mef(A), mef(E) and a new mef allele in macrolide-resistant Streptococcus spp. isolates from Norway.
OBJECTIVE
To type mef genes in a nationwide collection of clinical isolates of Streptococcus pneumoniae and Streptococcus pyogenes as well as pharyngeal carrier strains of viridans streptococci in Norway.


METHODS
Erythromycin-resistant mef-positive multilocus sequence-typed (MLST) clinical isolates of S. pneumoniae (n = 36) and S. pyogenes (n = 12) from the National Surveillance Program for Antimicrobial Resistance (NORM) as well as viridans streptococci (n = 20) from healthy adults were included. PCR-amplified mef genes were initially discriminated by BamHI digestion. Selected mef genes from representatives of different sequence types (STs) of S. pneumoniae (n = 11) and S. pyogenes (n = 4), and viridans group streptococcal species (n = 8) were typed by sequencing and their strains examined for co-resistances. Hydropathy plots of different mef-encoded proteins were performed.


RESULTS
A predominance of mef(A) was detected in S. pneumoniae (23/36) and S. pyogenes (9/12) due to the clonal spread of ST9 and ST39, respectively. mef(E) was the most widely distributed mef determinant occurring in nine different STs of S. pneumoniae and in four different viridans species. A new mef allele was identified in two STs of S. pyogenes.


CONCLUSIONS
mef(E) is the most widely distributed mef determinant in Norwegian clinical strains of S. pneumoniae and pharyngeal carrier strains of various viridans streptococci. However, mef(A) is more prevalent in S. pneumoniae and S. pyogenes due to clonal spread. A new mef allele was found in two different STs of S. pyogenes.
Sangvik
Maria
M
Reference Centre for Detection of Antimicrobial Resistance, Department of Microbiology, University Hospital of North Norway, University of Tromsø, N-9037 Tromsø, Norway.
Littauer
Pia
P
Simonsen
Gunnar Skov
GS
Sundsfjord
Arnfinn
A
Dahl
Kristin Hegstad
KH
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002353:Carrier State / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D015245:Deoxyribonuclease BamHI / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D018942:Macrolides / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009664:Norway; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013290:Streptococcal Infections / Q000382:microbiology; D013291:Streptococcus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D034363:Viridans Streptococci / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D018942:Macrolides; C117866:MefA protein, Streptococcus; C431304:MefE protein, Streptococcus pneumoniae; D008565:Membrane Proteins; D015245:Deoxyribonuclease BamHI