title: Clonality behind the increase of multidrug-resistance among non-invasive pneumococci in Southern Finland.
abstract: Multidrug-resistance among Streptococcus pneumoniae isolates, especially of serotype 19A, has increased in several countries recently. Even before the introduction of the pneumococcal conjugate vaccine into the Finnish National Vaccination Programme, the proportion of multidrug-resistant (MDR) pneumococci had doubled from 2007 to 2008, when it reached 3.6% in Southern Finland. Our aim was to look for a possible association between antimicrobial susceptibility and clonality among the MDR isolates. Twelve non-invasive isolates non-susceptible to penicillin, erythromycin, clindamycin, trimethoprim/sulfamethoxazole, and doxycycline from 2008 were available for serotyping, genotyping by multilocus sequence typing (MLST), and detection of genes encoding macrolide resistance and adherence-promoting pili. Two isolates were also resistant to ceftriaxone. Five serotypes, 19F, 19A, 6B, 23F, and 14, and six genotypes from three genetic lineages were found, among which CC320 was the largest. All isolates in this study carried the erm(B) macrolide resistance gene, and the CC320 isolates additionally carried the mef(A/E) macrolide resistance gene. Eleven isolates carried pilus islet 1, while the CC320 isolates also carried the pilus islet 2 genes. The findings emphasize the importance of the careful monitoring of antimicrobial susceptibility and serotype distribution among pneumococci, especially now that antimicrobials and pneumococcal vaccines are in widespread use.
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki and Turku, Finland. lotta.siira@thl.fi
authors.forename: L
authors.initials: L
authors.lastname: Siira
authors.forename: J
authors.initials: J
authors.lastname: Jalava
authors.forename: P
authors.initials: P
authors.lastname: Tissari
authors.forename: M
authors.initials: M
authors.lastname: Vaara
authors.forename: T
authors.initials: T
authors.lastname: Kaijalainen
authors.forename: A
authors.initials: A
authors.lastname: Virolainen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D010861:Fimbriae, Bacterial / Q000235:genetics; D005387:Finland / Q000453:epidemiology; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008780:Methyltransferases / Q000235:genetics; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C117866:MefA protein, Streptococcus; D008565:Membrane Proteins; C111078:ErmTR protein, bacteria; D008780:Methyltransferases