[Prevalence of the tetA and tetB genes as mechanisms of resistance to tetracycline and minocycline in Acinetobacter baumannii clinical isolates]

Enferm Infecc Microbiol Clin. 2006 Feb;24(2):77-80. doi: 10.1157/13085012.
[Article in Spanish]


Introduction: Two hundred twenty-one Acinetobacter baumannii clinical strains were collected from 25 hospitals in Spain. The aim of this study was to analyze the prevalence of the tetA and tetB genes in a collection of A. baumannii strains that were not epidemiologically related.

Methods: The strains were distributed in 79 clones by genomic DNA analysis with low frequency restriction enzymes and pulsed-field gel electrophoresis. The MICs for tetracycline and minocycline were determined by the E-test. One strain representing each of the tetracycline-resistant clones was analyzed by polymerase chain reaction (PCR) with specific primers for the tetA and tetB genes.

Results: Fifty-nine (74.7%) out of the 79 clones were tetracycline-resistant (MIC > or = 16 mg/l) and 40 (50.6% of the total) were also minocycline-resistant (MIC > 1 mg/l). One strain representative of each tetracycline-resistant clone was taken to study the prevalence of the tetA and tetB genes. The PCR analysis showed that 39 strains representing the same number of clones (66%) had the tetB gene, while only 8 (13.6%) were positive for the tetA gene. Twelve strains did not have any of these genes. None of the analyzed strains had both genes.

Conclusion: Although resistance to tetracycline in Acinetobacter baumannii clinical isolates is greater than that to minocycline, the tetB gene, which affects both antimicrobial agents, has a higher prevalence than the tetA gene, which affects only tetracycline.

Publication types

  • English Abstract

MeSH terms

  • Acinetobacter baumannii / drug effects*
  • Acinetobacter baumannii / genetics*
  • Anti-Bacterial Agents / pharmacology*
  • Antiporters / genetics*
  • Bacterial Proteins / genetics*
  • Genes, Bacterial*
  • Microbial Sensitivity Tests
  • Minocycline / pharmacology*
  • Prevalence
  • Spain
  • Tetracycline / pharmacology*
  • Tetracycline Resistance / genetics*


  • Anti-Bacterial Agents
  • Antiporters
  • Bacterial Proteins
  • tetA protein, Bacteria
  • Tetracycline
  • Minocycline