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Potency control of diphtheria component in adsorbed vaccines by in vitro neutralization tests.

Samples from 20 lots of dT vaccine and from 20 lots of DTP vaccine were used to standardize and validate the Vero cell and the toxin binding inhibition (ToBI) tests for the potency control of diphtheria component. For the Vero cell method, violet crystal solution was used to stain the cells and estimate the endpoint of diluted diphtheria antitoxin. Diphtheria anatoxin was used for performing the ToBI test instead of toxin. The results obtained by both in vitro tests were similar to those obtained by in vivo toxin neutralization test in guinea pigs. The various analysis and the chi(2) test applied to evaluate the reproducibility and homogeneity, respectively, among in vitro tests and in vivo toxin neutralization test did not detect statistical significant difference for both analysed vaccines. An excellent correlation among in vitro tests and in vivo neutralization test was observed by Spearman's correlation coefficient.

Adsorption↗

Booster vaccination against diphtheria and tetanus in man. Comparison of calcium phosphate and aluminium hydroxide as adjuvants--II.

Diphtheria and tetanus antibody levels were measured before and four weeks after booster vaccination of 313 Danish military recruits participating in a clinical trial to compare aluminium hydroxide and calcium phosphate as adjuvants in diphtheria-tetanus vaccines (DT). Twenty-eight percent of the men had a diphtheria pre-vaccination content below a protective level of 0.01 IU ml-1. The calcium phosphate adsorbed vaccine showed the highest efficacy for both antigens. Adverse reactions were rare but more frequent in the calcium group than in the aluminium group. No correlation was found between pre- or post-vaccination levels and adverse reactions and both vaccines gave rise to specific IgE formation. The results show that calcium phosphate is more effective but not a safer alternative to aluminium hydroxide when compared in vaccines containing 1.0 mg ml-1 of Ca or of Al.

Adjuvants, Immunologic↗

Effect of neonatal immunization with diphtheria and tetanus toxoids on antibody responses to Haemophilus influenzae type b conjugate vaccines.

We randomly assigned 150 newborn infants to receive diphtheria and tetanus toxoids (DT) or Hib oligosaccharide conjugate (HbOC) at birth to determine whether exposure to the Haemophilus influenzae type b (Hib) conjugate vaccines' carrier proteins would enhance immune responses to subsequent administrations of HbOC or PRP-tetanus toxoid conjugate (PRP-T) at 2, 4, and 6 months of age. Their antibody responses were compared with those of 100 children immunized with HbOC or PRP-T beginning at 2 months of age. No serious adverse reactions were associated with neonatal vaccination. Administration of HbOC at birth did not lead to earlier or higher antibody levels. Newborn immunization with DT did not prime children for enhanced antibody responses. Moreover, Hib antibody levels were lower in DT-primed children than in children immunized beginning at 2 months of age. Diphtheria antibody levels, but not tetanus antibody levels, were also lower in children immunized with DT at birth. We conclude that neonatal immunization with Hib conjugate vaccines is not a means to provide earlier protection against invasive Hib disease. Newborn DT administration does not enhance subsequent antibody responses to Hib conjugate vaccines, and may lead to suppression of Hib and diphtheria antibody responses.

Antibodies, Bacterial↗

Immunity to diphtheria in young British adults.

Of 906 recruits aged between 16 and 20 years who were Schick-tested upon entry to the Royal Air Force, 775 were tested for circulating Corynebacterium diphtheriae antitioxin by means of an indirect haemagglutination (IHA) method. Of the total population, 95.7% were Schick-test negative, 3.5% were Schick-test positive and 0.8% gave pseudo-reactions. Of those tested by the IHA test, 37.7% were regarded as immune, 47.0% as 'immune-susceptible' and 15.3% as non-immune. Discrepancies between the two tests were discovered. Of those persons found to be Schick-test positive, 34.6% possessed circulating antitoxin; of those Schick-test negative, 13.5% were regarded as non-immune. A history of diphtheria immunisation in childhood was found to be a poor predictor of immunity. A protocol for selective diphtheria immunisation of adults is proposed.

Adolescent↗

[Diphtheria immunity and its epidemiological significance].

Indirect haemagglutination test for antitoxic diphtheria antibodies was performed on 3503 sera of persons of all age groups. The results demonstrate that a high percentage of juveniles and adults with less than 0.01 IU/ml has either no (48.9% for juveniles, 35.6% for adults) or at 0.01-0.09 IU/ml only insufficient immunological protection (30% and 41%, respectively) against diphtheria and its toxic effects. But even among children up to 14 years of age, 28.5% are completely without and 20.5% without reliably protective antitoxic immunity, despite a high rate of immunization. There is thus a dangerously high epidemic potential of susceptible persons in the population of the Federal Republic of Germany. To erect a barrier of immunity against epidemic spread requires not only immunization of all children, but also re-immunization every five to six years, plus immunization of juveniles and young adults among a selected group with, at present, highest risk of infection. For this purpose there is a diphtheria toxoid of Behringwerke for adults with only 5 IU toxoid/0.5 ml, which, however, after single application produced an antitoxic immunity (greater than or equal to 0.1 IU/ml) in previously sensitized subjects (17 of 49). Of 32 primary seronegative persons 14 reacted to two injections, while a further 18 (36.7%) had no immune response within six weeks even after second injection.

