Characterizing the response of Acinetobacter baumannii ATCC 17978 to azithromycin in multiple in vitro growth conditions

Abstract

Multi-drug resistant (MDR) Acinetobacter baumannii is one of the most concerning pathogens in hospital infections. A. baumannii is categorized as an "Urgent Threat" by the U.S. Centers for Disease Control and the highest priority pathogen by the World Health Organization due to its propensity for broad antibiotic resistance and its associated high mortality rates. New treatment options are urgently needed for MDR A. baumannii infections. Our prior studies have demonstrated an unappreciated utility of the macrolide azithromycin (AZM) against MDR A. baumannii in tissue-culture medium. This finding is all the more surprising since AZM has no appreciable activity against A. baumannii in standard bacteriological media. The basis for this media-dependent activity of AZM against A. baumannii is not fully defined. In this study, we utilize a variety of techniques (growth dynamics, bacterial cytological profiling, RNA sequencing, and LC/MS) to profile the response of MDR A. baumannii to AZM in both standard bacteriological and more physiological relevant mammalian tissue-culture medium. Design type(s)• replicate design • transcription profiling design • sequence analysis objective Measurement(s) • minimal inhibitory concentration • cDNA • transcription profiling assay • timecourse exo metabolome • cellular morphology • bacterial growth • Genome sequence Technology Type(s) • RNA sequencing • fluorescence microscopy • liquid chromatography-tandem mass spectrometry • optical density measurement • Nanopore MinION • Illumina Hiseq 4000 Factor Type(s) • culture medium • biological replicate • experimental condition Sample Characteristic(s) • Acinetobacter baumannii • culturing environment

A Systematic Study of the Stability, Safety, and Efficacy of the de novo Designed Antimicrobial Peptide PepD2 and Its Modified Derivatives Against Acinetobacter baumannii

“…Following CLSI guideline M07-A11, single bacterial colonies of A. baumannii ATCC 17978 grown on Müller-Hinton agar (MHA) plates were picked and inoculated in 4 mL of Müller-Hinton broth (MHB) at 37 • C and shaken at 180 rpm for 4∼6 h. The bacterial broth was diluted in the same medium to give a cell density of 1∼2 × 10 8 CFU/mL (OD 600 = 0.38∼0.4 for A. baumannii) (Supplementary Figure 1; Dillon et al, 2020). Then, the broth was diluted 20-fold.…”