Dissociation and phagolytic characteristics of the Shigella isolated from patients with various clinical forms of dysentery

The relationship between the severity of the disease and the phagolysis of the isolated cultures of S. flexneri and S. sonnei has been established. In the moderately severe form of the disease the duration of the latent period of the development of the phage has been found to increase in comparison with that in the mild form of the disease.     

The excretion of Shigella antigens in persons recovering from dysentery]

Shigella antigens can be detected in the excreta of convalescents after dysentery for a long time. Most frequently these antigens occur in feces, less frequently in urine and rarely in saliva. According to indirect data, S. flexneri 1-6 antigens can be detected in excreta for a longer period after convalescence than S. sonnei antigens. When antigen indication is used for the diagnosis of dysentery and epidemiological analysis is carried out, one should bear in mind the length of the agent persistence in the body, related to Shigella type.     

A comparative analysis of the Salmonella typhi strains isolated from patients and bacterial carriers

The comparative analysis of 133 S. typhi clinical strains isolated from patients and carriers in Dnepropetrovsk Province in 1978-1987 was carried out. As shown by this analysis, 10 Vi phage types were represented in the set of strains under study, phage types A and F1 being the most numerous ones. Phage type F1 occurred less frequently among the strains isolated from carriers. 31.1% of the strains were found to contain plasmids with different molecular weight ranging from 96 to 0.5 MD. The occurrence of plasmid-containing strains remained at the same level during the whole period under study. Low-molecular plasmids occurred more frequently in the strains isolated from carriers. The minimal suppressive concentrations of a number of antibiotics, such as penicillin, ampicillin, monomycin, chloramphenicol, tetracycline, rifampicin and streptomycin, were determined. 7% of the strains were resistant to penicillin, 9% to monomycin, 15%--to tetracycline and 2.6% to chloramphenicol. The correlation between penicillin and monomycin resistance of the strains and the presence of the plasmid with a molecular weight of 60 MD in these strains was established. All strains were shown to be highly variable in the degree of their virulence: from 10(2) to 10(8). The strains isolated from patients possessed greater virulence.     

Comparative characteristics of cell-free filtrates of Shigella flexneri of different virulence]

It was shown for the first time that the virulent Sh. flexneri strain grown on Luria broth differed from the avirulent one by the yield of readily released surface-located complexes--lipopolysaccharide (determined by rhamnose) and protein into the filtrate. There was no distinct correlation between the strain virulence and the content of rhamnose-determined lipopolysaccharide in the filtrate; growing bacteria in the presence of Ca and Mg ions had no significant influence on the lipopolysaccharide release into the filtrate. Protein release into the cell-free filtrate was thrice that in the virulent shigella strain than in the avirulent one. When bacteria were grown in the presence of Ca ions protein release from the virulent strain increased 1.5-fold and changed but little in the avirulent culture. Cell-free filtrates of the virulent strain produced toxic action on L tissue culture cells; in conjunctival infection of guinea pigs they caused some reduction of the LD50 of the virulent strain and sharply aggravated the course of the infectious process. Heating of the filtrate at 100 degrees C for 15 min decreased their toxic action on L cells. The data obtained indicated that the active biological factor revealed in the virulent strain of Sh. flexneri was protein or its derivative.     

Comparative analysis of antibiotic sensitivity of Streptococcus pneumoniae strains isolated from patients and carriers

The data on antibiotic sensitivity of 38 strains of S. pneumoniae isolated from children and 46 strains isolated from carriers are presented. The isolates from the carriers had significantly higher sensitivity to benzylpenicillin, ampicillin, methicillin, oxacillin, cefazolin, erythromycin, oleandomycin and lincomycin. Resistance to gentamicin was more frequent in the strains isolated from the carriers. Among the strains of S. pneumoniae isolated from the patients and carriers representatives of serovar K19 were more frequent. There were no statistically reliable difference in them by sensitivity to benzylpenicillin, ampicillin, cefazolin, lincomycin and rifampicin. Still, the isolates from the carriers were much more sensitive to methicillin, oxacillin, oleandomycin and erythromycin.     

Duration of bacterial discharge in Sonne dysentery]

The authors report on the results of their observations during 3 epidemic outbreaks. Despite different intervals at which the bacteriological examinations were carried out comparable data were obtained: during 2 outbreaks when no chemotherapeutic agents were used in 78.0 and 79.9% of children shigella discharge ceased in 4 weeks. Daily bacteriological examinations carried out in the course of the 3rd outbreak showed the maximal intermittent bacterial discharge for up to 79 days in individual cases.     

