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.     

Resistance of Shigella to antibiotics

Antibiotic sensitivity of 104 Shigella clinical strains and 104 Escherichia coli strains isolated from patients with acute dysentery not treated with antibiotics in 1986-1987 was studied. It was shown that 100 per cent of the dysentery pathogens and colon bacilli were antibiotic resistant. Strains resistant simultaneously to chloramphenicol, ampicillin, streptomycin, tetracycline, monomycin and kanamycin were the most frequent among the dysentery pathogens. Colon bacilli and dysentery pathogens isolated from the same patient had specific sets of antibiotic resistance markers. Pathogenetic therapy of dysentery and exclusion of antibiotic use for several years did not result in lower numbers of Shigella antibiotic resistant strains.     

Increase in the sensitivity of Shigella to antibiotics

Passages of 10 Shigella strains for 10 times in meat-peptone broth supplemented with sodium nucleinate provided an increase in sensitivity of the cultures to levomycetin for a period of 264 hours. In three strains of S. sonnei, S. flexneri and S. newcastle the authors observed an increase in sensitivity to tetracycline, benzylpenicillin and streptomycin. Some nitrous bases included in sodium nucleinate were also able to increase antibiotic sensitivity in Shigella.     

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.