Extended Incubation of LST and BGB Tubes and the MPN Estimates of Coliforms

1994 ◽  
Vol 57 (8) ◽  
pp. 740-742 ◽  
Author(s):  
LAWRENCE A. ROTH ◽  
HAROLD BENGSCH ◽  
CHARLES DAVIDSON ◽  
JAMES S. DICKSON
Keyword(s):  
Incubation Time ◽  
Brilliant Green ◽  
Regulatory Compliance ◽  
Most Probable Number ◽  
Lauryl Sulfate ◽  
Interlaboratory Comparisons ◽  
Confidence Limits ◽  
Probable Number

Extending the incubation time past the standard 48 h for presumptive lauryl sulfate tryptose (LST) broth and confirmed brilliant green bile (BGB) broth tests for coliforms resulted in increases in most probable number (MPN) estimates. Whereas 40% of the samples showed an increase in the presumptive MPN when the incubation was extended from 48 to 72 h, only 5% showed confirmed MPNs, which exceeded the 95% confidence limits established for the 48-h confirmed MPNs. Extending the incubation of BGB tubes to 72 h resulted in less than 5% of the samples exhibiting increased MPNs, which exceeded the 48-h 95% confidence limits. Some loss in viability of coliforms was observed when LST tubes were incubated beyond 72 h. The study demonstrates the importance of adhering to standard incubation times for interlaboratory comparisons and ensuring regulatory compliance.

Comparison of Methods for Estimation of Coliforms, Fecal Coliforms and Enterococci in Retail Ground Beef

1978 ◽  
Vol 41 (4) ◽  
pp. 263-266 ◽  
Author(s):  
C. J. PIERSON ◽  
B. S. EMSWILER ◽  
A. W. KOTULA
Keyword(s):  
Escherichia Coli ◽  
Brilliant Green ◽  
Agar Medium ◽  
Ground Beef ◽  
Fecal Coliforms ◽  
Most Probable Number ◽  
Type I ◽  
Lauryl Sulfate ◽  
Comparison Of Methods ◽  
Probable Number

Seven recommended methods for estimation of coliforms, three for fecal coliforms and four for enterococci were tested on 30 retail ground beef samples. Lauryl sulfate tryptose broth gave higher coliform counts than did MacConkey's broth or brilliant green lactose bile broth 2% in 3-tube Most Probable Number (MPN) methods. With all MPN broths, coliforms counts were significantly (P ⩽0.05) higher after 48 than after 24 h of incubation. Presumptive coliform counts were higher with surface-overlay plating on violet red bile agar than with pour plating on the same agar or with the MPN broths. However, presence of Escherichia coli Type I was not confirmed as often from the agar medium as the broths. For estimation of fecal coliforms, counts did not differ significantly (P ⩽0.05) between EC broth (45.5 C) and brilliant green lactose bile broth 2% (44 C). Enterococci counts varied significantly (P ⩽0.05) among the four methods.

Prevalence of Clostridium botulinum in Commercial Liver Sausage

1983 ◽  
Vol 46 (3) ◽  
pp. 242-244 ◽  
Author(s):  
A. H. W. HAUSCHILD ◽  
R. HILSHEIMER
Keyword(s):  
Clostridium Botulinum ◽  
Type A ◽  
Most Probable Number ◽  
Confidence Limits ◽  
Probable Number ◽  
Toxic Cultures

Samples of 75 g of commercial liver sausage were cultured, with and without prior heating, for the presence of viable Clostridium botulinum. Three of 276 heated cultures and 2 of 276 unheated cultures produced botulinal toxin, all of type A. The most probable number of botulinal spores was estimated at 0.15/kg. The estimate for “total” C. botulinum, based on 5 toxic cultures in 276 heated and unheated pairs, was 0.24/kg. The 99% confidence limits were 0.02 to 0.53 per kg and 0.05 to 0.69 per kg, respectively .

Use of Iron Milk Medium for Enumeration of Clostridium perfringens

1982 ◽  
Vol 65 (5) ◽  
pp. 1129-1133 ◽  
Author(s):  
William D St John ◽  
Jack R Matches ◽  
Marleen M Wekell
Keyword(s):  
Clostridium Perfringens ◽  
Incubation Time ◽  
Incubation Temperature ◽  
Egg Yolk ◽  
Most Probable Number ◽  
Biochemical Tests ◽  
Probable Number ◽  
Large Numbers ◽  
Whole Milk ◽  
Short Incubation Time

