JAC Advance Access originally published online on June 17, 2009
Journal of Antimicrobial Chemotherapy 2009 64(3):507-510; doi:10.1093/jac/dkp210
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Original research |
Emergence of a multidrug-resistant clone (ST320) among invasive serotype 19A pneumococci in Spain
1 Microbiology Department, Hospital Universitari de Bellvitge, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Barcelona, Spain 2 CIBER de Enfermedades Respiratorias, ISCIII, Madrid, Spain 3 Centro Nacional de Microbiología, Laboratorio de Referencia de Neumococos, Instituto de Salud Carlos III, Ctra de Majadahonda a Pozuelo s/n, 28220 Majadahonda, Madrid, Spain
Received 12 March 2009; returned 9 April 2009; revised 21 May 2009; accepted 22 May 2009
* Corresponding author. Microbiology Department, Hospital Universitari de Bellvitge, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Barcelona, Spain. Tel: +34932607930; Fax: +34932607547; E-mail: c.ardanuy{at}bellvitgehospital.cat
Objectives: Multidrug-resistant Streptococcus pneumoniae isolates of serotype 19A have emerged all over the world in recent years. The aim of this study was to characterize highly penicillin-resistant pneumococcal strains of the 19A serotype, collected in Spain from 1997 to 2007 from patients with invasive disease.
Methods: Antibiotic susceptibility was studied by microdilution. All penicillin-resistant pneumococci were typed by PFGE and selected strains were studied by multilocus sequence typing (MLST). The presence of genes related to the Tn916 family of transposons was investigated by PCR.
Results: From a total of 1197 invasive pneumococcal isolates of serotype 19A received at the Spanish Reference Laboratory between 1997 and 2007, 51 (4.3%) strains showed high-level resistance to penicillin (MICs of 2–4 mg/L). These 51 isolates belonged to three multiresistant clones related to sequence type (ST)81 (n = 21), ST320 (n = 19) and ST276 (n = 11). All 51 serotype 19A pneumococci were tetracycline-resistant and had the tet(M) gene, and 41 strains were macrolide-resistant, harbouring the erm(B) gene. The presence of int and xis genes was detected in all strains associated with other genes of the Tn916 family.
Conclusions: The rise in penicillin-resistant serotype 19A invasive pneumococci in Spain was associated with the emergence and clonal spread of two worldwide-disseminated multiresistant clones (ST276 and ST320). The Spain23F-1-19A (ST81) clone remained stable throughout the study period. Multidrug resistance was associated with transposons of the Tn916 family.
Keywords: Streptococcus pneumoniae , resistance , transposons