1

The interface between microbiologist and clinician

A. Naessens

The interface

A surface which forms the boundary between

two phases or systems

The laboratory The clinician

2

The role of the physician

Physical examination

Differential diagnosis

Request adequate laboratory test to

confirm/exclude the diagnosis

Start adequate treatment

Role of the microbiological laboratory

The provision of accurate clinically significant data for the diagnosis and treatment of infections

The production of laboratory data is a culmination of sequential processes including preanalytic, analytic, and postanalytic laboratory activities and begins with the clinician’s request for a specific test in an individual patient

3

Interfaces

Physician Lab Physician

Request sample Sample processing

Generating result Interprete

result

Treat

Interfaces

Physician Lab Physician

Request sample Sample processing

Generating result Interpret

result

Exchange the information as rapidly as possible

As accurate as possible

As clearly as possible

4

Interfaces

Physician Lab Physician

Request sample Sample processing

Generating result Interpret

result

Treat

Sample request

Clinician’s responsability

Adequate sample for the

condition

Adequate transport

medium

Adequate labeling

Lab’s responsability

Instructions to sampling

and transportation

Easy acces

Up to date

Electronic version

5

6

7

8

Patient sampling

Clinician’s responsability

Adequate sample for the

condition

Adequate transport

medium

Adequate labeling

9

Adequate sample identification

Information

Add info only when it is important

Abces: cerebral/abdominal/prostetic joint

Blood culture: suspicion of brucella

Do not give info if the sample is clear cut

Urine, throat

Consise

Do not mention clinically unimportant items (fever, pain)

Info for specific search for certain MO

CMV

Interfaces

Physician Lab Physician

Request sample Sample processing

Generating result Interpret

result

Treat

10

Generate result

As soon as possible

Organization of the laboratory

Day 0 Sample processing in the lab.

Gram stain

Overnight incubation.

Day 1 Inspection of the culture for

bacterial growth.

If positive: presumptive

identification. Further work

out

If negative: further incubation

Day 2 Identification + reading

suceptibility

Imrove speed? What can be done

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Imrove speed of detecting micro-organisms

Molecular techniques

Molecular techniques

PCR:

Advantages:

“quick” result

Ideal for difficult to grow micro-organisms

Disadvantages

Cost

Technical more demanding

Contamination problems (false pos results)

Request for specific pathogens

Explosion of requests

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Dynamcis of rapid increase of pcr requests

1. PCR for pathogen became available

2. Diagnostic tool is used in wel circumscribed clinical entities on well defined samples

3. Diagnostic tool is used in less well defined entities in samples not well validated

4. A positive result is found!

5. An abstract of this case is presented at an international congress

6. ….

Need for a good interface

Dynamcis of rapid increase of pcr requests

1. All classical test results remaine negative in a

critically ill patient

2. Question from clinicician to the lab

We want to have tested this patient with all the

PCR’ tests that are available

Need for a good interface

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Interface

1 Restricted use of PCR on clinically relevant

samples (information in an easy to acces

laboratory guide)

2 Possibility to offer rapid testing in selected

cases

Interfaces

Physician Lab Physician

Request sample Sample processing

Generating result Interpret

result

Treat

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Result transmission

Rapid

Alert transmission

Blood cultures

TBC

Use the communication best suited for the situation

Limit the alert results to those which really matter

Alert results are dependent on the speciality

Interfaces

Physician Lab Physician

Request sample Sample processing

Generating result Interpret

result

Treat

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Interfaces

Physician Lab Physician

Request sample Sample processing

Generating result Interprete

result

Start empirical

treatment

Change

Treatment

Starting empirical treatment

Based on experience; determined from

experimental data

Starting therapy based on

The microorganisms most often isolated in the

respective infections

The antimicrobial sensitivity of the micro-organism

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Based on (inter)national recommendations

International guidelines

National guidelines

Need for national

epidemiology

Starting empirical treatment

How can the laboratory help in selecting the

empirical treatment?

17

Laboratory derived epidemiology and susceptibility

yearly epidemiological review of the isolated

microorganisms

Follow up of the susceptibility of the isolated

micro organisms

gevoeligheden van E Coli geisoleerd bij niet nosocomiale

sepsissen

70

80

90

100

88-89 92-93 96-97 00-01 02/03 04/05 06/07 08/09

jaren

%

S augmentine

S cefazoline

S cefuroxime

S temocilline

S gentamicine

S ciprofloxacine

Evolutie van de kiemen bij niet nosocomiale

sepsissen

0

5

10

15

20

25

30

35

40

45

88-

89

92-

93

96-

97

00-

01

02-

03

04-

05

06-

07

08-

09

jaren

%

E.coli

Ps.aeruginosa

S.aureus

S.pneumoniae

gevoeligheden van S. aureus bij niet nosocomiale sepsissen

50

60

70

80

90

100

110

88-89 92-93 96-97 00-01 02-03 04-05 06-07 8-09

% St. aureus S oxacilline

Linear (St. aureus S

oxacilline)

Evolutie van de kiemen bij nosocomiale

sepsissen op IZ

0

5

10

15

20

25

30

35

88-

89

92-

93

96-

97

00-

01

02-

03

04-

05

06-

07

08-

09

jaren

%

Ps.aeruginosa

S.aureus

Coag.neg.staf.

Gisten

18

Lab and clinician: the interfaces

The lab is helping the clinician

The lab need not perform blindly all request

from the clinician

Find a good balance

Realize and aknowledge the work

The better the lab and the clinician are working

together the better the patient will be cared for