Microbiology

Question 1

Gram staining results?

Answer 1

Gram +ve = purple

Gram -ve = pink

Question 2

What are the two main types of coccus bacteria and how do they appear?

Answer 2

Strep = chain
Staph = clusters

Question 3

How can you differentiate between Staph bacterium (will be GRAM +VE)

Answer 3

Coagulase test
Positive = S. aureus
Negative = S. epidermidis or S. saprophiticus

Question 4

How can you differentiate between Step bacterium (will be GRAM +VE)

Answer 4

Grow on blood agar
Alpha-haemolytic = dark green - S.pneumoniae, S. pralis, S.sanguis
Beta-haemolytic = pale yellow/transpartent - S.pyogenes (group A), S.agalactiae (group B)
Non-haemolytic = no change - S. mutans, S. milleri or eneterococcus faecalis

Question 5

What is the main gram positive bacilli? Is it aerobic or anaerobic?

Answer 5

Clostridium difficile (all clostridiums are anaerobic)

Question 6

What are the two main coccus gram negative bacteria?

Answer 6

N. meningitidis, N. gonorrhoea

Question 7

How do you differentiate between gram negative bacilli?

Answer 7

MacConkey plate
Lactose fermenters = pink - E.coli, K. pneumoniae
Non-lactose fermenters = pale - salmonella, shigella and proteus

Question 8

What test can differentiate between Staph and Strep bacteria?

Answer 8

Catalase test
Staph = produce gas bubbles
Strep = no bubbles

Question 9

What are the two actions of antibiotics?

Answer 9

Bacteriocidal = kill bacteria
Bacteriostatic = stop bacterial growth to allow the body to destroy the bacteria

Question 10

Which antibiotics inhibit cell wall synthesis?

Answer 10

Beta-lactams (penicillins, cephalosporins and carbapenems), vancomycin

Question 11

Which antibiotics inhibit neucleotide synthesis?

Answer 11

Trimethoprim, Metronidazole and Rifampicin

Question 12

Which antibiotics inhibit protein synthesis?

Answer 12

Clarithromycinm gentamicin and tetracyclines

Question 13

Which antibiotic treats specifically staph. aureus?

Answer 13

Flucloxacillin

Question 14

Which antibiotic is commonly used to treat MRSA?

Answer 14

Vancomycin

Question 15

What is the main causative organism in infective endocarditis and what is the AB treatment?

Answer 15

Step. viridans

4-6 weeks of IV benzylpenicillin +/- 2 weeks gentamicin

Question 16

What is the most common cause of CAP and what is the AB treatment?

Answer 16

Strep. pneumonia - depends on CURB65 score
0-1 = amoxicillin
2 = amoxicillin and clarithromycin
3+ = IV co-amoxiclav and clarithromycin

Question 17

What is the most common cause of HAP and what is teh AB treatment?

Answer 17

Saph. aureus/MRSA - IV gentamicin and a penicillin

Question 18

What are the three main TB symptoms?

Answer 18

Night sweats, productive/sputum cough and weight loss

Question 19

How do you test and AB treat TB

Answer 19

Test: Ziehl-Neelsen stain = active disease, Mantoux skin test = latent disease
Treatment = Rifampicin, Isoniazib, Pyrazinamide, Ethambutol (RIPE)

Question 20

What are the main causative organisms of SBP and what is the AB treatment?

Answer 20

E.coli, Klebsiella and Strep. pneumoniae (kids)

IV cefotaxime and metronidazole

Question 21

What is the AB treatment for appendicitis?

Answer 21

IV cefotaxime and metronidazole

Question 22

What are teh main causes of UTI and what is the AB treatment?

Answer 22

E.coli (70%), proteus miribilus and klebsiella

Trimethoprim or Nitrofurantoin if in 1st trimester of pregnancy

Question 23

What are the signs of sepsis?

Answer 23

Shivering/fever, Extreme pain, Pale skin, Sleepy/confused, Impending doom, SoB (SEPSIS)

Question 24

How do you treat HIV and when does it become AIDS?

Answer 24

HAART anti-retrovirals to treat HIV

Becomes AIDS when CD4 < 200 cells/ml and/or there is an AIDS defining illness present

Question 25

AB treatment for septic arthritis?

Answer 25

IV flucloxacillin and double steroids for 6 weeks

Question 26

What cuases osteomyelitis?

Answer 26

Staph. aureus, strep or enterococci in the immunosuppressed/diabetics post-joint surgery

Question 27

How do you treat the two main causes of reactive arthritis?

Answer 27

Chlamydia = docycyline (7 days) or 1 dose azithromycin | N. gonnorrhoea = ceftriaxone IM PLUS 1 dose axzithromycin

Question 28

What are the most common causes of meningitis?

Answer 28

EBV, herpes simplex virus and mumps - VIRAL = MOST COMMON | Bacterial: Strep. pneumoniae (most common), N. meningitidis (most severe), H. influenzae

Question 29

What is the AB treatment of meningitis in the community/hospital?

Answer 29

Community = IM benzypenicillin Hospital: <55 = IV cefotaxime, >55, immunocompromised or pregnant IV cefotaxime AND amoxycillin

Question 30

How do you treat close contacts in a meningitis case?

Answer 30

Give them rifampicin and Meningitis C vaccine

Question 31

What is the most severe cause of encephalitis and what is the AB treatmnet?

Answer 31

Herpes Simplex Virus | IV acyclovir

Question 32

What causes shingles and what is the AB treatment?

Answer 32

VZV - Acyclovir

Question 33

What are the most common causes of cellulitis and what is the AB treatment?

Answer 33

Staph aureus and strep - IV flucloxacillin and benzylpenicillin

Question 34

What are the cuases of malaria, how is it carried and how is it treated?

Answer 34

P. falciparum (main), P. malariae, P. vivax, P. ovalae Anopheles mosquitoe (female) Treat with quinine