Lecture 1: Bacteraemia Septicaemia

Question 1

Define bacteraemia

Answer 1

Presence of viable bacteria in the blood which may be transient and inconsequential

Question 2

Define Sepsis

Answer 2

Presence of microorganisms and/or their products in the blood that induces a systemic inflammatory response syndrome (SIRS)

Diagnosis based on

1) Presence of infection
2) SIRS criteria

Question 3

What happens in sepsis without adequate treatment?

Answer 3

Progression to severe sepsis and then septic shock

Question 4

SIRS criteria

Answer 4

Two or more of the following:

Fever or hypothermia: >38.5 or 90bpm

Pachypnoea >20/min, or PCO2 of <32mmHg

Question 5

What are the typical constitutional symptoms present with SIRS/Sepsis?

Answer 5

Fatigue, malaise, anxiety, altered mental state, etc

Question 6

What are non-infectious causes of SIRS (i.e. not sepsis)

Answer 6

Trauma
Burns
Venous Thrombosis
Myocardial or Pulmonary Infarcts
Pancreatitis
Drug product reaction
Malignant hyperthermia

Question 7

Epidemiology of Sepsis

Answer 7

Often rapid onset

Mortality rates are highest amongst infants and very old

Each 1 hour delay in institution of appropriate treatment leads to 9% increase in mortality

Question 8

Risk Factors for Sepsis

Answer 8

Underlying disease w/ associated immunosuppression (HIV, AIDS)

Foreign devices: catheters

Surgery, trauma, burns patients

Chronic renal failure

IV drug use

Alcoholism

Diabetes

Malnutrition

Extremes of age

Intestinal ulceration

Question 9

Sepsis: what are the possible origins of infections?

Answer 9

Primary blood stream infection (meningococcaemia, meningitis)

WOunds and Abscesses

Lungs (pneumonia)

GIT problems

Urinary Tract

Bacterial Endocarditis

Colonised IV lines, drains or shunts

Question 10

Pathogenesis of DIC

Answer 10

Systemic endothelial dysfunction resulting from the systemic inflammatory response results in uncontrolled activation of the coagulation cascade

Results in systemic microvascular clots - visible signs include petichiae on skin - within blood vessels.

Uncontrolled lotting increasingly consumes more coagulation factors and platelets, resulting in haemorrhage, possible organ dysfunction, or even death.

*Always consult haematologist and an infectious disease physician

Question 11

Severe Sepsis: Definition/Diagnosis

Answer 11

Presence of Sepsis (SIRS plus evidence of infection), PLUS one or more related sepsis-related organ dysfunction, hypo-perfusion or hypotension.

E.g. of organ dysfunctions:
Altered mental status, renal, liver, cardiac failure, hypoperfusion with lactic acidosis, Nausea, vomiting, diarrhoea, skin/cutaneous manifestations, coagulation abnormalities

Question 12

Septic Shock: Definition

Answer 12

Severe sepsis (SIRS + Infection + Evidence of organ dysfunction/hypo-perfusion/hypotension) PLUS Hypotension that is UNRESPONSIVE to fluid challenge.

Requires vasopressors (noradrenaline, adrenaline, dopamine, vasopressin, etc)

Question 13

Laboratory Tests when dealing with suspected Sepsis/Severe Sepsis/Septic Shock

Answer 13

Blood cultures: take at least 2 sets over a 24hr period - divide for aerobic and anaerobic incubation. Take before Abx administration

Urine tests (will also show UTI, renal dysfunction)

Sputum (lung infection or dysfunction?)

Check for wounds, abscesses

Cerebral spinal fluid (if suspect CNS infection)

Question 14

Other tests to diagnose Sepsis/Severe Sepsis/Septic Shock

Answer 14

Complete Blood Count: looking for leukocytosis/leukopenia or bandemia (immature blood cells)

Question 15

What kinds of organ dysfunction might we be looking for?

Answer 15

Acute Lung Injury

Renal Dysfunction

Hepatic Dysfunction

Haematological Dysfunction

Coagulation Abnormalities

Increased Biomarkers

Elevated Capillary Refill Time

Hyperlactaemia

Electrolyte Imbalances

Hyperglycaemia

Abnormal Chest Xrays

Question 16

Acute Lung Injury?

Answer 16

Arterial hypoxaemia, which may lead to ARDS

Question 17

Renal Dysfunction?

Answer 17

Acute Oliguria = urine output of <0.5 ml/kg/h for at least 2 hours.

Azotemia = waste products like creatinine increased in serum

Question 18

Hepatic Dysfunction?

Answer 18

Plasma total bilirubin elevated.

Presence of elevated liver enzymes in the urine: alkaline phosphatase, ALT, AST

Question 19

Haematological Dysfunction

Answer 19

Thrombocytopenia (sign of DIC)

Question 20

Coagulation Abnormalities?

Answer 20

Increased INR, PT or APTT

Question 21

Management of Sepsis/Severe Sepsis/Septic Shock

Answer 21

1) Commence IV fluids (even is patient not hypotensive)

**if not responsive to fluids, administer vasopressors

2) Administer O2 (intubate of mechanically ventilate where necessary)
3) Control source of infection if known - e.g. drain, surgical removal, debridement
4) Maintain adequate glycaemic control
5) Administer appropriate broad spectrum Abx AFTER obtaining blood cultures

Question 22

What governs choice of Empirical Abx treatment?

Answer 22

Whether the source of infection is apparent or not

Question 23

If no obvious source of infection?

Answer 23

Dicloxacillin/Flucloxacillin PLUS Gentamycin or Vancomycin

Use empirical therapy for 24-48 hours only and modify when organism and Abx susceptibilities are known

Question 24

If source of infection is known?

Answer 24

Follow therapeutic guidelines for choice of empirical Abx treatment for organisms likely to be associated with the infected organ

Use empirical Abx for 24-48 hours only, then modify to directed therapy when organism and Abx susceptibilities are known