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Emergence of a multidrug-resistant clone (ST320) among invasive serotype 19A pneumococci in Spain
Carmen Ardanuy1, Dora Rolo, Asunción Fenoll
1Microbiology Department, Hospital Universitari de Bellvitge, 08907 L'Hospitalet de Llobregat, Barcelona, Spain. c.ardanuy@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 Spain(23F)-1-19A (ST81) clone remained stable throughout the study period. Multidrug resistance was associated with transposons of the Tn916 family.
Insights
Multidrug-resistant Streptococcus pneumoniae serotype 19A strains emerged in Spain, driven by two global clones. Resistance was linked to Tn916 family transposons and specific genes.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Multidrug-resistant Streptococcus pneumoniae serotype 19A has become a global health concern.
- Characterizing these resistant strains is crucial for effective treatment and control.
Purpose of the Study:
- To investigate highly penicillin-resistant Streptococcus pneumoniae serotype 19A strains from invasive infections in Spain (1997-2007).
- To identify the genetic basis and clonal origins of multidrug resistance in these isolates.
Main Methods:
- Antibiotic susceptibility testing using microdilution.
- Molecular typing via PFGE and multilocus sequence typing (MLST).
- PCR to detect genes associated with Tn916 family transposons.
Main Results:
- 51 (4.3%) of 1197 invasive 19A pneumococcal isolates showed high penicillin resistance.
- These isolates belonged to three multiresistant clones: ST81 (n=21), ST320 (n=19), and ST276 (n=11).
- All isolates were tetracycline-resistant (tet(M) gene), and 41 were macrolide-resistant (erm(B) gene); Tn916 family genes were present.
Conclusions:
- The increase in penicillin-resistant 19A pneumococci in Spain is attributed to the clonal spread of ST276 and ST320.
- The ST81 clone (Spain(23F)-1-19A) remained stable.
- Multidrug resistance in these strains is associated with Tn916 family transposons.
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