Pearl L. Kendrick

Comparison of Pertussis Cultures by Mouse Protection and Virulence Tests

THE successful use of intracerebral infection in mouse protection tests of pertussis vaccine 1, 2 has called attention to a new method for measuring the virulence and protective properties of single cultures of Hemophilus pertussis. The practical value of such a study is apparent in relation to the criteria for selection of cultures for vaccine preparation. In the present study, the object has been to rank a group of cultures according to virulence and according to mouse protective properties, and to determine whether any correlation could be found between the two characteristics.

Cough Plate Examinations for B. Pertussis

HIS paper is a report on one phase of a more general study of the problem of whooping cough control in Grand Rapids, a city of 176,700 population. To be convinced of the importance of such a study in as many centers as possible, it is only necessary to consult morbidity and mortality statistics. Approximately 6,000 deaths from whooping cough are reported every year in the United States. Most of them are among children under 5 years. The importance of whooping cough as a cause of death in this age group is well illustrated by figures taken from reports of the Bureau of Records and Statistics of the Michigan Department of Health. occur, conscientious reporting by physicians, adequate isolation of infective cases by health departments, and the development and appropriate use of specific agents for its prevention. Our larger problem, therefore, falls naturally into several divisions, and includes: (1) an attempt to determine the practicability and value of maintaining a continuous cough plate diagnostic service in a community such as this; (2) an analysis of the applicability of the results of such a service in obtaining earlier diagnosis and a more adequate isolation and release program; (3) maintenance of a constant supply of freshly isolated cultures for study and for use in pertussis vaccine; (4) a study

Some Practical Considerations in B. Pertussis Vaccine Preparation

IN the preparation of all bacterial vaccines, the essential problem is the same-to make available the specific antigens in a product which is safe for injection. But even the simplest preparation-a killed suspension of the bacteria concerned-involves innumerable technical difficulties. Before there is any basis for expecting satisfactory results, the requirements for an active vaccine must be determined and met. It seems entirely possible that failure at this point is responsible for the irregular, unsatisfactory results of various workers with B. pertussis vaccineresults which led to its omission from the list of New and Non-afficial Remedies of the American Medical Association in 1931.1 Recent reports, especially those of Madsen,2 Sauer,3 and our own,4 in which more encouraging results have been obtained, emphasize particularly the need for using antigenically active cultures. A basis for considering this of great importance is found in the bacteriological studies of several workers, more recently by Leslie and Gardner,5 Lawson,6 and Shibley and Hoelscher.7 In order to have clearly in mind the essential features of the preparations in use for these more re-

USE OF HEMOLYZED SPECIMENS IN THE KAHN TEST.

THE SEROLOGICAL examination of hemolyzed blood specimens is a problem of considerable importance in a public health laboratory. Many of the specimens are mailed from considerable distances and thus subjected to marked changes in temperature as well as other conditions favoring hemolysis. In the laboratories of the Michigan Department of Health during the seasons when the temperature changes are extreme, there may be as high as 5 per cent of a daily run of specimens which are too badly hemolyzed for use and many others which show slight or moderate.hemolysis. It is generally recognized that Wassermann results with hemolyzed serums are not entirely dependable. Such serums may show non-specific absorption of complement-due, it is believed, to the presence of cellular substance released by the hemolysis of red cells. The color of the speci-men, moreover, interferes with the scale of reading the Wassermann results. These factors may explain why in the serological laboratory of the Massachusetts State Department of Health,1 Wassermann results with all specimens showing hemolysis are checked by the Kahn test. As to the use of hemolyzed specimens in the Kahn test, experience in this laboratory has suggested that such specimens, at least when hemolysis is only slight or moderate, may be run with safety. The present study was undertaken in an effort to experimentally determine whether the Kahn test with hemolyzed specimensespecially those showing more extreme hemolysis-is reliable. EXPERIMENTAL

EFFECT OF CONTAMINATIAN AND AGE OF SERUM ON KAHN PRECIPITATION TEST

INTRODUCTION IT MIGHT readily be assumed that contamination of serum. combined with age would exert an important influence on the serology of syphilis by precipitation. Just what this influence would be-whether, for example, positive serums would become negative or negative serums positive-could only be determined by experimentation. In the case of the Wassermann test, it is generally accepted that contamination is the major cause for the development of anticomplementary properties of serums. It is also known that in isolated cases contamination will change negative to positive reactions. Craig, for example, has shown that a negative serum, inoculated with one of the common organisms such as staphylococcus or B. subtilis and permitted to remain for a week at room temperature or for a lesser period in the incubator at 370 C., will frequently become capable of binding complement in the presence of antigen, thus giving a falsely positive reaction. It appears that under these conditions the serum becomes anticonmplementary in a special sense, so that with antigen it binds complement, but without antigen it is incapable of binding complement. Considering that in the Wassermann test we are dealing not only with serum and antigen but with carefully titrated amounts of complement, amboceptor and red cells, the occurrence of marked changes in the final reaction, due to comtamination, may be readily understood. The organisms may produce substances in the serum which are by themselves capable of binding complement either with or without the presence of antigen; and the mere binding of complement, as is well known, is not related to syphilis. Numerous substances, such as agar, kaolin, and, indeed, various bacterial suspensions, are capable of binding greater or lesser amounts of complement in a nonspecific manner. In the Kahn Precipitation Test, socalled anticomplementary properties of serum appear to exert no influence. A serum which is anticomplementary in the Wassermann test may be either positive or negative in the Kahn. It has been observed that blood specimens or spinal fluids reaching this laboratory in seemingly contaminated conditions, and often giving anticomplementary results in the Wassermann test, nevertheless gave specific reactions in the Kahn test. This brought up the question to what extent a serum may be contaminated and still give correct Kahn reactions. The present study was undertaken with a view of throwing light on this problem. It was desired to find whether a degree of contamination can be produced in serums which will give false reactions with the Kahn test. It was further desired to observe the parallel effect on the Wassermann.