blood clotting
  • Hyaluronidase, lipase, fibrinolysis: distribution pathogen in tissues
  • Catalase: prevent oxidative burst, catalyse hydrogen peroxide

> > diversity within one bacterial species

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22
Q

Enterotoxin A from S. aureus (food poisoning) is resistant to:

A

Heat and low pH.
> gastrointestinal

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23
Q

Sources SSSS and S. aureus food poisoning

A

Infected wound
Contaminated processed food

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24
Q

Course of infection determined by?

A

1 Route of contamination and invasion of the host
2 Properties of the microorganism
3 Properties of the host
> age
> healthy or reduced resistance
> vaccination

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25
Q

Normal vs hampered immune response

A

Immunosuppressed individuals (AIDS, cytostatica) have lower burden for colonization for the opportunistic bacteria

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26
Q

Neisseria meningitidis and streptococcus clinical pictures are …

A

Similar
> completely different causative agents
> both the throat as natural habitat

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27
Q

N. meningitidis character

A
  • Gram negative diplococcus (coccus form)
  • Humans are only natural host
    > can cause meningitis and sepsis
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28
Q

Vaccination campaign N. meningitidis

A

Target: polysaccharide capsule
> first against serotype C (based on capsule polysaccharide group C)
> now MenACWY
> serologic reactivity polysaccharide: groups A, B , C, Y, W

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29
Q

Gram positive bacterium

A

Purple on gram staining
> one cell membrane and thick peptidoglycan cell wall layer around it

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30
Q

How are the gram positive cocci genuses staphylococcus and streptococcus distinguished

A
  • Staphylococcus: Catalase positive
  • Streptococcus: Catalase negative
31
Q

Staphylococcus species classification

A
  • Coagulase positive: S. aureus
  • Coagulase negative: CONS like S. epidermidis
32
Q

Streptococcus species classification

A
  • Group alpha-hemolytics: make blood plate green because make hydrogen peroxide. Common in throat and mouth.
  • Group beta-hemolytics: make toxins to destroy blood cells in vitro
  • Group gamma-hemolytics: no hemolytic activity on blood plate
33
Q

Gram negative

A

Two cell membranes with thin peptidoglycan layer between them (in periplasmic space)
> pink on gram stain

34
Q

Name of bacteria

A

Genus name Species name

35
Q

Typhi is the result of ..

A

Some salmonella species

36
Q

Clostridium species character

A

Can form spores and survive most extreme envirnoments

37
Q

Infection and transmission > results

A

Transfer microorganisms from one place to another
> possible multiplication
> possible damage
> possible reaction of the host

38
Q

Ways of transmission

A
  • Direct: person-to person or droplet (saliva)
  • Indirect: fecal-oral (contaminated food), airborne (aerosol), fomites (infected objects)
  • Vector: insect bite
39
Q

Zoonosis

A

Infection through contact with animals
> both directions possible
> like ebola virus disease and salmonellosis

40
Q

HC13: Biofilms

A

Bacteriën gaan zo organiseren dat ze een eigen taak hebben (op plastic of geïnfecteerde protehese)

41
Q

Diversiteit en volhardendheid van bacteriën

A
  • Biofilms
  • Resistentie
  • Lastig te behandelen
  • Problemen zoals opnieuw opereren
42
Q

Gramkleuring bacteriën

A

Positief: violet
Negatief: roze

43
Q

Uitspraak bacterienamen

A

Klemtoon op twee na laatste lettergreep

44
Q

Rangschikking bacteriën

A

Ketens: streptococcus
Tros: staphylococcus

45
Q

Vorm bacteriën

A

Kok of staaf

46
Q

Indeling bacteriën op metabolism

A
  • Facultatief
  • Strikt aeroob / non fermenters
  • Anaeroben
47
Q

Gramkleuring Clostridioides difficile en Escherichia coli

A

C. difficile > positief
E. coli > negatief

48
Q

Hoe kweken anaerobe bacteriën

A

Apparatuur en reagentia om luchtdichte potten mt kweekplaten zuurstofvrij te maken

49
Q

Betrokkenheid van bacteriën is afhankelijk van locatie: in de keel

A
  • Vergroenende streptococcen (non hemolytisch)
  • Hemolytische streptokok
  • anaeroben
  • gram negatieve flora
  • gisten
50
Q

