According to Pathogenesis of Pneumococcal Infection co-chair Jeff Weiser the rapid expansion of genetic techniques is creating exciting new opportunities in pneumococcal pathogenesis research. “We can do very exciting things that were never possible before the age of genomics. Because we can now look at the genetics of both the host and the pathogen this field of research is moving in interesting new directions.”

It is thought that immunity to S pneumoniae is due to contact with the organism or with cross-reactive antigens. But until now little has been done to explore the relationship between carriage and immune response. Two studies presented here at ISPPD-4 investigate this connection. In a 10-month longitudinal investigation David Goldblatt and colleagues did a studied nasopharyngeal (NP) carriage of pneumococcus in families with young children and pneumococcal antibody levels in the adults of those families.

They found that the adults’ immune systems responded to their own NP carriage or to members of their families’ carriage by increasing levels of serotype-specific anti-capsular antibody (see IMM-06.) “

An investigation by Sundstrom and colleagues used a similar study design and looked at levels of active SPN antibodies in adults following pneumococcal carriage. By measuring the opsonophagocytic activity (OPA) of pneumococcal antibodies of adults in the study and comparing it to the serotypes of NP swabs within the families they could examine whether NP colonization in contacts resulted in an antibody response in the adults. They saw very similar results as those in the Goldblatt study (see IMM-47).

The availability of pneumococcal conjugate vaccines has led to a flurry of activity on their potential impact, ranging from otitis media in Aboriginal communities to effects on viral pneumonia. Studies from the United States, Australia, and South Africa give a glimpse of the exciting work already underway and the need for further research.

Because Australian Aboriginal children suffer very high rates of invasive pneumococcal disease and otitis media (OM) conjugate vaccine introduction was a priority in this community. Wigger and colleagues’ study found that although vaccine serotype carriage decreased after vaccination overall pneumococcal carriage and the rate of OM have remained high. They did, however, see a reduction in carriage of penicillin non-susceptible strains (see NEW-01).

Researchers working in the city of Atlanta, Georgia in the United States saw a dramatic decline in disease caused by macrolide-resistant pneumococci after the February 2000 introduction of the 7-valent PnCV vaccine (see NEW-03). This finding demonstrates the importance of vaccines as a tool in the management of antibiotic-resistant disease.

An interesting study from South Africa (see NEW-07) showed that the 9-valent PnCV had an impact on severe viral-associated pneumonia. The authors believe that the vaccine prevents viral pneumonia in children affected by these viruses by reducing the incidence of underlying pneumococcal infections. Unfortunately they saw no significant effect on viral-associated pneumonia in the HIV-infected children who comprised 6.02% of their study population. These findings could have significant implications for vaccine introduction in areas where viral pneumonia represents a large portion of the disease burden.