Abstract A simple iron milk medium was used for isolation and enumeration of Clostridium perfringens from soil, sludge, and water samples. The whole milk contained only iron powder as a reducing agent; no other inhibitors were added. The iron milk most probable number (MPN) procedure was compared with 4 plating media: sulfite-polymyxin-sulfadiazine, Shahidi-Ferguson perfringens, tryptose-sulfite- cycloserine (both with and without egg yolk), and tryptone-sulfite-neomycin. The selectivity of the iron milk relies solely on the rapid growth of C. perfringens at 45°C and the stormy fermentation reaction within 18 h. Isolates were confirmed as C. perfringens by standard biochemical tests. The iron milk MPN procedure compared very well with the 4 plating media tested. Selectivity of incubation temperature, short incubation time, and ease of identification by the characteristic stormy fermentation make this method ideal for enumerating C. perfringens from large numbers of samples.

scholarly journals Two Rapid Methods for Detection of Escherichia coli Exceeding 104/g Action Levels: Precollaborative Study

2006 ◽  
Vol 89 (5) ◽  
pp. 1317-1326
Author(s):  
Michael A Grant ◽  
Jane S Wernberg ◽  
Khanh T Van ◽  
Angelina M Albert
Keyword(s):  
Escherichia Coli ◽  
Membrane Filtration ◽  
Reference Method ◽  
Most Probable Number ◽  
Lauryl Sulfate ◽  
Probable Number ◽  
E Coli ◽  
Potential Alternative ◽  
Aoac Method ◽  
Action Levels

Abstract The current AOAC Method 966.24 for enumeration of Escherichia coli in foods uses a most probable number (MPN) procedure with extensive confirmation steps. Two new methods based on membrane filtration (MF) were compared to the MPN reference method for detection of high levels of E. coli in 5 food types, some of which represent categories for which the U.S. Food and Drug Administration (FDA) mandates additional testing if an action level of 104/g E. coli is exceeded. Ground beef, which is not FDA regulated, was also tested. The 5 food types were all inoculated at 3 levels: 102/g, ≥104/g, and ≥105/g E. coli. An MF protocol using either m-ColiBlue24® (CB) or lauryl sulfate tryptose plus BCIG (LST/BCIG) was an effective potential alternative to the reference method. Sensitivity and specificity for both CB and LST/BCIG were 98 and 100%, respectively. Agreement between MPN and both CB and LST/BCIG was 98%. The 2 proposed methods allow completion of both presumptive and confirmatory steps in 13 days, whereas the reference method requires as many as 11 days. Exclusivity testing with 50 non-E. coli strains indicated 100% were correctly ruled out by the proposed protocols. Inclusivity testing was used to determine whether typical results were obtained after incubation of E. coli cultures on CB or LST/BCIG for 24 h. Of 50 E. coli strains tested, 100% yielded typical results after incubation on CB, and 98% yielded typical results after incubation on LST/BCIG.

The “most probable number” estimate and its confidence limits

1993 ◽  
Vol 27 (5) ◽  
pp. 799-805 ◽  
Author(s):  
Benoit Beliaeff ◽  
Jean-Yves Mary
Keyword(s):  
Most Probable Number ◽  
Confidence Limits ◽  
Probable Number

Evaluation of Cultural Methods to Isolate Salmonella from Pressed Yeast and Dried Inactive Yeast

1975 ◽  
Vol 38 (7) ◽  
pp. 383-385 ◽  
Author(s):  
CLYDE R. WILSON ◽  
WALLACE H. ANDREWS ◽  
PAUL L. POELMA
Keyword(s):  
Most Probable Number ◽  
Distilled Water ◽  
Lauryl Sulfate ◽  
Improved Method ◽  
Probable Number ◽  
Examination Procedure ◽  
Cultural Methods ◽  
Modified Method ◽  
Current Procedure ◽  
Better Than

An improved method recently developed to isolate Salmonella from dried active yeast was evaluated for use with pressed yeast and dried inactive yeast. The method for dried active yeast consists of pre-enriching a 25-g sample in trypticase soy (TS) broth at a sample-broth ratio of 1:10, incubating at 35 ± 0.5 C for 24 ± 2 h, and transferring to lauryl sulfate tryptose (LST) and tetrathionate (TT) broths. After 24 ± 2 h at 35 C, the broths are streaked to selective agars. When evaluated for use with pressed yeast, Salmonella attained higher most probable number levels/ml with this method (7.9 × 104 – 3.3 × 106), than with 1% tryptone broth and a sample-broth ratio of 1:5 (1.7 × 103 – 1.7 × 106), which is the current examination procedure for pressed yeast. Salmonella was consistently isolated from selective agars streaked from TT broth, but was seldom isolated from selective agars streaked from LST broth because of massive overgrowth by non-salmonellae. With dried inactive yeast, this modified method was equal to, but not significantly better than, pre-enrichment of the yeast in sterile distilled water at a sample-broth ratio of 1:5, which is the current procedure for dried inactive yeast.

Alternative Indicator Bacteria Analyses for Evaluating the Sanitary Condition of Beef Carcasses

2000 ◽  
Vol 63 (1) ◽  
pp. 51-55 ◽  
Author(s):  
STEVEN C. INGHAM ◽  
DAVID J. SCHMIDT
Keyword(s):  
Most Probable Number ◽  
Lauryl Sulfate ◽  
Probable Number ◽  
Small Plant ◽  
E Coli ◽  
Sanitary Condition ◽  
Beef Carcasses ◽  
Enterococcus Spp ◽  
Plant Equipment ◽  
Agar Method

Sponge samples were obtained from 47 (study 1) and 32 (study 2) beef carcasses in a small plant over 6 months. In study 2, slaughter equipment surfaces were also sampled. In study 1, the Petrifilm method was used to count presumptive Escherichia coli and spread plating on kanamycin esculin azide (KEA) agar with and without 40% added bile was used to count presumptive Enterococcus spp. Qualitative testing for presumptive E. coli and Enterococcus spp. in study 1 was done using lauryl sulfate tryptone broth (LST) + 4-methylumbelliferyl-β-D-glucuronide (MUG) and KEA + 40% bile broth, respectively. In study 2, LST + MUG was used as a most probable number (MPN) method along with the Petrifilm method. In the two studies, 8 (17.0%) and 11 (34.4%) carcasses were contaminated with presumptive E. coli; all but one contaminated carcass contained <1 CFU/cm2. Presumptive Enterococcus spp. were recovered from 15 carcasses (31.9%) in study 1, but the KEA + 40% bile agar method lacked specificity (only 31.3% of isolates confirmed as Enterococcus spp.) The LST + MUG and Petrifilm methods were significantly (P < 0.05) related in terms of detecting presumptive E. coli, but the presence of presumptive Enterococcus spp. was not significantly related to the presence of presumptive E. coli. However, on slaughter plant equipment in Study 2 there was a statistically significant (P < 0.05) relationship between the presence of presumptive E. coli and presumptive Enterococcus spp. In study 2, there was no significant (P < 0.05) difference in numbers of presumptive E. coli (obtained using Petrifilm) on carcasses chilled 1 day (n = 16) and 7 days (n = 16), although more of the 7-day carcasses were contaminated (five and seven carcasses, respectively). For samples testing positive for presumptive E. coli, the 95% confidence intervals obtained using the LST + MUG MPN method included the Petrifilm value for all but one sample.

The influence of incubation time on adenovirus quantitation in A549 cells by most probable number

2016 ◽  
Vol 237 ◽  
pp. 200-203 ◽  
Author(s):  
Jennifer L. Cashdollar ◽  
Emma Huff ◽  
Hodon Ryu ◽  
Ann C. Grimm
Keyword(s):  
Incubation Time ◽  
A549 Cells ◽  
Most Probable Number ◽  
Probable Number

KUALITAS AIR MINUM ISI ULANG DI DAERAH PESISIR KOTA KENDARI

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Juminten Saimin ◽  
Tesa Ristanti ◽  
Hartati Hartati
Keyword(s):  
Brilliant Green ◽  
Most Probable Number ◽  
Probable Number

AbstrakAsupan air sangat penting diperhatikan karena dapat menimbulkan masalah kesehatan terutama bagi wanitahamil dan menyusui. Jumlah dan kualitas air minum belum terpenuhi dengan baik. Air minum isi ulang menjadipilihan bagi masyarakat di daerah pesisir karena kesulitan air bersih. Penelitian ini bertujuan untuk menilaikualitas air minum isi ulang di daerah pesisir Kota Kendari. Penelitian ini telah dilaksanakan pada bulan Juni2017, dengan metode Most Probable Number. Sampel air minum diambil dari Depot Air Minum Isi Ulang diKecamatan Abeli. Pemeriksaan sampel dilakukan di Laboratorium Mikrobiologi Fakultas Kedokteran UniversitasHalu Oleo. Hasil penelitian ini menunjukkan pada media lactose broth ditemukan bakteri pada 5 sampel dan 1sampel tidak ditemukan bakteri. Pada media Brilliant Green Lactosa Bile Broth didapatkan 4 sampel ditemukanbakteri coliform dan 2 sampel tidak ditemukan bakteri coliform. Jumlah bakteri coliform yang ditemukan palingtinggi sebesar 96 MPN/100 mL. Kesimpulan air minum isi ulang di daerah pesisir Kota Kendari sebagian besarterkontaminasi dengan bakteri coliform.Kata kunci: Air Minum Isi Ulang; Coliform; Kualitas Air 

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