Nasopharyngeal Strains Research Articles

Comparison of the Bactericidal Action of Human and Guinea-Pig Blood on Strains of the Meningococcus with the Mouse-Mucin Test for Virulence

Abstract In 1934 the authors (1) reported on the bactericidal action of samples of human blood on strains of the meningococcus. It was found that a sample of blood possessing no bactericidal power against a cerebrospinal fluid strain of the meningococcus behaved in a different manner towards nasopharyngeal strains from noncontact carriers. In a later article in 1935 they (2) demonstrated the specificity of this property and showed that it could be induced in the blood of guinea pigs by vaccination. During the latter part of 1935 and 1936 these studies on the bactericidal effect of samples of human blood on various strains of the meningococcus were extended. The bactericidal action of human and guinea-pig blood has been compared with the virulence of strains when tested by means of the mouse-mucin test described by Miller (3).

STUDIES ON MENINGOCOCCUS INFECTION

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 4(1/2) 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.

A Further Study of the Serological Reactions of Meningococci from the Spinal Fluid and the Naso-Pharynx, with Special Reference to their Classification and to the Occurrence of the Latter among Normal Persons

(1) Meningococci from 60 cases of cerebro-spinal fever have been submitted to serological tests and compared with meningococcus-like micro-organisms from the naso-pharynx of 71 normal persons. In these serological tests 19 monovalent anti-meningococcus of known pathogenic origin and eight with strains isolated from the naso-pharynx. The tests comprised careful estimation of the agglutinability of these 131 strains with the 19 different sera and also of the extent to which these strains absorbed and removed the agglutinin from one or more sera.(2) The simple agglutination reactions effected a rough sub-division of these 131 strains into two groups, Group I and Group II, and indicated that in Group I there was a main group comprising the majority and at least two smaller groups containing a few strains only.(3) Tests for absorption of agglutinin confirmed this rough subdivision into two groups and distinguished with much greater precision the different main groups and smaller groups. In general, each of these groups was found to differ in that they did not absorb the agglutinin for members of the others, and members of each produced sera from which members of the others similarly failed to absorb agglutinin.(4) Two of the smaller groups, however, represent two “scrap-heaps” of strains unidentified by absorption reactions but suggesting by their agglutination reactions that they belonged to Groups I and II respectively. In the former there were placed three strains of cerebro-spinal and one strain of naso-pharyngeal origin, and in the latter four strains of the former origin and thirteen strains of the latter.(5) The other main groups and smaller groups contained representatives of both cerebro-spinal and non-contact naso-pharyngeal strains, though not in equal numbers: in the main group of Group I there were placed 24 spinal strains and only one non-contact naso-pharyngeal; in the main group of Group II there were placed 16 spinal strains and 40 naso-pharyngeal, of which 23 were from non-contacts and 13 from contacts.(6) Variations in agglutinability and absorptive capacity were shown to be so great as to interfere seriously with the use of serological tests for identifying meningococci in practice.(7) An additional difficulty affecting both the identification of meningococcin and their classification into types or groups and sub-groups is that, even with seven sera, each corresponding to a different group, strains were found, both spinal and naso-pharyngeal, which failed to react typically with any and therefore could neither be ascribed to a particular type or group nor be identified on serological grounds with the other pathogenic strains.(8) Hence it was concluded (a) that it is impossible to regard these types or groups as representing distinct classes limited by hard and fast lines, and (b) that it is unsafe to exclude any strain from possible pathogenicity on the ground of its failure to agree serologically with any of such sets of sera as are likely to be available in practice, since even the large series I employed failed to include all pathogenic strains.(9) The conclusion in my first report is therefore maintained that any strain possessing the admitted morphological and cultural characters of the meningococcus should be regarded as potentially pathogenic without considering its serological reactions.(10) I have found, however, that the strains obtained from the majority of carriers show by absorption tests complete serological identity with known pathogenic strains. To this criterion 58 of my 71 naso-pharyngeal strains conform. These were distributed as follows: 16 out of 138 out-patients attending Lambeth Infirmary in June and July, 1915 (11·6 per cent.); 12 out of 57 non-contact soldiers in February, March and May, 1916 (21 per cent.); 13 out of 24 soldiers in March, 1916, who had had no direct connection with cerebro-spinal fever but in whose neighbourhood two cases had occurred (54 per cent.); 17 out of 62 soldiers who had been in direct contact with cases of the disease (27 per cent.).(11) Inclusion of those persons who were found to be carrying strains not fully identified serologically did not raise the percentage of carriers to a significant extent.

A Bacteriological Investigation of Organisms Resembling the Meningococcus found by examination of the Naso-Pharynx of Persons who had not been in contact with Patients suffering from Cerebro-spinal Fever

A Bacteriological Investigation of Organisms Resembling the Meningococcus found by examination of the Naso-Pharynx of Persons who had not been in contact with Patients suffering from Cerebro-spinal Fever