Epidemiological evaluation of the serological grouping of meningococci]

Use of the precipitation and hemagglutination inhibition tests to determine the serological group of 114 meningococcus strains which cannot be grouped by agglutination slide permitted to establish the serological group of 56% of the strains, this pointing to the greater diagnostic value of these tests. Nevertheless, 70% of 307 strains isolated from carriers could not be referred to any of the determinable groups (A, C, X, Y, and Z). Strains (417) isolated from the cerebrospinal fluid of patients with meningitis were grouped depending on the epidemic curve: only half of the cultures could be classified in sporadic cases, but from 80 to 100% of the strains were classified at the "peak" of the meningitis incidence rise. This rise was connected with increase of the incidence of cases caused by meningococcus, group A; at the decline these strains were eliminated, and cases due to the rarely encountered serological groups and nongrouping strains occurred. Marking meningococc by serological groups proved to be of no use for detection of epidemiological relations between the infected persons.     

Components of the regular surface array of Aquaspirillum serpens MW5 and their assembly in vitro.

The two-layered regular surface array of Aquaspirillum serpens MW5 was removed from cell envelopes and dissociated into subunits by treatment with 6 M urea. The surface components reassembled onto an outer membrane surface and self-assembled into planar sheets in vitro in the presence of Ca2+ or Sr2+. The two layers were removed sequentially from cell envelopes by a two-step extraction procedure involving initial treatment with a high-pH buffer to remove the outermost surface layer and subsequent treatment with 6 M urea to remove the innermost layer. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the outer and inner layers of the array were composed of two proteins with molecular weights of 125,000 and 150,000, respectively. The two layers assembled sequentially; the 150,000-molecular-weight protein formed an array on an outer membrane surface, and the 125,000-molecular-weight protein required that array as a template for its in vitro assembly.     

Streptococcus salivarius strains carry either fibrils or fimbriae on the cell surface

Strains of Streptococcus salivarius were screened by negative staining for the presence of surface structures. Two structural subgroups were found, carrying either fibrils or fimbriae, projecting from the cell surface. Eight strains carried a very dense peritrichous array of fibrils of two distinct lengths. Long fibrils had an average length of 175 nm, and short fibrils had an average length of 95 nm. Two strains carried only long fibrils, one strain carried only short fibrils, and another strain carried a lateral tuft of very prominent fibrils of two lengths, with a fibrillar fuzz covering the remainder of the cell surface. In all the strains in which they were present, the long fibrils were unaffected by protease or trypsin treatment. In contrast, the short fibrils were completely digested by protease and partially removed by trypsin. Neither long nor short fibrils were affected structurally by mild pepsin digestion or by lipase. The Lancefield extraction procedure removed both long and short fibrils. These twelve fibrillar strains were therefore divisible into four structural subgroups. Extracts of all the fibrillar strains reacted with group K antiserum. The second main structural subgroup consisted of nine strains of S. salivarius, all of which carried morphologically identical, flexible fimbriae arranged peritrichously over the cell surface. The fimbriae were structurally distinct from fibrils and measured 0.5 to 1.0 micron long and 3 to 4 nm wide, with an irregular outline and no obvious substructure. There was no obvious reduction in the number of fimbriae after protease or trypsin treatment. Extracts of the fimbriated strains did not react with the group K antiserum. The two serological and structural subgroups could also be distinguished by colony morphology.     

Antigenic structure of saprophytic leptospirae and their classification]

The authors present the results of study of the serological properties of 46 strains of saprophytic leptospirae of different origin. On the basis of the affinity of the antigenic structure detected in the cross microagglutination reaction (MAR) 38 strains under study were united into 8 serological groups; the rest 8 strains were serologically independent in this reaction. The fact that 9 strains of water leptospirae isolated in the Armenian SSR belonged to one serological group was proved in the cross MAR and the test of aglutinin adsorption. This serological group was new and was named L. armenica. Five individual serological types of saprophytic leptospirae were differentiated in its composition. Comparative study of the serological interrelations between the group of strains isolated in Armenia and the strains of some serological groups and serological types the closest serological connections were noted in the K-1030 (serological group Armenica) and Bovedo (serological group Andamana) strains. It is believed that the existing division of the saprophytic leptospirae into two serological groups (Semaranga and Andamana) required widening and supplement by new serological groups and serological types.     

Antibiotics sensitivity of "hospital" strains of S. typhimurium]

Sensitivity of Styphimurium strains isolated under conditions of a hospital infection to antibiotics were studied in comparison with the strains of the given serological type isolated from other sources and with the strains of other serological types of groups B, C, D and E. It was shown that the strains causing outbreaks of hospital infections were characterized by polyresistance to 7 out of 9 antibiotics tested. All the Salmonella strains tested were sensitive to gentamicin and about a half of them was sensitive to polymyxin M.     

