Nosocomial Infections

Question 1

Nosocomial infection, also called “…………..” can be defined as: ……………………….
◼ This includes…………………..

Answer 1

Nosocomial infection also called “hospital acquired infection (HAI)” can be defined as: An infection acquired by a patient during hospital care which was not present or incubating at the time of admission.
◼ This includes infections acquired in the hospital but appearing after discharge.

Question 2

Some nosocomial infections occur in……. (……)
– but majority are…….

Answer 2

Some infections occur in outbreaks or clusters (10%)
– but majority are endemic

Question 3

Examples of diagnostic or therapeutic procedures that result in nosocomial infections

Answer 3

Catheters in bladder or blood vessel, surgery

Question 4

Major sites of infection in medical
ICU

Answer 4

PNE
UTI
BSI

Question 5

SOURCES OF PATHOGENS IN NI (endogenous)

Answer 5

normal commensals of the skin,
respiratory, GI, GU tract

Question 6

SOURCES OF PATHOGENS IN NI (exogenous)

Answer 6

Inanimate environment: Aspergillus from hospital construction, Legionella from contaminated water
❑ Animate environment: hospital staff, visitors, other patients

Question 7

MECHANISMS OF TRANSMISSION of nosocomial infections

Answer 7

Contact
Airborne
Common-vehicle
Droplet

Question 8

SITES OF NOSOCOMIAL INFECTIONS

Answer 8

Urinary tract 40%
◼ Pneumonia 20%
◼ Surgical site 17%
◼ Bloodstream (IV) 8%

Question 9

What is NOSOCOMIAL PNEUMONIA?

Answer 9

Lower respiratory tract infection that develops during hospitalization but is not present or incubating at time of admission
◼ Does not become manifest in the first 48-
72 hours of admission

Question 10

Leading cause of death from NI

Answer 10

NOSOCOMIAL PNEUMONIA

Question 11

Early onset of Nos. pneu. (first 3-4 days of mechanical ventilation)

Answer 11

Antibiotic sensitive, community organisms
(S. pneumoniae, H. influenzae, S. aureus

Question 12

Late onset of Nos. pneu.

Answer 12

Antibiotic resistant, nosocomial organisms (MRSA, Ps. aeruginosa, Acinetobacter spp, Enterobacter spp)

Question 13

What are some predisposing factors for Nos. Pneu.?

Answer 13

Endotracheal intubation!!!!!!!!!!!!!!
◼ ICU
◼ Antibiotics
◼ Surgery
◼ Chronic lung disease
◼ Advanced age
◼ immunosuppression

Question 14

Hospitalized pts have high rates of……….. colonization

Answer 14

Hospitalized pts have high rates of gram negative colonization

Question 15

Clinical diagnosis of Nos. Pneu.

Answer 15

fever, change in O2, change in sputum, CXR

Question 16

How can Nos. Pneu. be prevented?

Answer 16

Change position q 2 hours
❑ Elevate head to 30-45 degrees
◼ Deep breathing, incentive spirometry
◼ Frequent suctioning
◼ Bronchoscopy to remove mucous plugging

Question 17

Nosocomial Urinary Tract Infections are…… related to……..
◼ Associated with…… of cases of nosocomial…………..

Answer 17

Nosocomial Urinary Tract Infections are 80% related to urinary catheters
◼ Associated with 2/3 of cases of nosocomial gram negative bacteremias

Question 18

Source of uropathogens
❑ Endogenous

Answer 18

catheter insertion
- retrograde movement up the urethrea (70-80%)
- patient’s own enteric flora (E.coli)

Question 19

Source of uropathogens (Exogenous)

Answer 19

cross contamination of drainage systems
- may cause clusters of UTI’s

Question 20

What are some major risk factors for getting Nos. UTI’s?

