New mutations and horizontal transfer of rpoB among rifampin-resistant Streptococcus pneumoniae from four Spanish hospitals.
A total of 103 (0.7%) of 14,236 Streptococcus pneumoniae isolates collected in four Spanish hospitals from 1989 to 2003 were resistant to rifampin (MICs, 4 to 512 microg/ml). Only sixty-one (59.2%) of these isolates were available for molecular characterization. Resistance was mostly related to human immunodeficiency virus (HIV) infection in adult patients and to conjunctivitis in children. Thirty-six different pulsed-field gel electrophoresis patterns were identified among resistant isolates, five of which were related to international clones (Spain23F-1, Spain6B-2, Spain9V-3, Spain14-5, and clone C of serotype 19F), and accounted for 49.2% of resistant isolates. Single sense mutations at cluster N or I of the rpoB gene were found in 39 isolates, while double mutations, either at cluster I, at clusters I and II, or at clusters N and III, were found in 14 isolates. The involvement of the mutations in rifampin resistance was confirmed by genetic transformation. Single mutations at clusters N and I conferred MICs of 2 microg/ml and 4 to 32 microg/ml, respectively. Eight isolates showed high degrees of nucleotide sequence variations (2.3 to 10.8%) in rpoB, suggesting a recombinational origin for these isolates, for which viridans group streptococci are their potential gene donors. Although the majority of rifampin-resistant isolates were isolated from individual patients without temporal or geographical relationships, the clonal dissemination of rifampin-resistant isolates was observed among 12 HIV-infected patients in the two hospitals with higher rates of resistance.
Ferrándiz
María José
MJ
Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain.
Ardanuy
Carmen
C
Liñares
Josefina
J
García-Arenzana
José María
JM
Cercenado
Emilia
E
Fleites
Ana
A
de la Campa
Adela G
AG
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D022761:Gene Transfer, Horizontal; D006761:Hospitals; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology; D012293:Rifampin / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D013030:Spain / Q000453:epidemiology; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D012293:Rifampin