Sensitivity of Gram-negative microflora to lysozyme]

Sensitivity to lysozyme of the representatives of various species of gramnegative microflora (476 strains) was studied with a new modified procedure, which is more exact and economic as compared to the method of serial dilutions in agar. High resistance of Eltor vibrio cholerae and Pseudomonas to lysozyme was found. Cultures of various sensitivity levels to lysozyme were detected among Aeromonas, enteropathogenic E. coli and NAG-vibrios.     

Sensitivity of Shigella to antibiotics]

Three hundred and twenty two Shigella cultures isolated from dysentery patients within 1986-1989 were tested with the use of standard paper disks for their sensitivity to levomycetin, streptomycin, tetracycline, monomycin, neomycin, kanamycin, erythromycin, gentamicin, carbenicillin, ampicillin, oxacillin, methicillin and doxycycline. The number of the cultures belonging to Shigella sonnei amounted to 85.1 per cent of the total number of the strains studied. 91.9, 89.5, 87.3, 87.3, 80.1 and 80.1 per cent of the cultures were sensitive to gentamicin, kanamycin, carbenicillin, neomycin, levomycetin and ampicillin, respectively. 99.4 per cent of the isolates were resistant to streptomycin and 97.2 per cent were resistant to tetracycline. The sensitivity to erythromycin remained rather high (70.2 per cent). The overwhelming majority of the Shigella sonnei isolates had multiple resistance.     

Sensitivity of Yersinia enterocolitica to antibiotics]

Sensitivity of 33 foreign and 10 native strains of Y. enterocolitica to tetracycline, aminoglycosides, penicillins, levomycetin and polymyxin was studied. All the strains proved to be resistant to penicillin, oxacillin and ampicillin: they produced penicillinase. The level of resistance to penicillin did not always correlate with penicillin activity. The ability of the native strains to acquire R-factor in vitro from Coli bacteria was shown.     

Sensitivity of beta-hemolytic streptococci to antibiotics]

Susceptibility of 64 beta-hemolytic streptococcal strains isolated from the patients with sore throat was studied by the method of serial dilutions in fluid nutrient medium (Konikov broth). Heterogenecity with respect to the sensitivity was investigated in 34 strains among separate populations of the microbes (10 to 15 in every strain). The MIC of benzylpenicillin, oxacillin and erythromycin ranged within 0.007--0.24 U/ml, 0.02--0.36 gamma/ml and 0.005--0.1 gamma/ml respectively. The MIC of benzylpenicillin with respect to separate populations most sensitive to it was 0.007--0.015 U/ml, while that with respect to the lease sensitive populations ranged from 0.015 to 0.24 U/ml. The respective values for oxacillin were 0.02--0.12 and 0.18--0.36 gamma/ml and those for erythromycin were 0.005--0.025 and 0.05--0.1 gamma/ml. Therefore, the beta-hemolytic streptococci isolated from the patients with sore throat were characterized by a rather high sensitivity to the antibiotics which was important precondition for their efficiency in treatment of the patients with the above disease.     

Sensitivity of pathogenic clostridia to antibiotics]

By the sensitivity levels of the gas infection causative agents, i. e. pathogenic Clostridia to antibiotics, the latter were conditionally divided into 4 groups. The 1st group included the most active antibiotics, such as tetracyclines,, penicillins, cephalosporins, rifampicin, 7-chlor-7-desoxylincomycin. Their minimum inhibitory and bactericidal concentrations did not usually exceed 2 gamma/ml. For most of the strains the inhibitory and bactericidal concentrations amounted to the tenth and hundredth fractions of gamma/ml. The antibiotics of the 2nd group, i. e. erythromycin, lincomycin,ristomycin and levomycetin inhibited multiplication and viability of pathogenic Clostridia in concentrations of 20 gamma/ml. Erythromycin was most active among them The 3rd group consisted of oleandomycin, novobiocin, geliomycin and azalomycin, the minimum inhibitory concentrations of them being 20 to 50 gamma/ml. The antibiotics of the 4th group, i. e. neomycin, monomycin, kanamycin, streptomycin, polymyxin and others affected pathogenic Clostridia at very high concentrations, amounting to the hundrenth and thousandth of gamma/ml.     

