Molecular characterization of multi-drug resistant (MDR) and extremely drug resistant (XDR) Streptococcus pneumoniae isolates from Canadian hospitals between 2007-2013.

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dc.contributor.authorRosenthal, Margot
dc.date.accessioned2015-06-01T19:58:36Z
dc.date.available2015-06-01T19:58:36Z
dc.date.issued2014-08-08
dc.description.abstractStreptococcus pneumoniae is a major pathogen causing pneumonia, otitis media, bacteremia, and meningitis across all age groups in Canada. Multi-drug resistant (MDR) S. pneumoniae represent approximately 2.8% of all S. pneumoniae isolates and are of increasing concern due to limited treatment options. Isolates for this study were obtained from the CANWARD surveillance study between 2007-13 and chosen based on their MDR phenotype. Antimicrobial susceptibility testing was performed according to CLSI methods. Phenotypic and genotypic relatedness were assessed by serotyping and pulsed-field gel electrophoresis (PFGE). Mechanisms of macrolide resistance mef(E) and erm(B) were detected by PCR analysis and mechanisms of penicillin resistance were assessed by PCR amplification followed by DNA sequencing of penicillin binding protein (PBP) genes 1 A, 28 and 2X. Detection of pilus type 1 (P1) and type 2 (P2) pathogenicity islets assessed by PCR. This study characterized MDR S.pneumoniae obtained from across Canada. MDR S. pneumoniae obtained from Canadian hospitals are genetically related and primarily composed of serotypes 19A and 19F. Within MDR isolates, resistance rates of >75% were associated with clarithromycin, clindamycin, doxycycline, penicillin and trimethoprim/sulfamethoxazole, with 72.4% of isolates displaying simultaneous resistance to all five antimibiotics. Isolates commonly carried resistance to penicillin + 4 other chemically unrelated classes of antibiotics, a level of resistance we termed extremely drug-resistant (XDR). All isolates tested positive for either macrolide resistance genes mef(E) (88.5%) or erm(B) (82.0%), with many of the isolates (70.5%) testing positive for both genes. Penicillin resistance was associated with highly similar amino acid substitutions in PBP1 A, 28 and 2X. The majority ot isolates carried P1 (80.3%) or P2 (73.8%), with 73.8% of isolates carrying both pili. PFGE revealed 4 clusters that were genetically related and associated with known clones Taiwan19F-14, England14-9, Spain9V-3, Spain23F-1.en_US
dc.identifier.urihttp://hdl.handle.net/1993/30557
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectmulti-drug resistanten_US
dc.subjectextremely drug resistant (XDR)en_US
dc.subjectStreptococcus pneumoniaeen_US
dc.titleMolecular characterization of multi-drug resistant (MDR) and extremely drug resistant (XDR) Streptococcus pneumoniae isolates from Canadian hospitals between 2007-2013.en_US
dc.typeOtheren_US
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