RESUMO
Purpose. Invasive pneumococcal disease (IPD) in the elderly is an important public health issue due to the increased proportion of this population in many countries including Brazil. We aimed to characterise pneumococci isolates in adults >50 years with IPD, following the introduction of the 10-valent pneumococcal conjugate vaccine (PCV10) as part of the National Childhood Immunisation Program for children ≤2 years in March 2010.Methodology. Between 2013 and 2015, pneumococcal isolates were collected and serotypes were determined using multiplex PCR and/or Quellung reaction. Antimicrobial susceptibility was defined by E-test (bioMérieux); genetic diversity was determined using Multiple-Locus Variable Number Tandem Repeat Analysis (MLVA) and, in selected isolates, Multi Locus Sequence Typing (MLST) was performed.Results/Key findings. Among 102 pneumococcal isolates, the most frequent serotypes were 19A, 13 of 102 (12.7â%) and 22F, 10 of 102 (9.8â%). Ninety-eight isolates were tested for antimicrobial susceptibility. Intermediate resistance to penicillin was present in 2/98 (2.0â%), ceftriaxone in 7/98 (7.1â%) and meropenem in 7/95 (7.4â%) of the isolates (non-meningitis breakpoint: 4 µg ml-1/2 µg ml-1/0.5 µg ml-1, respectively). Resistance to penicillin (meningitis breakpoint ≥0.12 µg ml-1) was observed in 31/98 (31.6â%) of the isolates. Genetic analysis presented two relevant clonal groups, belonging to non-PCV10 serotypes: 19A (ST320, linked to non-susceptibility) and 22F (ST6403).Conclusion. Our data suggest a predominance of non-PCV10 serotypes among IPD in the elderly population in circulating strains ca. 3 to 5 years after the introduction of PCV10 in Brazil.