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Diversity of mutations in the atpC gene coding for the c Subunit of F0F1 ATPase in clinical isolates of optochin-resistant Streptococcus pneumoniae from Brazil.

ABSTRACT: We report the characteristics of four optochin-resistant (Opt(r)) Streptococcus pneumoniae isolates from Brazil. All four Opt(r) isolates presented mutations in the nucleotide sequence coding for the c subunit of F(0)F(1) ATPase. Two isolates showed mutations in codons 23 (leading to the deduced amino acid substitution isoleucine instead of alanine) and 49 (serine instead of alanine, a novel type of mutation detected at this position), respectively. Two additional novel mutations, both located in codon 45, were detected in the other two isolates, corresponding to leucine or valine (instead of phenylalanine). The data indicate that three previously unrecognized alterations were detected in the atpC gene of S. pneumoniae and that Opt resistance among Brazilian pneumococcal isolates is not related to a specific pneumococcal serotype, antimicrobial-resistance profile, or clonal group.

SUBMITTER: Dias CA

PROVIDER: S-EPMC2045260 | biostudies-literature | 2007 Sep

REPOSITORIES: biostudies-literature

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Diversity of mutations in the atpC gene coding for the c Subunit of F0F1 ATPase in clinical isolates of optochin-resistant Streptococcus pneumoniae from Brazil.

Dias Cícero A CA Agnes Grasiela G Frazzon Ana Paula G AP Kruger Filipe D FD d'Azevedo Pedro A PA Carvalho Maria da Glória S Mda G Facklam Richard R RR Teixeira Lúcia M LM

Journal of clinical microbiology 20070711 9

We report the characteristics of four optochin-resistant (Opt(r)) Streptococcus pneumoniae isolates from Brazil. All four Opt(r) isolates presented mutations in the nucleotide sequence coding for the c subunit of F(0)F(1) ATPase. Two isolates showed mutations in codons 23 (leading to the deduced amino acid substitution isoleucine instead of alanine) and 49 (serine instead of alanine, a novel type of mutation detected at this position), respectively. Two additional novel mutations, both located i ...[more]

PMID: 17626173

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Project description:Streptococcus pneumoniae isolates resistant to several antimicrobial agent classes including trimethoprim-sulfamethoxazole have been reported with increasing frequency throughout the world. The MICs of trimethoprim, sulfamethoxazole, and trimethoprim-sulfamethoxazole (1:19) for 259 clinical isolates from South Africa were determined, and 166 of these 259 (64%) isolates were resistant to trimethoprim-sulfamethoxazole (MICs > or =20 mg/liter). Trimethoprim resistance was found to be more strongly correlated with trimethoprim-sulfamethoxazole resistance (correlation coefficient, 0.744) than was sulfamethoxazole resistance (correlation coefficient, 0.441). The dihydrofolate reductase genes from 11 trimethoprim-resistant (MICs, 64 to 512 microg/ml) clinical isolates of Streptococcus pneumoniae were amplified by PCR, and the nucleotide sequences were determined. Two main groups of mutations to the dihydrofolate reductase gene were found. Both groups shared six amino acid changes (Glu20-Asp, Pro70-Ser, Gln81-His, Asp92-Ala, Ile100-Leu, and Leu135-Phe). The first group included two extra changes (Lys60-Gln and Pro111-Ser), and the second group was characterized by six additional amino acid changes (Glu14-Asp, Ile74-Leu, Gln91-His, Glu94-Asp, Phe147-Ser, and Ala149-Thr). Chromosomal DNA from resistant isolates and cloned PCR products of the genes encoding resistant dihydrofolate reductases were capable of transforming a susceptible strain of S. pneumoniae to trimethoprim resistance. The inhibitor profiles of recombinant dihydrofolate reductase from resistant and susceptible isolates revealed that the dihydrofolate reductase from trimethoprim-resistant isolates was 50-fold more resistant (50% inhibitory doses [ID50s], 3.9 to 7.3 microM) than that from susceptible strains (ID50s, 0.15 microM). Site-directed mutagenesis experiments revealed that one mutation, Ile100-Leu, resulted in a 50-fold increase in the ID50 of trimethoprim. The resistant dihydrofolate reductases were characterized by highly conserved redundant changes in the nucleotide sequence, suggesting that the genes encoding resistant dihydrofolate reductases may have evolved as a result of inter- or intraspecies recombination by transformation.

Dataset Information

Diversity of mutations in the atpC gene coding for the c Subunit of F0F1 ATPase in clinical isolates of optochin-resistant Streptococcus pneumoniae from Brazil.

Publications

Diversity of mutations in the atpC gene coding for the c Subunit of F0F1 ATPase in clinical isolates of optochin-resistant Streptococcus pneumoniae from Brazil.

Similar Datasets

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