Coagulase negative staphylococcus

Question 1

General

Answer 1

• do not produce toxins
• have weak pathogenicity
• part of normal flora of:
  Skin
  Oropharynx
  Urogenital tract

Question 2

S. epidermis

Answer 2

• some strains produce slime
• adherence to smooth prosthetic surfaces
• slime producing S. epidermis is cause infection in:

Artificial heart valves
Indwelling intravascular catheter
CNS shunts
Artificial joints

• cause Bacteremia and sepsis in patients with implanted devices and especially in very young, old and immunocompromised persons

Question 3

S. saprophyticus

Answer 3

• urinary tract infections in young women

Question 4

Microbiological diagnosis

Answer 4

Culture:
Blood agar plate: white colonies with non-haemolysis

Specific tests:

• catalase positive
• clumping factor test negative
• tube coagulate test negative
• S. epidermidis: novobiocin- susceptible (S)
• S. saprophyticus: novobiocin- resistant (R)

Question 5

Treatment

Answer 5

Antimicrobial susceptibility tests:

Disk diffusion susceptibility testing should be done routinely on staphylococcal isolated from significant infections.