ECCMID: Meningitis Incidence Due to Penicillin G-resistant S. Pneumoniae : The Impact of Conjugate Vaccines and Antibiotic Policies
By David Jack
GLASGOW, SCOTLAND -- May 13, 2002 -- On
its own, vaccination may not be enough to reduce the burden of
resistant pneumococcal meningitis.
Dr. Laura Temime described the findings
of her group working at INSERM U444, in Paris, France, during the 13th
European Congress of Clinical Microbiology and Infectious Diseases.
Streptococcus pneumoniae is one of the main causes of pneumococcal
meningitis worldwide and it has a mortality rate of more than 10%
and a greater than 10% rate of neurological sequellae. There is now
serious concern that outcomes may deteriorate even further because
of the emergence of strains exhibiting high levels of resistance to
penicillin G.
In an attempt to combat this problem,
new conjugate vaccines have been developed. Although these vaccines
cover only up to 11 of the more than 90 serotypes involved in
S. pneumoniae, they have been shown to have short-term
effects; their long-term effects remain to be seen.
The researchers at INSERM used
mathematical modeling of the selection of pneumococcal resistance to
penicillin in an age-structured population (adults versus children)
to see the number of cases that could be prevented 10 to 15 years in
the future.
In addition to comparing adults with
children, the model also attempts to predict the effect of different
treatment policies aimed at reducing antibiotic exposure of children
on the number of cases prevented by vaccination. This is of
particular importance in France, which has the highest recorded use
of antibiotics in Europe.
Their study's findings show that with
vaccination the carriage rate of
S. pneumoniae remains stable and, at most, 5% of the
overall number of cases of meningitis in 15 years will be prevented
by vaccination. Their model also predicts that, after about 20
years, penicillin G-resistant meningitis will account for almost all
cases of S. pneumoniae meningitis, whether vaccination is performed
or not.
However, if vaccination were combined
with a strategy that reduces the frequency of treatment of children
by half, up to 25% of cases of resistant meningitis would be
prevented over the next 15 years. This gain remains large even if
vaccination rates are as low as 20%.
According to Dr. Temime, there should
be a synergistic effect between vaccination and reduction of
antibiotic exposure. However, it appears that, at least in France,
vaccination alone may not be enough to reduce the burden of
penicillin-resistant pneumococcal meningitis.
[Impact of Wide Vaccination of Children with Pneumococcal Conjugate Vaccines on Antibiotic Resistance. Abstract 72]