FT-IR microspectroscopy for early identification of some clinically relevant pathogens.
OBJECTIVE
To investigate the potentials and limitations of Fourier transform-infrared (FT-IR) microspectroscopy as a tool to identify, at the level of microcolonies, pathogenic bacteria frequently isolated in the clinical environment.


RESULTS
A total of 1570 FT-IR spectra from 164 gram-positive and gram-negative bacteria isolated from patients were recorded from 6 to 10-h old microcolonies of 50-150 microm size. A classification of 100% was obtained for the most frequent gram-positive bacteria, such as Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Enterococcus faecium at the species level. An average accuracy of about 80% was reached with Gram negative bacteria from the Enterobacteriaceae and Pseudomonaceae families; Enterobacter aerogenes, Enterobacter cloacae, Klebsiella spp., and Citrobacter koseri; and Proteus mirabilis and Escherichia coli. Results were comparable with FT-IR measurements on dried suspensions from 18-h cultures.


CONCLUSIONS
Early identification of young microcolonies is feasible with FT-IR microscopy with a very high accuracy for gram-positive bacteria. Some improvement in the transfer of microcolonies is necessary to increase the accuracy for gram-negative bacteria.


CONCLUSIONS
Combination of FT-IR microscopy and multivariate data analysis could be a complementary, rapid, and reliable tool for screening and discriminating, at species and subspecies level, micro-organisms of clinical, food-borne, or environmental origins.
Sandt
C
C
Unité MéDIAN, CNRS UMR 6142, UFR de Pharmacie, IFR53, Université de Reims-Champagne Ardenne, and Laboratoire de Bactériologie, Hôpital Robert Debré, Reims, France.
Madoulet
C
C
Kohler
A
A
Allouch
P
P
De Champs
C
C
Manfait
M
M
Sockalingum
G D
GD
D000818:Animals; D001419:Bacteria / Q000302:isolation & purification*; D015373:Bacterial Typing Techniques; D019295:Computational Biology; D016983:Enterococcus / Q000302:isolation & purification; D004926:Escherichia coli / Q000302:isolation & purification; D006801:Humans; D016014:Linear Models; D017550:Spectroscopy, Fourier Transform Infrared; D013211:Staphylococcus aureus / Q000302:isolation & purification