Microbiology

Question 1

What are the most likely pathogens responsible for a bone and joint infection?

Answer 1

Staph aureus
Strep A
Coliforms

Question 2

What pathogens may be responsible if it is a prosthetic joint infection?

Answer 2

Diphtheroids

Coag neg Staph (CoNS)

Question 3

How would an acute bone and joint infection present?

Answer 3

Pain, swelling, redness
Reduced mobility
Temperature

Question 4

What is needed to diagnose Systemic Inflammatory Response Syndrome (SIRS)?

Answer 4

TWO OR MORE OF: 
Temperature >38
HR >90
RR> 20 
WBC >12,000

Question 5

What is septic arthritis?

Answer 5

An infection of the joint space

Question 6

What bacteria causes septic arthritis?

Answer 6

MSSA

Question 7

What investigations are needed if septic arthritis is suspected?

Answer 7

Bloods
Joint fluid aspirate
USS
Plain xray

Question 8

What is the empirical therapy for septic arthritis?

Answer 8

Flucloxacillin

24-48 hours for lab to return sensitivities.

Question 9

What antibiotic should be added if pt is under 5 for septic arthritis?

Answer 9

Ceftriaxone

for H flu and Kingella

Question 10

What is osteomyelitis?

Answer 10

Inflammation of bone or medullary cavity

Question 11

Where does osteomyelitis usually affect?

Answer 11

Long bones or vertebrae

Question 12

What bacteria causes acute osteomyelitis?

Answer 12

MSSA

Strep

Question 13

What bacteria causes chronic osteomyelitis?

Answer 13

M. tuberculosis, Pseudomonas, salmonella, coliforms

Question 14

When is haematogenous spread more likely?

Answer 14

Acutely.

Question 15

If osteomyelitis spreads to the joint what is it called?

Answer 15

Septic arthritis

Question 16

Who is at higher risk of developing septic arthritis from osteomyelitis?

Answer 16

Infants

more vessels cross the metaphysis to the epiphysis

Question 17

What antibiotics should be given for chronic osteomyelitis?

Answer 17

Abx should be delayed until cultures are returned.

No immediate danger

Question 18

What abx are given for acute osteomyeltiis?

Answer 18

Flucloxacillin empirically. Tx should be modified after cultures.

Question 19

What are the risk factors for developing an infection in a prosthetic joint?

Answer 19

Diabetes
Malnutrition
Obesity
Rheumatoid arthritis

Question 20

What are the 3 types of implant infection?

Answer 20

Early postoperative, delayed and late.

Question 21

Describe the time scale, causes and signs of early postoperative infection.

Answer 21

0-3 months.
Staph aureus, Strep
fever, warmth

Question 22

True or False

Coagulase negative staphylococci are skin commensals

Answer 22

True

Question 23

Why is it difficult to diagnose a prosthetic joint infection?

Answer 23

Caused by common contaminants

Cultures are rarely positive

Question 24

What is the treatment for PJI?

Answer 24

removal of prosthesis and reimplantation after abx tx.

Question 25

What is necrotising fasciitis?

Answer 25

Acute and severe infection of the subcutaneous soft tissues

Question 26

Where is most commonly affected by necrotising fasciitis?

Answer 26

Limbs, abdominal wall, groin area, post operative wound.

Question 27

What causes necrotising fasciitis?

Answer 27

Anaerobes. | Group A strep.

Question 28

How is necrotising fasciitis diagnosed?

Answer 28

Pain is disproportionate to superficial appearances. | Take swabs and tissues biopsy for culture.

Question 29

What is the treatment for necrotising fasciitis?

Answer 29

Surgical debridement | Penicillin and clindamycin

Question 30

True or False | There is no need for infection control with necrotising fasciitis.

Answer 30

False. | Contact precautions should be taken as well as a risk assessment for droplet precautions.

Question 31

How are clostridium perfringens classified?

Answer 31

Gram positive (purple) Strictly anaerobes Rods

Question 32

What is gas gangrene?

Answer 32

Spores of C. perfringens germinate into tissue and accumulate into gas bubbles.

Question 33

What is the treatment for gas gangrene?

Answer 33

Urgent debridement. penicillin +/- metronizadole Hyperbaric oxygen

Question 34

What organism causes tetanus?

Answer 34

Clostridium tetani

Question 35

How is clostridium tetani classified?

Answer 35

Gram positive Strictly anaerobic Rods

Question 36

What are the symptoms of tetanus?

Answer 36

Spastic paralysis Lock jaw due to muscle spasm Stiffness of neck

Question 37

What is the incubation period for tetanus?

Answer 37

4 days- several weeks

Question 38

What is the treatment for tetanus?

Answer 38

Booster vaccination | Penicillin/ metronizadole

Question 39

What is the antibiotic of choice to treat staph and strep?

Answer 39

Flucloxacillin. | Vancomycin

Question 40

What antibiotic could be used for coliforms?

Answer 40

Gentamicin

Question 41

How many samples should be taken if PJI is suspected?

Answer 41

3. | To exclude contaminated bacteria from the culture.

Question 42

How long is the abx treatment for a hip PJI?

Answer 42

3 months

Question 43

How long is the abx treatment for a knee PJI?

Answer 43

6 months

Question 44

When should the first prophylactic abx be given?

Answer 44

Within 60 minutes of surgery

Question 45

What is the most common bacteria which contaminates in trauma?

Answer 45

Staph aureus

Question 46

What kind of patients do PVL commonly affect?

Answer 46

Young people with osteo infection.

Question 47

What antibiotic would you use if you suspected PVL?

Answer 47

Clindamycin

Question 48

How do CoNS affect prosthesis?

Answer 48

They are charged and stick to the plastic of the prosthesis and create a layer of biofilm which makes them harder to treat.

Question 49

What bacteria are the most common found in osteomyelitis in children?

Answer 49

Pseudomonas | Kingella

Question 50

True or False | BJIs never cause septic shock

Answer 50

False.

Question 51

What do microbiology do with a joint fluid aspirate?

Answer 51

Look for crystals for (pseudo)gout Check for white cells Gram stain

Question 52

What is the classic link with brucella infection?

Answer 52

Goats. | Especially drinking goats unpasteurised milk.

Question 53

What are the downsides of gentamicin?

Answer 53

Nephrotoxic. | Need permission to use longer than 3 days

Question 54

What kind of antibiotic is gentamicin?

Answer 54

Aminoglycoside

Question 55

What is a DAIR procedure?

Answer 55

Debridement and implant retention

Question 56

What blood tests need to be done if infection suspected?

Answer 56

CRP PV WCC if acute

Question 57

When is acute osteomyelitis most likely to occur?

Answer 57

Post-trauma | Open wound

Question 58

If an osteomyelitic patient has pus what is the right thing to do?

Answer 58

Drain the abscess

Question 59

What antibiotics can be used for cellulitis?

Answer 59

Flucloxacillin to cover staph and strep