Spectrum of Aminoglycoside Modifying Enzymes in Gram-Negative Bacteria Causing Human Infections

Abstract

Introduction Aminoglycosides are formidable broad-spectrum antibiotics used in clinical settings; woefully their usage has been reduced by the emergence and distribution of resistance mainly due to aminoglycoside modifying enzymes (AME). Purpose This study was performed to determine the diverse prevalence of AME and their pattern of occurrence in the clinical isolates of gram-negative bacteria. This study also aimed to detect the presence of AMEs that are prevalent in gram-positive bacteria, among gram negatives. Materials and Methods A total number of 386 clinical isolates were included in this study. Polymerase chain reaction revealed the prevalence rate of AMEs screened [aac(6′)-lb, aac(3′)-I, aac(3′)-II, aac(3′)-VI, ant(2′)-I, ant(4′)-IIb, aac(3′)-III, aac(3′)-IV, aph(2′)-Ib, aph(2′)-Ic, aph(2′)-Id, aac (6′)-Ie- aph(2′)-Ia, and aph(3′)-IIIa]. Conjugation experiment was performed for the clinical isolates which harbored any one of the AME which was prevalent in gram-positive bacteria [aph(3′)-IIIa, aac(6′)-Ie-aph(2′)-Ia]. Results aac(6′)-lb is the most prevalent AME, followed by aac(3′)-I, aph(3′)-VI, aac(3′)-VI, and aac(3′)-II. The AMEs such as ant (2′)-I, ant(4′)-IIb, aac(3′)-III, aac(3′)-IV, aph(2′)-Ib, aph(2′)-Ic, and aph(2′)-Id were not established in our study isolates. The rate of prevalence of aph(3′)-IIIa, aac(6′)-Ie-aph(2′)-Ia—the AMEs encountered in gram-positive and their co-existence was 19.68% and the conjugation experiment revealed their transfer via plasmids. Conclusion This is the first report from India revealing the presence and prevalence of AMEs which are often encountered among gram-positive bacteria in gram negatives and their presence on conjugative plasmids.

Exogenous NADH promotes the bactericidal effect of aminoglycoside antibiotics against Edwardsiella tarda

“…Given that NADH exhibits high synergy with various aminoglycosides, we hypothesized that NADH may inhibit the activity of aminoglycoside-modifying enzymes. Among the three types of aminoglycoside-modifying enzymes: aminoglycoside nucleotidyltransferases (ANTs), aminoglycoside phosphotransferases (APHs), and aminoglycoside acetyltransferases (AACs), capable of rendering aminoglycosides inactive [ 48 , 49 ], only AACs are expressed in ATCC15947. AutoDock analysis was performed using AACs as receptors and NADH as ligands to explore potential attachment interactions between NADH and AACs.…”

Occurrence of Antibiotic Resistance Genes in Hermetia illucens Larvae Fed Coffee Silverskin Enriched with Schizochytrium limacinum or Isochrysis galbana Microalgae

“…Although these ubiquitous genes could be associated with the H. illucens core microbiota, the higher number of tet (M) and erm (B) genes detected even in the first round of PCR, as well as the exclusive presence of the erm (A) and aac-aph genes in the larvae reared on the substrates enriched with I. galbana , could indicate a positive correlation between this microalga and the bacteria carrying these genes. The erm (A) gene is the most common AR determinant in staphylococci, mostly detected in methicillin-resistant strains [ 44 ], whereas the aac-aph gene conferring resistance to aminoglycosides has frequently been detected in Gram-positive bacteria mainly belonging to the genera Enterococcus , Staphylococcus , and Streptococcus and rarely in Gram-negative bacteria [ 45 ]. Finally, the highest number (6/12) of all tested AR genes was detected in larvae reared on substrates containing 25% I. galbana (HCsI25).…”

Antibiotic resistance spectrums of Escherichia coli and Enterococcus spp. strains against commonly used antimicrobials from commercial meat-rabbit farms in Chengdu City, Southwest China

“…strains, representative antibiotic resistance genes (ARGs) that belonged to β-lactams ( blaTEM ), tetracyclines ( tetA, tetB, tetM ), fluroquinoloncs ( qnrD, qnrS ), chloramphenicols ( fexA, floR ), and aminoglycosides ( aac[6']-Ib for E. coli strains , aac[6']-Ie-aph[2”]-Ia for HLGR Enterococcsu spp. strains) were detected using established PCR methods for these target genes ( 9 , 25 – 27 ) ( Supplementary Table 1 .).…”