Answer 20

1) Pathogenic bacteria in periurethral area
2) Indwelling urinary catheter
❑ Duration of catheterization

Question 21

ETIOLOGIC AGENTS: catheter associated UTI

Answer 21

E. coli 32%
Proteus spp 14%
Enterococcus 12%
Klebsiella 9%

Question 22

Nos. UTI treatment

Answer 22

No antibiotic treatment for bacteriuria
- resolves with catheter removal
-7-10 days of therapy for UTI
◼ Empiric therapy typically initiated pending microbiologic results

Question 23

Prevention of Nosocomial UTIs

Answer 23

Avoid catheter when possible &
discontinue ASAP- MOST IMPORTANT
◼ Aseptic insertion by trained HCWs
◼ Maintain closed system of drainage
◼ Ensure dependent drainage
◼ Minimize manipulation of the system
◼ Silver coated catheters

Question 24

What are Incisional infections?

Answer 24

❑ Infection at surgical site
❑ Within 30 days of surgery
❑ Involves skin, subcutaneous tissue, or muscle above fascia

Question 25

Incisional infections are accompanied by:

Answer 25

◼ Purulent drainage
◼ Dehiscence of wound
◼ Organism isolated from drainage
◼ Fever, erythema and tenderness at the surgical site

Question 26

What are Deep surgical wound infections?

Answer 26

Occurs beneath incision where operation took place
❑ Within 30 days after surgery if no implant, 1 year if implant
❑ Infection appears to be related to surgery

Question 27

Deep surgical wound infections occur at or beneath fascia with?…………

Answer 27

Purulent drainage
◼ Wound dehiscence
◼ Abscess or evidence of infection by direct exam
◼ Clinical diagnosis

Question 28

What is the risk of infection dependent upon?

Answer 28

It is dependent upon:
-Contamination level of wound
❑ Length of time tissues are exposed
❑ Host resistance

Question 29

PATHOGENS ASSOCIATED WITH SWI

Answer 29

S. aureus—-17
Enterococci—–13
Coag - Staph—–12
E. coli—-10
P. aeruginosa—-8

Question 30

What are the risk factors for surgical wound infections?

Answer 30

Age (extremes)
◼ Sex
◼ Underlying disease such as
* obesity (fat layer < 3 cm 6.2%; >3.5 cm 20%)
* malnutrition
* malignancy
* remote infection
Duration of pre-op hospitalization
* increase in endogenous reservoir
Pre-op hair removal
* esp if time before surgery > 12 hours
◼ Duration of operation
*increased bacterial contamination
* tissue damage
* suppression of host defenses
* personnel fatigue

Question 31

How can you prevent surgical wound infections?

Answer 31

Limit pre-op hospitalization
◼ Stabilize underlying diseases
◼ Avoid hair removal by shaving
❑ Clipping of skin is preferred
◼ Skin decolonization
❑ Chlorhexidine
❑ Intranasal Mupirocin for S.aureus carriers
◼ Impermeable drapes
❑ Maximum sterile barrier precautions

Question 32

About NOSOCOMIAL BACTEREMIA

Answer 32

4th most frequent site of NI
◼ Primary
* IV access devices
* gram positives (S. aureus, CNS)
◼ Secondary
* dissemination from a distant site
* gram negatives

Question 33

The…….. is the greatest risk factor for Nosocomial Blood Stream Infections

Answer 33

The Central Venous Catheter is the greatest risk factor for Nosocomial Blood Stream Infections

Question 34

PATHOGENESIS of blood stream infections

Answer 34

Direct innoculation
* during catheter insertion
◼ Retrograde migration
* skin→subcutaneous tunnel→fibrin sheath at vein
◼ Contamination
* hub-catheter junction
* infusate

Question 35

Risk Factors for Nosocomial BSIs

Answer 35

Heavy skin colonization at the insertion site
◼ Internal jugular or femoral vein sites
◼ Duration of placement
◼ Contamination of the catheter hub

Question 36

Prevention of Nosocomial BSIs

Answer 36

Limit duration of use of intravascular catheters
◼ Maximal barrier precautions for insertion
❑ Sterile gloves, gown, mask, cap, full-size drape
◼ Chlorhexidine prep for catheter insertion
❑ Significantly decreases catheter colonization; less clear evidence for BSI

Question 37

STRATEGIES TO REDUCE NI

Answer 37

Reduce patient exposure to pathogens
◼ Reduce the number and virulence of nosocomial pathogens

Question 38

EXPOSURE REDUCTION

Answer 38

-Aseptic technique during patient care
◼ Handwashing
◼ Proper isolation of patients known or suspected of harbouring infectious diseases