Application of a novel hydrophilic infrared-transparent membrane to the differentiation between microcolonies of Enterobacter sakazakii and Klebsiella pneumoniae.
A proof-of-concept study is reported for the differentiation between microcolonies of Enterobacter sakazakii and Klebsiella pneumoniae by means of a novel sample preparation for infrared (IR) analysis. A disposable, IR-transparent, microporous (0.2-microm pores), hydrophobic, polyethylene (PE) membrane (51 microm thick) was plasma treated under an oxygen atmosphere and used to (i) filter (or print microarrays of) dilute aqueous foodborne bacterial suspensions and (ii) subsequently grow bacterial microcolonies when the treated, hydrophilic PE membrane was placed over brain heart infusion agar medium and incubated. Because this unique membrane is transparent to IR light, isolated microcolonies (200 microm) of bacterial cells grown on this PE substrate for the first time could be directly fingerprinted by IR microspectroscopy in the transmission mode. Hence, time-consuming bacterial cell transfer from culture plates to an IR sample holder for subsequent measurement by IR spectroscopy was eliminated. Multivariate analysis of the observed IR spectra for microcolonies allowed the rapid differentiation between E. sakazakii and K. pneumoniae.
Mossoba
M M
MM
Division of Analytical Chemistry, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, 5100 Paint Branch Parkway, College Park, Maryland 20740-3835, USA. magdi.mossoba@fda.hhs.gov
Al-Khaldi
S F
SF
Curtis
S K
SK
Battrell
C F
CF
Fry
F S
FS
D015169:Colony Count, Microbial; D044083:Cronobacter sakazakii / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D007711:Klebsiella pneumoniae / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification; D008567:Membranes, Artificial; D015999:Multivariate Analysis; D010316:Particle Size; D010802:Phylogeny; D013045:Species Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
D008567:Membranes, Artificial