Differences in the DNA sequence of the translational attenuator of several constitutively expressed erm(A) genes from clinical isolates of Streptococcus agalactiae

• Published in: Journal of antimicrobial chemotherapy Vol. 56; no. 5; pp. 836 - 840
• Main Authors: Culebras, Esther, Rodríguez-Avial, Iciar, Betriu, Carmen, Picazo, Juan J.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.11.2005; Oxford Publishing Limited (England)
• Subjects: 5' Untranslated Regions - genetics; Anti-Bacterial Agents - pharmacology; Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacterial Proteins - genetics; Base Sequence; Biological and medical sciences; Clindamycin - pharmacology; clindamycin resistance; DNA Transposable Elements; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Drug Resistance, Bacterial - genetics; Erythromycin - pharmacology; gene regulation; Group B streptococci; Medical sciences; Methyltransferases - genetics; Microbial Sensitivity Tests; Molecular Epidemiology; Molecular Sequence Data; Pharmacology. Drug treatments; Point Mutation; Polymerase Chain Reaction; Polymorphism, Genetic; Sequence Analysis, DNA; Spain; Streptococcal Infections - microbiology; Streptococcus agalactiae; Streptococcus agalactiae - drug effects; Streptococcus agalactiae - genetics; Streptococcus agalactiae - isolation & purification; Spain; Human; Nucleotide sequence; Clindamycin; Gene expression; Genetic translation; clindamycin resistance; Resistance; Streptococcaceae; Antibiotic; Regulation(control); Gene; gene regulation; Streptococcus B; Bacteria; Micrococcales; Genetics; Group B streptococci; Antibacterial agent; Streptococcus agalactiae; Clinical isolate
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dki337

Objectives: To study the regulatory region of a constitutively expressed erm(A) gene in Streptococcus agalactiae clinical isolates. Methods: Thirty clinical isolates of S. agalactiae which were cross-resistant to erythromycin and clindamycin and with a clindamycin MIC higher than that of erythromycin were studied by PCR, sequencing and molecular typing. Results: PCR analysis revealed that all the strains harboured the erm(A) gene, either alone (26 isolates) or in combination with erm(B) (four isolates). Sequencing of the region upstream of erm(A) showed that all isolates possessed two types of genetic alteration. Most of the strains showed point mutations in the second leader peptide (mainly A137C) and, in four isolates (two clones), an insertion fragment with high homology to IS1381 and transposase genes was detected. Epidemiological analysis of strains indicated several clonal origins of isolates. Conclusions: The mutations described here are thought to result in increased or constitutive expression of the erm(A) gene.