Microbiological Evaluation of PJIsSurvey Results

Lorenzo DragoIRCCS Galeazzi Institute – University of Milan

Dear ISOC Members, based on an initiative from the ISOC group

during the last meeting in Hamburg, it was decided to send out a questionnaire to map the present microbiological routine used for the diagnosis of prosthetic joint infections.

We would like to have only one answer from each ISOC unit. The answers will be aggregated and presented in Mexico.

In addition the actual literature will be searched and a guideline document discussed in a workshop during the next ISOC meeting. Subsequently a document will be published on behalf of the ISOC group.

Galeazzi Institute Ortho Dept Lund HSS

ADDRESS

• Economic Impact of PJIs - wrong or delayed diagnosis

• Questionnaire answers examination

• Improving and debating matters

Guest editorial Prosthetic joint infections – a need for health

economy studies

• “An increase in the rate of revision due to infection….Needs

• “A rapid economic evaluation…..

• “A clear and common definition of deep infection…...

• “No model can depict the numerous possibilities……..

Acta Orthopaedica 2014

Costs Influences in PJIs

• Factors related to the patients• Revision Modalities• Surgical management Strategy• One-stage/two-stage

Economic burden of Hip PJI (UK)

0

5000

10000

15000

20000

25000

Mea

n co

st (£

)

Aseptic loosening Deep infection

Peri-prosthetic fracture Dislocation

+ 53%+ 84%

- 8.4%

Vanhegan IS et al. J Bone Joint Surg 2012

Complications for infections

Vanhegan IS et al. J Bone Joint Surg 2012

Indication Mean operating time

Mean blood loss

Complications rate

Hospital stay

Revision surgery

+41% +160% +32% Generally longer

Hip cost AnalysisIRCCS Galeazzi

The case of hip prosthesis” (full cost)

4,1%0,2 %

41,7%

4,3%

19,5%

3,5 %

Indirect costs

12,4%

14,4%

COSTS %

Instruments 0,2%

Lab 3,5%

Personnel 4,1%

drugs 4,3%

Consumables 12,4%Medical staff 14,4%

Indirect costs 19,5%

Prosthetic material 41,7%Total 100%

Variable costs increase of 30-50%

Other relevant factorsMicroorganisms-Dependent

• Culture negative PJI

• Factors related to the virulence

• MDR pathogens

PJIThe Economic Impact of Methicillin-Resistant

Infections

Parvizi J. et al. J Atrhoplasty, 2010

Irrigation and Debridment + 74

Resection artrhoplasty + 29

Revision (1-stage) + 41

Reimplantation + 30

Cost Per Procedure %

Days in hospital per visit + 50%

Days in hospital per patient + 78%

Microorganisms dependent factors

• Polymicrobial Infection + 41%

• Culture-Negative -29%

Journal of Hospital Infection, 2013

False negative!!!Biofilm notably hinders sampling and culturing;

Difficult to detach biofilm-embedded bacteria from prosthetic surfaces.

ISSUES FOR ORTHO-MICROBIOLOGISTS!

Up 30% of False Negative

Wrong or delayed diagnosis of PJIs

What is the financial impact of wrong or delayed diagnosis of PJI?

?

Wrong or delayed diagnosis of PJI

• Deterioration of bone• Complications risk (i.e. Longer stay)• Drugs (es. Antibiotics)• Diagnostic procedures (i.e. Imaging)• Loss of Medical Confidence• Patient’s psycological consequences

AIM ISOC Questionnaire

Mapping the microbiological routine used for the diagnosis of prosthetic

joint infections.

ISOC Questionnaire

Diagnosis of PJI

Criteria for Diagnosis of PJIIDSA

Presence of a sinus tract communicating with the prosthesis

Same

Same

Same

Presence of purulence without another known etiology surrounding the prosthesis

Growth of virulent microorganisms in a single specimen

MSIS

Major criteriaSame

Same

Minor criteria (3/5)CRP>10 mg/dL for acuteCRP> 1 mg/dL - ESR >30mm/hr chronic

Same

Elevated WBC, PMN% and ++ leukocyte esterase in synovial fluid

A single positive culture

AAOS

Positive cultures aspirate joint and elevated cell count/differential

Two or more intraoperative cultures +/- yielding the same organism.