Serologic properties of strains of Cl. perfringens isolated from the intestinal contents of healthy subjects]

A study was made of the quantitative content in the intestine of C1. perfringens strains in 6 healthy persons who stayed in a hermetically sealed space for 1 month and for 1 year. C1. perfingens strains were isolated from the fecal samples of each of the volunteers at various periods of the trial. A total of 570 strains of C1. perfringens of type A with anticellular sera obtained to the strains of various serological groups were studied. Serological properties of C1. perfringens strains of type A present in the intestinal contents of man were nonhomogeneous. This pointed to the simultaneous presence in the intestine of strains belonging to several serological types. A partial or complete replacement of one strain by another (differing by serological properties) occurred in the course of not over one month. C1. perfringens strains of type A present in the intestine of each volunteer were subdivided into serological types individual for each of the persons under observation. This pointed to the fact than no interexchange of strains of the mentioned bacteria occurred between different persons in the hermetically sealed space.     

Strains of salmonella with altered antigenic structure]

The authors studied 260 freshly isolated and laboratory cultures of salmonellae belonging to different serological groups. Heterogeneity of the majority of the strains studied by colour fluorescence of the colonies in the oblique light flux was demonstrated. Genetically bound spontaneous stable mutants with a different antigenic composition were selected by this method from a number of serological types. The isolated mutants were in the S-form and failed to differ by morphological, cultural and biochemical properties from the initial parental strains. A study of the antigenic structure by the method of agar immunoelectrophoresis and determination of their serological properties showed the mutants to have disturbances in the processes of O- or K-antigen synthesis.     

Antigenic properties of genetic recombinants of serologically typed E. coli]

The conjugation between the typed strains of E. coli belonging to various serological groups and conjugation between typed and untyped E. coli strains were studied. Genetic determinant controlling the synthesis of the O100 antigen proved to be closely linked with histidine locus. Among recombinants obtained in crossing the typed E. coli strains there were such belonging to the serological type different from the serological types of donor and recipient cells.     

Spiroplasma Species, Groups, and Subgroups from North American Tabanidae

Twenty-one triply cloned spiroplasma strains from the United States east of the Rocky Mountains, all isolated from tabanid (Diptera:Tabanidae) flies or serologically related to strains from tabanids, were compared reciprocally by spiroplasma deformation (DF) and metabolism inhibition (MI) serological tests. Many of the strains were also tested against 28 antisera representing known spiroplasma groups, subgroups, and putative groups isolated from nontabanid hosts. Relationships among strains were indicated by reciprocal cross-reactivity in both DF and MI tests. The strains were found to represent 11 recognized spiroplasma groups or subgroups. On the basis of serological, biochemical, and genomic data, strain BARC 1901 from Tabanus lineola appeared to represent a previously unrecognized candidate group. Strain BARC 2649, also from T. lineola, also appeared to represent a new group, but its morphology, arginine utilization, and some one-way serological crossing patterns suggested that it may be distantly related to group VIII spiroplasmas. Morphological, serological, and genomic data were used to place tabanid spiroplasma strains into three informal clusters. These are (i) groups IV (strain B31) and XXXI (strain HYOS-1); (ii) the three existing subgroups and a new candidate subgroup of group VIII represented by strain BARC 1357 plus ungrouped strain BARC 2649; and (iii) 14 strains, including EC-1 and TATS-1 (group XIV); strains TN-1 and TAAS-2 (group XVIII); strains TG-1, TASS-1, and BARC 4689 (group XXIII), strains TALS-2 (group XXVII), strain TABS-2 (group XXXII), and strains TAUS-1 and TABS-1 (group XXXIII) and ungrouped but closely related strains BARC 1901, BARC 2264 and BARC 2555. Analysis of tabanids from other geographic regions probably will substantially increase the number of known spiroplasma groups from this insect family. Received: 23 April 1997 / Accepted: 31 May 1997     

Role of horizontal genetic exchange in the antigenic variation of the class 1 outer membrane protein of Neisseria meningitidis