Sensitivity of Neisseria gonorrhoeae to antibiotics]

Since 1976 strains of Neisseria gonorrhoeae producing beta-lactamase have been isolated in many countries. Strains with high level resistance to tetracycline have been also described. The appearance of resistant strains implies a constant surveillance of the isolated gonococcus and the study of their antibiotics sensitivity.     

Sensitivity of antibiotic-resistant strains of Salmonella to new antibiotics and chemotherapeutic agents]

One hundred and sixty two antibiotic resistant strains of Salmonella isolated within 1984-1988 in Leningrad and the Leningrad Region were tested with respect to their sensitivity to new antibiotics and chemotherapeutics developed or being developed in the USSR. At the background of high numbers of circulating Salmonella strains resistant to the routinely used antibiotics such as doxycycline, streptomycin and gentamicin they appeared to be highly sensitive to amikacin, ciprofloxacin, pefloxacin and the 3rd generation cephalosporins i.e. ceftazidime and cefotaxime as well as to thienamycin. These modern antibacterial agents are possibly to be the drugs of choice in etiotropic treatment and chemoprophylaxis of septic acute intestinal infections due to Salmonella strains with multiple resistance. Resistance of individual Salmonella strains to cefotaxime and ceftazidime indicated that it was possible to use their property for additional labeling of the pathogens within a serological type of Salmonella while conducting epidemiological examinations during outbreaks of acute intestinal infections of Salmonella etiology.     

Sensitivity of Vibrio and Aeromonas to antibiotics]

The antibiotic sensitivity of 696 cultures belonging to the family Vibrionaceae (V. cholerae O1, V. cholerae non-O1, V. albensis, V. parahaemolyticus, V. alginolyticus and Aeromonas spp.) was studied and general regularities of the antibiotic sensitivity were shown: a high sensitivity to broad-spectrum antibiotics (tetracycline and chloramphenicol) and a low sensitivity to ++beta lactams (carbenicillin and ampicillin). The comparative examinations revealed similarity in the antibioticograms of V. cholerae O1 (el Tor++), V. cholerae non-O1 and V. albensis, especially the latter two groups, as well as the tested halophilic Vibrio cultures by the range of the MICs, Mo, Me and the nature of the antibiotic resistance. Cultures of V. cholerae and luminescent Vibrio tended to preserve a high sensitivity. High resistance levels were noted in the halophilic Vibrio and Aeromonas cultures. No significant differences in the sensitivity of the strains of various origin (from man and environmental objects) were detected. However, several more resistant strains were isolated from the environmental objects.     

Influence of antibiotics on some intestinal microflora associated characteristics

Intestinal functions related to the presence of microbes in host organisms are normally heavily influenced by administration of antimicrobial drugs. We have investigated the effect of several antibiotics in man and rat, on some MACs (Microflora Associated Characteristics). A MAC is defined as the recording of any anatomical structure, biochemical or physiological function in the host organism which is influenced by microflora. When functional, active microbes are absent as in germfree animals, healthy newborns, or in relation to antimicrobial therapies, a MAC defined as a GAC (Germfree Animal Characteristic). Faecal samples have been collected prior to, during and up to several weeks after the antimicrobial administration in order to investigate different MAC/GAC patterns. Microbial conversion of cholesterol to coprostanol, bilirubin to urobilinogen and 7-alpha-dehydroxylation of cholic acid have been investigated to evaluate hepatic/intestinal co-functions, and degradation of intestinal mucin in order to evaluate the integrity in the intestinal mucosa. Furthermore, degradation of the dietary derived beta-aspartylglycine, the level of faecal trypsin and production of short chain fatty acids were investigated to evaluate dietary/intestinal co-functions. It is concluded that each antimicrobial drug creates its own profile, both with regard to duration and function.     