Adolescent↗

Polymerase chain reaction for the detection of toxigenic Corynebacterium diphtheriae.

Several conventional methods have been described for the detection of Corynebacterium diphtheriae toxin, including Elek immunodiffusion, tissue culture using VERO cells and guinea pig inoculation. All these methods have the disadvantage of being either slow to complete or technically demanding, particularly when performed infrequently. We examined 64 strains of C. diphtheriae by PCR and Elek immunodiffusion, and strains showing a positive result in either assay were inoculated into guinea pigs. Seven isolates were positive in both Elek and PCR assays and subsequently positive in guinea pig inoculation assay. One isolate was negative in Elek testing but positive in PCR assay and guinea pig inoculation. All other isolates were negative in both Elek and PCR assays. The PCR assay is rapid with cycling and detection complete within 3-4 hrs of receipt of strains. PCR has now become the routine method for detection of C. diphtheriae toxin in our laboratory.

Animals↗

The effect of diphtheria toxin on the metabolism of HeLa cells.

The effect of diphtheria toxin on certain metabolic processes in growing HeLa cells has been described. It was found that both aerobic respiration and glycolysis are insensitive to toxin action. The incorporation of S(35)-methionine was found to be completely inhibited by toxin prior to the appearance of any visible cell damage. It was also observed that toxin levels above 0.3 Lf per ml. had no further effect on the kinetics of inhibition of methionine uptake. The kinetics of intoxication were studied by adding diphtheria antitoxin to a partially intoxicated culture at various times and measuring the resulting rate of methionine uptake. Low temperatures were found to block intoxication. Using this information, data were obtained suggesting that the initial step in the process of intoxication consists of a rapid adsorption of toxin by the cell. The kinetics of toxin action on protein synthesis were compared with those of cyanide and 2,4-DNP. Diphtheria toxin eliminates completely any methionine uptake remaining after exposure of the cell to either of these respiratory inhibitors. The significance of these results is discussed.

Animals↗

The effects of diphtheria toxin on the Cecropia silkworm.

1. The metamorphosis of the Cecropia silkworm is accompanied by large and systematic changes in the insect's sensitivity to diphtheria toxin. 2. Injection of less than 1 gamma of toxin into mature caterpillars, prepupae, or developing adults causes cessation of development followed by delayed death 1 to 5 weeks later. 3. Dormant pupae, on the contrary, are resistant to 70 gamma of toxin and may survive even this enormous dose for over 4 weeks. One-hundredth of this dose, however, prevents pupae from initiating adult development. 4. Tetanus toxin, to which the insect is insensitive, failed to duplicate any of these effects. 5. Maximal sensitivity to diphtheria toxin is characteristic of those stages in the life history which depend on the presence and function of the cytochrome system. Resistance to the toxin, as in the case of the diapausing pupa, is correlated with the existence and utilization of metabolic pathways other than the usual cytochrome system. 6. This correlation persists within the individual insect. Thus, within the diapausing pupa, the toxin fails to affect the heart in which a normal cytochrome system is absent, but, within the same insect, causes a degeneration of the intersegmental muscles in which an intact cytochrome system is present. 7. These several lines of evidence are interpreted in support of the conclusion that diphtheria toxin acts by blocking the synthesis of one or more components in the cytochrome system.

Animals↗

Diphtheria in Estonia, 1991-1996.

Clinical diphtheria reappeared in Estonia in 1991. Between 1991 and 1996, 61 cases and 5 deaths occurred; 19 cases were among children 5-9 years of age, and 11 were among persons 40-49 years of age. From 1993-1995, vaccine supplies donated by Finland were used in vaccination programs. In 1995, the International Federation of Red Cross and Red Crescent Societies and the Estonian Red Cross launched a mass vaccination campaign targeting the adult population. By the end of 1997, it was estimated that 46% of adults had received at least one dose of vaccine. Although the vaccination campaigns did not target the pediatric population, vaccination coverage in school-aged children remained high due to continuing routine vaccination programs. The reappearance and epidemic of clinical diphtheria cases and the mass vaccination campaign efforts demonstrated that preventive measures are important and must be maintained in order to keep diphtheria under control.

