Bacteriology

Question 1

Name three slow growing Mycobacterium

Answer 1

M.tuberculosis complex
M.avium-intracellulare
M.leprae

Question 2

Clinical features of mycobacteria?

-air, motility, staining, growth, colours

Answer 2

Microaerophilic, aerophilic
Weak gram + 
Acid fast bacilli staining- ZN STAINING
Slow growing
Fastidious
Photo/scoto/non-chromagen
Rod shape

Question 3

Why is mycobacteria wall naturally resistant to many antibiotics?

Answer 3

High lipid content; hard for drug to enter

Question 4

How does mycobacterium cell wall assist to resist immune system?

Answer 4

Survive phagocytosis
Avoid complement reaction
Impermeable cell wall

Question 5

Five organisms that form M.Tuberculosis complex?

Answer 5

M.tuberculosis
Africanum
Cannetti
Bovis
Microti

Question 6

What could reactivate latent TB?

Answer 6

HIV. Diabetes, immunosuppression, tobacco,

Question 7

What is the target of elimination?

Answer 7

No animal no environmental reservoir

Question 8

Two dominant problems with TB?

Answer 8

TB-HIV in Africa

MDR-TB in Former Soviet Union

Question 9

What does DOTS stand for?

Answer 9

Directly observed therapy shortcourse

Question 10

Name three environmental mycobacteria.

Answer 10

M.Ulcerans
Marinum
Avium

Question 11

What does M.ulcerans cause? How can we treat?

Answer 11

Analgesia from mycolactone. Affects Angiotensin pathway.

Streptomycin

Question 12

M.Marinum characters?

Answer 12

Photochromagen
Traumatic abscesses
Rapid growing

Question 13

How does M.Avium spread and what are the consequences?

Answer 13

Air
Slow growing
Nonchromagen
Lymphadenitis in immune competent child
Lung disease in adults with already lung disease

Disseminated disease in HIV

Question 14

What are the two animal mycobacteria?

Answer 14

M. Bovis and avium

Question 15

Syphilis is caused by what bacteria?

Answer 15

Treponema pallidum

Question 16

What does T.p.endemicum/ pertenue/ carateum cause?

Answer 16

Bejel
Yaws
Pinta

Question 17

How is Syphilis transmitted?

Answer 17

Mostly MEM

HETEROSEXUAL

Question 18

Describe the structure of T. Pallidum

Answer 18

Helical
Axial filament- motile
Gram-
Low surface protein 
No LIPOPOLYSACCHARIDES

Question 19

Why is T.pallidum so difficult to study?

Answer 19

Microaerophillic
Cant be cultured
Slow growing
Infectiousness lost within 2days of harvest

Question 20

Why is T. Pallidum so fussy?

Answer 20

Small genome
No oxidase or catalase
Poor metabolism
No heat shock protein

Question 21

Is T.pallidum invasive? How does it do it?

Answer 21

Highly invasive
Fibronectin binding proteins present for adhering
Propels by rotation along axis using endoflagella (axial filaments)

Question 22

How does T.Pallidum evade immune system?

Answer 22

Sits in immune privileged site -eye & bone

Independent from iron
Low immunogenicity since no LPS
CHANGES ANTIGENICS

Question 23

What is ID50 mean?

Answer 23

No of organisms needed to infect 50% of host

Question 24

Define clinical stages of syphilis

Answer 24

Contact with T.pallidum
Primary (ulcer, painless, genital)
Secondary (rashes, alopecia. Eyes and neurological)
Immune clearance causes Latency
Tertiary (neurological, cardiovascular, gummatous, destroys joints)

Question 25

Why cannot T.pallidum can be molecularly typed?

Answer 25

Cannot be sustained in artificial culture Serology will not discriminate between strains

Question 26

What is Arp and Tpr used for typing system of T. Pallidum?

Answer 26

Arp is ACIDIC REPEAT P Determine the size of gene and calculate how many repeats TPR is Treponema pallidum repeat Nested pcr and analyse the type 14f

Question 27

What sequence does enhanced typing sequence?

Answer 27

Tp0548

Question 28

What is the current treatment for syphilis?

Answer 28

Penicillin No resistance

Question 29

Can you use macrolide for Syphilis?

Answer 29

No | Macrolide resistance due to point mutation

Question 30

Name three staphylococcus species?

Answer 30

S.Aureus Epidermidis Saprophyticus

Question 31

What is the characteristic of staphylococci?

Answer 31

Round Gram+ Cluster Non motile

Question 32

What does all pathogenic staphylococci secrete in common?

