Healthcare Associated Infections

Question 1

What is a healthcare associated infection (HCAI)?

Answer 1

• An infection occurring as a result of healthcare activity, not incubating at the time of initial healthcare exposure
• Cut off usually 48-72h

Question 2

What are the most common HCAIs?

Answer 2

1) Hospital acquired bacteraemia/sepsis
2) UTI
3) Surgical site infection
4) C.difficile colitis
5) HAP

Question 3

What are some examples of resistant organisms?

Answer 3

1) MRSA - can decolonise patient bc it lives on the skin
2) CRO - difficult to decolonise bc lives in gut, v few interventions
3) VRE
4) ESBL

Question 4

What are endogenous pathogens?

Answer 4

Pathogens in skin, gut and urogenital flora that live on/in patients

Question 5

What are exogenous pathogens?

Answer 5

Pathogens acquired from the hospital environment that live on us and other patients

Question 6

Which bacteria are present in organ systems in flora of someone in a hospital that are not normally present in the community?

Answer 6

1) Enterococci bacteria e.g. E.coli, Klebsiella sp.
2) Candida sp.
3) Pseudomonas sp.

Question 7

Which endogenous gram positive skin flora can cause line infections or infections from a cardiac device?

Answer 7

S.epidermis (and S.aureus)

- Can see clot on end of pacemaker using echo

Question 8

Which gram positive bacteria normally present in the nose and perineum (colonising 10-40%) has 80-100% colonisation in eczema?

Answer 8

S.aureus

Question 9

Describe resident skin flora

Answer 9

• Protective function
• Not easily removed by routine hand washing
• Cause infection only via skin breaks

Question 10

Describe transient skin flora

Answer 10

• Loosely attached to skin surface
• Therefore easily transferred by direct contact
• Easily removed with routine hand washing
• Most abundant around finger tips
• Important source of cross-infection

Question 11

How does endogenous gut flora change as you go down the GI tract?

Answer 11

Increases to the point where 60% of faecal dry mass is bacteria

Question 12

What bacteria are present in duodenal flora and higher in achlorhydria or malabsorption?

Answer 12

1) Streptococci
2) Lactobacilli
3) Bacteroides

Question 13

What are 3 bacteria are present in large bowel dense flora (many)?

Answer 13

1) E.coli
2) Enterobacter
3) Klebsiella

Question 14

Describe what happens in vaginal flora

Answer 14

• It changes in relation to age, hormone levels and pH
• Transient organisms e.g. candida are a frequent cause of vaginitis (common but only need to treat if have clinical signs)

Question 15

Describe the contents of distal urethra flora

Answer 15

• Contains a mixture of skin and GI tract organisms (relevant with catheter)
• Sparse mixed flora (hence clean catch/MSU)
• Contains enterococci, S.epidermis, diphtheroids, E.coli, proteus and non-pathogenic neisseria

Question 16

What exogenous pathogens can patients be infected with from the hospital environment?

Answer 16

1) C.difficile (spores problem in people who are vulnerable or on abx)
2) Pseudomonas - live in air cooling systems
3) Aspergillus
4) S.aureus
5) Legionella

Question 17

What exogenous pathogens can patients be infected with from staff and other patients?

Answer 17

1) C.difficile
2) S.aureus
3) Influenza
4) Norovirus
5) Blood borne viruses

Question 18

What type of bacteria surface is very hard to treat?

Answer 18

Biofilms formed by pathogens on surfaces e.g. hip prosthetic = might not be able to treat with abx, might need to take prosthetic out

Question 19

What can line infections cause?

Answer 19

Hospital acquired bacteraemia and disseminated infection e.g. IV, dialysis

Question 20

When should you suspect a line infection?

Answer 20

When the patient is febrile without an obvious source and has an IV line

Question 21

How do you manage a line infection?

Answer 21

1) Take line out
2) Blood culture from both IV line and peripheral vein
3) IV line positive > 2 hours earlier than peripheral culture suggestive

Question 22

What organisms cause line infections in different types of patients?

Answer 22

1) Normal = coagulase negative staphylococci, S.aureus, candida (non-albicans), enterococcus faecalis - mostly not resistant
2) Oncology = E.coli, E.faecium e.g. VRE, viridans streptococci - often resistant
3) Burns/neutropenic - pseudomonas, enterococci bacteria
4) Long-term parenteral nutrition - candida

Question 23

Why are oncology patients more at risk of gram negative GI organisms?

