β-Lactamase diversity in <i>Acinetobacter baumannii</i>
Andrew R Mack, Andrea M. Hujer, María F. Mojica, Magdalena A. Taracila, Michael Feldgarden, Daniel H. Haft, William Klimke, Arjun Prasad, Robert A. Bonomo
Abstract
ABSTRACT Acinetobacter baumannii is a clinically important, Gram-negative pathogen responsible for a wide variety of nosocomial and community-acquired infections. Antibiotic resistance is a serious concern, as the organism has a wide variety of intrinsic resistance mechanisms, including chromosomal class C ( bla ADC ) and D ( bla OXA-51 family) β-lactamases, and the ability to readily acquire additional β-lactamases. Surveillance studies can reveal the diversity and distribution of β-lactamase alleles, but are difficult and expensive to conduct. Herein, we describe an approach using publicly available data derived from whole genome sequences, to explore the diversity and distribution of β-lactamase alleles across 28,330 isolates. The most common intrinsic alleles at the time of writing were bla ADC-73 , bla ADC-30 , bla ADC-222 , bla ADC-33 , and bla OXA-66 , and the most common acquired allele was bla OXA-23 . Interestingly, only 63.0% of assigned bla ADC alleles were encountered and the 10 most common bla ADC and intrinsic bla OXA alleles represented approximately 75% of their respective gene totals while dozens were extremely infrequent. Differences were observed over time and geography. Surprisingly, more distinct unassigned (i.e., lacking a bla ADC or bla OXA number) alleles were encountered than distinct, assigned alleles. Understanding the diversity and distribution of β-lactamase alleles helps to prioritize variants for further research, selects targets for drug development, and may aid in selecting therapies for a given infection.