COMPARISON OF THE ROLE OF INITIAL SURVEILLANCE

CULTURES AND THE SERIAL SURVEILLANCE CULTURES IN PREDICTING THE VENTILATOR

ASSOCIATED PNEUMONIA (VAP) ETIOLOGY

Gül Gürsel, Müge Aydoğdu, Türkan Nadir Öziş, Seçil Taşyürek

Gazi University Medical Faculty Pulmonary Diseases Department Intensive Care Unit

VAP is one of the most common infections in intensive care units with very high mortality. Early diagnosis and appropriate antibiotic therapy can decrease mortality.

Broad spectrum antibiotics used emprically have the risk of increasing antibiotic resistance; whereas antibiotics started depending on the culture results have the risk of increased mortality.

Many studies are being published indicating that surveillance cultures may be helpfull in initiating appropriate antibiotic therapy by previously predicting the VAP pathogen

INTRODUCTION

Surveillance cultures can be used; To follow the yearly incidence, causative

pathogens and resistance patterns of nosocomial infections.

To identify whether patients are colonized or not, when they are hospitalized

With the help of serial surveillance cultures to identify the hospital acquired pathogens that patients are colonized with

INTRODUCTION

But the routine use of surveillance cultures are not recommended. Since; Its evidence-based benefit can not be shown Cost-effectivity is unknown How, when, from where and with what

frequency cultures should be obtained? All unknown.

The evidences for its contribution to initiate the appropriate antibiotic therapy and to improve survival are still lacking

INTRODUCTION

AIM To compare the diagnostic value of

initial endotracheal aspirate cultures (I-ETA) with serial surveillance (SS-ETA) cultures in predicting the VAP etiology.

MATERIAL AND METHOD A total of 92 patients receiving at least 4 days of

mechanical ventilation therapy were included in the study.

ETA cultures were obtained from all patients at the day of intubation and then in every other day.

Patients were followed daily for VAP development and VAP diagnosis were made clinically and microbiologically.

I-ETA and SS-ETA cultures were compared for their predictive capability of VAP pathogens .

Sensitivity,spesificity, PPV and NPV were calculated.

RESULTS

From 92 patients; 92 I-ETA cultures 250 SS-ETA cultures were obtained

DEMOGRAPHIC and ICU PROPERTIESn=92 (mean ±

sd)Age, year 71 ±13Sex, M, n(%) 47 (52)APACHE II 21 ± 7Comorbidity, n(%) 63 (69)Charlson comorb. score 3± 2Admission SOFA 6±3CPIS, 7±2VAP, n (%) 59 (64)VAP,day 10±5Polymicrobial, n(%) 3(3.3)Length of MV 13± 10Length of ICU stay 15±10Length of hospitalization 24±13

Admission diagnosis of patients:Admission Diagnosis nCOPD acute attack 26Community acquired pneumonia 24Malignancy 7Hospital acquired pneumonia 7Neuromuscular disease and scoliosis 7ARDS 5Obesity hypoventilation syndrome 5Pulmonary embolism 4Other 7Total 92

VAP Pathogens:n=59

Acinetobacter baumanii (AB) 23Pseudomonas aeruginosa (PA) 10MRSA 12E Coli 4Klebsiella 2Candida 1Enterobacter 2Coagulase negative staphylococcus (CNS) 1Stenotrophomonas maltophilia 1Klebsiella +AB 1MRSA+PA 1MRSA+AB 1

Pathogens identified in Initial surveillance (I-ETA) cultures:Branhamella catarrhalis 2

Methicilline sensitive Staph. Aureus 5

Acinetobacter Baumannii 4

Streptococcus pneumonia 3

Pseudomonas Aeruginosa 3

Klebsiella 2

Candida albicans 2

Serratia marcessens 1

Coagulase negative staphylococcus 1

E coli 1

MRSA+P Aeruginosa 1

MRSA+A Baumannii 1

MRSA 1

Enterobacter 1

Toplam 28

Diagnostic values of I-ETA ve SS-ETA cultures:

I-ETA SS-ETA

Sensitivity 6/50 (%12) 24/55 (%44)

Specificity 22/33 (%67) 26/33 (%79)

Positive predictive value

6/17 (%35) 24/31 (%77)

Negative predictive value

22/66 (%33) 26/57 (%46)

Diagnostic values of I-ETA ve SS-ETA cultures :

I-ETA SS-ETATP 6(%7) 24(%27)

TN 22(%27) 26(%30)

FP 11(%13) 7(%8)

FN 44(%53) 31 (%35)

Discordance 9(%10) 83 4(%4) 88

Total 92 92

Diagnostic value (TP+TN)

% 34 %57

DISCUSSION SS-ETA cultures predicted the causative

pathogen of VAP in 27% of the patients with VAP who were using antibiotics and gave negative result in 30% of patients without VAP.

In both conditions the predictive value of SS-ETA cultures for VAP pathogen were identified as superior to I-ETA cultures

But SS- ETA can give false positive result in 8% and false negative result in 35% of the patients.

Type of surveillance

Predictive rate

Previous antibiotic

use

TP Carrel Initial %69 No use

KM Sanders Initial and/or serial

%50 in pts. receiving antibiotics

%100

F Michel Serial %83 %37

P Depuyt Serial Sensit: %69Specif:%96PPV:%90NPV: %80

%85

Gürsel ve ark. Initial and serial

Sensit: %44Specif:%79PPV:%77NPV:%46

%100

Limitations of the study: Low patient number No cost-effectivity analysis Not being in the study design, the

effect of surveillance cultures on appropriate antibiotic therapy and survival are unknown

CONCLUSION The value of SS-ETA is quite much higher

than I-ETA in predicting the VAP etiology in patients who have been using antibiotics .

But as a whole since its specificity and sensitivity is still low, the use of SS-ETA cultures routinely can not be recommended in all intubated and mechanically ventilated patients.

Thank You…