Answer 23

They have disruption of GI mucosa

Question 24

How do you prevent line infections at insertion?

Answer 24

1) Is the line needed? - does patient really need IV abx over oral
2) Wash hands
3) Clean site e.g. chlorhexidine
4) Anti-septic non touch technique

Question 25

How do you prevent line infections after insertion?

Answer 25

1) Daily line checks

2) Timely removal

Question 26

When would you use soap and water over alcohol hand rub?

Answer 26

1) Spore forming pathogens 2) Hands visibly soiled/dirty

3) After using the toilet

Question 27

What is the most common cause of nosocomial bacteraemia?

Answer 27

Catheter-associated UTI

Question 28

How should you treat suspected CAUTI?

Answer 28

• Distinguishing from infection and colonisation is difficult bc will grow bacteria from urine in catheter
• Give abx and remove catheter if have fever and no other symptoms

Question 29

What kind of bacteria cause CAUTI?

Answer 29

1) Coliforms
2) Pseudomonas
3) Enterococci

Question 30

What type of catheter is always colonised within 7 days?

Answer 30

Long term catheter (LTC)

Question 31

How are rates of CAUTI reduced?

Answer 31

1) Newly inserted urinary catheters should be removed within 48h to reduce urinary sepsis and restore normal bladder function
2) Nurses can decide to take out the catheter if they don’t need it anymore, don’t need doctor’s approval

Question 32

Why should you not assume it is a UTI bc the patient has a positive dipstick and look for other sources of sepsis?

Answer 32

Many people esp. women have asymptomatic bacteriuria esp. > 65

Question 33

Describe hospital acquired pneumonia

Answer 33

1) 48-72h cut off, excluding bugs at admission
2) Remember to think of it in re-admissions
3) Tends to be gram negative (unlike CAP where gram positive)
4) Confirm radiologically and microbiologically (temp, raised WBCs)

Question 34

What are criteria to consider HAP as a diagnosis?

Answer 34

1) Purulent tracheal secretions and new/persistent infiltrate on CXR, which is otherwise unexplained
2) Increased oxygen requirement
3) Core temperature > 38.3
4) Blood leucocytosis or leucopenia

Question 35

What are common causes of HAP?

Answer 35

1) P.aeruginosa
2) Klebsiella
3) E.coli
4) Acinetobacter
5) S.aureus
6) Strep pneumoniae
7) H.influenzae

Question 36

What are common sources of bacteria?

Answer 36

1) Food e.g. salmonella, E.coli
2) Water (air cooler units) e.g. legionella, cryptosporidium
3) Equipment e.g. pseudomonas, acinetobacter, stenotrophomonas, gram negatives
4) Contaminated IV fluids e.g. HIV, Hep B/C, malaria, klebsiella, serratia
5) Air e.g. cryptococcus, aspergillus

Question 37

What can C.difficile cause?

Answer 37

Diarrhoea and inflammation of colon, C diff colitis, toxic megacolon

Question 38

What are risk factors for C.difficile?

Answer 38

1) Antibiotic exposure in the preceding 1-8 weeks
2) Chemotherapy agents with antibiotic activity
3) Co-morbidity incl. malignancy and uraemia
4) Anti-motility agents/PPIs
5) Major abdominal surgery
6) Poor host IgG response
7) Burns
8) Older age

Question 39

What are the most frequently associated antimicrobials with C.difficile or colitis?

Answer 39

1) Cephalosporins
2) Ampicillin and amoxicillin
3) Clindamycin
4) Other penicillins
5) Erythromycin and other macrolides
6) Tetracyclines
7) Trimethoprim-sulfamethoxazole

Question 40

What are the four Cs of antibiotics that cause C.difficile to remember?

Answer 40

1) Cephalosporins
2) Co-amoxiclav
3) Clindamycin
4) Ciprofloxacin

Question 41

What diseases are spread by droplet?

Answer 41

Measles, influenza, norovirus

Question 42

What diseases are spread by aerosol (suspended in air currents indefinitely)?

Answer 42

Chickenpox, TB, norovirus e.g. generated by toilet flush/vomiting

Question 43

When would you use a negative pressure ventilation room?

Answer 43

An infected patient in source isolation e.g. TB

Question 44

When would you use a positive pressure ventilation room?

Answer 44

A susceptible patient in protective isolation e.g. bone marrow transplant