Infectious Diseases Sepsis and Antibiotics

Question 1

List and classify gram positive bacteria

Answer 1

GM +VE COCCI Aerobic:

Staphylococcus:
Coagulase Positive = Staph Aureus
Coagulase Negative = Staph Epidermidis

Streptococcus:

Alpha Haemolytic = (Strep viridians) * Strep Pneumoniae
Beta haemolytic = Strep pyogenes, Strep Agalactiae
Y-Haemolytic = Enterococcus - faecalis / faecium

NB Group A strep= Strep pyogenes

GM +VE COCCI Anaerobic:

Strep viridians*

GM +VE BACILLI Aerobic:

Anthrax

GM +VE BACILLI Anaerobic:

Listeria
C difficile
C.perfinigens

Question 2

Gram negative bacteria - classify and list

Answer 2

GM -VE COCCI - Aerobic:

Neisseria - meningitidis, gonorrhea
Moraxella

GM -VE BACILLI - Aerobic:

Pseudomonas aeruginosa
Haemolphilus influenzae
Serratia marcescens
Bordatella pertussis
Burkholderia (tropics, wet seasons from soil)
Leigonella
Stenotrophamonas maltophilia
Acitenobacter
Vibrio vulnificus - contaminated fish / seawater
Vibrio cholerae

GRAM -VE BACILLI - Facultative Anaerobes:

Enterobacter
Klesbiella
Ecoli
Citrobacter kozeri
Campylobacter
Salmonella / shigella
Proteus

GRAM -VE BACILLI - True Anerobes

Bacteriodes

Question 3

What kind of bacteria is Vibrio Vulnificus and how does it present?

Answer 3

Vibrio Vulnificus:

“fisherman presents to ED with hypotension, three days after falling on a coastal slipway and suffering extensive abrasions to both lower limbs. Abrasions transforming into haemorrhagic bullae.”
* Gram negative, warm seawater
* Transmission -> ingestion of contaminated seafood / through open wounds
* GI illness -> if severe septic shock
* Contaminated wounds -> large haemorrhagic bullae if severe
* Can cause septic shock and tissue necrosis if severe

• Rx = Tetracycline e.g. Doxycycline and a 3rd gen cephalosporin e.g. ceftriaxone ceftazidime

Question 4

What is Q fever?

Answer 4

Q fever AKA as Coxiella burnetii
* Gram -ve bacteria
* Zoonotic infection
* @ risk groups - abattoir and livestock workers who inhale infected dust particles / aerosolised particles from animals
* Asymptomatic -> febrile illness -> haemoptysis / IE / Atypical pneumonia
* Ix: serology
* Rx: Doxycycline
Vaccination available for high risk groups

Question 5

A patient presents with confusion and localised paresthesia after being bitten by a flying fox. What is the likely organism? ~

Answer 5

• Lyssa Virus = group of RNA viruses
  
  • Australian Bat Lyssa Virus present in flying foxes
  • Lyssa Viruses causes the disease rabies
  • Usually presents as progressive fatal encephalitis
  • Vaccine available for @ risk groups

Question 6

What is the likely cause of gram -ve sepsis in a patient recently returning from PNG during the wet season or from the Northern territory?

Answer 6

Burkholderia pseudomallei = a gram -ve rod which causes clinical syndrome Melioidosis
It resides in the soil, water and plants of endemic regions.
* Transmission is usually through skin or infected aerosol particles
* Risk factors: wet seasons, agricultural workers
* Most common presentation is pneumonia
* Meliodosis is aka as the ‘great mimicker’ -> misdiagnosed as CAP at presentation
* 50% have bacteraemia at presentation.
* Can cause cutaneous lesions and organ abscesses
* Ix: Culture (Note that lots of people will be antibody positive from endemic regions)
* Mx: carbapenem + Bactrim

Question 7

Name the organism which causes Melioidosis

Answer 7

Melioidosis is a gram negative sepsis caused by Burkholderia pseudomallei

* Gram negative, aerobic rod that resides in the soil, water and plants of endemic regions - NT, tropics 
* Transmission through skin /infected aerosol particles
* RF: wet seasons, agricultural workers
* Common presentation is pneumonia
* Melioidosis is aka as the 'great mimicker' -> misdiagnosed as CAP at presentation
* 50% have bacteraemia at presentation.  Can cause cutaneous lesions and organ abscesses

Ix: Culture
Rx: Carbapenem + Bactrim

Question 8

List the likely culprit organisms responsible for a Gram -ve Sepsis in a patient who has been on meropenem for 1/52:

Answer 8

Gram -ve sepsis resistant to meropenem may include:
Stenotrophomonas
Enterobacter
Citrobacter
Serratia

Question 9

List the commonest causes of meningitis in a patient post splenectomy:

Answer 9

Post splenectomy @ r/o infection from encapsulated organisms:

Strep Pneumoniae - GM +ve cocci, alpha haemolytic

Neiserria Meningitidis - GM -ve cocci
Haemophilus Influenzae GM -ve bacillus

Question 10

Likely cause of fever, confusion, facial nerve palsy and black nasal d/c in a diabetic patient:

Answer 10

Mucor (mucormycosis)
*Mould which can cause invasive fungal infection in diabetics and immunocompromised patients.

Question 11

Define Sepsis and Septic shock as per the new Sepsis III definitions

Answer 11

Sepsis = life threatening organ dysfunction due to a dysregulated host response to infection

Organ dysfunction = an increase of 2 points or more in the Sequential Organ Failure Assessment (SOFA) score.
(Each 2 points = 10% mortality increase)

A quick SOFA = HAT ( 3 DOMAINS)
Hypotension < 100 systolic
Altered mental state <GCS 15
Tachypneoa > 22

Septic Shock = Sepsis and (despite adequate volume resuscitation) hypotension requiring vasopressors for MAP > 65 and Lactate greater than or = 2

Septic shock > hospital mortality > 40%