Description of macrolide-resistant and potential virulent clones of Streptococcus pyogenes causing asymptomatic colonization during 2000-2006 in the Lisbon area.
The asymptomatic oropharyngeal colonization rate by Streptococcus pyogenes was 10.7% in children (901 among 8,405 children 0-16 years old) and 3.3% in adults (37 among 1,126 households of children) in the Lisbon area during 2000-2006. Macrolide-resistant S. pyogenes from children (n = 149) was variable with time: 9.8-10.7% in 2000-2002, 28.1% in 2003, 19.6-2.7% in 2004-2005 and 14.6% in 2006. Eight lineages (97.3% of isolates) were identified based on at least 80% similarity of PFGE patterns, T types, emm types and multilocus sequence types (ST). The elevated frequency of macrolide resistance was associated with M phenotype lineages I (emm12/ST36) and V (emm4, emm75/ST39 and a novel emmstMrp6 type) and with one cMLS(B) lineage IV (emm28/ST52) known to be associated with upper respiratory tract and invasive infections. Significant associations (p < 0.05) between emm type/virulence genotype were found, such as emm1/speA (+) ssa (-), emm4/ssa (+) prtF1 (+), emm12/speA (-) ssa (-). The high prevalence (>20%) of speC, prtF1 or ssa was probably caused either by clonal dissemination (speC), or to horizontal gene transfer events (prtF1 and ssa). This report contributes to a better understanding of the molecular epidemiology and evolution of macrolide-resistant S. pyogenes causing symptom-free oropharyngeal colonization. These colonizing strains carry macrolide resistance and virulence genes capable of being transferred to other bacterial species sharing the same niche.
Centro de Recursos Microbiológicos, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus de Caparica, 2829-516, Caparica, Portugal.
R
R
Pires
D
D
Rolo
A
A
Morais
A
A
Brito-Avô
C
C
Johansson
B
B
Henriques-Normark
J
J
Gonçalo-Marques
I
I
Santos-Sanches
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000942:Antigens, Bacterial / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006801:Humans; D007223:Infant; D018942:Macrolides / Q000494:pharmacology*; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D009960:Oropharynx / Q000382:microbiology; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification* / Q000472:pathogenicity; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D018942:Macrolides; D037521:Virulence Factors; C014689:streptococcal M protein