staph a bacteraemia

Question 1

how does staphylococcus aureus cause disease

Answer 1

through both toxin-mediated and non-toxin mediated mechanisms

Question 2

what type of bacteria is staph a

Answer 2

gram positive cocci

Question 3

colonisation of staph a

Answer 3

~20-25% may be peristently or transiently colonised

colonisation sites act as reservoir for future infections

anterior nares most frequent site colonisation

Question 4

who is most likely to be colonised with staph a

Answer 4

insulin dependent diabetics
HIV patients
haemodialysis
skin damage

Question 5

primary or secondary s.aureus blood stream infection

Answer 5

absence or presence of identified associated sites of infection

Question 6

spectrum of s. aureus infection

Answer 6

skin and soft tissue infection
localised pyogenic staphylococcal infections: furuncles, carbuncles
deep-seated abscesses, necrotising fasciitis
osteomyelitis, septic arthritis, discitis
infective endocarditis
pneumonia, empyema
wound infection, vascular line, catheter-related

Question 7

frequent site of distant septic metastases in patients with s.auereus bacteraemia

Answer 7

bones and joints, esp when prosthetic materials present
epidural space and intervertebral discs
narice and prosthetic cardiac valces
visceral abscesses in spleen, kidneys, lung

Question 8

investigations

Answer 8

microscopy and culture of specimens (pus and any discharge)
2sets blood cultures before antib
repeat blood cultures 48-72hrs after starting antib
biopsy samples for bone infections
imaging: x-ray, CT, MRI
transthoracic echocardiography

Question 9

basis of treatment for staphylococcal infection

Answer 9

antib therapy
source identification and clearance
approp surgical intervention

Question 10

what antib is first line for drug sensitive s.aureus

Answer 10

flucloxacillin (14 days)

Question 11

which antib is first line for MRSA

Answer 11

vancomycin