Microbiology

Question 1

How does pathogenic infection occur

Answer 1

Exposure to pathogens leads to adhesion. These invade the epithelium causing colonization. Toxins are released which cause tissue damage and disease

Question 2

What are pathogens

Answer 2

Any microbes that can cause disease

Question 3

What is virulence

Answer 3

Likelihood of causing a disease

Question 4

Which cells are mostly responsible for dealing with viruses

Answer 4

T lymphocytes

Question 5

Cholecystitis vs Cholangitis

Answer 5

Cholecystitis is inflammation of gallbladder whereas cholangitis is infection of bile duct

Question 6

Gram positive vs negative peptidoglycan layer

Answer 6

Gram positive have a think peptidoglycan layer that traps crystal violet. Gram negatives have a thin peptidoglycan layer with an outer membrane on top

Question 7

What are coliforms

Answer 7

Gram-negative bacilli that can ferment lactose, ex: Enterobacteriaceae

Question 8

What type of bacteria are E.coli

Answer 8

Gram negative bacillus lactose fermenters

Question 9

How do Enterobacteriaceae cause diseases

Answer 9

Flagellum - Motility contain H antigen that inhibit phagocyte killing
LPS layer - Endotoxins inducing fever + O antigens that prevent phagocytic killing
Release enterotoxins - Diarrhoea
FImbriae - Attachment to host

Question 10

Molecular testing methods for pathogens

Answer 10

MALDI-TOF

Question 11

What is analysed in MALDI-TOF

Answer 11

Protein composition of bacterial cell wall

Question 12

Prominent bacterial population in stomach

Answer 12

Lactobacilli (E.coli), streptococci, staphylococci

Question 13

Prominent bacterial population in small intestine

Answer 13

Lactobacilli, E.coli, Enterococcus faecalis

Question 14

Prominent bacterial population in large bowels

Answer 14

Lactic acid bacteria, Bacteroids, Bifidobacterium bifidum, Clostridium sp. and anerobic cocci

Question 15

Normal flora of bile duct

Answer 15

Usually sterile

Question 16

What are Charcots triad

Answer 16

Fever, right upper quadrant pain and jaundice signifying cholangitis or inflammation of common bile duct

Question 17

When should a clinical review and decision be taken after prescribing antibiotics

Answer 17

At 48 hours

Question 18

What should be considered after 48 hours of starting antimicrobial treatment

Answer 18

IV to oral switch if patient is getting better. Change to narrow-spectrum. Continue and review again after further 24 hours. Consider OPAT - Outpatient parenteral antimicrobial therapy

Question 19

What can be administered for Enterococcus sp. found in GI tract infection

Answer 19

IV Amoxicillin or Vancomycin if resistant to penicillin

IV to Oral Antibiotics Swtich Therapy (IVOST) cotrimoxazole

Question 20

Which Enterococcus is more common

Answer 20

Enterococcus faecalis whereas Enterococcus faecium is more resistant

Question 21

Most common pathogens in GI tract

Answer 21

Enterococcus, Gram negatives and Anaerobes

Question 22

Sepsis vs septic shock

Answer 22

Patient with overwhelming immune response to an infection develops sepsis. When a septic patient is given IV fluids but is unresponsive, patient is said to be in septic shock

Question 23

Antimicrobial therapy for C.difficile

Answer 23

Non-severe: Metronidazole PO

Severe - Vancomycin PO +/- IV Metronidazole

Question 24

Peritonitis/biliary tract/intra-abdominal

Answer 24

IV Amoxicillin + Metronidazole + Gentamicin
Step down to -
PO Co-trimoxazole + Metronidazole

Question 25

What can be administered if allergic to Amoxicillin

Answer 25

Vancomycin

Question 26

Antibiotics treatment acute gastroenteritis

Answer 26

None required, supportive treatment

Question 27

Acute pancreatitis antibitoics

Answer 27

Antibiotics unlikely to affect outcome

Question 28

Indications of Sepsis in a ward

Answer 28

NEWS score > 5 and an infection

Question 29

General features of sepsis

Answer 29

Hypotension, systolic BP < 100
Tachypnoea, RR > 22
Altered mental state, confused

Question 30

Management plan for large abscess

Answer 30

A large abscess has no blood supply, hence antibiotics won’t get to it (small abscess might response to antibiotics). Hence, large abscess need to be incised and drained, call surgeon

Question 31

Types of peritonitis

Answer 31

Spontaneous and secondary peritonitis
Spontaneous - Infection that occurs without warning or cause such as of ascitic fluid
Secondary - Peritoneum get’s inflamed or infected without an apparent cause

Question 32

Surgical prophylaxis antibiotics should be limited to

Answer 32

24 hours

Question 33

What antibiotics administration is preferred

Answer 33

Oral over IV

Question 34

Drug choice for sepsis and enterococci in GI tract

Answer 34

Amoxicilin, Vancomycin if allergic

Switch to co-trimoxazole for oral administration

Question 35

Drug choice for sepsis and coliforms

Answer 35

Gentamicin (IV), Aztreonam if contraindication

Co-trimoxazole for oral switch

Question 36

Drug choice for sepsis and anaerobes

Answer 36

Metronidazole, IV and same for oral switch

Question 37

Measuring minimum inhibitory concentration of antibiotics

Answer 37

Broth dilution method