New Mutations and Horizontal Transfer of rpoB among Rifampin-Resistant Streptococcus pneumoniae from Four Spanish Hospitals

Abstract

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 g/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 (Spain 23F -1, Spain 6B -2, Spain 9V -3, Spain 14 -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 g/ml and 4 to 32 g/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.

Molecular mechanisms and epidemiology of resistance in Streptococcus pneumoniae in the Middle East region

“…Mutations in clusters N and II were also detected in rifampicin-resistant strains disseminated in HIV patients and children with conjunctivitis from four different Spanish hospitals [83]. In addition, the detection of a high level of variation within rpoB suggested a horizontal transfer origin, with the viridans group as potential donors [83].…”

Rifampin Combination Therapy for Nonmycobacterial Infections

“…Most of the data for using rifampin combination therapy for pneumococcus were obtained from case reports (123,189). When treating PRSP, the emergence of rifampin resistance via the rfoB gene can occur quickly, and its spread can be tracked through communities (84,167,253). The rapid spread of rifampin-resistant S. pneumoniae strains within hospitals and communities may limit the role of rifampin combination therapy in meningitis.…”

“…Rifampin resistance can develop through either insertions, deletions, or point mutations in the rpoB gene and depends on the bacterial organism affected (263,268). The rpoB gene can be utilized to determine if there are clonal outbreaks of rifampin-resistant organisms in clinical settings (84).…”

A Problem of Species Determination Using Housekeeping Genes in the <i>Streptococcus anginosus</i> Group

“…By contrast, direct sequencing methods using housekeeping genes such as the 16S rRNA gene, sodA, groEL, rpoB, and tuf have been generalized for taxonomic analysis among the streptococcal species 10) . Regardless of the usefulness of genotyping methods using housekeeping genes such as the 16S rRNA gene, incorrect phylogenetic classifications are occasionally obtained for some bacterial species such as SAG strains 11) . One of the reasons is considered to be the low discriminative power of 16S rRNA for closely related species such as SAG strains.…”