ABSTRACT
The prophylaxis of typhoid fever in Romania is usually achieved with fluid heat-killed phenolized vaccine. However the shelf life of this vaccine is only two years. The long term storage of an intradermal typhoid vaccine is made possible by lyophilization. A heat-inactivated bacterial suspension with a high concentration of organisms, at least 25 X 10(9) cells per ml, was freeze-dried at a temperature not higher than 30 degrees C. The final vaccine obtained had a residual moisture content of not more than 5%. Active and passive protection tests in mice, specific agglutinin production in humans and rabbits, the innocuity and the toxicity for mice, and the investigation of post-vaccinal adverse reactions in man, showed that the lyophilized typhoid vaccine could be stored at 4 degrees C for at least five years without loss of potency. Consequently, the vaccine may be stored without risk of deterioration for rapid emergency mass immunization with Jet-injector apparatus.
Subject(s)
Typhoid-Paratyphoid Vaccines/administration & dosage , Animals , Antibodies, Bacterial/analysis , Freeze Drying , Humans , Immunization , Injections, Intradermal , Mice , Rabbits , Salmonella typhi/immunology , Typhoid-Paratyphoid Vaccines/adverse effectsSubject(s)
Bacterial Vaccines/immunology , Lactones/pharmacology , Propiolactone/pharmacology , Salmonella typhimurium/immunology , Agglutination Tests , Animals , Bacterial Vaccines/toxicity , Immunization , Lethal Dose 50 , Mice , Propiolactone/toxicity , Salmonella typhimurium/drug effects , Vaccines, Inactivated/immunology , Vaccines, Inactivated/toxicityABSTRACT
Investigations were carried out on 781 S. typhi strains isolated from patients and carriers. Testing of the sensitivity to chemotherapeutical agents by diffusiometry and the incorporation technique led to the detection of four resistant strains: 1 strain isolated by coproculture from a carrier since 1958, resistant to A, K, N, Ca and Cf and 3 strains isolated by coproculture, biliculture and uroculture from a carrier since 1974, resistant to A and Ca. The R factors of these strains were transferred in their totality. The resistant strains did not manifest any particular pathogenicity for the laboratory animal, and their immunogenic potential was below that of the current typhoid vaccine. None of the 781S typhi were resistant to Cmx, C, G, T, Co and Po. Consequently, in Romania Chloramphenicol may be used in continuation in the treatment of typhoid fever, and Cotrimoxazol, Gentamycin, Tetracyclin and Ampicillin are and remain reserve substitutes. The possible unexpected appearance of resistant S. typhi strains demand, however, further control of the sensitivity to chemotherapeutics of all the isolated strains.
