A STUDY OF TWO HUNDRED CULTURES OF GRAM-NEGATIVE BACILLI ISOLATED FROM CASES OF GENITO-URINARY INFECTION

Abstract

In 12 of the 200 cases the organism was recovered also from the blood stream. All were members of the colon group, or were related forms. For convenience, these cultures were divided into 4 groups: I. 100 Escherichia cultures, comprising 4 subgroups; II. 79 Aerobacter cultures, with 3 subgroups; III. 5 Proteus cultures; and IV. 16 miscellaneous cultures falling into the genera, Alcaligenes, Eberthella, Shigella and Salmonella. The behavior of these 200 strains in regard to the Voges-Proskauer and methyl red tests, citrate utilization, gelatin liquifaction, indol production, action on milk, urea decomposition, hemo-lysis, motility, and capsule formation, as well as their action on 20 carbohydrates, was studied. Grouped according to these reactions the cultures fell into 65 types. Group I contained 30 of these types; group II, 20. The impossibility of accurately assigning these types to definite species of current classifications is discussed, and the merits and shortcomings of some of these classifications are presented concretely. A study of the literature indicates that the incidence of Aerobacter in urological infections is much higher than in the intestines. A comparison of the culture groups with the clinical infections with which they were associated showed that: 75% of the blood stream invasions were due to Aerobacter as compared with 8.3% due to Escherichia. Aerobacter strains were found in 48% of cases of lithiasis; Proteus, in 12%; Escherichia, in 25%. Two of the 3 cases of abcess formation developed blood stream invasions. This work establishes a basis for further study.