The nucleotide sequences of the genes encoding the class 1 outer membrane protein of Neisseria meningitidis (PorA) from 15 meningococcal isolates have been examined. These strains, isolated over a number of years, represented a variety of serological types, clonal groups, and geographical locations. Analysis of the aligned nucleotide sequences showed that the known serological relationships between these proteins were not necessarily reflected throughout the nucleotide sequences of their genes. The uneven distribution of base substitutions, revealed by a comparison of the informative bases, suggested that these genes possessed a mosaic structure. This structure probably resulted from the horizontal transfer of DNA between strains and would have contributed to both the generation and the spread of novel antigenic variants of the protein. In addition, the nucleotide differences between porA genes from different strains were not consistent with the nucleotide sequence divergence of the whole chromosome, as indicated by pulsed-field gel electrophoresis (PFGE) fingerprinting techniques: some strains with divergent PFGE fingerprints shared porA genes with extensive regions of nucleotide sequence identity and, conversely, some strains with similar chromosome structures possessed porA genes with different nucleotide sequences and serological properties. This suggested that entire genes had been exchanged between strains. Given that the meningococcal class 1 OMP is a major component in novel vaccines, some of which are currently undergoing field trials, the potential of horizontal genetic exchange to generate antigenic diversity has implications for the design of such vaccines.     

Host specificity of the colonization of murine gastric epithelium by lactobacilli

Abstract Strains of Lactobacillus isolated from animals of several species were examined for their capacity to colonize the lumens and form layers on the keratinized nonsecreting epithelium in the stomachs of monoassociated ex-germfree mice. All strains tested could be cultured at comparable population levels from the stomachs of the mono-associated mice. With one exception, however, only strains previously isolated from rodents were able to form thick continuous layers on the gastric epithelial surface. The exception was a strain isolated from calf feces. This strain formed a layer on the epithelial surface, comparable to layers seen in animals associated with strains from rodents.     

The characteristic and clinical importance of bacteria of the genus Citrobacter isolated from patients with acute intestinal infections on the territory of Volgograd

A total of 309 Citrobacter strains isolated from patients with acute intestinal infections of obscure aetiology and from healthy subjects were investigated. Species specificity of the bacterial cultures was determined by biochemical tests recommended by the International Enterobacteriaceae Subcommittee. Citrobacter strains were titrated serologically in the reaction of agglutination on glass with a living culture and adsorbed 0-antisera. Eighteen serological 0 groups were identified; 0 groups 3, 9, 23, 1 and 8 were found most frequently. Citrobacter was isolated more frequently from patients with acute intestinal infections than from healthy subjects. Seasonal circulation of Citrobacter strains in spring and summer was established. The number of culture findings of Citrobacter in the patients increased against the background of reduction in the number of cases of bacteriologically confirmed dysentery.     

Serologic pattern of meningococci in a focus of infection]

The authors present the results of typing of meningococci (isolated from the patients and carriers) by the sera of serological groups A, B, C, D, X, Y, and Z made at the Leningrad Institute of Vaccine and Sera. The causative agents of serological group A were most frequently isolated from the patients with the generalized forms of meningococcus infection. The percentage of detection of meningococci of serological group A was the greatest in the patients and much less in the carriers in and outside the foci of this infection. Many dissociated cultures were revealed among the strains isolated from the carriers. Sera of the Leningrad Institute of Vaccine and Sera have permitted typing of meningococci cultures belonging to various serological groups in accordance with the international classification.     

Detection of the etiologic structure of generalized and localized forms of meningococcal infection using the passive hemagglutination test

Preparations of formalin-treated erythrocytes sensitized with meningococcus polysaccharides of serological groups A, C, X, Y, and Z were used for the purpose of examination of patients with meningococcus infection; these preparations were highly specific in the tests of precipitation, hemagglutination and hemagglutination inhibition. Indirect hemagglutination test with the sera of 99 patients suffering from generalized forms of meningococcus infection was conducted with the mentioned preparations in Moscow and Novosibirsk in 1974--1975 when a stable morbidity decline was noted in these towns after an epidemic rise. The diagnostic value of this test was confirmed: it permitted to diagnose meningococcus etiology beginning from the 5th day of the disease and to decipher it from the aspect of individual serological groups. As shown, the incidence of cases caused by serological group A, reaching 87% at the height of the epidemic rise, fell to 49.5% at the stage of decline. Cases caused by group Y which was not encountered formerly were revealed in 16.2% of the patients. Among 127 patients with miningitis of nonmeningococcus etiology meningococcus antibodies to groups A and Y were revealed with the same frequency (in titres of not over 1 : 20--1 : 80), but the leading role of serological group A in the etiology of the manifest forms permitted to draw a conclusion on the presence of a higher invasiveness in the strains of group A.     

