Vincent I. Ahonkhai

The Efficacy in Navajo Infants of a Conjugate Vaccine Consisting of Haemophilus influenzae Type b Polysaccharide and Neisseria meningitidis Outer-Membrane Protein Complex

BACKGROUND AND METHODS Several conjugate vaccines against Haemophilus influenzae type b have been developed in the search for one that induces protection even in young infants. We evaluated the safety and efficacy of a conjugate vaccine that links the H. influenzae type b capsular polysaccharide to the outer-membrane protein complex (OMPC) of Neisseria meningitidis serogroup B. We conducted a double-blind, placebo, controlled trial in Navajo infants, who are at high risk for systemic infections caused by H. influenzae type b. The infants were randomly assigned to receive the first dose of vaccine or placebo at 42 to 90 days of age and the second at 70 to 146 days of age. RESULTS Of the infants in the trial, 2588 were assigned to receive the vaccine and 2602 to receive placebo. The mean follow-up was 269 days in the vaccine group and 267 days in the placebo group. Before the age of 18 months, there was 1 systemic H. influenzae type b infection in the vaccine group, as compared with 22 in the placebo group (P less than 0.001; point estimate of efficacy, 95 percent; 95 percent confidence interval, 72 to 99 percent). Of the 22 H. influenzae type b infections in the placebo group, 13 were meningitis. Among the children who received both doses, there was 1 H. influenzae type b infection in the vaccine group (n = 2056) and 14 in the placebo group (n = 2105) (P less than 0.001; point estimate of efficacy, 93 percent; 95 percent confidence interval, 53 to 98 percent). The single infection in the vaccine group occurred at 15 1/2 months of age in an infant with osteomyelitis. Between the first and second doses there were no H. influenzae type b infections in the vaccine group and eight in the placebo group (P less than 0.005; point estimate of efficacy, 100 percent; 95 percent confidence interval, 41 to 100 percent). CONCLUSIONS The H. influenzae type b OMPC vaccine, administered at 2 and 4 months of age, is safe and induces a high rate of protection against invasive disease caused by H. influenzae type b in infants under the age of 18 months. Protection begins after the first dose.

Review of adverse experiences and tolerability in the first 2,516 patients treated with imipenem/cilastatin

The clinical and laboratory data relating to the adverse experiences and tolerability of imipenem/cilastatin in the first 2,516 patients treated with the antibiotic are reviewed, with special reference to the last 793. Clinical adverse experiences were predominantly related to the gastrointestinal system (nausea and vomiting), local injection site, and allergy (rash). A low frequency of drug-related seizures was also reported. The most frequent adverse laboratory experiences were transient elevations of liver function test values. In general, the safety profile was similar to that of other beta-lactam antibiotics.

Failure of Pneumococcal Vaccine in Children with Sickle-Cell Disease

POLYVALENT pneumococcal vaccines have recently been used in infants,1 children2 and adults.3 They are safe, immunogenic and protective against pneumococcal disease in normal adults.3 However, all p...

Safety and immunogenicity of a haemophilus influenzae type b conjugate vaccine in a high risk american indian population

The safety and immunogenicity of a Haemophilus influenzae type b polysaccharide conjugate vaccine linked to the outer membrane protein complex of Neisseria meningitidis (Hib-OMP) were evaluated among Apache and Navajo infants and children. One dose of the Hib-OMP was given to 42 children who were from 12 and 60 months of age. Ninety-two infants 6 to 8 weeks old were given one dose of Hib-OMP at the time of enrollment. A subsequent dose of the vaccine was given 2 months later and a third dose was offered between 12 and 15 months of age. All the 12− to 60-month-old children achieved a protective antibody concentration (>1 μg/ml) 1 month postvaccination. Among the 6− to 8-week-old infants only 11% of the Apaches and 8% of Navajos had a protective anti-PRP antibody concentration prevaccination. One month post vaccination 68% of the Apaches and 69% of the Navajos had protective anti-PRP antibody concentrations. One month after the second immunization 67% of the Apaches and 75% of Navajos had protective anti-PRP concentrations. Among the infants that received the third (booster) immunization (N = 28) 74% had protective anti-PRP antibody titers just before the booster immunization. One month after the booster immunization all of the infants had protective concentrations of anti-PRP antibody. We conclude that the Hib-OMP is safe and highly immunogenic among Apache and Navajo infants and children.

Safety and immunogenicity of Haemophilus influenzae type B-Neisseria meningitidis group B outer membrane protein complex conjugate vaccine mixed in the syringe with diphtheria-tetanus-pertussis vaccine in young Gambian infants.

To ensure compliance and to reduce costs it is important, especially in less developed countries, that programs of child immunization should require as few clinic attendances and as few injections as possible. Therefore we have investigated whether a Haemophilus influenzae type b conjugate vaccine could be given safely and effectively with diphtheria-tetanus-pertussis vaccine (DTP). One hundred twenty-six Gambian infants were given both polyribosylribitol phosphate (PRP)-outer membrane protein complex (PedvaxHIB) and DTP on the same day at 8, 12 and 16 weeks of age; 60 were given the vaccines mixed in the syringe and 66 were given the vaccines separately. To minimize the injection volume the dose of PRP-OMPC used in both groups was 7.5 micrograms, which is half the usual dose. There were no significant differences in anti-PRP antibody titers between the groups after 1, 2 or 3 doses. The geometric mean titers of antibody for the two groups combined were 0.29 micrograms/ml 1 month after the first dose, 1.03 micrograms/ml after the second dose and 1.11 micrograms/ml after the third dose. Concentrations of antibodies to diphtheria, tetanus and pertussis 1 month after the third dose were not significantly different between the two groups. Systemic side effects were reported with equal frequency in the two groups and were similar to those reported elsewhere for DTP. Tenderness at the injection site was more common where the combined injection (0.75 ml) had been given than where DTP alone (0.5 ml) had been given. The main drawback to the use of these 2 vaccines together is the complexity of the mixing procedure used in this clinical trial.

