Microbiolgy

Question 1

which antibiotics are beta lactams (inhibit cell wall formation)?

Answer 1

penicillins

cephalosporins

Question 2

which antibiotics are bacteriostatic (inhibit protein synthesis)?

Answer 2

aminoglycosides (cause misreading of mRNA)

chloramphenicol

macrolides (e.g. erythromycin)

tetracyclines

fusidic acid

Question 3

what antibiotics inhibit DNA synthesis?

Answer 3

quinolones (e.g. ciprofloxacin)

metronidazole

sulphonamides

trimethoprim

Question 4

which antibiotics inhibit RNA synthesis?

Answer 4

rifampicin

Question 5

what is the mechanism of resistance for penicillin?

Answer 5

Bacterial penicillinase (β-lactamase) cleaves β-lactam ring

Question 6

what is mechanism of resistance for cephalosporins?

Answer 6

Changes to penicillin-binding-proteins (PBPs), which are types of transpeptidases

Question 7

what is the mechanism of resistance for macrolides?

Answer 7

Post-transcriptional methylation of the 23S bacterial ribosomal RNA

Question 8

what is the mechanism of resistance for tetracyclines?

Answer 8

Increased efflux of the bacteria by plasmid-encoded transport pumps, ribosomal protection

Question 9

what is the mechanism of resistance for sulfonamides

Answer 9

Bacteria increase synthesis of PABA, mutation to gene encoding dihydropteroate synthetase

Question 10

what is the mechanism of resistance for vancomycin

Answer 10

Alteration to the terminal amino acid residues of the NAM/NAG-peptide subunits (normally D-alanyl-D-alanine) to which the antibiotic binds

Question 11

Rifampicin

Answer 11

Mutations altering residues of the rifampicin binding site on RNA polymerase

Question 12

which streptococci have alpha haemolysis? (partial haemolysis)

Answer 12

pneumococcus

streptococcus viridans

Question 13

which streptococci do beta haemolysis (complete haemolysis)?

Answer 13

Group A - strep pyogenes

Group B - agalactiae

Group D - enterococcus

Question 14

compare how beta haemolysis would look like to alpha haemolysis in a blood agar tray?

Answer 14

beta will be very yellow and large area

alpha will be smaller area and darker

Question 15

what is the main route of infection for strep viridans?

Answer 15

GI tract

Question 16

what criteria is used to asses endocarditis?

Answer 16

DUKE’s criteria

Question 17

what is FEVER PAIN score used to assess?

Answer 17

Strep Pharyngitis

Question 18

what is centor criteria used for ?

Answer 18

group A strep

strep pharyngitis

Question 19

what does enterococcus faecalis cause on blood agar ?

Answer 19

no haemolysis ( gamma haemolytic)

Question 20

Which of these is not included in the list of ‘typical organisms’ in the major criteria for diagnosing endocarditis

(2 separate positive blood cultures in the absence of alternative source)
Select one:

Staphylococcus aureus

Enterococcus faecalis

Viridans streptococci

Escherichia species

HACEK group organisms

Answer 20

Escherichia species

Question 21

what does the QSOFA markings indicate?

Answer 21

sepsis

altered mental state

resp rate <30

systolic BP <100

Question 22

what bacteria is Proton pump inhibitors a risk factor for?

Answer 22

Clostridium difficile

Question 23

how do you test for clostridium difficile?

Answer 23

Clostridium difficile toxin (CDT) in the stool

Question 24

what are the risk factors of C.difficile infection?

Answer 24

Antibiotics within the preceding 3 months

Proton pump inhibitors

Prolonged hospitalisation

Immunosuppression

Question 25

what is the clinical presentation of Haemolytic uraemic syndrome?

Answer 25

acute kidney injury microangiopathic haemolytic anaemia thrombocytopenia

Question 26

what two types of haemolytic uraemic syndrome are there?

Answer 26

typical HUS - secondary caused: Shiga toxin-producing Escherichia coli (STEC) 0157:H7 pneumococcal infection HIV rare: systemic lupus erythematosus, drugs, cancer atypical HUS (primary caused: complement dysregulation

Question 27

how do you diagnose HUS?

Answer 27

full blood count: anaemia, thrombocytopaenia, fragmented blood film U&E: acute kidney injury stool culture looking for evidence of STEC infection PCR for Shiga toxins

Question 28

how do you manage HUS?

Answer 28

no antibiotics! supportive: fluids, blood transfusion and dialysis

Question 29

what drugs are used in anaerobes only?

Answer 29

1. metronidazole

Question 30

what drugs are used in both anaerobes and aerobes?

Answer 30

1. penicillin 2. amoxicillin 3. clindamycin 4. co trimoxazole 5. moxiflacin 6. ceftriaxone 7. cefepime 8. tigecylcine 9. Piperacillin – tazobactam

Question 31

what drugs are used in gram positive only?

Answer 31

flucloxacillin vancomycin

Question 32

what drugs are used in gram negative only?

Answer 32

azithromycin erythromycin

Question 33

give examples of penicillins.

Answer 33

1. penicillin 2. amoxicillin 3. flucloxacillin 4. Piperacillin-tazobactam

Question 34

give examples of sulfonamides.

Answer 34

co-trimoxazole trimethoprim

Question 35

give examples of aminoglycosides.

Answer 35

gentamicin tobramycin

Question 36

give examples of fluoroquinolones? (quinolones)

Answer 36

moxifloxacin Ciprofloxacin Aztreonam levofloxacin

Question 37

give examples of CEPHALOSPORINS.

Answer 37

cephazoline cefuroxime ceftriaxone

Question 38

what class is vancomycin part of?

Answer 38

glycopeptides

Question 39

what are the 4c antibiotics?

Answer 39

Clindamycin Levofloxacin (fluroquinolones) Ceftazidime (cephalosporins) Co-amoxiclav