Investigations on the antigenic structure of actinomycetales IX. Serological classification of the Nocardiae with the polysaccharide fractions of their cell walls

Summary Polysaccharide fractions were extracted with 7.5% sulphosalicylic acid from defatted cell walls of 43 strains of nocardiae. All the polysaccharides, except those ofN. turbata, revealed chromatographically glucosamine, galactose, glucose and arabinose. Rhamnose was only found in the fractions isolated from some strains.The complement-fixation test with the polysaccharide fractions and anti-cell-wall sera allowed to distinguish four serological groups and 21 types among the strains examined. A method and a pattern of the serological classification of nocardiae has been presented.This work was partly conducted under a Von Humboldt Associate-Professor Fellowship in the Hygiene-Institute, University of Bonn, in 1963.Part of this paper was read at the meeting of the International Society of Human and Animal Mycology during the International Botanical Congress in Edinburgh, Scotland, 1964.     

Comparative study of the antibiotic sensitivity of Proteus hauseri bacteria belonging to different serological groups]

Sensitivity to 9 antibiotics of 1040 strains of Proteus belonging to the serological groups 03, 05, 06, 07, 010, 011, 013, 023, 024, 026, 027, 028 and 030 was studied. It was found that the above strains were sensitive and highly sensitive to the aminoglycosides and streptomycin, slightly sensitive to levomycetin and resistant to tetracyclines, erythromycin and penicillin. All the strains were polyresistant and 99.6 per cent of them were resistant to 4--9 antibiotics. Ten types of resistance were found. Proteus strains with the resistance type PETOtCht were most common. No relation between the occurrence of the strains of various serological groups and the character and level of their resistance to the antibiotics was found.     

Antigenic affinities of the root-nodule bacteria of legumes

Antisera prepared against 58 strains of root-nodule bacteria and against 16 strains belonging to the genusAgrobacterium were tested against 113 strains ofRhizobium, 20 strains ofAgrobacterium and 20 strains of other, possibly related, bacteria.Three serologically distinct groups of root-nodule bacteria were noted: (1)Rh. trifolii, Rh. leguminosarum andRh. phaseoli; (2)Rh. lupini, Rh. japonicum andRhizobium spp.; (3)Rh. meliloti. Strains ofRh. meliloti showed serological affinities withA. radiobacter andA. tumefaciens. All groups showed wider flagellar than somatic agglutination, and many different serotypes were apparent.The groupings obtained from this investigation are compared with those derived from other taxonomic studies, and the use of serological methods in rhizobial classification is discussed.     

Characteristics of the serological passage of Escherichia isolated from children and adults with acute intestinal infections

The serological picture of Escherichia (5,910 strains), isolated from 1,430 inpatients (486 adults and 944 children) with acute intestinal infections by means of new diagnostic preparations (Escherichia rapid agglutinating O- and H-systems), was studied. In 15% of the adults and 26-28% of the children no Escherichia were detected. The serological picture of Escherichia proved to comprise 143 O-groups and 334 serovars; about 50% of the strains belonged to 11 prevailing O-groups: O1, O2, O4, O6, O7, O8, O9, O16, O21, O75, O85. The serological picture in the adults was more variegated than that in the children: from most of the patients (77.2%) Escherichia were isolated as a mixture of 2-9 serovars. The isolation rate of Escherichia monocultures and the incidence of Escherichia belonging to different O-groups were the same in patients of different ages, with the exception of groups O4, O6, O26, O55 and O111 which were more frequent in young children.     

Application of immunoprecipitation in agar gel for the serological typing of soybean root-nodules

The results of serological typing of root-nodule homogenates from soybean plants inoculated by mixed bacterial inocula under field and greenhouse conditions are submitted. The inocula were prepared from strains capable of serological differentiation on the basis of their somatic antigens. Individual root-nodule homogenates were typed serologically by immunoprecipitation in agar with antisera against the inoculum strains. This method gave accurate determination of the origin of 605 out of a total of 616 serologically typed root-nodules and of the individual bacterial strains which participated in their formation.     

Experience with epidemiologic studies of pyocyaneus infections. I. Feasibility of using serotypes and antibiotic resistance as a epidemiologic label for clinical strains]

The authors carried out serological typing of 98 Pseudomonas aeruginosa strains, isolated from patients of burn department of the Sklifosovsky First Aid Institute in January-July, 1974, and of 215 strains obtained from other sources; their sensitivity to 13 antibiotics was determined. Pseudomonas aeruginosa cultures isolated from the patients were typed with O-sera of 10 serological types. The presence of several hospital strains of Pseudomonas aeruginosa was found by means of serological typing; along with these there were revealed cultures of this causative agent sporadically appearing in the department. Sensitivity to some antibiotics could serve as an additional criterion for differentiation of Pseudomonas aeruginosa strains of the same serological type.