The Classification of Coli‐aerogenes Bacteria Isolated From Farm Water Supplies

Abstract

Summary: The methods suggested in the Report of the Coliform Sub‐Committee of the Society for Applied Bacteriology (Report, 1949) have been used in isolating and studying the coli‐aerogenes content of 142 samples of farm water supplies in two distinctive areas of Britain. The Gram‐negative cultures were grouped into typical, anaerogenic, non‐lactose‐fermenting and ‘unclassifiable’types, forming 54.2, 2.9, 10.9 and 32.0% of the 384 cultures respectively. Among the 261 coli‐aerogenes cultures, Bact. coli, intermediate and aerogenes‐cloacae organisms were found with frequencies of 32.2, 19.5 and 48.3% respectively. The majority of anaerogenic coli‐aerogenes organisms resembled Bact. coli type II while the predominant non‐lactose‐fermenters resembled Bact. cloacae and Bact. aerogenes type I. The reactions of 123 ‘unclassifiable'strains were such that very few could be regarded as Bact. coli types owing to the high incidence of gelatin liquefaction and growth in citrate broth.

Coli‐aerogenes Bacteria Isolated From Grass

“…aerogenes type I , a high proportion (45.1%) of the 144 cultures was 37" negative. Sixteen of the 18 paracolon cultures isolated during this investigation resembled aerogenes-cloacae types on IMViC reactions, confirming the previous finding of Thomas, Jones & Franklin (1951) that paracolon organisms isolated from natural sources are mainly of this type.…”

“…Cultures which developed an acid reaction but did not produce gas in lactose broth within 5 days at 30" are termed ' anaerogenic ' and Gram-negative rods isolated from colonies on eosin methylene blue agar plates but which did not produce acid or gas in 5 days in lactose broth a t 30" are considered to be ' paracolon ' types. (Thomas, Jones & Franklin, 1951) and 16.6% in soil (Thomas & Franklin, 1952). The incidence of unclassifiable cultures was also relatively low, being 9.1% in ungrazed herbage and 14.7% in grazed pasture, compared with 32.0% in surface water and 48-1y0 in soil.…”

“…cloacae on the grounds of gelatin liquefaction has been consistently made since Jordan (1890) first described the organism, and in view of its predominance in soil, in water and on plants we consider that its differentiation is necessary for ecological and taxonomic purposes. Thomas, Jones & Franklin (1951) reviewed the results of the application of other tests for the differentiation of Bact. cloacae and Bact.…”

“…on incubation at 37". The present investigation on the incidence of the different types of coli-aerogenes bacteria occurring on grass is complementary to an investigation of the types isolated from surface water (Thomas, Jones & Franklin, 1951).…”

Coli‐aerogenes Bacteria in Raw Milk

“…Only one of any replicate cultures from the same milk sample showing identical reactions was retained for classification. Details of the technique of isolation and differential tests were similar to those used by Thomas, Jones & Franklin (1951), Thomas & McQuillin (1952) and Thomas, Hobson, Elson & Price-Roberts (1954). Cultures which failed to produce gas in lactose broth in 5 days at 30", but which resembled coli-aerogenes bacteria in other respects (e.g.…”