DETECTION OF 16S rRNA GENE IN FLAG POSITIVE CULTURE NEGATIVE BacT ALERT BOTTLES IN A TERTIARY CARE HOSPITAL.

Abstract

BACKGROUND: Bloodstream infections have become major nosocomial infections. Accurate diagnosis of these infections is important for patient management and can done by conventional, automated and molecular methods. 16S rRNA has emerged as more accurate and reliable method, for identification of rarely isolated , phenotypically aberrant strains and non culturable bacteria.

OBJECTIVES:  1: Detection of 16S rRNA gene in flag positive but culture negative BacT Alert bottles by using PCR amplification method. 2: Determination of the percentage of false instrument positives detected in BacT Alert using 16S rRNA gene PCR amplification.

PARTICIPANTS: 105 BacT Alert blood culture flagged positive bottles with no growth on subculture were evaluated.

STUDY DESIGN: Hospital based prospective study.

METHODS: Study samples were subjected to DNA Extraction using QIAGEN QIAamp® DNA Blood Mini extraction kit and PCR Amplification.

RESULTS: The percentage of instrument false positives was very low 0.94% and only 10 samples (9.5%) showed amplification of 16S rRNA gene on PCR and rest of the 95 samples (90.5%) did not show any amplification on PCR.

CONCLUSIONS: Patient with clinical suspicion of bloodstream infections with negative blood culture results should be processed at molecular level.

IMPLICATIONS: Molecular diagnosis is important not only for diagnosis but also identification of culture negative blood stream infections.