Darmen bacteriën

A
  • Gram negatieve staven
  • Anaeroben
  • Enterokokken
  • Gisten
51
Q

Gewicht feces is …. aan bacteriën

A

1/3
> hoog dragerschap en kolonisatie

52
Q

Diagnose bacterie: de bron

A

Patientenmateriaal
> bloed, urine, feces, wond uitstrijk, sputum, neuskeelspelsel, BAL (longspoeling), catheter tip, IUD, heupkop

53
Q

Determinatie bacterie

A

species genus

54
Q

Resistentiebepalingen staan in een …

A

antibiogram
> voor welke antibiotica resistentie en gevoeligheid

55
Q

Diagnose op welke vlakken?

A
  • Determinatie
  • Resistentiebepaling
  • Virulentiefactoren: hoe pathogeen
  • Clusteranalyse: verwantschap
56
Q

Diagnostiek: microscopie

A
  • Directe kleuring patientenmateriaal
    > of kleuring bacteriële isolaten na kweek
  • Kleuringen
    > kleuring
    > fluorescentie
    > immuunfluorescentie met specifieke antilichamen
    » techniek afhankelijk van celwand
57
Q

Gramkleuring inhoudelijk

A

Fixeren en dan kleuring
> crystal violet > joodoplossing > tegenkleuring
» werkt goed doordat het de biologie van de bacterie matcht
> kleur spoelt weg bij gramnegatief: geen binding peptidoglycaan

58
Q

Gramnegatieve staven vaak bij ..

A

Urineinfecties

59
Q

Locatie van de kweek beïnvloedt de ..

A

gebruikte kweekmedia

60
Q

Determinatie bacterie

A

Massaspectrometrie
> MALDI-TOF
> Laser: ionisatie > door buis heen
> tijd tot detector geeft massa
> call voor een bepaalde bacterie door software

61
Q

Oude determinatie: bonte rij

A

Pak kolonie en doe in buizen
> in elke buis, bepaald substraat en indicator
> in stoof
> kleurtje: beslisboom gebruiken in boek en classificatie

62
Q

Geautomatiseerde bonte rij

A

Alles in well plates
> kleurencode in lab en afgelezen
> biochemische eigenschappen gebruikt voor determinatie

63
Q

Antibiogram maken

A

Kaart met read gemaakt
> zuigt vacuum
> wells met antibioticum en verschillende concentraties op well
> in draaimolen
> gaan bacteriën groeien of niet
> scannen en detectie
> kaart is vooraf gemaakt met de antibiotica erin

64
Q

MIC bepaling

A

Bepalen minimal inhibitory concentration
> gebruik plaatjes met antibioticum en gradient
> minimale concentratie voor resistentie

65
Q

Resistentie mechanismen

A
  • Intrinsieke resistentie
  • Verandering antibioticum target
  • Enzymproductie
  • Lagere permeabiliteit celwand
  • Efflux mechanismen
66
Q

Waarom antibioticum met ijzermineraal erin?

A

Verleiden bacterie om het op te nemen

67
Q

Toepassing verkregen resultaat antibiogram

A

> naar arts en RIVM
hoge incidentie resistentie: minder antibioticum geven > adviezen op RIVM
gaat per centrumL infecties en resistenties verschillen per medisch centrum

68
Q

Empirische antibioticakuur

A

Starten met antibiotica zonder kennis van veroorzaken micro-organismen, in afwachting van kweekuitslagen, op basis van RIVM cijfers

69
Q

Serologie

A

Detectie antigen / antilichamen in patientenmateriaal

70
Q

Agglutinatietesten

A
  • Antistoffen tegen deel antigenen bacterie samenbrengen
  • Soms ter determinatie
  • Meerdere antigeen en antistof complexen moeten bundelen
71
Q

Lateral flow assay

A

Corona zelftest of zwangerschapstest
> membraan met antilichaam voor toxines van bepaalde bacterie/virus

72
Q

PCR test

A

Voor virale infecties handig, lastig te kweken, of lastige bacterien

73
Q

Sequentie analyse

A

Determinatie
> resistentiemechanismen voor specifieke genen
> clusteranalyse: verwantschapsonderzoek

Medical Microbiology (11 decks)

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