Objective
Surveillance of S. pneumoniae subtype distribution and antibiotic resistance trends following introduction of an improved vaccine (Prevenar 13).
Results
A total of 803 invasive S. pneumoniae strains isolated at 29 clinical laboratories were analysed at the national reference laboratory between 2011-2014. The strains included 54 types and the most predominant were 5 (10%), 1 (9%) and 12F (9%). The 12F serotype, which is not included in the current Prevenar 13 vaccine, accounted for 5%, 10%, 13% and 11% during the four years analysed.
Penicillin-nonsusceptibility (I/R) was detected by E-test in 26%, 21%, 40% and 31% of the strains during 2011-2014 respectively. The average penicillin MIC among nonsusceptible strains over four years were: 0.51, 0.56, 0.59 and 0.56 µg/ml respectively. The prevalent types among penicillin-nonsusceptible strains and average penicillin MIC were 12F (23%, 0.17 µg/ml), 19A (21%, 0.67 µg/ml), 14 (10%, 1.05 µg/ml) and 19F (6%, 1.2 µg/ml). The 12F strains were mostly penicillin intermediate (78%) and no resistant strains were observed. However, the average MIC of 12F strains increased during the four-year period: 0.08, 0.10, 0.16 and 0.20 µg/ml.
Antibiotic resistance rates among 12F isolates were tetracycline (15%), trimethoprim/sulfamethoxazole (8%), erythromycin (1%). All 12F strains were sensitive to ceftriaxone, vancomycin, clindamycin and rifampin.
Conclusions:
The serotype 12F, not included in the Prevenar 13 vaccine, is the third most prevalent invasive pneumococcal serotype in Israel and the predominant penicillin-nonsusceptible type. Our results indicate S. pneumoniae 12F should be considered as a vaccination target and as a future public health challenge.
