Emergence of a multidrug-resistant clone (ST320) among invasive serotype 19A pneumococci in Spain.
OBJECTIVE
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 Spain(23F)-1-19A (ST81) clone remained stable throughout the study period. Multidrug resistance was associated with transposons of the Tn916 family.
Ardanuy
Carmen
C
Microbiology Department, Hospital Universitari de Bellvitge, 08907 L'Hospitalet de Llobregat, Barcelona, Spain. c.ardanuy@bellvitgehospital.cat
Rolo
Dora
D
Fenoll
Asunción
A
Tarrago
David
D
Calatayud
Laura
L
Liñares
Josefina
J
D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D002648:Child; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D015995:Prevalence; D012703:Serotyping; D013030:Spain / Q000453:epidemiology; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial