Enumeration of Total Coliforms, Fecal Coliforms, and Escherichia coli in Foods by Hydrophobic Grid Membrane Filter: Collaborative Study

Abstract

A collaborative study was conducted in 18 laboratories to assess the performance of the hydrophobic grid membrane filter method against that of the AOAC official first action method 46.013-46.016 for enumerating total and fecal coliforms and Escherichia coli. The study was carried out on frozen breaded fish, raw comminuted poultry, unroasted walnut pieces, ground black pepper, and cheddar cheese. The hydrophobic grid membrane filter method recovered significantly larger numbers of target bacteria in 7 of the food/analysis combinations: fecal coliforms in fish; E. coli in poultry; fecal coliforms and E. coli in walnuts; and total coliforms, fecal coliforms and E. coli in black pepper. Random error (Sr2) associated with the hydrophobic grid membrane filter method was significantly lower than that of the reference method in over 30% of the paired sample series. The hydrophobic grid membrane filter method for total coliform, fecal coliform, and E. coli enumeration in foods has been adopted official first action.

Development and application of a spiral plating method for the enumeration of Escherichia coli O157 in bovine faeces

“…A number of different methods exist for the enumeration of bacteria, including standard plate counting, most probable number (MPN) (Cochran 1950), spiral plate count method (SPCM) (Jarvis et al. 1977), hydrophobic grid membrane filter (Entis et al. 1984) and quantifiable PCR (Heid et al.…”

A tentative national reference procedure for isolation and enumeration of Escherichia coli from bivalve molluscan shellfish by most probable number method

“…1984;Arnold 1984) despite further developments in the procedures (Holbrook & Anderson 1982). The usefulness of hydrophobic grid membrane filter methods (Entis 1984) remains to be evaluated for raw bivalve shellfish examination.…”

Enumeration of Fluorescent Pseudomonads on Poultry by using the Hydrophobic‐Grid Membrane Filter Method

“…The HGMF consists of a standard membrane filter divided into a grid containing many cells of equal size, the result is a precise MPN system with a wide counting range (Sharpe and Michaud, 1975). The HGMF method has been adopted by the Association of Official Analytical Chemists as official first action for the enumeration of total coliforms, fecal coliforms and Escherichia coli (Entis, 1984) and Salmonella (Andrews, 1985). The method, however, has received little attention in the enumeration of spoilage organisms, an area for which it may be ideally suited.…”