It was demonstrated by Edwards (1) more than 30 y e a r s ago that cultures accepted as typical strains of Aerobacter aerogenes, and isolated under circumstances which did not indicate that they had any immediate connection with the intestinal tract of man or animals, were indistinguishable f r o m Klebsiella cultures and, indeed, some of them were biochemically and serologically identical with classical Friedlander strains. In spite of this observation, and al

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The, l a t e s t report (1 ) of t h e Enterobacteriaceae Subcommittee (1953) d e f i n e s t h e K l e b s i e l l a group, ( i n c l u d i n g Aerobacter aerogenes) a s made up of nonmotile, indole-negative, MR-negat i v e , VP-positive, c i t r a t e -p o s i t i v e , non-gelatin-liquefying, Gram-negative rods. They a l s o decompose urea, although t h e i r u r e a s e a c t i v i t y is much weaker t h a n t h a t of Proteus. While a l l t h e s e biochemical c h a r a c t e r s a r e considered t y p i c a l of t h e group, t h e r e p o r t a l s o mentions t h a t included i n t h e group a r e i n d i v i d u a l c u l t u r e s which give aberrant r e s u l t s i n one o r more of t h e s e t e s t s . Although it was r e a l i z e d t h a t m o t i l e and nonmotile s t r a i n s had many c h a r a c t e r s i n common, a s t h e Subcommittee e l i m i n a t e d m o t i l e s t r a i n s from K l e b s i e l l a , it was possible t o c o r r e l a t e m o t i l i t y with biochemical behaviour. There a r e , t h e r e f o r e , sound reasons f o r p l a c i n g t h e s e m o t i l e s t r a i n s i n a s p e c i a l group of t h e i r own, t h e Cloaca group.Brooke (2) compared 108 c u l t u r e s of Cloaca, 71 of them motile, with 303 nonmotile K l e b s i e l l a s t r a i n s . He found t h a t a l l s t r a i n s of Cloaca l i q u e f i e d g e l a t i n , none produced g a s from g l y c e r o l , one fermented i n o s i t o l , one d u l c i t o l , 20 were u r e a -p o s i t i v e and o n l y 9 promptly fermented s a l i c i n . A l l 303 Klebsiella cultures produced gas €ran glycerol, 296 promptly fermented i n o s i t o l , 91 d u l c i t o l , 1 7 l i q u e f i e d g e l a t i n , 300 were u r e a -p o s i t i v e and 302 fermented s a l i c i n i n 24 hours.He concluded t h a t g e l a t i n l i q u e f a c t i o n , m o t i l i t y , i n a b i l i t y t o produce g a s from g l y c e r o l , and t o ferment i n o s i t o l , a r e t h e b e s t characters t o i d e n t i f y Cloaca, while d u l c i t o l , s a l i c i n and urea t e s t s may a l s o be useful. H i s c u l t u r e s of Klebsiella included 13 MR-positive s t r a i n s , 12 i n d o l e producers, and 1 VP-negative s t r a i n . C e l l o b i o s e and s t a r c h were not used by Brooke. For t h e urea t e s t he used t h e Christensen medium a s modified by K r i s t e n s e n , w i t h phenol r e d i n d i c a t o r a s recommended by Kauffmann ( 3 ) . Moeller ( 4 )

A t l a n t a , Georgia W i t h i n r e c e n t y e a r s t h e r e h a s been renewed d i s c u s s i o n concerning t h e taxonomy and nomenclature of organisms c l a s s if i e d i n t h e genera K l e b s i e l l a and A e r o b a c t e r . I t h a s been

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