Sepsis/Micro

Question 1

Sepsis

Answer 1

Life-threatening condition

Causes by abnormal/uncontrolled host response to infection

Question 2

Risk factors for sepsis

Answer 2

Very young (<1) and older (>75)
Frailty
Immunocompromised: chemotherapy, splenectomy, sickle cell, DM, long term steroids, immune modulating drugs
Surgery/invasive procedures <6 weeks
Any breach of skin integrity
IVDUs
Indwelling lines/catheters
Pregnancy (<6 weeks ago)

Question 3

High risk criteria for sepsis

Answer 3

Altered mental state
RR >25
New need for O2 to maintain SaO2 92%
Systolic BP <90
HR >130
Not passed urine for 18hrs/<0.5ml/kg/hr
Mottled/ashen skin.
Cyanosis
Non-blanching rash

Question 4

Moderate to high risk criteria for sepsis

Answer 4

History of new onset altered behaviour
RR 21-24
Syst BP 91-100
HR 91-130, new onset arrhythmia
Not passed urine 12-18hrs or 0.5-1ml/kg/hr
Temp <36
Skin signs of potential infection: erythema/swelling/discharge/wound breakdown

Question 5

Septic shock

Answer 5

Persisting hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) of 65 mmHg or more and having a serum lactate level of greater than 2 mmol/l despite adequate volume resuscitation

Question 6

Pyrexia in the surgical patient

Answer 6

7 Cs:
Chest
Cut (wound)
Catheter/UTI
Collections
Calves (DVT/PE)
Cannula
Central line

Question 7

Sepsis management

Question 7

Complications from Sepsis

Answer 7

Short term:
Mortality 30-40%
Organ failure, can be Multi-system: AKI (60%), cholestasis, heart failure, ARDS, acute lung injury, bone marrow suppression, gut failure
Secondary infection (Hospital acquired infections)
Malnutrition
Coagulopathy (VTE/DIC)
Encephalopathy/delirium

Long term/chronic:
Recurrent infections
Chronic pain/fatigue
PTSD/anxiety

Question 8

Types of pathogens

Answer 8

Bacteria
Virus
Fungi
Parasites
Prions

Question 9

Classification of bacteria

Answer 9

Shape
Gram-staining
Aerobic/anaerobic

Question 10

Classification of bacteria: shape

Answer 10

Bacilli: rods
Cocci: spherical, grouped (Clusters: staphylococci, streptococci: lines, diplococci: paired)
Spirilla: spiral shaped
Vibrios: flagellated (tailed)
Spirochaete: tightly coiled

Question 11

Classification of bacteria: gram-staining

Answer 11

Gram-positive: peptidoglycan cell wall

Gran-negative: thin/no layer of peptidoglycan

Question 11

Classification of bacteria: gram-staining

Answer 11

Gram-positive: peptidoglycan cell wall

Gran-negative: thin/no layer of peptidoglycan

Question 11

Classification of bacteria: gram-staining

Answer 11

Gram-positive: peptidoglycan cell wall

Gran-negative: thin/no layer of peptidoglycan

Question 12

Classification of bacteria: Aerobic/anaerobic

Answer 12

Aerobic: require O2
Anaerobic: can survive without O2, or require environment with no O2 (obligate anaerobes)

Question 13

Gram-positive cocci

Answer 13

Staphylococcus aureus
Coagulase-negative staphylococcus
Beta-haemolytic streptococci
Streptococcus pneumoniae
Enterococcus faecalis

Question 14

Gram-negative cocci

Answer 14

Neisseria meningitidis
Neisseria gonorrhoea
Moraxella catarrhalis

Question 15

Gram-positive bacilli

Answer 15

Listeria monocytogenes
Bacillis anthracis
Bacillus cereus

Question 16

Gram-negative bacilli

Answer 16

Escherichia coli
Klebsiella pneumoniae
Salmonella typhi
Pseudomonas aeruginosa
Haemophilus influenza

Question 17

Functions of the spleen

Answer 17

White pulp: nodules called Malpighian corpuscles.

• APCs activate T cells stored here
• Pathogens enter lymphoid follicles (rich in naive B cells) and detected by B cells
• Opsonisation of encapsulated bacteria

Red pulp (80%); cords

• Removal of old/damage/dead RBCs
• Phagocytosis of opsonised bacteria
• Sequestration of platelets
• Storage of RBCs

Question 18

Encapsulated organisms

Answer 18

Streptococcus pneumonia
Haemophilus influenzae
Neisseria minigitidis

Question 19

Classes of antibiotics

Answer 19

Beta-lactams (penicillins/ carbapenems/ monobactams/cephalosporins)
Glycopeptides
Polymyxins
50s inhibitors (macrolides/ clindamycin)
30s inhibitors (tetracyclines/ aminoglycosides)
Quinolones
Sulfonamides

Question 20

Penicillins MoA

Answer 20

Irreversibly & competitively inhibit penicillin-biding proteins such as enzyme DD-transpeptidase
Weakens cell walls and induces lysis

Question 21

Cephalosporins/Carbapenems

Answer 21

Inhibit cross-linking of peptidoglycans in bacteria cells wall
Cephalosporins: cefotaxime, ceftraxone, cefuroxime
Carbapenems: meropenem
Coverage: broad spectrum, more suited gram neg.
Cross reactivity with penicillin: 10%
Highest risk of developing C diff

Question 22

Glycopeptides

Answer 22

Bind to proteins in cell call preventing DD-transpeptidase from binding
Examples: vancomycin, teicoplanin
Accumulation with renal disease

Question 23

Aminoglycosides

Answer 23

Inihibit bacterial protein synthesis by binding to ribosome 30S subunit
E.g.: Gentamicin
SEs: nephrotoxicity, ototoxicity

Question 24

Macrolides

Answer 24

Inhibit bacterial protein synthesis by binding to ribosome 50s subunit
E.g.: Clarithroymcin, erythromycin, azithromycin
SEs: CYP450 inhibitor (increases drug concentration of CYP450: warfarin). Prolonged QT. Ototoxicity

Question 25

Quinolones

Answer 25

Inhibit bacterial DNA duplication through inhibition of topoisomerases (interfere with DNA unwinding)
E.g.: ciprofloxacin
Gram negative
SEs: prolonged QT, high risk of C diff
Equal bioavailability IV/oral

Question 26

Metronidazole

Answer 26

Inhibits bacterial DNA synthesis
Specific for anaerobes
Used for C diff
Inhibits CYP450: increases drugs conc.

Question 27

Nitrofurantoin

Answer 27

Damages bacteria DNA causing cell death
UTIs: gram-pos + gram-neg
Contraindicated in pregnancy

Question 28

Trimethoprim

Answer 28

Inhibits dihydrofolate reductase and bacterial folate synthesis
UTIs: gram-pos/gram-neg
SEs: skin rash, hypersensivity, hyperkalaemia
CIs: 1st trimester