Infection

Question 1

Resistance mechanisms

Answer 1

-inactivation- beta lactamase.
-target alteration- penBP mutation.
-alter metabolic paths- use pre formed folic acid.
-reduce IC AB accumulation-
Reduce permeability eg Pa lose carabepenem poring.
Increase active efflux eg tetracyclines.

Question 2

Resistance prevention

Answer 2

-antimicrobial stewardship-
Right AB at right time.
Right dose, frequency and duration.
-infection control.

Question 3

Sepsis signs

Answer 3

High EWS score- High temperature, Tachyc+p, Hypotension
Pallor
Bounding pulse
Specific eg stiff neck, purpuric rash.
Red flags- high RR, low BP, unresponsive.

Question 4

Sepsis definitions

Answer 4

• sepsis= life threatening organ dysfunction due to dysregulated host response to infection.
• septic shock= persistent hypotension requires tx to maintain BP despite fluid resus. Imminently fatal w/o acute tx.
• bacteraemia- bacteria in blood with or w/o clinical features. Blood culture.
• septacaemia- generalised sepsis of blood.

Question 5

Sepsis 6

OBIV FML

Answer 5

Oxygen
Blood culture
IV AB
Fluid challenge 
Measure urine output
Lactate

Question 6

Sepsis other investigations

Answer 6

All bloods including CRP
Coagulation studies 
ABG
Samples culture 
Blood culture and PCR
CSF analysis- PCR< glucose, protein, turbidity, microscopy.

Question 7

N meningitidis

Answer 7

Polysaccharide capsule= increase adherance, reduce phagocytosis, pills, LPS.
OM endotoxin.
Serogroup ABC UK, B most common.
25% young adults asymptomatic carriers.
Aerosol and NP secretion transmission.
C conjugated vaccine, also ACWY, and now serogroup B.

Question 8

Sepsis pathology

Answer 8

Local cytokine release and inflammatory response.
Systemic cytokines in circulation stimulate HF, mac, pl etc.
If not controlled then overreaction= circulatory insult and sepsis. Activation humoral casacdes and RE system.
Risk DIC.
Cytokines activate thrombin and inhibit fibrinolysis so macrovascular thrombosis= organ ischaemia, dysfunction and failure.
Macrovascular injury may cause shock and multi organ fail.
Progressive necrosis.

Question 9

Sepsis tx

Answer 9

Specif AB
Empiric AB eg ceftriaxone for meningitis
Supportive physiological restoration 
Monitoring and re assessment 
Sepsis 6

Question 10

Sepsis complications

Answer 10

Irreversible hypotension
Respiratory failure
AKI
RICP
Ischaemic necrosis extremities.

Question 11

Skin Commensals

Answer 11

Papilloma virus, HSV
Gram pos- Sa, coagulase neg staph, corynebacterium 
Gram neg- enterobaceria 
Candida, dermatophytes
Mites

Question 12

commensal infection mechanisms

Answer 12

Direct invasion- strep pyogenes pharyngitis
Migration- ecoli UTI
Inoculation- coagulase neg staph prosthetic
Haematogenous- viridans endocarditis

Question 13

Heart valve infection

Answer 13

Over 1 year post op- viridans, enterobacteria faecalis, Sa, HACEK, candida.
Under 1 year- coagulase negative staph.

Question 14

Biofilm

Answer 14

EC polusacccharide ma
Small bacteria long t/o so AB not effective
Reduce AB diffusion 
AB neutralisation by EPS binding
Quorum sensing

Question 15

Malaria symptoms

Answer 15

Cyclic fever and chills 
Cough
Headache
Pain
Fatigue
Nausea

Question 16

malaria signs

Answer 16

Tachyc
Hypotension
Arrhythmia
Diarrhoea
High LFTs and bilirubin
AKI
CNS confusion, fits
Low WCC and RBC, DIC
Metabolic acidosis
Hypoglycaemia

Question 17

Malaria investigation

Answer 17

3 x blood smear
All bloods including coagulation
CT head
CXR

Question 18

Malaria tx

Answer 18

Falciparum- artesunate, quinine+doxycycline

Others- chloroquinine, primaquine

Question 19

HIV pathmenmonic

Answer 19

Candida albicans
Caposi sarcoma HHV8
PCP fungus

Question 20

HIV infections as CD4 decrease

Answer 20

Bacterial skin infection, HSV, VZV, fungus.
Caposi sarcoma
TB, leukoplakia
PCP, toxoplasmosis, CMV, lymphoma, MAC.

