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High level aminoglycoside resistance and distribution of aminoglycoside resistant genes among clinical isolates of Enterococcus species in Chennai, India.

ABSTRACT: Enterococci are nosocomial pathogen with multiple-drug resistance by intrinsic and extrinsic mechanisms. Aminoglycosides along with cell wall inhibitors are given clinically for treating enterococcal infections. 178 enterococcal isolates were analyzed in this study. E. faecalis is identified to be the predominant Enterococcus species, along with E. faecium, E. avium, E. hirae, E. durans, E. dispar and E. gallinarum. High level aminoglycoside resistance (HLAR) by MIC for gentamicin (GM), streptomycin (SM) and both (GM + SM) antibiotics was found to be 42.7%, 29.8%, and 21.9%, respectively. Detection of aminoglycoside modifying enzyme encoding genes (AME) in enterococci was identified by multiplex PCR for aac(6')-Ie-aph(2'')-Ia; aph(2'')-Ib; aph(2'')-Ic; aph(2'')-Id and aph(3')-IIIa genes. 38.2% isolates carried aac(6')-Ie-aph(2'')-Ia gene and 40.4% isolates carried aph(3')-IIIa gene. aph(2'')-Ib; aph(2'')-Ic; aph(2'')-Id were not detected among our study isolates. aac(6')-Ie-aph(2'')-Ia and aph(3')-IIIa genes were also observed in HLAR E. durans, E. avium, E. hirae, and E. gallinarum isolates. This indicates that high level aminoglycoside resistance genes are widely disseminated among isolates of enterococci from Chennai.

SUBMITTER: Padmasini E

PROVIDER: S-EPMC3932257 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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High level aminoglycoside resistance and distribution of aminoglycoside resistant genes among clinical isolates of Enterococcus species in Chennai, India.

Padmasini Elango E Padmaraj R R Ramesh S Srivani SS

TheScientificWorldJournal 20140204

Enterococci are nosocomial pathogen with multiple-drug resistance by intrinsic and extrinsic mechanisms. Aminoglycosides along with cell wall inhibitors are given clinically for treating enterococcal infections. 178 enterococcal isolates were analyzed in this study. E. faecalis is identified to be the predominant Enterococcus species, along with E. faecium, E. avium, E. hirae, E. durans, E. dispar and E. gallinarum. High level aminoglycoside resistance (HLAR) by MIC for gentamicin (GM), streptom ...[more]

PMID: 24672306

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Project description:Enterococcus is a genus of Gram-positive bacteria that are commensal to the gastrointestinal tracts of humans but some species have been increasingly implicated as agents of nosocomial infections. The increase in infections and the spread of antibiotic-resistant strains have contributed to renewed interest in the discovery of Enterococcus phages. The aims of this study were (1) the isolation, characterization, and genome sequencing of a phage capable of infecting an antibiotic-resistant E. faecalis strain, and (2) the comparative genomic analysis of publicly-available Enterococcus phages. For this purpose, multiple phages were isolated from wastewater treatment plant (WWTP) influent using a high-level aminoglycoside-resistant (HLAR) E. faecalis strain as the host. One phage, phiNASRA1, demonstrated a high lytic efficiency (?97.52%). Transmission electron microscopy (TEM) and whole-genome sequencing (WGS) showed that phiNASRA1 belongs to the Siphoviridae family of double-stranded DNA viruses. The phage was approximately 250 nm in length and its complete genome (40,139 bp, 34.7% GC) contained 62 open reading frames (ORFs). Phylogenetic comparisons of phiNASRA1 and 31 publicly-available Enterococcus phages, based on the large subunit terminase and portal proteins, grouped phage by provenance, size, and GC content. In particular, both phylogenies grouped phages larger than 100 kbp into distinct clades. A phylogeny based on a pangenome analysis of the same 32 phages also grouped phages by provenance, size, and GC content although agreement between the two single-locus phylogenies was higher. Per the pangenome phylogeny, phiNASRA1 was most closely related to phage LY0322 that was similar in size, GC content, and number of ORFs (40,139 and 40,934 bp, 34.77 and 34.80%, and 60 and 64 ORFs, respectively). The pangenome analysis did illustrate the high degree of sequence diversity and genome plasticity as no coding sequence was homologous across all 32 phages, and even 'conserved' structural proteins (e.g., the large subunit terminase and portal proteins) were homologous in no more than half of the 32 phage genomes. These findings contribute to a growing body of literature devoted to understanding phage biology and diversity. We propose that this high degree of diversity limited the value of the single-locus and pangenome phylogenies. By contrast, the high degree of homology between phages larger than 100 kbp suggests that pangenome analyses of more similar phages is a viable method for assessing subclade diversity. Future work is focused on validating phiNASRA1 as a potential therapeutic agent to eradicate antibiotic-resistant E. faecalis infections in an animal model.

Project description:Enzymatic modification of aminoglycosides by nucleotidyltransferases, acetyltransferases and/or phosphotransferases accounts for the majority of aminoglycoside-resistant Acinetobacter isolates. In this study, we investigated the relationship between aminoglycoside resistance and the presence of aminoglycoside-modifying enzymes in Acinetobacter baumannii clinical isolate groups with different resistance profiles. Thirty-two clinical A. baumannii isolates were included in this study. Acinetobacter isolates were divided into 4 groups according to results of susceptibility testing. The presence of genes encoding the following aminoglycoside-modifying enzymes; aph (3')-V1, aph (3')-Ia, aac (3)-Ia, aac (3) IIa, aac (6')-Ih, aac (6')-Ib and ant (2')-Ia responsible for resistance was investigated by PCR in all strains. The acetyltransferase (aac (6')-Ib, aac (3)-Ia) and phosphotransferase (aph (3')-Ia) gene regions were identified in the first group, which comprised nine imipenem, meropenem, and gentamicin-resistant isolates. The acetyltransferase (aac (6')-Ib, aac (3)-Ia), phosphotransferase (aph (3')-VI) and nucleotidyltransferase (ant2-Ia) gene regions were identified in the second group, which was composed of nine imipenem-resistant, meropenem-resistant and gentamicin-sensitive isolates. The acetyltransferase (aac (3)-Ia) and phosphotransferase (aph (3')-Ia) regions were identified in the fourth group, which comprised eight imipenem-sensitive, meropenem-sensitive and gentamicin-resistant isolates. Modifying enzyme gene regions were not detected in the third group, which was composed of six imipenem, meropenem and gentamicin-sensitive isolates. Our data are consistent with previous reports, with the exception of four isolates. Both acetyltransferases and phosphotransferases were widespread in A. baumannii clinical isolates in our study. However, the presence of the enzyme alone is insufficient to explain the resistance rates. Therefore, the association between the development of resistance and the presence of the enzyme and other components should be investigated further.

Dataset Information

High level aminoglycoside resistance and distribution of aminoglycoside resistant genes among clinical isolates of Enterococcus species in Chennai, India.

Publications

High level aminoglycoside resistance and distribution of aminoglycoside resistant genes among clinical isolates of Enterococcus species in Chennai, India.

Similar Datasets

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