Resistance Plasmids of Aeromonads

Hedges, R. W.; Smith, Peter G.; Brazil, G.

doi:10.1099/00221287-131-8-2091

Cited by 28 publications

(32 citation statements)

References 18 publications

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“…Antibiotic-resistant strains of Aeromonas have been isolated from aquatic environments and this resistance is principally plasmid mediated (Hedges et al 1985, Borrego et al 1991. Similar to other reports (Altwegg & Geiss 1989) all our isolates were resistant to ampicillin and 95% to cephaloridine.…”

Section: Discussionsupporting

confidence: 77%

Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water

Ghenghesh

El-Ghodban

Dkakni

et al. 2001

Mem. Inst. Oswaldo Cruz

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Section: Discussionsupporting

confidence: 77%

Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water

Ghenghesh

El-Ghodban

Dkakni

et al. 2001

Mem. Inst. Oswaldo Cruz

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“…Human as well as environmental Aeromonas isolates do often contain conjugative R-plasmids, some of which have been assigned to incompatibility groups C and U (14,30). Both groups have wide host ranges, yet IncU plasmids have only been detected occasionally in genera other than Aeromonas (14,44).…”

Section: Discussionmentioning

confidence: 99%

“…Both types of resistance have been reported to be encoded by transferable plasmids within the genus Aeromonas (1,3,7,14). Several classes of tetracycline resistance determinants have been described on R-plasmids within this group of bacteria (1,2,5,8,9,30).…”

mentioning

confidence: 99%

Incidence, Distribution, and Spread of Tetracycline Resistance Determinants and Integron-Associated Antibiotic Resistance Genes among Motile Aeromonads from a Fish Farming Environment

Schmidt¹,

Bruun²,

Dalsgaard³

et al. 2001

Appl Environ Microbiol

255

192

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A collection of 313 motile aeromonads isolated at Danish rainbow trout farms was analyzed to identify some of the genes involved in high levels of antimicrobial resistance found in a previous field trial (A. S. Schmidt, M. S. Bruun, I. Dalsgaard, K. Pedersen, and J. L. Larsen, Appl. Environ. Microbiol. 66:4908-4915, 2000), the predominant resistance phenotype (37%) being a combined oxytetracycline (OTC) and sulphadiazine/trimethoprim resistance. Combined sulphonamide/trimethoprim resistance (135 isolates) appeared closely related to the presence of a class 1 integron (141 strains). Among the isolates containing integrons, four different combinations of integrated resistance gene cassettes occurred, in all cases including a dihydrofolate reductase gene and a downstream aminoglycoside resistance insert (87 isolates) and occasionally an additional chloramphenicol resistance gene cassette (31 isolates). In addition, 23 isolates had "empty" integrons without inserted gene cassettes. As far as OTC resistance was concerned, only 66 (30%) out of 216 resistant aeromonads could be assigned to resistance determinant class A (19 isolates), D (n ‫؍‬ 6), or E (n ‫؍‬ 39); three isolates contained two tetracycline resistance determinants (AD, AE, and DE). Forty OTC-resistant isolates containing large plasmids were selected as donors in a conjugation assay, 27 of which also contained a class 1 integron. Out of 17 successful R-plasmid transfers to Escherichia coli recipients, the respective integrons were cotransferred along with the tetracycline resistance determinants in 15 matings. Transconjugants were predominantly tetA positive (10 of 17) and contained class 1 integrons with two or more inserted antibiotic resistance genes. While there appeared to be a positive correlation between conjugative R-plasmids and tetA among the OTCresistant aeromonads, tetE and the unclassified OTC resistance genes as well as class 1 integrons were equally distributed among isolates with and without plasmids. These findings indicate the implication of other mechanisms of gene transfer besides plasmid transfer in the dissemination of antibiotic resistance among environmental motile aeromonads.

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“…In the early 1970s Aoki et al (1972) published on the plasmid location of genes involved in resistance to sulphonamides and plasmids encoding resistance to sulphonamides and to both sulphonamides and trimethoprim have been detected in isolates made in Scotland and Ireland (Hedges et al, 1985;Inglis et al, 1993). The very significant advances in our understanding of the genetics of resistance have recently been documented by Sørum (2006).…”

Section: Bacteriamentioning

confidence: 93%

The advantages of the use of discs containing single agents in disc diffusion testing of the susceptibility of Aeromonas salmonicida to potentiated sulphonamides

Douglas¹,

Ruane²,

Geary³

et al. 2007

Aquaculture

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The susceptibilities of 106 strains of Aeromonas salmonicida to trimethoprim/sulfamethoxazole (SFT) were determined in two laboratories using the Clinical and Laboratory Standards Institute's M42-A disc diffusion protocols. The data generated by the use of discs containing 25 μg SFT (SFT25) allowed the strains to be placed into two groups. Strains in one group (17 strains) generated no inhibition zones and the zones obtained from the other 89 strains were distributed over a wide range but showed no natural division into separate sub-classes. A further investigation performed by one of the participating laboratories, of the susceptibility of 91 of these 106 strains used discs containing 100 μg sulfmethoxazole (SFM100) and 5 μg trimethoprim (TMP5). Application of normalised resistance interpretation to these data allowed the estimation of epidemiological cut-off values for WT strains of ≥ 9 mm for SFM100 and ≥ 21 mm for TMP5. This investigation demonstrated the presence of three distinct phenotypic classes, one containing strains manifesting wild type susceptibility to both agents, another containing strains manifesting non-wild type susceptibility to both and a third containing strains manifesting wild type susceptibility with respect to TMP but non-wild type with respect to SFM. Analysis demonstrated the inability of SFT25 discs to generate data that allowed the separate identification of strains that were fully susceptible to both TMP and SFM from those that were fully susceptible to TMP but were not fully susceptible to SFM.It is recommended that, in investigation of the susceptibility to potentiated sulphonamides of isolates from diseased fish, separate discs, containing the individual components of the mixture, should be employed.

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Resistance Plasmids of Aeromonads

Cited by 28 publications

References 18 publications

Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water

Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water

Incidence, Distribution, and Spread of Tetracycline Resistance Determinants and Integron-Associated Antibiotic Resistance Genes among Motile Aeromonads from a Fish Farming Environment

The advantages of the use of discs containing single agents in disc diffusion testing of the susceptibility of Aeromonas salmonicida to potentiated sulphonamides

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