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Distribution and in-vitro transfer of tetracycline resistance determinants in clinical and aquatic Acinetobacter strains.

Abstract：

:Following characterisation by phenotypic tests and amplified ribosomal DNA restriction analysis (ARDRA), 50 tetracycline-resistant (MIC > or = 16 mg/L) Acinetobacter strains from clinical (n = 35) and aquatic (n = 15) samples were analysed by PCR for tetracycline resistance (Tet) determinants of classes A-E. All the clinical strains were A. baumannii; most (33 of 35) had Tet A (n = 16) or B (n = 17) determinants, and only two did not yield amplicons with primers for any of the five tetracycline resistance determinants. The aquatic strains belonged to genomic species other than A. baumannii, and most (12 of 15) did not contain determinants Tet A-E. Strains negative for Tet A-E were also negative for Tet G and M; further analysis of two aquatic strains with specific primers for Tet O and Tet Y and degenerate primers for Tet M-S-O-P(B)-Q also showed negative results. Transfer of tetracycline resistance was tested for 20 strains with three aquatic Acinetobacter strains and Escherichia coli K-12 as recipients. Transfer of resistance was demonstrated between aquatic strains from distinct ecological niches, but not from clinical to aquatic strains, nor from any Acinetobacter strain to E. coli K-12. Most transconjugants acquired multiple relatively small plasmids (<36 kb). Transfer did not occur when DNA from the donor strains was added to the recipient cultures and was not affected by deoxyribonuclease I, suggesting a conjugative mechanism. It is concluded that Tet A and B are widespread among tetracycline-resistant A. baumannii strains of clinical origin, but unknown genetic determinants are responsible for most tetracycline resistance among aquatic Acinetobacter spp. These differences, together with the inability of clinical strains to transfer tetracycline resistance in vitro to aquatic strains, contra-indicate any important flow of tetracycline resistance genes between clinical and aquatic acinetobacter populations.

journal_name

J Med Microbiol

journal_title

Journal of medical microbiology

authors

Guardabassi L,Dijkshoorn L,Collard JM,Olsen JE,Dalsgaard A

doi

10.1099/0022-1317-49-10-929

keywords:

subject

Has Abstract

pub_date

2000-10-01 00:00:00

pages

929-936

issue

eissn

0022-2615

issn

1473-5644

journal_volume

pub_type

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Distribution and in-vitro transfer of tetracycline resistance determinants in clinical and aquatic Acinetobacter strains.