Indwelling device infections

Question 1

what is an implant

Answer 1

object or material inserted or grafted into the body, for prosthetic, therapeuticc, diagnostic or experimental purposes

Question 2

can an implant be experimental

Answer 2

yes

Question 3

are hard surfaces essential for biofilms

Answer 3

no

Question 4

none shedding surfaces in the body?

Answer 4

teeth
bones
heart
nails

Question 5

why are medical implants good for bacteria

Answer 5

provide a non shedding surface easily colonised

Question 6

are infection rates for revision higher?

Answer 6

yes

Question 7

are biofilms easy to identify in a medical device

Answer 7

no, more circumstantial

Question 8

can micro labs identify if there’s a biofilm

Answer 8

not usually- need a special procedure a swab doesn’t tell us how they are arranged in the original sample

Question 9

explain the biofilm life cycle

Answer 9

attach and colonise with time
production of polymeric matrix
leave via mechanism and recolonise other places e.g. from one implant to somewhere else in the body

Question 10

source of implant infections?

Answer 10

skin bacterial origin from during the procedure

circulating in blood- blood borne infections

Question 11

what are the 3 phases of periprosthetic infection?

Answer 11

acute postoperative
late chronic
acute hematogenous

Question 12

when is the acute postoperative period?

Answer 12

within 3 months

Question 13

when is the late chronic period

Answer 13

3-24 months

Question 14

when is acute hematogenous

Answer 14

any time but needs to demonstrate casual and chronological relations to running infection at any site in the host body

Question 15

problems with ID’ing bacteria in a biofilm

Answer 15

difficult to isolate
not get a representative sample
mild ultrasonication of prosthesis after removal

viable and present MOs but doesn’t grow on agar- uncultivable

Question 16

what is the Dempsey study

Answer 16

10 consecutive revisions by 2 surgeons
5 were due to clinical infections and 5 because of aseptic loosening (didn’t take due to non infectious cause)
preoperative and Perioperative specimens were obtained from each patient and subjected to culture
all 10 were positive for bacterial presence

Question 17

treatment of biofilms?

Answer 17

replacement is successful in 83%

early recognition and aggressive treatment

Question 18

how do prophylactic antibiotics form?

Answer 18

attack before they have attached when in a planktonic form

Question 19

what is better than treating the biofilm

Answer 19

preventing attachment

Question 20

what are the effects of implants on an infective dose

Answer 20

significant decreases

less MOs needed to cause an infection

Question 21

3 ways to prevent t formation?

Answer 21

antibiotics before the biofilm can form
intelligent surfaces that are difficult to colonise or are antimicrobial
smooth surface to make it harder for them to attach

Question 22

what is the first thing to attach to an implant after insertion

Answer 22

host proteins

Question 23

advantages of preventing biofilm formation

Answer 23

avoids needing systemic use of antibiotics
prevention reduces risk of resistance
decreases risk of needing to remove implant

Question 24

what is the parsek-singh criteria

Answer 24

criteria for recognising biofilm infections

Question 25

what is the parsek-singh criteria to identify biofilm formation

Answer 25

 Pathogenic bacteria are associated with a surface
 Direct examination of infected tissue demonstrates aggregated cells in cell clusters encased in a matrix, which may be of bacterial and host origin.
 Infection is confined to a particular site in the host- e.g. where implant was placed
 Recalcitrance to antibiotic treatment despite demonstrated susceptibility of planktonic bacteria- when talking about tolerance we aren’t talking about AB resistance, can be susceptible to the AB but because of the chemistry they might not respond
 Culture-negative result in spite of clinically documented high suspicion of infection (since localized bacteria in a biofilm may be missed in a conventional blood sample or aspirate).
 Ineffective host clearance evidenced by the location of bacterial cell clusters (macrocolonies) in discrete areas in the host tissue associated with host inflammatory cells