# Characterization of a novel aminoglycoside resistance gene, aadA34, identified from Serratia ureilytica S24

## TL;DR

A new gene called aadA34 was found in a bacteria from poultry farm sewage, which makes it resistant to certain antibiotics.

## Contribution

The discovery of aadA34, a novel aminoglycoside resistance gene with high catalytic efficiency and unique length.

## Key findings

- The aadA34 gene provides resistance to spectinomycin and streptomycin with MIC increases of 64- and 128-fold.
- AadA34 shares 60.09% amino acid identity with AadA16 but is approximately 160 amino acids longer.
- The gene is commonly found in Serratia species, including clinically relevant ones like S. ureilytica and S. marcescens.

## Abstract

Bacterial resistance to aminoglycoside drugs is becoming increasingly severe due to their widespread use in agriculture and human medicine. Based on the whole-genome sequencing and molecular methods, a novel aminoglycoside resistance gene designated aadA34 was identified from a multiple-drug-resistant bacterium Serratia ureilytica S24, which was isolated from sewage at a poultry farm. The aadA34 gene conferred resistance to spectinomycin and streptomycin, with MIC levels increased by 64- and 128-fold, respectively, for spectinomycin and streptomycin compared with the control strain (pUCP20/E. coli DH5α). The amino acid (aa) sequence of AadA34 was found to share the highest identity (60.09%) with the function-characterized aminoglycoside nucleotidyltransferase AadA16. Corresponding to the MIC results of the aadA34 gene, the enzyme AadA34 exhibited high affinity and catalytic efficiency against spectinomycin or streptomycin. Approximately 160 aa longer than other functionally characterized AadA proteins, the aadA34 gene was found to be generally encoded in bacteria of the genus Serratia, especially in the species S. ureilytica and S. marcescens, which were isolated from various sources including some of clinical significance.