ESR and CRP abnormal values

Histopathology of periprosthetic tissue suggestive for acute inflammation

Criteria for PJIs diagnosis

• MSIS criteria: 5 Centers• AAOS criteria: 7 Centers• IDSA criteria: 1 Center

• 1 Center: Presence of a fistula or sinus tract and elevated WBC count in joint fluids

• 1 Center: Elevated ESR and CRP values + positive cultures from prosthetic joint drainage or sinus

• 1 Center: Fistula, positive joint fluid culture and wbc count

What cut-off levels of ESR and CRP do you consider significant to suspect a prosthetic

infection?

MSISChronic: ESR: >30mm/hr

CRP>1mg/dLAcute: CRP>10mg/L

Do you consider the possibility of infection only in patients with abnormal ESR and/or CRP

values?MSIS

No: Clinical judgement should not be outweighed

by use of diagnostic algorithm or any individual test

CRP LABORATORY TESTING

Primary pathogens Low grade pathogens0

3

6

9

12

15

CR

P (

mg/

dL)

MEDIAN

Low levels of CRP may be found in infections with less virulent pathogens (Corynebacteria and Propionibacteria)

Joint aspiration prior to surgery in suspected infections

What cut-off value for WBC count and neutrophils percentage in joint aspirates do

you consider suggestive for PJIs?

MSISChronic: >3000 WBC

>80% PMNAcute: >10000 WBC

>90% PMN

Is joint aspiration enough to proceed with surgical treatment if it gives a positive culture?

Do you perform cultures from sinus tract in all patients?

MSISA sinus tract is pathognomonic

finding for PJI.

NO SWABS or CULTURE!!

Transport of samples to Laboratory

0

2

4

6

8

10

12

Inside Lab. Outside Lab0

2

4

6

8

10

Within 1hr

Within 2hrs

Within 6 hrs

After 6 hrs

How many samples do you usually send for cultures?

MSISMore than 3

but not more than 6

Do you take tissue samples with the same surgical instrument?

0

2

4

6

8

10

YES NO

MSISEach sample should

be taken with an unused instrument

In your laboratory is sonication reserved to particular cases?

MSISSonication should be

limited to cases of suspected or proven PJI

Drago et al. Clin Orthop Relat Res. 2012 Jun 14.

Is DTT method reproducible and comparable to the

Sonication one?

Italian Association of Clinical MicrobiologistsAMCLI

Q8-9: Does your laboratory perform enrichment cultures and for how many days?

0

2

4

6

8

10

12

14

16

YES NO

MSISEnrichment cultures are

advisable

MSIS5-14 days or longer

Q10: What is your opinion about the use of molecular methods?

PROs•It may be useful in particular cases (n=7)

– Difficult to grow microorganisms (n=7)

– Suspected M. tuberculosis (n=3)

CONs•Oversensitive (n=4)

– Risk of false positive results (no differences between live and dead microorganisms)

•No data on susceptibility pattern (n=1)•Not useable in polymicrobic infections (n=1) •Not useful (n=1)

MSISNucleic acid based testing is not currently

a recommended routine diagnostic test for PJI

In cases of negative cultures or other diagnostic tests, molecular techniques

may help identify the unknown pathogens

Q11-12:Use of molecular methods

0

1

2

3

4

5

6

7

Multiplex P

CR

Real-time PCR

16S Sequencin

g

Not known

Q13: Usefulness of preliminary report

ALL:It is advisable to report isolation of each

microorganism as soon as possible. A preliminary report for negative samples after 5 days may be useful for clinicians, followed by a

conclusive report at the end of enrichment.

Conclusive Remarks• “Moderate” concordance

time to:

• Drafting a unique document

• Single Procedure

• Try to understand “discordances”

• Improve Methods and Procedures

• External Lab is a debating matter

Future “ISOC” Directions• Create Epidemiological Database

(Pathogens, Resistant %, Drugs used, Drugs rotation)

• Create “ISOC” Registry of Infections (per site, age, comorbidities)

• Create “ISOC” BIOBANK (study virulence, Biofilm, ATB susceptibility, new and old ATBs)

• Create New Fellowships (Microbiologists, Labs)

NOT WITHOUT A UNIQUE MICROBIOLOGICAL AND LAB

PROCEDURE!!!

….many thanks to:

• All of you

• Thomas SculcoIlsa Klinghoffer!!!