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Phase 2 > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Microbiology:

Define: Pathogen,
Commensal,
Opportunistic pathogen, Virulence/pathogenicity
and asymptomatic carriage

A

• Pathogen
Organism that causes or is capable of causing disease
• Commensal
Organism which colonises the host but causes no disease in normal circumstances
• Opportunistic Pathogen
Microbe that only causes disease if host defences are compromised
• Virulence/Pathogenicity
The degree to which a given organism is pathogenic
• Asymptomatic carriage
When a pathogen is carried harmlessly at a tissue site where it causes no disease

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2
Q

Microbiology:

Morphology of coccus/bacillus
Chains
Clusters
Curved rod? 
Spiral rod?
A

Coccus - ball
chain/clusters of cocci

Bacilllus - rod
Curved rod = vibrio
Spiral rod = spirochaete

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3
Q

Microbiology:

Normal sterile areas of the body

A

Lungs, kidneys, bladder, gall bladder, vasculature

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4
Q

Microbiology:
Gram staining
Purple?
Pink/red?

A 
Purple = Gram positive (thick layer of peptidoglycan absorb stain)
Pink/red = Gram negative (thin layer due to 2 membranes)
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5
Q

Microbiology:

Test for mycobacterium?(tuberculosis)

A

Ziehl-neelsen stain

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6
Q

Microbiology:

Endotoxin vs Exotoxin 
What is it? 
Gram +/-?
Heat stable?
Antigenicity?
Can you make a toxoid?
A

Endotoxin - bacterial membrane component e.g. lipopolysaccharide Gram NEGATIVE
Heat stable
weak antigenicity
No toxoid

Endotoxin - secreted proteins both Gram +ve and -ve (mainly +ve)
Unstable in heat
Strong antigenicity
CAN BE MADE INTO A TOXOID VACCINE

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7
Q

Microbiology:

Bacterial gene transfer?
3 methods

A

Transformation - DNA transfer via plasmids

Bacterial conjugation - sex pilus

Transduction - Phages transfer genetic material

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8
Q

Microbiology:

Gram positive bacteria:
Staphylococcus
+ve coagulase?
how is it spread?

Virulence factors?
TSST?

A

S. aureus
- spread by aerosol and touch (carriers and shedders)

Virulence factors:

  • Pore forming toxins
  • Proteases
  • Toxic shock syndrome toxin (TSST)
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9
Q

Microbiology:

What is MRSA multi-resistant s. aureus resistant to?
Treatment?

A

Beta-lactams
Gentamycin
Erythromycin
Tetracycline

Treatment = vancomycin

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10
Q

Microbiology:

Gram positive bacteria:
Staphylococcus
-ve coagulase?

A

S. epidermidis (biofilms)

S. saprophyticus (acute cystitis)

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11
Q

Microbiology:
Clusters or chains?

Staphylococcus
Streptococcus

A

Staphylococcus = clusters

Streptococcus = chains

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12
Q

Microbiology:
Clusters or chains?

Staphylococcus
Streptococcus

A

Staphylococcus = clusters

Streptococcus = chains

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13
Q

Microbiology:

Strep classification steps
-Haemolysis alpha or beta?

A

Alpha = partial, greening of blood agar plate

Beta = complete haemolysis clean strip around bacteria on BA

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14
Q

Microbiology:

Streptococci examples:

  • Causes tonsillitis, cellulitis, impetigo
  • Causes pneumonia and meningitis
  • Oral Strep/Dental
A

1) S. pyogenes
2) S. pneumoniae
3) Viridan’s streptococci (alpha haemolytic)

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15
Q

Microbiology:

Streptococci examples:

  • Causes tonsillitis, cellulitis, impetigo
  • Causes pneumonia and meningitis
  • Oral Strep
A

1) S. pyogenes
2) S. pneumoniae
3) Viridan’s streptococci (alpha haemolytic)

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16
Q

Microbiology:

Corynebacterium diphtheriae
Type of vaccine?
Toxin?

A

Toxin inhibits protein synthesis

Vaccine is a toxoid

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17
Q

Microbiology:

Gram negative bacteria:
Lipopolysaccharide
Endo or exotoxin
Which part of LPS is toxic?

A

Endotoxin

Toxic part is the lipid in the outer membrane

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18
Q

Microbiology:

Agglutination test: antiserum to detect cell antigens
H - antigen is?
A - antigen is?

A 
H-antigen = flagellum
A-antigen = polysaccharide
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19
Q

Microbiology:

Strains;
ETEC? toxins?
EHEC? toxin?
EPEC?

Which is the most pathogenic?

Pedestal ones?

