Introduction The severity of pneumococcal empyema varies according to serotype. Invasive disease due to serotype 19A has become a major concern, particularly in the USA and Asia with an increasing incidence of virulent often antibiotic resistant variants. This has not been a significant problem in the UK until now. We describe changes in the incidence of this problem in England and the characteristics of serotype 19A disease.
Methods Data on paediatric empyema patients requiring pleural drainage between September 2006 and March 2011 were collected from 19 collaborating UK-ESPE centres. Pneumococcal serotypes were identified by non-culture multiplex polysaccharide antigen detection assay on culture negative pleural fluid. Kruskal–Wallis and Fisher's exact test were used for continuous and categorical variables. Multivariate models were used for length of stay data.
Results The incidence of empyema due to S pneumoniae serotype 19A more than quadrupled from 0.48 in 2006/2007 to 2.41 cases per million children in 2010/2011 (p=0.03). Of cases where full clinical details were available (n=12), 25% had a positive blood culture but all had culture negative pleural fluid. No evidence of antibiotic resistance was reported. Cases of 19A were significantly younger compared to other pneumococcal cases (median 2.0 years vs 4.3 (p=0.004)), had more reported complications (33% vs 11% (p=0.047)), were more likely to have been admitted to intensive care (50% vs 12% (p=0.008)) and to have required assisted ventilation (50% vs 9% (p=0.003)). Duration of hospital admission at the centre managing the empyema was increased by >50% in patients with 19A disease compared to all other serotypes (adjusting for age/sex—HR: 0.47, 95 % CI 0.24 to 0.91, p=0.024). One 19A case died, no further deaths were reported.
Conclusions Empyema due to S pneumoniae serotype 19A infection is a particularly serious disease. The incidence of this problem has increased dramatically. Prevenar 7©, the first version of the conjugate pneumococcal vaccine introduced into the UK vaccination programme did not offer protection against this serotype, the second generation vaccine Prevenar 13© introduced in 2010 contains antigen for 19A, but continued surveillance will be required to determine whether this is effective in our population.