title: Molecular basis and clonal nature of increasing pneumococcal macrolide resistance in South Africa, 2000-2005.
abstract: The prevalence and molecular epidemiology of pneumococcal macrolide resistance in South Africa was investigated. Minimum inhibitory concentrations and serotypes of pneumococcal isolates causing invasive disease from 2000-2005 (n=15982), collected through a national laboratory-based surveillance system, were determined. Randomly selected isolates from 2005 (51%; 260/508) had resistance mechanisms determined, and clonality was investigated by pulsed-field gel electrophoresis (PFGE) (n=64) and multilocus sequence typing (n=7). Macrolide resistance increased from 9% (160/1828) in 2000 to 14% (508/3656) in 2005 (P<0.001). Serotype 14 was the most common macrolide-resistant serotype (40%; 760/1921). The majority of macrolide-resistant isolates (75%; 1437/1921) displayed the macrolide-lincosamide-streptogramin B (MLS(B)) phenotype. Of the strains screened genotypically, 57% (147/260) contained erm(B), 27% (71/260) contained mef(A) and 15% (40/260) contained erm(B) and mef(A); 1% (2/260) contained ribosomal mutations. Macrolide-resistant isolates were predominantly penicillin-non-susceptible and multidrug-resistant. Isolates clustered according to serotype by PFGE, and 22% (14/64), 11% (7/64) and 5% (3/64) of isolates were related to the Taiwan(19F)-14, England(14)-9 and Spain(9V)-3 global clones, respectively. Routine use of the 7-valent pneumococcal conjugate vaccine (PCV-7) could reduce the burden of macrolide-resistant pneumococcal disease in South Africa.
authors.affiliation: Respiratory and Meningeal Pathogens Research Unit, National Institute for Communicable Diseases, Medical Research Council and University of the Witwatersrand, Sandringham, South Africa. nicolew@nicd.ac.za
authors.forename: Nicole
authors.initials: N
authors.lastname: Wolter
authors.forename: Anne
authors.initials: A
authors.lastname: von Gottberg
authors.forename: Mignon
authors.initials: M
authors.lastname: du Plessis
authors.forename: Linda
authors.initials: L
authors.lastname: de Gouveia
authors.forename: Keith P
authors.initials: KP
authors.lastname: Klugman
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018942:Macrolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D011008:Pneumococcal Infections / Q000382:microbiology*; D012703:Serotyping; D013019:South Africa; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D018942:Macrolides