Day 5: Introduction Bacteriology and Diagnosis Flashcards
HC12, 13
1
Q
HC12: Microbiome
A
Human-associated microorganisms
> 4* 10^13
> 500-1000 different species
2
Q
There are different microbiota on different parts of the body, why?
A
- Temperature
- Moisture
- more location specific factors
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
4
Q
Balance microbiota should be towards…
A
Commensals and not pathogens
5
Q
Pathogen
A
Microorganism causing disease
6
Q
Commensal
A
Microorganism in symbiotic relationship with host
7
Q
Commensialism
A
Presence microorganisms multiplying in host without damage and reaction from the host (no advantage or disadvantage for host)
8
Q
Infection
A
Presence (invasion) of microorganisms multiplying in the host, with damage to and reaction of the host
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
10
Q
Carrier
A
Host that harbors potential pathogen without disease
11
Q
Pathogenicity
A
Ability to produce disease in host organism
12
Q
Virulence
A
The degree of pathogenicity of the microbe
13
Q
Virulence factor
A
Microbial component that contributes to disease-making ability
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
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
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
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
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
19
Q
Tropism types
A
Cellular, tissue and host tropism
20
Q
Virulence factors S. aureus: toxins
A
- Cytolytic toxins: tissue destruction/abscess formation
- Enterotoxins (A-E): toxicity
- Exfoliative toxin: blistering: loss of desmosomes
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
22
Q
Enterotoxin A from S. aureus (food poisoning) is resistant to:
A
Heat and low pH.
> gastrointestinal
23
Q
Sources SSSS and S. aureus food poisoning
A
Infected wound
Contaminated processed food
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
25
Normal vs hampered immune response
Immunosuppressed individuals (AIDS, cytostatica) have lower burden for colonization for the opportunistic bacteria
26
Neisseria meningitidis and streptococcus clinical pictures are ...
Similar
> completely different causative agents
> both the throat as natural habitat
27
N. meningitidis character
- Gram negative diplococcus (coccus form)
- Humans are only natural host
> can cause meningitis and sepsis
28
Vaccination campaign N. meningitidis
Target: polysaccharide capsule
> first against serotype C (based on capsule polysaccharide group C)
> now MenACWY
> serologic reactivity polysaccharide: groups A, B , C, Y, W
29
Gram positive bacterium
Purple on gram staining
> one cell membrane and thick peptidoglycan cell wall layer around it
30
How are the gram positive cocci genuses staphylococcus and streptococcus distinguished
- Staphylococcus: Catalase positive
- Streptococcus: Catalase negative
31
Staphylococcus species classification
- Coagulase positive: S. aureus
- Coagulase negative: CONS like S. epidermidis
32
Streptococcus species classification
- 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
Gram negative
Two cell membranes with thin peptidoglycan layer between them (in periplasmic space)
> pink on gram stain
34
Name of bacteria
Genus name Species name
35
Typhi is the result of ..