Adolescent↗

Evaluation of a single dose of diphtheria toxoid among adults in the Republic of Georgia, 1995: immunogenicity and adverse reactions.

To determine the immunogenicity and safety of a single dose of diphtheria toxoid among adults, blood samples for detecting serum antitoxin levels were obtained from 18- to 59-year-old subjects (n=248) before and 30 days after immunization with Td (tetanus-diphtheria toxoids; manufactured by Serum Institute of India). By day 30, the seroprevalence of antitoxin levels >/=0.1 IU/mL increased from 22.6% to 81.5%; median antitoxin levels increased from 0.01 to 4.0 IU/mL. These parameters were lowest among subjects who were 40-59 years old, especially among those 40-49 years old. Adverse reactions (local redness, swelling, induration, fever>39 degrees C) were reported by 5.3% of participants. Our findings suggest that, in general, one dose of the Indian-produced Td vaccine is efficacious and safe in inducing an adequate immune response against diphtheria in adults; however, in Georgia, persons 40-59 years old, especially those 40-49 years old, will require additional doses of toxoid to achieve protective levels of antitoxin.

Adolescent↗

Assessment of vaccination coverage among adults 30-49 years of age following a mass diphtheria vaccination campaign: Ukraine, April 1995.

Ukraine has been experiencing epidemic diphtheria since 1991. In efforts to control this epidemic, a mass vaccination campaign was held in April 1995. Persons not vaccinated in the previous 3 years were considered eligible for vaccination with tetanus-diphtheria toxoids (Td). Two cluster sample surveys were conducted to determine vaccination coverage achieved. In the urban and rural survey areas, respectively, 628 and 618 persons 30-49 years of age were interviewed. Fifty-nine percent of urban and 58% of rural participants were eligible for vaccination. During the vaccination campaign, 58% (95% confidence interval [95% CI], 47.1-69.2) of eligible persons received Td in the urban area, compared with 92% (95% CI, 89.2-95.3) in the rural area. Apparent barriers to vaccination included misconceptions about the safety, efficacy, and need for booster doses of Td. Future vaccination campaigns should include targeted information and education messages. Mass vaccination campaigns can be successful in vaccinating large numbers of adults; however, in urban areas, additional efforts may be required to achieve levels of coverage adequate to confer herd immunity and interrupt the diphtheria epidemic.

Adult↗

Infective endocarditis due to nontoxigenic Corynebacterium diphtheriae: report of seven cases and review.

We report seven cases of endocarditis due to nontoxigenic Corynebacterium diphtheriae that occurred between October 1990 and September 1991. The patients all lived in the state of New South Wales, Australia. Three patients had preexisting cardiac abnormalities, and one patient used intravenous drugs regularly. The other three patients had no known risk factors for endocarditis. Notable clinical features were the aggressive nature of the infection, the occurrence of septic arthritis in four patients, and major vascular complications in four patients, one of whom died. One patient required urgent mitral valve replacement. All of the isolates were identified as non-toxigenic C. diphtheriae var gravis. Sporadic cases of endocarditis due to C. diphtheriae have rarely been reported; septic arthritis complicating endocarditis due to this organism has not previously been described. This report highlights the importance of identifying Corynebacterium isolates from normally sterile sites at the species level.

Adult↗

Safety and immunogenicity of Chiron/Biocine recombinant acellular pertussis-diphtheria-tetanus vaccine in infants and toddlers.

OBJECTIVE: To evaluate the safety and immunogenicity of the recombinant acellular pertussis-diphtheria-tetanus (aPDT) vaccine (C-aPDT, Chiron/Biocine). STUDY DESIGN: This is a randomized blinded trial evaluating the safety and immunogenicity of the recombinant aPDT vaccine (C-aPDT, Chiron/Biocine) in 2000 infant recipients compared with 498 controls who received whole cell diphtheria-pertussis-tetanus (wDPT; Connaught) vaccine at 2, 4 and 6 months of age. In addition the safety and immunogenicity of the same C-aPDT vaccine were evaluated as a booster dose in a subset of the same population when given at 15 to 18 months of age and compared with licensed Lederle aPDT vaccine. RESULTS: The C-aPDT vaccine was associated with very few local or systemic reactions when compared with wDPT. In toddlers the local and systemic side effects observed were similar after either acellular vaccine. When the immunogenicity of the C-aPDT vaccine was compared with the wDPT (Connaught) in infancy, the vaccines were equivalent for anti-diphtheria response, the wDPT developed higher anti-tetanus response and the C-aPDT vaccine was significantly more immunogenic for all other antigens tested. In toddlers the C-aPDT acellular vaccine exhibited equal or improved immunogenicity for antigens tested as compared with Lederle aPDT except for a higher anti-filamentous hemagglutinin response with the Lederle aPDT vaccine. CONCLUSION: The Chiron/Biocine aPDT vaccine offers an improved safety profile as well as improved immunogenicity when compared with a licensed wDPT product.

