STUDIES ON MENINGOCOCCUS INFECTION : I. BIOLOGICAL PROPERTIES OF "FRESH" AND "STOCK" STRAINS OF THE MENINGOCOCCUS

Freshly isolated strains of meningococci present a number of characteristics which can be shown to differ not inconsiderably from those of stock strains long maintained on artificial media. Rough variants of the different types can be demonstrated, either arising spontaneously in vivo or in vitro, or evoked in the laboratory by the method described by Enders. Neither the freshly isolated strains—which are smooth— nor, in most cases, the rough variants of them are stable, both showing a tendency to pass over into the stock form or variant. The stock strains in the course of transformation from the freshly isolated strains show changes in morphology and cultural characteristics, and in viability in defibrinated blood

PATHOLOGY OF PNEUMOCOCCUS INFECTION IN MICE FOLLOWING INTRANASAL INSTILLATION

Pneumonia can be produced in mice, which have not been previously prepared, by intranasal inoculation of broth cultures of certain strains of pneumococci. Lesions which are quantitatively different can be produced in different breeds of mice by inoculation of the same type of pneumococcus. Similar inoculation of different types of pneumococci into one breed of mice results in lesions which are qualitatively different. In general, these lesions are as follows: a diffuse pneumonia and an acute glomerular nephritis in unselected mice receiving Type I strains; a confluent pneumonia and a tubular nephritis in the case of Type II strains; and as result of Type III strains, an interstitial pneumonia with extensive gelatinous pleurisy, together with necrosis and abscess formation in the spleen and cervical lymph nodes. Resistant strains of mice with Type III pneumococci show slight changes in the lungs, but marked lesions in the spleen and cervical nodes, while susceptible mice with the same type of pneumococcus show marked changes in the lung and moderate lesions in the spleen and cervical nodes. The method of development of Type III pneumonia, studied by means of serial sections of nasally infected mice, appears to proceed in the stages of vascular engorgement, interalveolar interstitial exudate, albuminous fluid exudate into the alveoli and the perivascular lymphatics draining the affected site, and finally, a frank pneumonia with a cellular exudate in the alveoli but without much fibrin

PATHOGENESIS OF PNEUMOCOCCUS INFECTIONS IN MICE

Unprepared mice given intranasal inoculations of certain strains of pneumococci develop pneumonia. The proportion of inoculated mice which will show the pneumonia at autopsy is dependent upon the strain and type of organism and the breed of mice used. It has been shown that, with the technique employed, the pneumococci reach the lower respiratory tract and alveoli almost immediately; moreover, that an invasion of the blood stream occurs very rapidly and can be demonstrated in a third of mice during the first 10 minutes. There is some evidence that invasion of the tissues and the blood stream may occur both through the upper respiratory tract, probably the nasal mucosa, and through the alveolar walls. It is uncertain which route of invasion, if either, is of the most importance. It has been possible to produce pneumonia by direct intravenous inoculation of pneumococci. It may be that the pneumonia is favored by a reaction at the point of invasion through the alveolar walls in the intranasally inoculated mice, but the results of the intravenous inoculation make it clear that such a local lesion is unnecessary for the production of pneumonia in mice

