New aminoglycoside acetyltransferase gene, aac(3)-Id, in a class 1 integron from a multiresistant strain of Vibrio fluvialis isolated from an infant aged 6 months.
OBJECTIVE
To characterize the molecular basis of antibiotic resistance in a multidrug-resistant clinical isolate of Vibrio fluvialis H-08942.


METHODS
V. fluvialis H-08942 was isolated from a hospitalized infant aged 6 months suffering from cholera-like diarrhoea in India in 2002. The broth microdilution method was used to determine the MICs of a range of antibiotics for this strain. PCR, DNA sequencing, Southern hybridization, cloning and expression were used to characterize the molecular basis of antibiotic resistances.


RESULTS
V. fluvialis H-08942 showed resistance to chloramphenicol, streptomycin, spectinomycin, co-trimoxazole, ampicillin, furazolidone, nalidixic acid and gentamicin. A class 1 integron that contains a novel aminoglycoside acetyltransferase gene, aac(3)-Id, and aminoglycoside adenyltransferase gene, aadA7, was characterized. The aac(3)-Id gene product was found to share 50%, 45% and 44% identity to AAC(3)-Ic, AAC(3)-Ia, and AAC(3)-Ib, respectively. Both aac(3)-Id and aadA7 genes were cloned and expressed in Escherichia coli. Phylogenetic analysis suggested that the aac(3)-Id represents a fourth evolutionary lineage in the aminoglycoside acetyltransferase genes. Southern hybridization showed that this integron is located in the chromosome.


CONCLUSIONS
In this study we identified a new type of aminoglycoside acetyltransferase gene, aac(3)-Id. In addition, this is the first report of identification of antibiotic resistance genes and a class 1 integron in V. fluvialis.
Ahmed
Ashraf M
AM
Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Japan.
Nakagawa
Tomoko
T
Arakawa
Eiji
E
Ramamurthy
Thandavarayan
T
Shinoda
Sumio
S
Shimamoto
Tadashi
T
D000123:Acetyltransferases / Q000235:genetics*; D000595:Amino Acid Sequence; D015139:Blotting, Southern; D002876:Chromosomes, Bacterial; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007223:Infant; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014733:Vibrio / Q000187:drug effects* / Q000235:genetics*; D014735:Vibrio Infections / Q000382:microbiology*
D004269:DNA, Bacterial; D000123:Acetyltransferases; C019681:aminoglycoside acetyltransferase