Answer 32

Catalase | Converts h2o2 into h2o and o2

Question 33

How can you distinguish between S.aureus and the other two?

Answer 33

Coagulase test Coagulase cleaves prothrombin to thrombin causing blood clotting ProteinA: bind to inhibit antibodies Clumpingfactor A clumps blood plasma Mannitol: certain sugars are used

Question 34

Compare staphylococci and streptococci

Answer 34

Staphylococcus in clusters 3D and has catalase Streptococcus in chain, no catalase

Question 35

Name 3 toxin-mediated disease by staphylococcus

Answer 35

Gastroenteritis By enterotoxins ‘superantigen’ TSS toxic shock syndrome By TSST1 superantigen SSSS STAPHYLOCOCCUS SCALDED SKIN SYNDROME By exfoliation toxin A,b,d Cleaves human desmoglein1 so skin peeling

Question 36

Define superantigen

Answer 36

Toxin that can activate T cell even with no antigens, hyperactivating immune system

Question 37

Name some diseases from S.aureus

Answer 37

``` Meningitis Septic arthritis Pneumonia Osteomyelitis Sepsis ```

Question 38

How is peptidoglycan made?

Answer 38

Monomers of PENTAPEPTIDES are made inside the cell, attached to GLYCAN backbone THis is flipped across membrane Glycan chains are synthesised and CROSSLInks form by PENICILLIN BINDING PROTEINS

Question 39

How does Penicillin and Methicillin work?

Answer 39

They resemble pentapeptides and prevent peptidoglycan formation. Transpeptidase enzymes of the PBP cleaves the drug instead of the substrates

Question 40

What does all PBP 1-4 have in common?

Answer 40

TRANSPEPTIDASE ACTIVITY for making peptide cross links

Question 41

Which is the PBP Type that had both transpeptidase and transglycosylase?

Answer 41

2

Question 42

What is the mechanism of Penicillin resistance?

Answer 42

S.Aureus secretes B-lactamase that cleaves the B-lactam ring of penicillin therefore penicillin cannot inactivate PBPs.

Question 43

Can Methicillin be cleaved by B-lactamase?

Answer 43

X

Question 44

How has S.Aureus established resistance for Methicillin?

Answer 44

Extra PBP PBP2A which has LOW affinity for Methicillin So no cleavage of PBP2A

Question 45

What are the characteristics of H. influenzae?

Answer 45

Gram - Blood loving Dependent on Haem and NAD (factorV)

Question 46

When does H. Influenzae cause issues?

Answer 46

Normally in Nasopharynx | If access lungs can cause meningitis. Septicaemia. OSTITIS MEDIA. COPD

Question 47

What is the Haemophilus influenzae that is risky for asplenics, complement deficient patients or very young?

Answer 47

HiB

Question 48

Characteristics of important capsule of HIB?

Answer 48

Inhibits MAC of complement system Inhibits C3b deposition Less opsonisation triggered phagocytosis

Question 49

Why is conjugate vaccines are better than PRP vaccines for H.influenzae?

Answer 49

T cell dependent response Memory B cells Herd immunity by preventing nasopharynx colonisation

Question 50

What does NON-typable H.Influenzae consequence?

Answer 50

Serious ostitis media Bad COPD HIGHLY VARIED- hard to make vaccines and not many are conserved

Question 51

Is Neisseria Meningitidis gram +?

Answer 51

No, -

Question 52

Which types of Neisseria Meningitidis are important?

Answer 52

5 Capsulated serogroup A B C Y W135

Question 53

How does meningitis occur even without septicaemia?

Answer 53

By infecting through olfactory nerve.

Question 54

What is the clinical features of N. meningitidis?

Answer 54

Flu like Stiff neck Vomit Rash (Glass test)

Question 55

What can we use to treat meningitis?

Answer 55

BENZYL PENICILLIN AMPICILLIN Rifampicin to those at risk

Question 56

What else contributes to infectivity of Meningitidis?

Answer 56

Host susceptibility

Question 57

Name 4 polymorphism locations that causes host to be susceptible for Meningitis.

Answer 57

Mannose Binding Lectin Factor V Leiden Toll receptor 4 Factor H

Question 58

Two classes of vaccines for Serogroup A C Y W135?

Answer 58

Capsule (no T cell and no memory) Conjugate

Question 59

Vaccines for serogroup B meningitis?

Answer 59

Outer membrane vesicle vaccines Bexsero: 3 antigens+Omw + adjuv