Infections in children with sickle cell anemia. Special reference to pneumococcal and salmonella infections.

Pneumococcal sepsis and/or meningitis are major causes of morbidity and mortality in young children with sickle cell disease. Abnormal complement activity, poor splenic function and a lack of type-specific pneumococcal antibody are responsible for the severity and frequency of these infections. A program consisting of early institution of antibiotic therapy for febrile episodes, antimicrobial prophylaxis, and administration of pneumococcal vaccine may be effective in reducing the incidence of pneumococcal disease. Specific guidelines for infection prevention are presented. Other infections that are more frequent or more severe in children with sickle cell disease (e.g., Salmonella, Haemophilus and mycoplasma infections) are also discussed.

Imipenem-cilastatin in pediatric patients: an overview of safety and efficacy in studies conducted in the United States

Imipenem-cilastatin was evaluated for tolerability and efficacy in a multicenter open, noncomparative trial involving 178 infants and children with bacterial infections. Imipenemcilastatin was administered in total daily dosages of 100 mg/kg for patients up to 3 years of age and 60 mg/kg for those more than 3 years of age. Favorable clinical response was achieved in 98 of 100 patients judged evaluable for efficacy. Adverse effects were generally mild and reversible and included diarrhea alone or with vomiting (5.1%), irritation of intravenous infusion site (3.3%) and rash (2.2%). Changes in laboratory test values reported most frequently were thrombocytosis (8.9%), elevations in aspartate aminotransferase (7.9%) and alanine aminotransferase (5.6%) and eosinophilia (8.4%). This safety profile appears to be comparable to that of other beta-lactam antibiotics. Moreover imipenem-cilastatin was effective in infections caused by a broad spectrum of pathogens that include Haemophilus influenzae, Staphylococcus aureus, P. aeruginosa and anaerobes. These attributes suggest that imipenem-cilastatin should be safe and effective in selected pediatric patients.

Clinical experience with PedvaxHIB, a conjugate vaccine of Haemophilus influenzae type b polysaccharide—Neisseria meningitidis outer membrane protein

PedvaxHIB, a Haemophilus influenzae type b (Hib) conjugate vaccine composed of Hib capsular polysaccharide covalently bound to an outer membrane protein complex of Neisseria meningitidis serogroup B, was evaluated for immunogenicity and safety in infants and children 2 months of age and older. A significant and consistent antibody response was seen after a single dose of the vaccine in all age groups, including infants as young as 2 months of age. In addition, the vaccine elicited a good booster response when given at 12 to 17 months of age. Subjects from diverse subpopulations, including those with impaired antibody response to Hib polysaccharide vaccines, showed a significant response to vaccination. The vaccine was well tolerated when administered alone or concurrently with other paediatric vaccines. A protective efficacy study, recently completed, has shown the vaccine to be highly effective in 2-month-old infants.

Persistence of antibody at 18 months following vaccination of young Gambian infants with PRP-OMPC Haemophilus influenzae type b conjugate vaccine

The rate of decline in anti-PRP antibody levels was measured in two groups of Gambian children who had been given PRP-OMPC at 1 and 3 months or 2 and 4 months of age. In the younger group (n = 70), the geometric mean titre fell from 1.32 micrograms/ml at 4 months to 0.44 micrograms/ml at 18 months. In the older group (n = 54), the geometric mean titre fell from 1.18 micrograms/ml at 5 months to 0.46 micrograms/ml at 18 months. The proportion of vaccinated children with antibody levels over 1.0 microgram/ml fell from 54% 1 month after the second dose of vaccine to 27% at the age of 18 months, while the proportion with levels over 0.15 micrograms/ml fell from 82% to 60%, with no significant differences observed between the vaccination groups. For those children who did not show evidence of environmental boosting, the half-life of anti-PRP antibody was about 100 days. This did not differ between the groups. These findings suggest that to provide lasting immunity PRP-OMPC should be given with a late booster dose at 12-15 months, as is the current practice in the USA. The need for a late booster dose may limit the value of this vaccine in developing countries where vaccination of children is difficult after the 1st year of life.

In vitro activity of U-57930E, a new clindamycin analog, against aerobic gram-positive bacteria.

The in vitro activity of U-57930E, a new clindamycin analog, against aerobic gram-positive cocci was studied by microdilution broth susceptibility tests and compared with the activities of clindamycin, vancomycin, oxacillin, and ampicillin. U-57930E inhibited methicillin-susceptible Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus viridans at concentrations of less than or equal to 1 microgram/ml. This degree of activity was generally slightly less than that of the other antimicrobial agents tested. Methicillin-resistant Staphylococcus aureus, coagulase-negative staphylococci, penicillin-resistant Streptococcus pneumoniae, and enterococci were resistant to U-57930E. At the concentrations used, U-57930E exhibited bactericidal activity against most susceptible organisms, and a minimal effect of inoculum size was noted.