Some salmonella species
36
Clostridium species character
Can form spores and survive most extreme envirnoments
37
Infection and transmission > results
Transfer microorganisms from one place to another
> possible multiplication
> possible damage
> possible reaction of the host
38
Ways of transmission
- Direct: person-to person or droplet (saliva)
- Indirect: fecal-oral (contaminated food), airborne (aerosol), fomites (infected objects)
- Vector: insect bite
39
Zoonosis
Infection through contact with animals
> both directions possible
> like ebola virus disease and salmonellosis
40
HC13: Biofilms
Bacteriën gaan zo organiseren dat ze een eigen taak hebben (op plastic of geïnfecteerde protehese)
41
Diversiteit en volhardendheid van bacteriën
- Biofilms
- Resistentie
- Lastig te behandelen
- Problemen zoals opnieuw opereren
42
Gramkleuring bacteriën
Positief: violet
Negatief: roze
43
Uitspraak bacterienamen
Klemtoon op twee na laatste lettergreep
44
Rangschikking bacteriën
Ketens: streptococcus
Tros: staphylococcus
45
Vorm bacteriën
Kok of staaf
46
Indeling bacteriën op metabolism
- Facultatief
- Strikt aeroob / non fermenters
- Anaeroben
47
Gramkleuring Clostridioides difficile en Escherichia coli
C. difficile > positief
E. coli > negatief
48
Hoe kweken anaerobe bacteriën
Apparatuur en reagentia om luchtdichte potten mt kweekplaten zuurstofvrij te maken
49
Betrokkenheid van bacteriën is afhankelijk van locatie: in de keel
- Vergroenende streptococcen (non hemolytisch)
- Hemolytische streptokok
- anaeroben
- gram negatieve flora
- gisten
50
Darmen bacteriën
- Gram negatieve staven
- Anaeroben
- Enterokokken
- Gisten
51
Gewicht feces is .... aan bacteriën
1/3
> hoog dragerschap en kolonisatie
52
Diagnose bacterie: de bron
Patientenmateriaal
> bloed, urine, feces, wond uitstrijk, sputum, neuskeelspelsel, BAL (longspoeling), catheter tip, IUD, heupkop
53
Determinatie bacterie
*species* genus
54
Resistentiebepalingen staan in een ...
antibiogram
> voor welke antibiotica resistentie en gevoeligheid
55
Diagnose op welke vlakken?
- Determinatie
- Resistentiebepaling
- Virulentiefactoren: hoe pathogeen
- Clusteranalyse: verwantschap
56
Diagnostiek: microscopie
- Directe kleuring patientenmateriaal
> of kleuring bacteriële isolaten na kweek
- Kleuringen
> kleuring
> fluorescentie
> immuunfluorescentie met specifieke antilichamen
>> techniek afhankelijk van celwand
57
Gramkleuring inhoudelijk
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
Gramnegatieve staven vaak bij ..
Urineinfecties
59
Locatie van de kweek beïnvloedt de ..
gebruikte kweekmedia
60
Determinatie bacterie
Massaspectrometrie
> MALDI-TOF
> Laser: ionisatie > door buis heen
> tijd tot detector geeft massa
> call voor een bepaalde bacterie door software
61
Oude determinatie: bonte rij
Pak kolonie en doe in buizen
> in elke buis, bepaald substraat en indicator
> in stoof
> kleurtje: beslisboom gebruiken in boek en classificatie
62
Geautomatiseerde bonte rij
Alles in well plates
> kleurencode in lab en afgelezen
> biochemische eigenschappen gebruikt voor determinatie
63
Antibiogram maken
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
MIC bepaling
Bepalen minimal inhibitory concentration
> gebruik plaatjes met antibioticum en gradient
> minimale concentratie voor resistentie
65
Resistentie mechanismen
- Intrinsieke resistentie
- Verandering antibioticum target
- Enzymproductie
- Lagere permeabiliteit celwand
- Efflux mechanismen
66
Waarom antibioticum met ijzermineraal erin?
Verleiden bacterie om het op te nemen
67
Toepassing verkregen resultaat antibiogram
> naar arts en RIVM
> hoge incidentie resistentie: minder antibioticum geven > adviezen op RIVM
> gaat per centrumL infecties en resistenties verschillen per medisch centrum
68
Empirische antibioticakuur
Starten met antibiotica zonder kennis van veroorzaken micro-organismen, in afwachting van kweekuitslagen, op basis van RIVM cijfers
69
Serologie
Detectie antigen / antilichamen in patientenmateriaal
70
Agglutinatietesten
- Antistoffen tegen deel antigenen bacterie samenbrengen
- Soms ter determinatie
- Meerdere antigeen en antistof complexen moeten bundelen
71
Lateral flow assay
Corona zelftest of zwangerschapstest
> membraan met antilichaam voor toxines van bepaalde bacterie/virus
72
PCR test
Voor virale infecties handig, lastig te kweken, of lastige bacterien
73
Sequentie analyse
Determinatie
> resistentiemechanismen voor specifieke genen
> clusteranalyse: verwantschapsonderzoek