Antibodies, Bacterial↗

Seroprotection against diphtheria and tetanus among Russian and Norwegian teenagers.

Russian children between 7 and 10 years of age have been shown to have significantly higher seroprotection against diphtheria compared to Norwegian children. That was due to a reinforcing dose given on entering school to Russian but not to Norwegian children. The next booster was given at the age of 11-12 years in both countries. We have compared diphtheria and tetanus antitoxin levels among 13- to 14- and 15- to 16-year-old teenagers to see if the difference was maintained among the older age group. Serum samples obtained from 106 Russian and 117 Norwegian teenagers were tested by enzyme immunoassay. The Russian and Norwegian adolescents exhibited adequate rates of protection against diphtheria with similar geometric mean antitoxin concentrations of 1.26 and 1.15 IU/ml, respectively, at 13-14 years, and 0.33 and 0.29 IU/ml at 15-16 years. Differences within the age groups were not significant. However, at 13-14 years the Norwegians were much better protected 2 years after a reinforcing dose of tetanus toxoid than the Russians who had not been boosted for 7 years. At the age of 15-16 the difference diminished and became statistically not significant.

Adolescent↗

Microtissue culture test for the titration of low concentrations of diphtheria antitoxin in minimal amounts of human sera.

A microtissue culture method for the assay of low concentrations of diphtheria antitoxin in human sera has been developed, using a monkey kidney cell (VERO) culture technique. Results obtained with sera from nonvaccinated children and with immune sera from children vaccinated with three and four injections of diphtheria pertussis tetanus vaccine were in agreement with antitoxin levels considered necessary to denote immunity to diphtheria. The use of microplates and organic buffer for culturing the animal cells improved the stability of the tissue culture system. The described method is sensitive, economical, and applicable for the titration of antitoxin in human sera particularly from infants and children from whom a minimum amount of serum is available.

Animals↗

Genotypic and phenotypic characteristics of Corynebacterium diphtheriae strains isolated from patients in belarus during an epidemic period.

One hundred two Corynebacterium diphtheriae strains (93 of the gravis biotype and nine of the mitis biotype) isolated from clinical cases during the Belarus diphtheria epidemic were characterized by biotyping, toxigenicity testing by the Elek test and an indirect hemagglutination assay, phage typing, and ribotyping. The gravis biotype strains were characterized as high and medium toxin producers, and strains of biotype mitis were characterized as low and medium toxin producers. Most strains (82 of 102) were distributed among five phage types. Seventy-two strains (64 of the gravis biotype and 8 of the mitis biotype) belonged to phage type VI ls5,34add. Hybridization of genomic DNA digested with BstEII and PvuII revealed five ribotype patterns, namely, D1, D4, D6, D7, and D13. The majority of gravis biotype strains belonged to ribotypes D1 (49 of 93) and D4 (33 of 93) and included one clonal group of C. diphtheriae. This clone predominated in all regions in Belarus. There was a statistical association between ribotypes and phage types but not between ribotypes and levels of toxin production.

Bacterial Typing Techniques↗

Polymerase chain reaction for screening clinical isolates of corynebacteria for the production of diphtheria toxin.

AIMS: To assess the performance of the polymerase chain reaction (PCR) when used to screen rapidly large numbers of corynebacteria for toxin production; and to determine the incidence of false positive PCR results with non-toxigenic Corynebacterium diphtheriae isolates. METHODS: Eighty seven recent British isolates of corynebacteria were assayed by PCR. All isolates were assayed from both blood and tellurite agar within a five day period. Thirty three non-toxigenic isolates of C diphtheriae from six countries were also tested by PCR and by the Elek immunodiffusion assay. RESULTS: There was complete concordance between the results of PCR and traditional methods on the recent British isolates, with one exception: an Elek positive "C ulcerans" isolate, which was PCR positive from tellurite but not from blood agar. One of the thirty three (3%) non-toxigenic isolates of C diphtheriae was PCR positive. CONCLUSIONS: These results suggest that PCR compares favourably with traditional methods for the detection of toxigenic corynebacteria and that it represents a powerful new tool in the diagnosis of an old disease.

Base Sequence↗

Imported cutaneous diphtheria, United Kingdom.

Cutaneous diphtheria is endemic in tropical countries but unusual in the United Kingdom. Four cases occurred in the United Kingdom within 2 months in 2002. Because cutaneous diphtheria causes outbreaks of both cutaneous and pharyngeal forms, early diagnosis is essential for implementing control measures; high diphtheria vaccination coverage must also be maintained.

Adult↗