healthcare associated infections

Question 1

pathogen, risk factors and symptoms of CA-UTI

Answer 1

most common culture = E coli

risk factors
= women, duration of catheter, poor care

symptoms
= fever, confusion, lethargy, sometimes flank pain
(pyuria alone or smelly/cloudy urine is not diagnostic)

Question 2

candida albicans

Answer 2

• common cause of infection

- cause of thrush, nappy rash, candidiasis, only causes UTI when catheter present

Question 3

management of CA-UTI

Answer 3

• if no othecause of fever found -> remove catheter

- urine sample after catheter removed (not required if symptoms stop after removal)

Question 4

define biofilm

Answer 4

microbial community of cells attached to surface and each other, embedded in matrix of extracellular polymeric substance

Question 5

bacterial pathogens causing device infections

Answer 5

gram +ve
= S. aureus or S. epidermis

gram -ve
= E. coli

Question 6

device factors that favour adhesion

Answer 6

• device material e.g. PVC
• synthetic materials
• textured/irregular surfaces
• polymeric tubing > wire mesh

Question 7

problems with biofilm-associated bacteria

Answer 7

• antibiotics hard to reach deep bacteria
• slow growth rate (more resistant to antibiotics)
• undergo change in phenotype

Question 8

strategies to reduce device infections

Answer 8

• avoid catheter use
• hand washing before and after touching device
• insert using septic technique (avoid femoral site)
• remove unnecessary devices
• monitor devices carefully for infection signs

Question 9

clostridium difficile infection

Answer 9

C. difficile is part of the normal flora of the GI tract

• spreads from person to person
  e.g. diarrhoea - contaminates environment
  long lived bacterial endospores

Question 10

risk factors for C. difficile

Answer 10

• hospital patients receiving antibiotics
  - removes competition allows C. difficile to grow
• longer than 1 week in hospital
• other treatment that disrupts colonic flora

Question 11

colonisation of C. difficile

Answer 11

• antibiotics reduces number of major non-spore forming anaerobes in colon
• C. difficile grows in high number, produces toxins
• can survive as endospores and out-compete other species when treatment stops

Question 12

virulence factors of C difficile and consequence

Answer 12

• toxin A and toxin B causes actin cytoskeleton collapse. results in malabsorption from lumen and diarrhoea

potentially causing pseudomembranous colitis

Question 13

diagnostic test of C. difficile

Answer 13

• test stool for suspected C. difficile associated diarrhoea
• antibody based assay for toxins
• PCR for toxin genes
• presence of bacteria may not be diagnostic as colonisation is common

Question 14

treatment of C difficile

Answer 14

• discontinue predisposing antibiotics
• treat with anti-C difficile antibiotics
  = IV metronidazole or oral vancomycin
• support fluid loss and pain
• attention to hygiene and cleanliness to prevent outbreak

Question 15

endospores

Answer 15

• only produces by bacillus and clostridium
• dormant survival structure (not reproductive)
• killed by autoclaving (121), chemicals
• not killed by antibiotics, oxygen or pasteurisation