STUDIES ON MENINGOCOCCUS INFECTION : VI. THE CARRIER PROBLEM

Of the three studies which have been reported in this paper, the most thorough and therefore the most instructive was that made upon the Rockefeller Institute group of 24 individuals. The ten carriers discovered in this group were found to fall into three categories; namely, chronic, intermittent and transient carriers. It is, perhaps, a matter for surprise, in view of the weight of evidence in the literature, that half of the carriers should appear in the chronic group, being constantly affected for periods over 2 years and continuing to carry throughout this period what was, to all tests, the same strain of microorganism. It has been shown that no claim of relief from the carrier condition can be based on three consecutive negative swabs at weekly intervals since apparent spontaneous "cures," as evidenced by negative swabs, may last for 4½ months and finally be terminated by the reappearance of the same strain as that carried before. The effect of coryza and pharyngitis on the persistence and degree of the meningococcal infection has been studied and, while the results are scanty, indications have been found that coryza, unassociated with any increase in numbers of the nasopharyngeal pathogens or streptococci, causes no change in the number of meningococci present in the throat. On the other hand, a streptococcal pharyngitis or any infection in which other throat pathogens increase greatly in number is usually associated with a marked diminution or actual disappearance, whether temporary or permanent, of the meningococci from the nasopharynx. This is in accordance with the work of Colebrook and Gordon. Of the 26 carrier strains which were isolated in these three groups of individuals, only eight could be identified with Gordon's four types which are isolated from the majority of cases of meningitis. It is considered as certain, however, that the other 18 strains are to be regarded as true meningococci. Not only do they show the same cultural characteristics and fermentative reactions as the typical strains, but serological tests, especially that of absorption, have revealed that they are allied to the two main types, I-III and II, and can be regarded as belonging to the broad serological Groups I and II which include these typical Gordon types. Moreover, atypical Type II* strains, identical with those isolated from the nasopharynx of carriers, have recently been found to be the cause of two cases of frank cerebrospinal fever. Only five of the 26 strains belong to Group I while the other 21 are members of Group II. This is interesting in view of the work of Scott who found that Group II strains predominate in carriers during interepidemic periods like the present. In periods of epidemics the carrier strains from both contacts and noncontacts in the epidemic zone are more often of Group I and even more constantly tend to be of the typical Gordon types rather than atypical forms. As has been pointed out in an earlier paper (35), the viability of these carrier strains when planted in defibrinated rabbit blood is low as compared to the typical and freshly isolated meningitis strains. The exact significance of this fact is not known. It has not been possible up to the present to do comparative virulence tests between spinal fluid and nasopharyngeal strains owing to the absence of a sufficiently susceptible animal

THE RAPID INVASION OF THE BODY THROUGH THE OLFACTORY MUCOSA

1. Prussian blue particles pass rapidly from the surface of the olfactory mucosa and within 2 minutes are found in the tissue spaces, in blood and lymph vessels, in the perineural spaces of the olfactory nerve fibers and in the subarachnoid space and pia-arachnoid membrane. 2. There is great affinity of pigment particles for the olfactory sensory cells. 3. Preliminary treatment of the olfactory mucosa with tannic acid does not alter the speed with which this absorption occurs. It does, however, cause an inflammation of the mucosa and appears to prevent the pigment from entering the olfactory sensory cells. 4. Both pneumococci and S. enteritidis pass through the olfactory mucosa and reach the tissue spaces, the vessels and the subarachnoid space with the same rapidity as the pigment. This can be demonstrated both microscopically and by distribution tests. They invade by passage between the cells of the mucosa and there is no apparent affinity of the organisms for the olfactory sensory cells. 5. Tannic acid treatment of the olfactory mucosa in no way alters this invasion of organisms through the mucosa. 6. The pantropic virus, equine encephalomyelitis, was detected in the forebrain as promptly as were pigment and bacteria; neurotropic viruses, however,—those of St. Louis encephalitis, rabies and louping ill,—were not demonstrated in less than 24 hours