Recurrent Sonne dysentery morbidity caused by Shigella of varying enzymatic types]

The proportion of repeated cases of dysentery caused by Sh. sonnei does not exceed 3.59% of the total number of bacteriologically confirmed cases of this infection. The frequency of reinfection depended on the enzymatic type of the causative agent. The rarest cases of reinfection were those occurring after the primary infection with Sh. sonnei, biochemical type 2, whereas the most frequent after the primary infection with Sh. sonnei, type 3. Reinfection with heterologous Sh. sonnei was registered mostly 6-12 months after the primary infection, and with homologous Sh. sonnei after a 1 year and later.     

Latex test used for diagnosis of dysentery caused by Shigella sonnei]

The aim of this study was to evaluate the usefulness of latex reagent coated with immunoglobulins specific for antigens of phase I and II of S. sonnei for detection of these antigens in primary, mixed bacterial cultures. The study was performed on 919 fecal samples from individuals with clinical symptoms of dysentery, convalescents and from contact individuals. Material used for the test was bacterial suspension collected from McConkey or SS agars and a culture from selenite F broth heated at 100C. The results of the latex test were compared with the results of isolation of S. sonnei from the same cultures. S. sonnei was isolated from feces of 140 individuals (15.2%), while the latex test was positive in 215 cases (23.4%). The highest testing effectiveness , significantly higher than when isolation of pathogen was performed, was obtained only when 18-20 hr culture on Selenite F medium was used for latex test. The correlation between efficacy of testing for S. sonnei and phosphate content of Selenite F and a mode of its preparation was found. The latex test allows to eliminate from further bacteriological studies cultures free of S. sonnei thus it gives measurable economical profits and it shortens significantly time period of bacteriological examination.     

Antibiotic sensitivity of Shigella isolated from patients from 1974-1985

Antibiotic sensitivity of 3524 Shigella cultures isolated from patients in 1974-1982 and 414 cultures isolated in 1983-1985 was assayed with standard paper disks. The isolates of 1974-1982 were mostly responsive to ampicillin, carbenicillin, kanamycin, gentamicin, monomycin, neomycin and chloramphenicol. Certain differences in the level of the antibiotic resistance were observed in the Shigella isolates belonging to diverse species. Polyresistant cultures of Shigella amounted to 96.5% and ranged from 88.5 to 99.4% in different years. The number of the cultures with multiple resistance among Shigella sonnei was somewhat higher than that among the Flexneri and Newcastle bacilli. The Shigella isolates of 1983-1985 were mostly responsive to gentamicin, carbenicillin, neomycin, kanamycin and monomycin. 55.5% of the Shigella isolates were responsive to chloramphenicol and only 3.1% to tetracycline. Almost all the causative agents of dysentery isolated within that period were polyresistant. Phenotypic characteristics of multiple resistance in the Shigella cultures were studied.     

Sensitivity to antibacterial preparations of the pathogenic staphylococci isolated from carriers]

After discontinuation of the use of antibiotics for sanation of the carriers of pathogenic staphylococci among the staff of a maternity unit, the number of the strains resistant to penicillin, streptomycin, chlortetracycline, tetracycline, levomycetin, erythromycin, monomycin and neomycin decreased 1.3, 2.9, 10,4.3,5.5,1.5,3.9 and 2.4 times respectively. The differences were statistically reliable. The causes of the antibiotic resistance decrease require further investigation.     

Ways of determination of the intensity of the epidemic process in Shigella sonnei dysentery]

Proper view on the true prevalence of Sonne dysentery characterised by polymorphous clinical picture in which many cases coursed in subclinical form could be reached only by using additional active methods for detecting the infection rate of the population. For this purpose the authors applied passive hemagglutination test which permitted to reveal the response of the organism to the antigenic stimulation in the course of two months after the sustained sickness. Over 12 000 persons were examined. According to the results of passive hemagglutination test seasonal activization of the epidemic process occurred one month earlier than it was revealed by recording of the incidence of the disease. The results of the mentioned test also showed infection rate of the population with Sonne dysentery to be as a rule greater than established by the official statistics.