Streptococcus pneumoniae Invasive Disease, 2011

Statewide active surveillance for invasive Streptococcus pneumoniae (pneumococcal) disease began in 2002, expanded from the metropolitan area, where active surveillance was ongoing since 1995. In 2011, 582 (11.0 per 100,000) cases of invasive pneumococcal disease were reported. By age group, annual incidence rates per 100,000 were 14.1 cases among children aged 0-4 years, 2.5 cases among children and adults aged 5-39 years, 11.1 cases among adults 40-64 years, and 39.8 cases among adults aged 65 years and older.

In 2011, pneumonia occurred most frequently (63% of infections), followed by bacteremia without another focus of infection (19%), and pneumococcal meningitis (6%). Seventy-one (12%) cases died. Health histories were available for 67 (94%) of the 71 cases who died. Of these, 62 had an underlying health condition reported. The conditions most frequently reported were chronic obstructive pulmonary disease (19), atherosclerotic cardiovascular disease (19), smoking (14), solid organ malignancy (14), and diabetes (10). In 1999, the year before the pediatric pneumococcal conjugate vaccine (Prevnar [PCV- 7]) was licensed, the rate of invasive pneumococcal disease among children <5 years in the metropolitan area was 111.7 cases/100,000. Over the years 2000-02 there was a major downward trend in incidence in this age group (Figure 5). Rates in each of the subsequent 9 years were level or somewhat higher, although there has not been a continuing upward trend (Figure 5). Based on the distribution of serotypes among isolates from these cases, this increase was limited to disease caused by non-vaccine serotypes (i.e. serotypes other than the 7 included in PCV-7) (Figure 5). This small degree of replacement disease due to non-PCV-7 serotypes, similar to that seen in other parts of the country, has been far outweighed by the declines in disease caused by PCV- 7 serotypes. This trend supports the need for ongoing monitoring, however, because further increases due to nonvaccine serotypes are possible.

In March 2010, the U.S. Food and Drug Administration approved a new 13-valent pediatric pneumococcal conjugate vaccine (PCV-13 [Prevnar 13]) which replaced PCV-7. The new vaccine provides protection against the same serotypes in PCV-7, plus 6 additional serotypes (serotypes 1, 3, 5, 6A, 7F, and 19A). Since 2007, the majority of invasive pneumococcal disease cases among children <5 years of age have been caused by the 6 new serotypes included in PCV-13 (Figure 5). In 2011, 30% of cases occurring among Minnesotans of all ages were caused by 3 of the new PCV-13-included serotypes: 19A (11%), 3 (10%), and 7F (9%). Of the 560 isolates submitted for 2011 cases, 133 (24%) isolates were resistant to penicillin using meningitis breakpoints. Using non-meningitis breakpoints, 8 (1%) of 560 isolates were resistant to penicillin and 32 (6%) exhibited intermediate level resistance (Note: CLSI penicillin breakpoints changed in 2008; refer to the MDH Antibiogram on pages 26-27) Multi-drug resistance (i.e., high-level resistance to two or more antibiotic classes) was exhibited in 144 (26%) isolates.

• For up to date information see>> Streptococcus pneumoniae (Pneumococcal Disease)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2011