Sepsis/Micro Flashcards
Sepsis
Life-threatening condition
Causes by abnormal/uncontrolled host response to infection
Risk factors for sepsis
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)
High risk criteria for sepsis
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
Moderate to high risk criteria for sepsis
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
Septic shock
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
Pyrexia in the surgical patient
7 Cs: Chest Cut (wound) Catheter/UTI Collections Calves (DVT/PE) Cannula Central line
Sepsis management
Complications from Sepsis
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
Types of pathogens
Bacteria Virus Fungi Parasites Prions
Classification of bacteria
Shape
Gram-staining
Aerobic/anaerobic
Classification of bacteria: shape
Bacilli: rods Cocci: spherical, grouped (Clusters: staphylococci, streptococci: lines, diplococci: paired) Spirilla: spiral shaped Vibrios: flagellated (tailed) Spirochaete: tightly coiled
Classification of bacteria: gram-staining
Gram-positive: peptidoglycan cell wall
Gran-negative: thin/no layer of peptidoglycan
Classification of bacteria: gram-staining
Gram-positive: peptidoglycan cell wall
Gran-negative: thin/no layer of peptidoglycan
Classification of bacteria: gram-staining
Gram-positive: peptidoglycan cell wall
Gran-negative: thin/no layer of peptidoglycan
Classification of bacteria: Aerobic/anaerobic
Aerobic: require O2
Anaerobic: can survive without O2, or require environment with no O2 (obligate anaerobes)
Gram-positive cocci
Staphylococcus aureus Coagulase-negative staphylococcus Beta-haemolytic streptococci Streptococcus pneumoniae Enterococcus faecalis
Gram-negative cocci
Neisseria meningitidis
Neisseria gonorrhoea
Moraxella catarrhalis
Gram-positive bacilli
Listeria monocytogenes
Bacillis anthracis
Bacillus cereus
Gram-negative bacilli
Escherichia coli Klebsiella pneumoniae Salmonella typhi Pseudomonas aeruginosa Haemophilus influenza
Functions of the spleen
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
Encapsulated organisms
Streptococcus pneumonia
Haemophilus influenzae
Neisseria minigitidis
Classes of antibiotics
Beta-lactams (penicillins/ carbapenems/ monobactams/cephalosporins)
Glycopeptides
Polymyxins
50s inhibitors (macrolides/ clindamycin)
30s inhibitors (tetracyclines/ aminoglycosides)
Quinolones
Sulfonamides
Penicillins MoA
Irreversibly & competitively inhibit penicillin-biding proteins such as enzyme DD-transpeptidase
Weakens cell walls and induces lysis
Cephalosporins/Carbapenems
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
Glycopeptides
Bind to proteins in cell call preventing DD-transpeptidase from binding
Examples: vancomycin, teicoplanin
Accumulation with renal disease
Aminoglycosides
Inihibit bacterial protein synthesis by binding to ribosome 30S subunit
E.g.: Gentamicin
SEs: nephrotoxicity, ototoxicity
Macrolides
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
Quinolones
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
Metronidazole
Inhibits bacterial DNA synthesis
Specific for anaerobes
Used for C diff
Inhibits CYP450: increases drugs conc.
Nitrofurantoin
Damages bacteria DNA causing cell death
UTIs: gram-pos + gram-neg
Contraindicated in pregnancy
Trimethoprim
Inhibits dihydrofolate reductase and bacterial folate synthesis
UTIs: gram-pos/gram-neg
SEs: skin rash, hypersensivity, hyperkalaemia
CIs: 1st trimester