Microbiology Flashcards
Patient presents with vomiting, epigastric pain and diarrhoea, 6 hours after eating a meat and cheese pie.
What is the cause?
How do you treat them?
Staphylococcus aureus (exotoxin)
Supportive care: fluids, electrolytes
Patient presents with vomiting, epigastric pain and diarrhoea, 6 hours after eating reheated rice.
What is the cause?
Bacillus cereus (exotoxin)
Supportive care: fluids, electrolytes
Pt presents with vomiting, headache and watery diarrhoea.
A stool PCR detects norovirus. Where did they likely pick this up?
Cruise ship. Nursing home.
Patient has just returned from their travels. They present with watery diarrhoea.
What is the likely cause? What is the treatment?
Enterotoxin E Coli
Ciprofloxacin
Patient presents with severe watery, “rice-water” stool.
A stool culture detects a pathogen; what is the likely cause? What is the treatment?
Vibrio CHOLERAE
Supportive care - IV fluids.
Patient presents with weeks of loose diarrhoea, cramps, frequent belching and flatulence, and a fatty foul stool.
Their ImmunoCard STAT shows an antigen.
What is the likely cause? What will their stool microscopy show?
What is the treatment?
Giardia Lamblia
Stool microscopy: ova + parasite cysts
Metronidazole
Patient presents with watery diarrhoea and is febrile. They recently ate cheese with raw cold vegetables.
What is the likely cause?
Listeria monocytogenes
Causes of non-inflammatory diarrhoea (ie watery, non-bloody)
SBEVNGL
Staph aureus Bacillus cereus Enterotoxin E coli Vibrio cholerae Norovirus Giardia Lamblia
Listeria monocytogenes (febrile)
Some Bitches Eat Vulgar Non-inflammatory Goats, Leisurely
Patient presents with bloody diarrhoea. She recently had some rare beef with fresh veg from a farm,
What will her stool culture likely show?
What is the treatment?
Shigella-toxin E Coli
None.
Do NOT give Abx to children - can cause Haemolytic Uraemic Syndrome (HUS)
Patient comes in with diarrhoea containing blood and pus.
Their stool culture is positive. Likely cause? Treatment?
Shigella
Ciprofloxacin
Patient comes in with bloody diarrhoea and fever. They recently ate some undercooked eggs with raw vegetables and pink chicken.
Likely cause? Treatment?
Salmonella
Ciprofloxacin
Patient presents with fever and diarrhoea, after eating unpasteurised cheese.
What is the likely cause? Treatment?
What neurological condition are they at a higher risk of?
Campylobacter jejuni
Azithromycin/ Ciprofloxacin
Guillain Barre Syndrome
Patient develops bloody diarrhoea and fever whilst in hospital.
What is the likely cause? What may be seen on a colonoscopy?
Treatment?
C. difficile
Colonoscopy: pseudomembranous colitis
Metronidazole
What are the causes of inflammatory diarrhoea?
SSSCC
STEC Shigella Salmonella Campylobacter jejuni C difficile
Causes of appendicitis
Normal colonic flora:
Escherichia coli
Peptostreptococcus
Bacteroides fragilis
Pseudomonas
Causes of Diverticulitis
Bowel flora
B. fragilis
E. coli
Malaria pathogens + transmission
P falciparum - 80% P Vicax P Ovale (mild) P Malariae (persists yrs) P Knowlesi
Sporozoites via Anopheles mosquito > hepatocytes > schizonts > rupture > merozoites
Malaria presentations
Fever/sweats
Haemolytic anaemia
Hepatosplenomegaly
Malaria investigations
Thick + Thin Blood Smear with FIELD’s/ GIEMSA stain (light microscopy)
1L: FBC - haemolytic anaemia, thrombocytopenia, abnormal LFTs
Malaria treatments
QUINOLINES
- chloroquine
- Quinine
ANTIFOLATES
- pyrimethamine
- Sulfonamides
RIBSOSOME INHIBITORS
- Tetracycline
- Doxycycline
- Clindamycin
Supportive
Pt presents with quickly spreading erythema on the legs, which is tender and warm to touch. There is a wound at the site.
What is the likely diagnosis? Treatment?
Cellulitis: B-haemolytic streptococci - S. pyogenes, S. agalactiae. Staph aureus.
Treatment:
- elevate + mobilize limb
- washout wound
- Empiric IV Flucloxacillin (or Clindamycin)
If MRSA cellulitis: VANCOMYCIN
Pt develops warm, tender erythema around surgical site following operation. Their skin is blue-gray (hypoperfused) and there’s a loss of sensation. Crepitus is found on exam, as well as Fournier’s gangrene.
Cause? Treatment
Necrotizing Fasciitis
Tx:
- Emergency surgical exploration
- Empirical piperacillin-tazobactam + clindamycin
- S. pyogenes - penicillin + clindamycin
Gram negative bacteria are grown on which type of agar?
MacConkey agar
Pink colonies grow on a MacConkey Agar plate.
What clinically relevant bacteria could these be?
- E coli
- Klebsiella
= Lactose-fermenting Gram Negative Bacillus
= Enterobacteriae
Name some gram negative aerobic COLIFORM species
- Escherichia
- Klebsiella
- Salmonella
- Shigella
EKSS
Name some gram negative aerobic VIBRIO species
- Vibrio cholerae
- Campylobacter
- Helicobacter
- Haemophilus
VCHH
Gram positive cocci are grown on which agar?
Blood Agar
Cream yellow colonies grow on a blood agar plate. What’s the likely species? What other test can be performed to detect this bacteria?
Staphylococcus aureus
Coagulase/ DNAase test will be positive
Gram positive chains =
Streptococcus
Gram positive cocci =
Staphylococcus
An optochin test is performed. The area around is clear.
Streptococcus pneumoniae
= Gram positive alpha-haemolytic streptococcus
An optochin test is performed. It has absolutely no effect x
Viridians streptococcus
Lancefield grouping is used to categorise…
Gram positive beta-haemolytic streptococci
Streptococcus pyogenes is which lancefield group?
Group A Gram positive beta-haemolytic
Streptococcus agalactiae is which Lancefield group?
Group B gram positive beta-haemolytic
Enterococcus faecalis is which Lancefield group?
Group D gram positive beta-haemolytic
What culture is used to grow Mycobacterium tuberculosis?
Lowenstein-Jensen
What culture is used to grown anaerobes? Give an example of anaerobe
Blood agar
Fusobacteria
What culture is used to grow aerobes? give an example of an aerobe
Chocolate agar
Strep pneumoniae
What cutlture is used to grow gram-negative bacilli?
MacConkey agar
1, 3 beta-D-glucan assay
Examples of organisms
= Chitin :. detects fungi
Aspergillus fumigatus
Candida albicans
Pneumocystitis jirovecii
Cholera pathogenesis
Toxin. Deregulates ion transport in epithelial cells