STUDIES ON MENINGOCOCCUS INFECTION : VII. THE STUDY OF AN ISOLATED EPIDEMIC

The investigation of this isolated epidemic of meningococcus meningitis at a C.C.C. camp gave an opportunity to examine the carrier state in contacts carrying what were presumably virulent epidemic strains of organisms. With the aid of Miller's technique for the enhancement of the demonstrable virulence of meningococci for mice, it proved possible to test the virulence of the carrier strains from Camp Rusk. These results were consistent despite the interval of from 3 to 4 weeks which intervened between the isolation of the strains and the virulence titrations. Type I strains were found to have a high virulence, while the virulence of Type II strains was moderately high but definitely less than that of the Type I, and atypical strains and strains of N. catarrhalis isolated from carriers showed a very low virulence. The question of the precise nature of the carrier state was investigated. No evidence has been obtained yet as to the existence of a relationship between pharyngitis, coryza or upper respiratory disease and the presence and degree of the carrier state. This is unlike the situation with regard to pneumococcus carriers. On the other hand, it has proved possible to demonstrate reactions within the body to the meningococci in the nasopharynx, consisting of the formation of agglutinins and protective antibodies in the blood serum. 32.3 per cent of Type I and 60 per cent of Type II carrier sera showed moderate or good agglutinins for homologous organisms and 80 per cent of Type I and 40 per cent of Type II sera showed moderate or good protective antibodies against virulent homologous strains. No idea could be obtained as to the relationship of the presence or absence and the degree of serological reaction and the duration of the carrier state

STUDIES ON MENINGOCOCCUS INFECTION : II. MONOVALENT DIAGNOSTIC SERA PREPARED FROM "FRESH" AND "STOCK" STRAINS

The production of monovalent sera for agglutinin or precipitin reactions with freshly isolated strains of meningococci is described. Agglutination reactions with such sera can be carried out more rapidly, at lower temperatures and in lower dilutions, than with the standard monovalent sera prepared from stock cultures, while the results so obtained are more satisfactory owing to the relative absence of cross-agglutination

STUDIES ON MENINGOCOCCUS INFECTION : V. THE PRESENCE OF MENINGOCOCCUS PRECIPITINOGENS IN THE CEREBROSPINAL FLUID

Precipitin tests, carried out on the cerebrospinal fluid from cases of meningococcal meningitis with monovalent sera, demonstrate the presence in that fluid of type-specific precipitinogens of the meningococcus. Negative results are secured when the spinal fluid is obtained after the commencement of intrathecal serum treatment and also occasionally when the numbers of infecting organisms are very small. The reaction offers an easy and rapid method of ascertaining to which type of meningococcus a particular case of meningitis is due, and facilitates the immediate use of monovalent therapeutic antimeningococcal serum. Typing by means of the precipitin reaction can be confirmed by agglutination of the strain of organism responsible for the infection, if such strain be isolated. Confirmation by means of agglutination has been possible in all the cases discussed in this report. Spinal fluids from other diseases of the meninges and central nervous system fail to give any precipitin reaction with the monovalent sera

EXPERIMENTAL HYPERTHYROIDISM AND ITS EFFECT UPON THE MYOCARDIUM IN GUINEA PIGS AND RABBITS

A study has been made of the pathological changes in the hearts and other tissues of animals rendered hyperthyroid with thyroxine. Forty-four rabbits and seventeen guinea pigs were given intramuscular injections of thyroxine every other day and sacrificed at varying intervals. Tissues from a series of normal animals (twenty guinea pigs and forty-three rabbits) were examined as a control. The changes in the heart and other tissues of hyperthyroid animals were insignificant and varied but little from changes seen in normal control animals. Of eight thyrotoxic guinea pigs that developed coincidental infection (bronchisepticus) all showed myocardial lesions. Of nine thyrotoxic guinea pigs, free of infection, only one gave evidence of myocardial change. It is pointed out that hyperthyroidism, per se, cannot be held responsible for these lesions, which would appear to have been associated with the infection. It was noted that rigor mortis of the skeletal muscles occurred much sooner in the bodies of hyperthyroid animals than in normal animals

STUDIES ON LYMPHOGRANULOMA VENEREUM : I. DEVELOPMENT OF THE AGENT IN THE YOLK SAC OF THE CHICKEN EMBRYO

Making use of the fact that the cells of the yolk sac of the developing embryo are readily infected with the agent of lymphogranuloma venereum and that the virus bodies can be readily observed in these cells because of the structure of the latter, the development of this agent has been followed at short intervals. It has been found to go through a regular cycle of development similar to that described for psittacosis in the spleen and less fully for lymphogranuloma venereum in the brain of infected mice. The development as observed microscopically can be shown to run parallel to changes in the infective titre of the yolk sac as tested in other eggs