Detection of a Novel aph(2") Allele ( aph[2"]-Ie ) Conferring High-Level Gentamicin Resistance and a Spectinomycin Resistance Gene ant(9)-Ia ( aad9 ) in Clinical Isolates of Enterococci
Department of Hygiene, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan. Microbial Drug Resistance
(Impact Factor: 2.49).
02/2005; 11(3):239-47. DOI: 10.1089/mdr.2005.11.239
Aminoglycoside-modifying enzymes (AMEs) are major factors that confer aminoglycoside resistance to enterococci. In an epidemiologic study on distribution of 12 AME genes in 534 recent clinical strains isolated from a Japanese hospital, two uncommon AME genes, ant(9)-Ia and a novel aph(2") allele, aph(2")-Ie, were detected. ant(9)-Ia had been reported only in Staphylococcus aureus and encodes spectinomycin adenylyltransferase ANT(9)-I, which confers resistance to spectinomycin. The ant(9)-Ia gene was detected in three strains, a single strain each of Enterococcus faecalis, E. faecium, and E. avium. Nucleotide sequences of ant(9)-Ia from these three enterococcal species were identical to that reported for S. aureus and considered to be located on Tn 554. The new aph(2") allele, designated aph(2")-Ie, was identified in three E. faecium strains. The aph(2")-Ie allele was genetically close to aph(2")-Id reported in E. casseliflavus (93.7% amino acid sequence identity; 96.3% similarity), while distant from aph(2")-Ia, aph(2")-Ib, or aph(2")-Ic (26.3-29.5% amino acid sequence identity). Sequence divergence between APH(2")-Id and APH(2")-Ie was mostly located in amino-terminal half. In contrast, sequences corresponding to the three motifs required for aminoglycoside phosphotransferase were conserved except for a single amino acid. Three E. faecium strains having aph(2")-Ie showed high-level resistance to gentamicin and streptomycin, but not to kanamycin, dibekacin, and tobramycin, unlike enzyme specificity described for aph(2")-Id in E. casseliflavus. Such a difference in resistance phenotype was suggested to be related to amino acid sequence divergence between APH(2")-Id and APH(2")-Ie.
Available from: Guido Werner
- "It is the most prevalent form of acquired gentamicin resistance in both species and associated with homologues of transposon Tn4001/Tn5281 flanked by two copies of IS256 and most probably originating from staphylococci (Casetta et al., 1998; Hallgren et al., 2003; Saeedi et al., 2004). Gentamicin resistance may also be encoded by other determinants such as aac(6')-Ii, aph(2 " )-Ie, and ant(6)- Ia (Jackson et al., 2004; Jackson et al., 2005; Zarrilli et al., 2005; Mahbub et al., 2005). High-level streptomycin resistance is encoded by the aadE gene which is an integral part of a multiresistance gene cluster aadE-sat4-aphA encoding streptomycin-streptothricin-kanamycin resistance. "
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ABSTRACT: A beam-switchable scanning leaky-wave antenna (LWA) integrated with p-I-n diode switch circuits has been developed in this paper. This LWA with a two-terminal feeding microstrip line structure is integrated with a SPDT (single port double throw) switch as a control circuit. Compared with traditional leaky-wave antennas, this configuration offers the advantage of one/dual beam scanning radiation pattern. On the dual-beam mode, the scanning angle is steered over a range of 36° to 64° for the right beam and 144° to 116° for the left beam. On the one-beam mode, the scanning angle is measured over 20° for the right beam. The measured result shows that we can change the one-beam mode or the dual-beam mode electronically by controlling the on/off status of a SPDT
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ABSTRACT: The genes coding for 4 aminoglycoside-modifying enzymes AAC(6')-APH(2"), APH(3'), ANT(4') and ANT(6) were determined in 44 Slovak clinical isolates of Enterococcus faecalis with high-level resistance to gentamicin (HLGR, collection 1) and 48 E. faecalis isolates with resistance to amikacin (AR, collection 2). The occurrence of spotted genes was (collection 1 vs. collection 2): aac(6)-aph(2") 81.8 vs. 8.3 %, ant(4') 52.3 vs. 81.3 %, aph(3') 50 vs. 56.3 % and ant(6) 6.8 vs. 4.2 %, the most frequent combinations of genes in the HLGR collection were aac(6')-aph(2") + ant(4') and aac(6')-aph(2") + aph(3). In contrast, the aph(3') + ant(4') gene profile was predominant in AR isolates. None of the isolates contained all four AGME genes simultaneously.
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