Streptococcus pneumoniae Invasive Disease, 2009

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 2009, 686 (13.1 per 100,000) cases of invasive pneumococcal disease were reported. By age group, annual incidence rates per 100,000 were 27.3 cases among children aged 0-4 years, 4.1 cases among children and adults aged 5-39 years, 14.1 cases among adults 40-64 years, and 36.7 cases among adults aged 65 years and older.

In 2009, pneumonia accounted for 407 (59%) cases of invasive pneumococcal disease among all cases (i.e., those infections accompanied by bacteremia or isolation of pneumococci from another sterile site such as pleural fluid). Bacteremia without another focus of infection accounted for 222 (32%) cases statewide. Pneumococcal meningitis accounted for 27 (4%) cases. Sixty-four (9%) cases died. Health histories were available for 48 (75%) of the cases who died. Of these, 40 had an underlying health condition reported. The conditions most frequently reported were solid organ malignancy (14), diabetes (10), and atherosclerotic cardiovascular disease/coronary artery disease (10).

In 1999, the year before the pediatric pneumococcal conjugate vaccine (Prevnar, Wyeth-Lederle [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 2000-2002 there was a major downward trend in incidence in this age group (Figure 6). Rates in each of the subsequent 7 years were somewhat higher, although there has not been a continuing upward trend. 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 6]). 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 non-vaccine serotypes are possible.

In March 2010, the FDA approved a new 13-valent pediatric pneumococcal conjugate vaccine (PCV-13 [Prevnar 13, Wyeth Pharmaceuticals]) which will replace 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 under the age of 5 years have been caused by the 6 new serotypes included in PCV-13 (Figure 6). In 2009, almost half of cases occurring among Minnesotans of all ages were caused by 3 of the new PCV-13-included serotypes: 7F, 19A, and 3.

Of the 639 isolates submitted for 2009 cases, 153 (24%) isolates were resistant to penicillin and 7 (1%) exhibited intermediate-level resistance using nonmeningitis breakpoints (Note: CLSI penicillin breakpoints changed in 2008; refer to the MDH Antibiogram [see pages 28-29] for details.); 136 isolates (21%) exhibited multi-drug resistance (i.e., high-level resistance to two or more antibiotic classes).

Figure 4. Invasive Pneumococcal Disease Incidence Among Children <5 and Adults >65 years of Age, by Year and Serotype, Twin Cities Metropolitan Area, 1999-2008

Updated Friday, 19-Nov-2010 15:16:38 CST