Polyclonal Population Structure of Streptococcus pneumoniae Isolates in Spain Carrying mef and mef plus erm (B)

Abstract

Macrolide resistance among Streptococcus pneumoniae clinical isolates has risen to prominence. The rate of resistance to macrolides is even higher than that to penicillin, particularly in Spain and some other European countries, such as France, Poland, Greece, and Portugal (17, 23). In most European countries, erythromycin resistance is mainly due to the presence of the erm(B) gene. This gene encodes an rRNA methylase responsible for the macrolide-lincosamide-streptogramin B resistance (MLS B ) phenotype and is associated with conjugative transposons. The clonal dispersion of erm(B)-positive S. pneumoniae isolates and the horizontal transfer of transposable elements carrying this determinant have been associated with the increase in the rate of erythromycin resistance in this organism (4,12). Erythromycin resistance may also be associated with the expression of efflux pumps encoded by mef genes that endow the macrolide resistance (M) phenotype (7). This phenotype has traditionally been more prevalent in North America than in Europe (7,12).In recent years, the presence of both the erm(B) and the mef(E) genes in S. pneumoniae clinical isolates has been increasingly recognized, but they are more prevalent in Asian countries than in Europe and the United States (10, 11). Despite the interest in this association on the evolution of macrolide and ketolide resistance, very few studies have investigated the population biology of a collection of isolates recovered during different time periods and/or from different geographic origins (13,26). In Spain, population structure studies have shown that resistance in S. pneumoniae international clones, such as clones Spain 9V -3 and England 14 -9, are mainly associated with those endowed with the M phenotype (1, 2), whereas clones Spain 23F -1 and Spain 6B -2 are associated with isolates endowed with the MLS B phenotype (14). This type of analysis with S. pneumoniae isolates with both the erm(B) and the mef genes has not been reported. In the present study, the population structure and clonal relatedness of 45 mef-positive isolates [62.2% of which had both the erm(B) and the mef genes] identified within a collection of 712 S. pneumoniae isolates recovered from different Spanish hospitals from 1999 to 2003 were fully investigated. Moreover, the corresponding resistance phenotypes and antibiotic susceptibility patterns were also studied.

Evolution of macrolide resistance in Streptococcus pyogenes over 14 years in an area of central Italy

“…The presence of known genetic resistance determinants was verified in all erythromycin-resistant isolates: ermTR was confirmed to be responsible for the iMLS phenotype (Varaldo et al, 2009); the coexistence of two erm alleles (ermB/ ermTR) was found in 5.6 % of all MLS isolates, although only one was phenotypically expressed, as reported previously in streptococcal and pneumococcal isolates (Cascone et al, 2002;de la Pedrosa et al, 2008;Giovanetti et al, 2012;Silva-Costa et al, 2008). In our study, certain emm types were specifically recovered among erythromycin-resistant isolates, and were associated with different phenotypes: emm75, emm2 and emm4 with an M phenotype and emm77 with an iMLS phenotype.…”

mef(A) is the predominant macrolide resistance determinant in Streptococcus pneumoniae and Streptococcus pyogenes in Germany

“…Chromosomal DNA was isolated using a standardised procedure (DNeasy Blood & Tissue Kit; QIAGEN, Hilden, Germany). The distinction between mef(A) and mef(E) was made using a multiplex PCR [20] with the following primers: mefAF, 5 -AATACAACAATTGGATT-3 ; mefEF, 5 -AAGGAGTTGTGGTTCTGA-3 ; and mefR, 5 -CCAATGATTTACACCGATT-3 . The PCR mixture for 25 L contained 15 mM Tris-HCl, 50 mM KCl (pH 8.0), 25 mM MgCl 2 , 100 M of each nucleotide, 0.15 mM of mefAF and mefEF primer and 0.25 mM of the mefR primer plus 1.5 U of AmpliTaq Gold ® DNA Polymerase (Applied Biosystems, Darmstadt, Germany).…”

Clonal Spread of Levofloxacin-Resistant Streptococcus pneumoniae Invasive Isolates in Madrid, Spain, 2007 to 2009

“…However, to our knowledge, this is the first report of resistance to levofloxacin in strains belonging to this clone. In addition, it is noteworthy that we have detected resistance to fluoroquinolones among usually antibiotic-susceptible clones circulating in Spain: Netherlands 7F -ST191, ST1201 (19A), and ST2639 (10A) (1,6,19).…”