2026-08-20T01:13:03Zhttps://docta.ucm.es/rest/oai/request

oai:docta.ucm.es:20.500.14352/1071692025-02-14T17:05:31Zcom_20.500.14352_14col_20.500.14352_15

Cafini, Fabio Del Campo, Rosa Alou Cervera, Luis Sevillano Fernández, David Morosini, María Isabel Baquero, Fernando Prieto Prieto, José 2024-07-29T10:42:48Z 2024-07-29T10:42:48Z 2005-12-20 Cafini F, del Campo R, Alou L, Sevillano D, Morosini MI, Baquero F, Prieto J; Spanish Pneumococcal Network (G03/103). Alterations of the penicillin-binding proteins and murM alleles of clinical Streptococcus pneumoniae isolates with high-level resistance to amoxicillin in Spain. J Antimicrob Chemother. 2006 Feb;57(2):224-9. 0305-7453 10.1093/jac/dki442 https://hdl.handle.net/20.500.14352/107169 1460-2091 https://doi.org/10.1093/jac/dki442 https://academic.oup.com/jac/article/57/2/224/804622 Aims: The aim of this study was to analyse the nucleotide sequences of regions encoding the penicillin-binding domains of pbp1A, pbp2B and pbp2X genes and murM alleles from 14 selected amoxicillin-resistant Streptococcus pneumoniae isolates (MICs 8-16 mg/L) obtained in Spain. Methods: PFGE and dideoxynucleotide chain termination sequencing were used. Results: Analysis of PFGE profiles showed that the amoxicillin-resistant S. pneumoniae strains belonged to six different PFGE patterns including the Spain23F-1, Spain6B-2, Spain9V-3 and Spain(14)-5 international clones; however, 8 of the 14 strains belonged to the Spain9V-3 clone. These strains showed the typical changes in penicillin-binding proteins (PBPs) 1A and 2X and had 10 unique changes in the 590-641 region of PBP2B as described previously. Transformation experiments tried to incorporate the transpeptidase domain of PBP2B including the 590-641 region associated with amoxicillin-resistant pneumococci. Sequencing of the pbp2B genes revealed that part of the 3' region of the pbp2B sequence encoding a region of the domain (around amino acid 514-538 to the C terminus of PBP2B) did not recombine with the R6 pbp2B gene. The murM sequence analysis showed that 6, 6 and 2 amoxicillin-resistant S. pneumoniae strains had murMA, murMB5 and murMB6 alleles, respectively. However, strains with murMB5 or murMB6 alleles showed a single mutation (N537D) in the 537-581 region of PBP2B, while strains with the murMA allele had 12 unique changes. Conclusions: Ten unique changes in the 590-641 region of PBP2B and no specific murM alleles were found in S. pneumoniae strains isolated in Spain with an amoxicillin MIC>or=8 mg/L (MICs from 6 to 12 mg/L by 1 mg/L step dilution). In addition, the presence of specific mutations in PBP2B seems to play a key role in the presence of different murM alleles in these amoxicillin-resistant pneumococcal strains. eng restricted access Alterations of the penicillin-binding proteins and murM alleles of clinical Streptococcus pneumoniae isolates with high-level resistance to amoxicillin in Spain journal article