Lecture 1: Bacteraemia Septicaemia Flashcards
Define bacteraemia
Presence of viable bacteria in the blood which may be transient and inconsequential
Define Sepsis
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
What happens in sepsis without adequate treatment?
Progression to severe sepsis and then septic shock
SIRS criteria
Two or more of the following:
Fever or hypothermia: >38.5 or 90bpm
Pachypnoea >20/min, or PCO2 of <32mmHg
What are the typical constitutional symptoms present with SIRS/Sepsis?
Fatigue, malaise, anxiety, altered mental state, etc
What are non-infectious causes of SIRS (i.e. not sepsis)
Trauma Burns Venous Thrombosis Myocardial or Pulmonary Infarcts Pancreatitis Drug product reaction Malignant hyperthermia
Epidemiology of Sepsis
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
Risk Factors for Sepsis
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
Sepsis: what are the possible origins of infections?
Primary blood stream infection (meningococcaemia, meningitis)
WOunds and Abscesses
Lungs (pneumonia)
GIT problems
Urinary Tract
Bacterial Endocarditis
Colonised IV lines, drains or shunts
Pathogenesis of DIC
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
Severe Sepsis: Definition/Diagnosis
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
Septic Shock: Definition
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)
Laboratory Tests when dealing with suspected Sepsis/Severe Sepsis/Septic Shock
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)
Other tests to diagnose Sepsis/Severe Sepsis/Septic Shock
Complete Blood Count: looking for leukocytosis/leukopenia or bandemia (immature blood cells)
What kinds of organ dysfunction might we be looking for?
Acute Lung Injury
Renal Dysfunction
Hepatic Dysfunction
Haematological Dysfunction
Coagulation Abnormalities
Increased Biomarkers
Elevated Capillary Refill Time
Hyperlactaemia
Electrolyte Imbalances
Hyperglycaemia
Abnormal Chest Xrays
Acute Lung Injury?
Arterial hypoxaemia, which may lead to ARDS
Renal Dysfunction?
Acute Oliguria = urine output of <0.5 ml/kg/h for at least 2 hours.
Azotemia = waste products like creatinine increased in serum
Hepatic Dysfunction?
Plasma total bilirubin elevated.
Presence of elevated liver enzymes in the urine: alkaline phosphatase, ALT, AST
Haematological Dysfunction
Thrombocytopenia (sign of DIC)
Coagulation Abnormalities?
Increased INR, PT or APTT
Management of Sepsis/Severe Sepsis/Septic Shock
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
What governs choice of Empirical Abx treatment?
Whether the source of infection is apparent or not
If no obvious source of infection?
Dicloxacillin/Flucloxacillin PLUS Gentamycin or Vancomycin
Use empirical therapy for 24-48 hours only and modify when organism and Abx susceptibilities are known
If source of infection is known?
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