Question 21

HAART highly active anti retro viral therapy

Answer 21

3 drugs to prevent resistance.
-nucleoside reverse transcriptase inhibitor eg tenofovir. X2. 
-nnRTI eg nevirapine. 
OR protease inhibitor eg atazanavir
OR integrate inhibitor eg raltegravir 
OR CCR5 entry inhibitor eg maraviroc

Question 22

hypersensitivity

Answer 22

• T1 immediate- IgE mast activation. Eg allergies, asthma, anaphylaxis.
• T2 cytotoxic- cytotoxic Abs and complement. Eg graves, MG, AI haemolytic anaemia, pernicious anaemia, goodpastures.
• T3 immune complex- Abs, complement and leucocytes. Eg AI disease SLE, hypersensitivity, pneumonitis, RA, glomerulonephritis.
• T4 delayed- T cells, mac, IL, cytokines. eg granuloma TB, leprosy, schistosomiasis, sarcoid, coeliac.

Question 23

Anaphylaxis

Answer 23

Systemic activation of mast cells by IgE.
Signs- hypotension, CVS collapse shock, urticaria, angiooedma, breathing restriction.
Tx- IM adrenaline= vasoconstriction, decrease oedema, stops hypotension, brocho relax, increase myocardial force, inhibits mast activation. Saves time, may need other dose.

Question 24

UTI common organism

Answer 24

Ecoli
Klebsiella pneumonia
Proteus
Pa

Question 25

CF infection

Answer 25

``` H influ Sa Pa Atypical mycobacteria Candida albicans Aspergillus fumigatus ```

Question 26

COPD exacerbation infections

Answer 26

H influ Pa RSV

Question 27

DM infections

Answer 27

-Reduced huomoral immunity, reduced lymphocyte and leucocyte function, reduced perfusion, reduced sensation. -so get common UTI, ENT infection, skin/ST infection. -egs Pa otitis externa Mould causing rhinocerebral mucormycosis- sinus colonisation and invasion. Hyphi. Neurogenic bladder due to neuropathy= defective emptying. Risk ecoli and Pa bacteruria, pyuria, cystitis, UUTI. Foot ulcer and necrotising fasciitis- Sa, GBS, enterobacteria, various anaerobes.

Question 28

Signs of immunodeficiency | SPUR

Answer 28

Severe Persistent Unusual Recurrent

Question 29

Immunodeficiency age of symptom onset and type of infection

Answer 29

- under 6 month- T cell of phagocyte defect. Eg SCID (combined B and T). - 6 month to 5 yr- B cell, Ab, or phagocyte defect. Eg x linked Brutons. Chronic granulomatous disease aspergillus. - over 5yr- B cell, Ab, complement defect or secondary immunodeficiency (malnutrition, infection, liver disease, lymphoproliferative disease, splenectomy). Eg CVID. - virus and fungi- T cells deficiency - bacteria and fungi- B or granulocyte deficiency.

Question 30

Immunodeficiency tx

Answer 30

``` Prophylaxis Immunisation, avoid live attenuated Nutrition IV or SC Ig haematopoietic SC therapy sometimes Tx comorbidities- CA, organ damage. ```

Question 31

Spleen

Answer 31

Immune function -bloodbourbe pathogen, especially encapsulated bacteria. -Ab production- acute IgM, LT IgG. -splenic mac- remove opsonised microbes, remove immune complexes. Asplenic suceptible to encapsulated eg H influ, S pneum, N meningitidis. Tx- pen prophylaxis for life, immunisation against encapsulated, alert band.