Molecular analysis of Streptococcus pyogenes macrolide resistance of paediatric isolates during a 7 year period (2007-13).
The molecular characterization of paediatric group A Streptococcus (GAS) isolates regarding macrolide resistance and relevant emm types in Athens, Greece.



Pharyngeal and non-pharyngeal GAS isolates were collected during a 7 year period (2007-13) and examined for antibiotic susceptibility, macrolide resistance genes [mef(A), erm(A) and erm(B)] and relevant emm types.



Overall, 20.4% (270/1324) of GAS isolates were resistant to macrolides. The macrolide resistance rate varied during the study period with a maximum rate observed in 2008 (29.57%) and a minimum rate observed in 2013 (10.95%) (P value for trend = 0.007). During the same period, consumption of macrolides was gradually reduced by 56.6%. No difference was observed in macrolide resistance between pharyngeal and non-pharyngeal isolates (P = 0.7). Among macrolide-resistant isolates, mef(A) was detected in 87 (32.2%), erm(A) in 136 (50.4%), erm(B) in 44 (16.3%) and both mef(A) and erm(A) in 3 (1.1%) isolates. The most prevalent emm types among macrolide-resistant isolates were emm77 (31.5%), emm4 (18.1%) and emm12 (10.7%). Ten emm types (77, 4, 12, 28, 1, 22, 11, 2, 44 and 89) accounted for 90.3% of macrolide-resistant isolates. emm types 4, 22, 44 and 77 were more prevalent in macrolide-resistant compared with macrolide-susceptible isolates, whereas emm types 1, 3, 5, 6, 75 and 89 were more prevalent in macrolide-susceptible compared with macrolide-resistant isolates.



GAS macrolide resistance remained significant in our area during the study period. A substantial decline in the resistance rate was observed in the last year of the study, which may be related to reduced consumption of macrolides.
First Department of Paediatrics, National and Kapodistrian University of Athens, Division of Infectious Diseases, 'Aghia Sophia' Children's Hospital, Athens, Greece amichos@med.uoa.gr.
Athanasios
A
Michos
First Department of Paediatrics, National and Kapodistrian University of Athens, Division of Infectious Diseases, 'Aghia Sophia' Children's Hospital, Athens, Greece.
Foteini I
FI
Koutouzi
Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
Athanasios
A
Tsakris
First Department of Paediatrics, National and Kapodistrian University of Athens, Division of Infectious Diseases, 'Aghia Sophia' Children's Hospital, Athens, Greece.
Panagiota
P
Chatzichristou
First Department of Paediatrics, National and Kapodistrian University of Athens, Division of Infectious Diseases, 'Aghia Sophia' Children's Hospital, Athens, Greece.
Emmanouil I
EI
Koutouzis
First Department of Propaedeutic Medicine, National and Kapodistrian University of Athens, Athens, Greece.
George L
GL
Daikos
Department of Microbiology, 'Aghia Sophia' Children's Hospital, Athens, Greece.
Angeliki
A
Stathi
First Department of Paediatrics, National and Kapodistrian University of Athens, Division of Infectious Diseases, 'Aghia Sophia' Children's Hospital, Athens, Greece.
Vassiliki P
VP
Syriopoulou
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000942:Antigens, Bacterial / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005260:Female; D005798:Genes, Bacterial; D005838:Genotype; D006115:Greece / Q000453:epidemiology; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008297:Male; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D018942:Macrolides; C014689:streptococcal M protein