The term dysentery was originally used to describe any condition having as a symptom diarrhoea with stools containing blood and mucus. The discovery of Entamoeba histolytica by Losch (1875) and its incrimination as a cause of dysentery was the first step in the more accurate classification of this group of diseases. In 1898 Shiga described a non-lactose fermenting coliform bacillus and produced convincing evidence that infection with this organism gives rise to acute inflammatory and ulcerative colitis. Closely related bacilli, differing from Shiga's organism in their biochemical reactions and antigenic pattern, were isolated from cases of dysentery by Plexner (1900), Strong (1900) and others. In 1915 Sonne found yet another type, and In 1917 Schmitz added one more to the list. A critical review by Murray in 1918 gave convincing confirmation of the existence of four main types of dysentery bacilli. Three of these, Shiga's bacillus, Sonne's bacillus, and Schmitz's bacillus, were clearly defined in their biochemical reactions and antigenic structure. The fourth type - or more correctly, group - embracing the organisms named after Flexner, Strong, Hiss, Russell, and Lentz, had identical biochemical reactions, but,*though closely related, were not wholly alike in their antigenic pattern. This latter group was investigated by Andrewss and Inman (1919) and divided into five types, which they named V, W, X, Y and Z. According to their conception, these types shared four main antigens. Each of the strains, V, W, X and Z was believed to contain a dominant quantity of one of these antigens and minor quantities of the other three, while Y contained approximately equal amounts of all four. For purposes of identification, a polyvalent antiserum was prepared from all five strains, and it was hoped that this would enable all organisms of the Flexner "spectrum" to be recognised with certainty. This hope did not materialise. Experience in India revealed that about 30io of all strains having the general and biochemical characters of the group failed to react with this 'polyvalent' antiserum. For purposes of diagnosis these inagglutinable strains were regarded as atypical but none the less pathogenic Flexner-group bacilli, but this compromise had many disadvantages, and failed to carry conviction to many who at that time still believed in the widespread occurrence of amoebic dysentery. IDENTIFICATION OF NEW TYPES OF MANNITOL-FERMENTING DYSENTRY BACILLI. In view of this state of affairs, an investigation was started which had as its object the differentiation by serological methods of these inagglutinable strains, and the confirmation, or otherwise, of their pathogenic action. Annexures I and II cover the initial part of this work. In all, nine distinct strains were identified which had the biochemical characters of the Flexner group but could be recognised as separate entities by virtue of their antigenic structure. These nine strains could be divided into two groups. The first, consisting of three members, not only resembled Andrewss' types biochemically, but also exhibited a certain degree of cross-agglutination with them. There was no reasonable doubt that they were members of this series, and would have been recognised as such by Andrewes had they found their way into his collection, which contained only one strain emanating from India. The remaining six strains fell into a different category, as they had no demonstrable antigenic relationship with the Flexner group. Their claims to be considered pathogenic are discussed in detail, and at the date of publication of Annexure II, it was considered that three of them could be incriminated. (Abstract shortened by ProQuest.)
