Epidemiology of penicillin-non-susceptible pneumococci in Iceland, 1995-2010
Objectives The first penicillin-non-susceptible pneumococci (PNSP) were identified in Iceland in 1988. A rapid increase followed, associated with expansion of a single multiresistant clone, Spain6B-2, peaking at 19.8% in 1993. After interventions led to reduced antimicrobial use in children, the pre...
| Published in: | Journal of Antimicrobial Chemotherapy |
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| Main Authors: | , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
2013
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| Subjects: | |
| Online Access: | http://jac.oxfordjournals.org/cgi/content/short/dkt470v1 https://doi.org/10.1093/jac/dkt470 |
| Summary: | Objectives The first penicillin-non-susceptible pneumococci (PNSP) were identified in Iceland in 1988. A rapid increase followed, associated with expansion of a single multiresistant clone, Spain6B-2, peaking at 19.8% in 1993. After interventions led to reduced antimicrobial use in children, the prevalence of PNSP decreased until 1995. The aim of this study was to follow the evolution of PNSP from 1995 to 2010, the period preceding the introduction of conjugated pneumococcal vaccines into the vaccination programme. Methods The laboratory at the Landspitali University Hospital serves ∼85% of the Icelandic population. All pneumococci isolated from 1995 to 2010 ( n = 13 937) were stored (−80°C). Oxacillin-resistant isolates were serotyped and penicillin MICs were determined. Selected strains were genotyped by PFGE and multilocus sequence typing. Results In 1995, the rate of PNSP was 24.2%, declining to 13.6% in 2001, and then increasing to 38.6% in 2010. Similar changes were observed for resistance to erythromycin and tetracycline. In 1995, 60.7% of PNSP were serotype 6B, mainly the Spain6B-2 clone, declining to 5.7% in 2010. PNSP of serotype 19F rapidly increased after 2004 to comprise 85.8% of all serogrouped PNSP in 2010, with most isolates belonging to a single multiresistant PFGE clone identified as sequence type (ST) 271 and ST1968, representing single- and double-locus variants of the international clone Taiwan19F-14, respectively. PNSP were most common among young children, from the nasopharynx, middle ear and lower respiratory tract. Conclusions The epidemiology of PNSP was dominated by two multiresistant clones. The second expanded rapidly when the first one was disappearing, causing higher antibiotic resistance rates among pneumococci than seen before in Iceland. |
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