A

ETEC = Enterotoxigenic E. coli – travellers diarrhoea (heat liable and heat stable enterotoxins = Cl- efflux)

EHEC = Enterohemorrhagic E. coli - bloody diarrhoea (Shigella like toxin - SLT)

EPEC = Enteropathogenic E. coli
EHEC most pathogenic

EHEC and EPEC = pedestal formation

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20
Q

Microbiology:

Strains;
ETEC?
EHEC/EPEC
EHEC

A

ETEC = Entero-toxigenic E. coli – travellers diarrhoea

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21
Q

Microbiology:

Salmonella

3 forms of salmonellosis?

What they causes?
Dose needed?
How does it penetrate the intestinal epithelia?

A
  1. serovars enteritidis = gastroenteritis (food poisoning)
  2. serovars typhi/paratyphi = Enteric fever - TYPHOID

High infective dose needed
Penetrates through M-cells

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22
Q

Microbiology:

Salmonella

2 strains?
What they causes?
Dose needed?
How does it penetrate the intestinal epithelia?

A
  1. serovars enteritidis = gastroenteritis (food poisoning)
  2. serovars typhi/paratyphi = Enteric fever - TYPHOID

High infective dose needed
Penetrates through M-cells

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23
Q

Microbiology:

Funghi

Eukaryote or prokaryote? 
Cell wall? 
Heterotrophic
2 forms of funghi? 
are they budding/hyphea or spore forming
A

Funghi are eukaryote

Chitinous cell wall

Heterotrophic - need to acquire carbon

Moulds - spore forming and hyphae

Yeasts - budding

24
Q

Microbiology:

Fungal infections
Common not severe
Rarely severe

Athletes foot/fungal nail infections caused by?

A

“mycosis” = fungal infection

Onychomycosis = fungal nail infection
caused by dermatophyte moulds

25
Q

Microbiology:

Candidiasis?

A

Fungal infection caused by a yeast called Candida

Oral and Vaginal candida

26
Q

Microbiology:

Treatment for fungal infections?
difficult as eukaryotic cells are similar to our own cells

A
  • Echinocandins target cell wall
  • Polyenes
  • Azoles - pore forming by targeting cholesterol synthesising pathway
27
Q

Microbiology:

Principles of IPC (infection prevention control) - EPS?

A

Environment - cleaning, ward design
Patient - Isolation
Staff - PPE, isolation

28
Q

Microbiology:

example of commensal bacteria that can cause UTIs and Intra-abdominal infections
Resistant to?

A

“Coliforms” - Carbapenemase producing enterobacteriaceae

Colonise the skin below the waist, large bowel and most
of the body

Resistant to carbapenems and other beta lactams

29
Q 
Microbiology: 
what kills each of these? alcohol gel or hand washing?
Norovirus 
C. difficile
MRSA
A

Norovirus = hand washing
C. difficile = hand washing
MRSA = alcohol gel

30
Q

Microbiology

Virus - define
structure?
Are they living?

A

An infectious obligate intracellular parasite comprised of RNA/DNA surrounded by a protein coat

Not technically living

31
Q

Microbioogy:

Viral replication steps? (5)

A

1) Attachment
2) Cell entry
3) Host cell interaction + replication
o Translation of viral mRNA to produce structural proteins
4) Assembly of virion
5) Release of new virus particles

32
Q

Microbiology:

How do viruses cause disease? 5 ways
example for each?

A
  • destruction of host cells e.g. Polio
  • modification of host cell e.g. HIV?
  • Over-reactivity of immune system e.g. Hep B
  • Damage through proliferation e.g. HPV
  • Evasion of host defences e.g. Herpes zoster/virdae
33
Q

Microbiology:

Varicella and shingles? caused by what virus?

A 
Varicella zoster virus 
chickenpox in early life (varicella)
Shingles later (herpes zoster)
34
Q

Microbiology:

Protozoa is a..?
Classes? (4)

A

Single celled eukaryote

Amoeboids - pseudopodia
Ciliates - cilia movement
Sporozoa – non-motile
Flagellates – flagella

35
Q

Microbiology:

Geography!
African protozoa?
South/Central american protozoa?
Protozoa of poverty (asia, africa, south america)

A

African Trypanosomiasis ‘Sleeping sickness’ - Tsetse fly

American Trypanosomiasis ‘chagas disease’ - Triatomine bug

Leishmaniasis - female sand fly

36
Q

Microbiology:

Toxoplasma gondi infection?
Typical sign?
Pregnancy problem?

A

Toxoplasmosis

Ring enhancing lesion on CT scan

Foetus can develop retinal defects

37
Q

Microbiology:

Which Malaria strains have Dormant Human Liver Stages?
how long until relapse?

