W07 - Clinical 2 - S Aureus; Sepsis; Influenza; Zoonoses Flashcards
Spectrum of S. aureus infections and source of bacteraemia
- staphylococci = gram+ = grape-like clusters
- highly virulent = HAI causes
- colonisation sites act as resevoir for future infection
*S. aureus commonly identified agent for skin and soft tissue infections
=> local complications or distant septic mets
- bones and joints (esp w/ prosthetics)
- epidural space and intervertebral discs
- native and prosthetic cardiac valves
- visceral abscesses in spleen, kidney, lungs
Investigations of S.aureus bacteraemia
Microscopy + culture before commending Abx Rx
Repeat cultures after commencing AbxRx
Biopsy (bone)
XR, CT, MRI, Radionuclide imaging
- lung abscess
- septic lung emboli? = CT pulmonary angiogram
Transthoracic echo.= TOE
Management of S. aureus bacteraemia
> FLUCLOX: uncomplicated S. aureus for 14d
(Vancomycin for allergies)
> TEICOPLANIN: single daily dosing adv.
> LINEZOLID: bacteriostatic, good bone penetration and oral bioavailability
> DAPTOMYCIN: well tolerated. daily dosing.
> VANCOMYCIN: poor penetration, slow bactericidal activity, inconvenient administration
Define sepsis and septic shock using the Sepsis -3 guidelines
life-threatening organ dysfunction caused by dysregulated host response to infection
+ SOFA >2
sepsis with persisting hypotension requiring vasopressors to maintain MAP >65mmHg and having a serum lactate of >2mmol/l despite adequate volume resuscitation
Be able to use qSOFA to determine whether a patient is more likely to require intensive care
- HypoT, systolic <100
- Altered mental
- Tachy, RR >22/min
≥2 suggest greater risk of poor outcome
Understand the pathophysiology of sepsis, including the reasons why some infections present differently under different circumstances
• breach of host barriers, resulting in infection reaching bloodstream = *uncontrolled inflamm response * features of imm suppr - delayed hypersensitivity - Inability to clear infection - Predisposition to nosocomial infection
1) Release of bacterial toxins
LPS (gram -ve); MAMP (gram +ve); SuperAg TSST or exotoxins (gram +ve)
2) Release of mediators LPS requie binding proteins to bind to macrophages whereas LTA (MAMP) do not = pro-inflamm mediators or = anti-inflamm mediators (to compensate)
3) Effects of specific excessive mediators
= dysbalance between mediator forces
anti-inflamm = septic shock w/ organ failure and death
pro-inflamm = Immunoparalysis with uncontrolled infection and multiorgan failure
Describe the clinical presentation of sepsis and septic shock
Altered mental
Tachypnoea
Jaundice; ⇧LiverEnz. ⇧PT ⇩Albumin
Oliguria/Anuria ⇧Creatinine
Tachycardia, HypoT
⇧PT ⇧D-Dimer ⇩Platelets ⇩Protein C
Fever/Hypothermia
Hyperglc. >8mmol/l in absence of DM
Outline the principles of clinical management of sepsis using Sepsis 6
take:
blood cultures, blood lactate, urine output
give:
O2 sats 94-98
IV abx
IV fluid challenge (30ml/kg)
2As
Air + Abx
2Bs
Blood culture + Blood gas with lactate (lactate marker of generalised hypoperfusion/severity + mitochondrial toxins, alcohol, malignancy)
2Cs
Crystalloid Bolus
Catheter
Appreciate importance of the individual components of Sepsis 6.
a
Understand the importance of empiric antimicrobial therapy in patients presenting with sepsis and in whom there is no positive microbiology
a
Outline the classification and typing of influenza viruses, including the importance of antigenic shift and drift.
(human only)
INFLUENZA B
INFLUENZA C
Haemagglutinin (H) Antigen (attachment and entry into cell)
Neuraminidase (N) Antigen (enables new virion to bereleased from host cell)
Ag Drift = genetic variation point mut. for Ab-binding sites = imm system cannot combat properly and produces vaccine mismatch
Ag Shift = abrupt major change in virus resulting new H/N combos = species jump, or creation of new subtype + genetic reassortment
Outline the epidemiology of seasonal, epidemic and pandemic influenza
Pandemic affects more of the population, more complications, sporadic timing, affects greater age range
Outline the laboratory diagnosis of influenza
a
Describe the presentation of influenza in the community and of severe disease (including possible complications) in a hospital setting
Incubation = 2-4d
Abrupt fever \+cough \+sore throat \+ myalgia \+headache \+malaise
systemic
viral swabs; PCR
* CXR
* blood culture
=> acute bronchitis;
2º bacterial pneumonia - CURB65
Describe the role of antiviral agents in the treatment of influenza
within 48hr of symptom onset and risk of complication development
NEURAMINIDASE INHIBITORS
> OSELTAMIVIR (oral) - uncomplcated
n/v, abdo pain, diarrhoea
> ZANAMIVIR (inhaled/IV)
rare adverse effects
Prego
> Oseltamivir (oral)
