Specific multigenotypic diagnosis of nosocomial pneumonia in ICU
© The Author(s) 2001
Received: 15 January 2001
Published: 2 March 2001
Mortality rate of nosocomial pneumonia in ventilated ICU patients (pts) is about 20-25%. Despite advances in critical care, standard criteria for pneumonia are still inaccurate. Antibiotherapy is often started on a 'best guess' basis to anticipate frequently negative bacteriological results (Ba-cul). Main etiological pathogens are staphylococci, streptococci, pseudomonads and enterobacteriaceae. A multigenotypic and sequential molecular identification (Mol-id) was applied on bronchoalveolar lavages (BAL) from 12 pts with clinical-radiological evidence of infection with (n = 9)/without (n = 3) positive Ba-cul. DNA extraction and duplicate specific amplification of 16S rDNA from BAL was first used to identify signals corresponding to the presence of Gram + (G+), Gram - (G-), or mixed G+/G-. Any G+ signal was followed by femA and mecA multiplex (mpx)-PCR for species-specific identification of staphylococci and methicillin resistance, and by mpx-PCR for S. pneumoniae. Any G- signal was followed by mpx-PCR for species-specific identification of Pseudomonads (aeruginosa, cepacia, maltophilia) vs other G- for which the 16S rDNA amplicon was sequenced.
Mol-id identified mixed G+/G- in 2/3 negative Ba-cul. Ba-cul gave G+ or G- only in 3 and 4/12 pts, respectively. Among these, Mol-id confirmed either G+ (2/3) or G- (2/4), and found a mixed signal in 3/7 pts. Mixed G+/G- was found by Ba-cul and Mol-id in 2/12 BAL, but in one case, S. epidermidis was found by Mol-id and enterococci by Ba-cul. Staphylococci (MRSA, other) and Ps. aeruginosa were found by Ba-cul and Mol-id in 2 and 3 pts, respectively.
Current results suggest that Mol-id is a useful adjunct bringing more insight to standard criteria of nosocomial pneumoniae in ICU and can be a timely relevant guide for antibiotherapy.