Emergence of Colistin-Resistant <i>Acinetobacter junii</i> in China

• Main Authors: Zhiren Wang (Author), Xuanyang Fan (Author), Shuyi Wang (Author), Shuguang Li (Author), Yue Gao (Author), Hui Wang (Author), Henan Li (Author)
• Format: Book
• Published: MDPI AG, 2022-11-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

The increasing number of multidrug-resistant Gram-negative bacteria presents a serious threat to global health. However, colistin-resistant <i>Acinetobacter junii</i> has rarely been reported. We identified a colistin-resistant <i>A. junii</i> clinical isolate, AJ6079, in blood. The colony of AJ6079 presented a dry phenotype, and it was difficult to form a bacterial suspension, whilst transmission electron microscopy revealed that AJ6079 possessed a thick outer membrane. The phenotypic and genomic comparisons were conducted with one colistin-susceptible <i>A. junii</i>, which had the same antibiotic susceptibility profile except for colistin, and had the same KL25 capsule biosynthesis locus. The AJ6079 exhibited a slower growth rate, indicating that colistin-resistant <i>A. junii</i> possesses a higher fitness cost. The genome of AJ6079 had a G+C content of 38.7% and contained one 3,362,966 bp circular chromosome with no plasmid or mobile colistin resistance (<i>mcr</i>) gene. Comparative genomic analysis revealed that the AJ6079 contained several previously unreported point mutations in colistin-resistance-related genes involving amino acid substitutions in PmrB (N5K, G147C), LpxA (I107F, H131Y), and LpxD (F20I, K263R), which might be correlated with colistin resistance in <i>A. junii</i>. Further research is needed for verification as the genetic background was not exactly the same between the two isolates.

Item Description

10.3390/antibiotics11121693
2079-6382