5. BAMS Micro

Question 1

Microbes

1. What are the stages of virus replication
2. What is a capsule and what is its function
3. Name 3 alert micro-organisms

Answer 1

1. Attachment, penetration, uncoating, synthesis of viral components, assembly, release
2. Thick layer of polysaccharide chains that forms a distinct barrier surrounding bacteria and mediates adhesion, immune evasion, protection from desiccation and is a reserve for CHO
3. VISA, MRSA, VRE, C. diff, C. auris

Question 2

Biofilms

1. What are the stages in biofilm development
2. What are the 3 key features of biofilm development

Answer 2

1. Adhesion, colonisation, accumulation, maturation and formation of complex communities and dispersal
2. Micro-organisms, conditioning film (pellicle), surface

Question 3

Sepsis

1. What is bacteraemia
2. What is septicaemia
3. What is SIRS and what are the 4 SIRS criteria
4. What is sepsis
5. Give 4 signs/symptoms of sepsis
6. What is severe sepsis
7. What is septic shock
8. How is sepsis treated
9. What is the sepsis six

Answer 3

1. Transient presence of bacteria in the bloodstream
2. Persistent presence of bacteria in the bloodstream with attendant signs and symptoms

3. Systemic inflammatory response syndrome based upon 2 or more of the 4 criteria
Temp <36C/>38C
HR >90
RR >20 (or PaCO2 <4.3kPa)
WCC <4,000/mm3 or >12,000/mm3

4. Infection + SIRS. Uncontrolled, unregulated, self-sustaining intravascular inflammation involving cytokine storm
5. High/low temp, uncontrolled shivering, confusion, cold/blotchy hands and feet, reduced urine output, general malaise, drowsy, difficult to rouse
6. Sepsis and organ failure
7. Sepsis and shock refractory to fluid resuscitation (unresponsive to fluid resuscitation)
8. Aggressive broad-spectrum antibiotics, IV fluids, oxygen, blood cultures

9. Method used to monitor/prevent sepsis
O2 to keep SATS >94%
Blood cultures
IV antibiotics 
Fluid challenge
Measure lactate
Measure urine output

Question 4

Antibiotics

1. Define antibiotics
2. Give 3 ideal properties
3. Give 3 methods of antimicrobial action
4. Give 4 types of antibiotic misuse
5. How does antimicrobial resistance occur
6. What is antimicrobial stewardship

Answer 4

1. Chemical substances produced by one organism that is destructive to another
2. Selective toxicity against the target, long plasma half-life, good tissue distribution, oral and parenteral preps, no adverse interactions with other drugs
3. Inhibit cell wall synthesis, inhibit protein synthesis, inhibit nucleic acid replication and transcription, injury to plasma membrane, inhibit essential metabolites
4. Using outdated/weakened antibiotics, inappropriate use/prescribing, use in animal feed, failing to complete prescribed regime, using someone else’s prescription
5. When microbes change in ways that render the medications used to cure the infections they cause ineffective. Fail to penetrate through biofilm, trapped and destroyed by enzymes, inactive against non-growing organisms, expression of biofilm-specific resistance genes, stress response to hostile environmental conditions
6. Coherent set of actions which promote using antimicrobials responsibly

Question 5

Caries Biofilm

1. Give 4 functions of saliva
2. How does caries progress
3. Give 2 types of cariogenic bacteria
4. Give 5 virulence factors of one answer to 3
5. Describe systemic, topical and antimicrobial effects of fluoride
6. Give 4 ways caries can be prevented
7. Give 4 factors of high caries risk

Answer 5

1. Acid buffering, remineralisation, digestion, lubrication, antimicrobial effects, bolus formation, taste
2. Adhesion, survival and growth, biofilm formation, complex plaque, acid, caries formation
3. S. mutans, lactobacillus acidophilus
4. Adhesins, binding proteins, sugar-modifying enzymes, polysaccharides (gluons), acid tolerance and adaptation
5. Systemic - incorporation into developing enamel
   Topical - surface layer of enamel converted into fluoroapatite
   Antimicrobial - inhibits plaque metabolism
6. Fluoride, mechanical disruption, diet, microbial inhibition
7. Acid-producing bacteria, low unstimulated saliva flow rate, frequent consumption of high levels of sucrose and other fermentable CHOs, little/no fluoride intake

Question 6

Perio Biofilm

1. Name 3 key perio pathogens
2. Give 3 virulence factors of one answer to 1
3. Describe how one virulence factor acts
4. Name 3 systemic disease implicated in perio disease

Answer 6

1. P. gingivalis, T. denticola, T. forsythia
2. Gingipains, host cell tissue adherence and invasion (fimbriae), elongation of proteases, endotoxins, capsular polysaccharide and outer membrane vesicles, tissue toxic metabolic by-products
3. Actively degrade chemokines and activate MMPs
4. Diabetes, CVD, RA,

Question 7

Candida Biofilm

1. Give 4 risk factors for developing a candidal infection
2. Name 3 types of candidal species
3. Give 2 virulence factors of one answer to 2
4. Describe the action of 2 types of anti fungal agents

Answer 7

1. Immunocompromised, catheters, LT steroid use, broad-spectrum antibiotics, diabetes
2. C. albicans, C. auris, C. tropicalis, C. gladrata, C. krusei
3. Hyphae, hydrolytic enzymes (phospholipase, haemolysis, protein)
4. Polyenes (nystatin) directly target the ergosterol in the fungi cell wall and cause perforation and leakage of intracellular contents. Fungicidal (actively kill cells), has a higher virulence but is less well tolerated.

Azoles (miconazole and fluconazole) work by indirectly targeting the ergosterol in the fungi cell wall by interrupting the activity of the enzyme involved in its production, 14-alpha demethylase. Fungistatic as they target dividing cells. They are not so effective against biofilms and certain candida species can be naturally resistant (C. krusei and C. glabrata).