A

P. vivax and P. ovale

Relapse in weeks to years later

38
Q

Microbiology:

Malaria life cycle main stages?

A 
Injection of sporozites
Human liver stages leadsing to merozoite release (Schizont/Hypnozoites certain strains)
Asexual blood cycle
Production of gametocytes
Mosquito blood meal 
Vector stages
Re-injection
39
Q

Microbiology:

Blood stage - asexual blood cycle?

A 
Merozoites from hepatocytes/Erythrocytes (schizont) enter Erythrocytes 
Immature trophozoite
Mature trophozoite
Schizont formation 
Schizont rupture 
Cycle restarts
40
Q

Microbiology:

Malaria treatment

A

Antimalarials: Quinine, Doxycyclin

Primaquine - eliminates hypozoites in liver in P. vivax and P. ovale

41
Q 
Microbiology: 
Define: 
Pathogenicity
Infectivity
Virulence
Invasiveness
A

Pathogenicity - the disease producing capability of a pathogen

Infectivity - the ability to become established in the host

Virulence - the ability to cause harm once established

Invasiveness -

42
Q

Microbiology:

Viral infection
Humoral response effectors
Cell mediated response

A

Humoral:
Antibodies: Block viral binding (IgA), opsonization of virus, agglutination, neutralisation
Complement: Lysis,
Opsonization (C3b)

Cell mediated:
IFN - antiviral
NK cells + macrophages - ADCC Antibody dependent cellular cytotoxicity

43
Q

Microbiology:

What are adhesins
Biofilms

A

adhesins help bacteria bind to mucosal surfaces

Biofilms - bacteria secrete extracellular polymeric substance which allows them to stick on surfaces e.g. catheter

44
Q

Microbiology:

2 stages of infection?
What mediates each stage?

A

Blood stage = humoral immunity

Tissue stage = cell mediated immunity

45
Q

Microbiology:

Eosinophils are associated with which type of infectioN?
Which interleukin?

A

Eosinophils = parasitic infections

IL-5

46
Q

Microbiology:

Antibiotic targets with example: 
Beta lactams?
Glycopeptides?
Aminoflycosides? 
Tetracylcins? 
Macrolides?
A

Beta lactams - cell wall synthesis e.g. penicillins/aminopenicillins (amoxicillin)

Glycopeptides - Protein synthesis e.g. Vancomycin

Aminoglycosides - Protein synthesis e.g. Gentamycin

Tetracylcins - Protein synthesis e.g. Doxycylin

Macrolides - protein synthesis e.g. erythromycin, clarithromycin

47
Q

Microbiology:

Mycobacteria
which stain?
Mycobacteria OWA?

A

Mycobacteria = Ziehl Neelsen stain

“acid fast bacilli”

48
Q

Microbiology:

Characteristics of mycobacteria

A 
Aerobic
Lipid rich cell wall 
SLOW growing (insidious) 
Can't use gram stains
Granulomas
Dormancy
49
Q

Microbiology:

Mycobacterial disease immunology
Describe process

A

Phagocytosed by macrophages
Mycobacteria resistant to phagolysosomal killing
Antigens presented to T-cells
SIEGE to mycobacteria = granulomas
Mycobacteria then reduce metabolism to survive - dormancy

50
Q

Microbiology:

HIV phases

A

Acute primary infection
Asymptomatic phase (years)
Early symptomatic HIV “AIDs related complex”
AIDS - immune deficiency CD4+ <200

51
Q

Microbiology:

Marker of progression in HIV? (2)

A

Viral load

CD4+ T-cell count

52
Q

Microbiology:

AIDS infection phase = how many CD4+ cell count

A

<200 CD4+

53
Q

Microbiology:

Steps of HIV replication? (9)

A 
HIV replication: 
Attachment
Entry 
Uncoating 
Reverse transcription of vRNA 
Genome integration
Transcription of viral DNA
Splicing of mRNA
Assembly of new virions 
Budding
54
Q

Microbiology:

HIV evolved from?
CD4 or CD8 T-cell replication?
Which receptors allow binding?

A

HIV-1 is evolved from simian immunodeficiency virus in chimpanzees

CD4+ T-cells due to CD4 and CCR5 receptors

55
Q

Microbiology:

Varicella Zoster virus
Primary infection?
Secondary infection?

A

Primary infection = Varicella “chickenpox”

Secondary infection = Herpes Zoster shingles

56
Q

Microbiology:

Herpes viruses demonstrate…
Hide where?
Reactivation characteristic?

A

Dormancy
Viral dormancy in dorsal root or cerebral ganglion
Reactivation due to immunocompromisation and restricted to one dermatome usually

Phase 2 (4 decks)

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