|
ISS
820 East 20th Street
Cookeville, TN 38501 USA
931 526 1106
Bob@sproutnet.com
中文版
En espaņol
| |
Membrane
filter method based on FC-5-bromo-4-chloro-3-indolyl-beta-D-glucuronide medium
facilitates enumeration of Escherichia coli in foods and poultry carcass rinses.
J Food Prot 1998 Mar;61(3):360-4
Sharpe AN, Parrington LJ.
Bureau of Microbial Hazards, Health Canada, Tunney's Pasture, Ottawa, Onatrio,
Canada.
Three enumeration methods for Escherichia coli in foods, the Health Protection
Branch most-probable-number (MPN) method MFHPB-19, a hydrophobic grid membrane
filter method MFHPB-26 (HGMF-indole), and a hydrophobic grid membrane filter
method utilizing 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide in a (modified)
mFC agar (HGMF-FC-BCIG) were compared in 80 food samples that included naturally
and artificially contaminated raw vegetables, mung bean and alfalfa sprouts, raw
meats, and chicken carcass rinses. The number of samples confirmed as positive
for E. coli were 44, 36, and 42 for the MPN, HGMF-indole, and HGMF-BCIG methods,
respectively. By the MPN method, E. coli was detected in 3 samples at levels
below the limits of detection of the HGMFs; but the MPN method was very
time-consuming. With the HGMF-indole procedure E. coli was missed in 4
artificially contaminated samples. With the HGMF-FC-BCIG method E. coli was
enumerated in 1 sample of bean sprouts missed by both the MPN and HGMF-indole
procedures. High levels of indole-positive Klebsiella spp. in bean sprouts
interfered with the HGMF-indole method, but the blue colonies of E. coli were
easily observed in the HGMF-FC-BCIG method. Specificity of the HGMF-FC-BCIG
method is high enough that routine confirmation should be unnecessary; however,
confirmation of presumptive E. coli is easier since no lethal indole-staining
step is involved. It appears to be a very simple method for quantifying E. coli
in foods or carcass rinses.
|