Structure of the microflora of suppurative wounds and its sensitivity to antibiotics]

Clinico-bacteriological examination of patients with purulent infections showed that Staphylococcus was the predominating microflora in the wounds. Simultaneously an increasing role of gram-negative conditionally pathogenic bacteria was shown. Multiple drug resistance was found in the organisms tested. The highest sensitivity levels were observed to gentamicin, kanamycin, tetracycline, levomycetin. It was shown by means of special typing methods that staphylococci of phage group III and Ps. Aeruginosa of serotype II predominated in the infected wounds. When the pathological material contained the antibiotic resistant cultures of Ps. aeruginosa, Proteus, Klebsiella and toxigenic strains of Staphylococcus, a tendency for prolongation of the suppurative process was observed.     

Efficacy of some new antibiotics in treating experimental brucellosis]

Brucella pathogens are highly susceptible in vitro to pefloxacin, lomefloxacin, meropenem and azithromycin. High efficacy of these drugs was demonstrated for experimental brucellosis treatment, azithromycin being the most active. Meropenem and azithromycin implementation resulted in more rapid and full normalization of the bactericidial and energy systems of the experimental animals peripheral blood cells.     

Sensitivity of the pathogen of Campylobacter infection to various antibiotics]

Antibiotic sensitivity of 21 Campylobacter strains isolated from humans, monkeys and birds with diarrhea was assayed and the findings are presented. It was shown that all the isolates were highly sensitive to ofloxacin, pefloxacin, ciprofloxacin, josamycin, pipemidinic acid and amoxyclav (a combination of amoxycillin and clavulanic acid). The predominating majority of the strains were resistant to rifampicin, amoxycillin and phosphomycin. The majority of the cultures were sensitive to erythromycin and roxithromycin while some of the isolates were resistant to them which could be used as an additional biological characteristic of Campylobacter cultures and considered in choosing agents for antibiotic therapy.     

Sensitivity of microflora isolated in the process of preparing solizyme to antimicrobial drugs]

Microorganisms isolated from intermediate products of microbial lipase (solysime) and auxiliary raw materials, reagents and water used in the production of the enzyme belonged to diverse taxonomic groups. They were mainly susceptible to antibiotics (aminoglycosides, rifampicin, chloramphenicol and others) as well as to antiseptics and chemotherapeutics. However, certain isolates were moderately resistant to some of the antimicrobial agents (they were more frequent among Pseudomonas spp.). The bacteriostatic action of many of the drugs was more pronounced than the bactericidal one. It was especially evident after increasing of the microbial load (from 10(5) to 10(8) CFU/ml). At a temperature of 10 degrees C against 37 degrees C the susceptibility of the cultures to the bactericidal action of the drugs usually decreased.     

Sensitivity of clinical Proteus strains to antibiotics and their combinations]

In 1976 isolation of Proteus from wounds of patients with various purulent processes amounted to 14.5 per cent. Serotypes 0-10, 0-3 and H-3 predominated among the isolates. Sensitivity of 35 clinical strains of Proteus to 10 antibiotics, furagin and nevigramone was studied by the method of serial dilutions in liquid media. All the isolates were highly resistant to the antibiotics except gentamicin, furagin and nevigramone, the MIC of which for most of the strains was 3.12, 1.6-3.12 and 6.25-12.5 gamma/ml, respectively. The effect of 14 combinations of chemotherapeutics was also studied. The combinations of gentamicin with carbenicillin, gentamicin with ampicillin and monomycin with ampicillin proved to be most effective against the Proteus strains tested. The following combinations may be of practical value: monomycin + carbenicillin, kanamycin + ampicillin, kanamycin + carbenicillin, ampicillin + furagin, gentamicin + nevigramone. The combinations of carbenicillin with furagin and gentamicin with furagin were also rational.