Lytic transglycosylase contributes to the survival of lipooligosaccharide-deficient, colistin-dependent Acinetobacter baumannii
- Authors
- Lee, J.-Y.; Lee, H.; Park, M.; Cha, Chang-Jun; Shin, D.; Ko, K.S.
- Issue Date
- Sep-2019
- Publisher
- Elsevier B.V.
- Keywords
- Acinetobacter baumannii; Colistin dependence; Lytic transglycosylase; relA; spoT
- Citation
- Clinical Microbiology and Infection, v.25, no.9, pp 1156.e1 - 1156.e7
- Journal Title
- Clinical Microbiology and Infection
- Volume
- 25
- Number
- 9
- Start Page
- 1156.e1
- End Page
- 1156.e7
- URI
- https://scholarworks.bwise.kr/cau/handle/2019.sw.cau/18439
- DOI
- 10.1016/j.cmi.2019.02.004
- ISSN
- 1198-743X
1469-0691
- Abstract
- Objectives: The phenomenon of colistin dependence in Acinetobacter baumannii has been described in a situation in which colistin is now considered as the last resort for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. In this study, we aimed to reveal a gene associated with colistin dependence in A. baumannii. Methods: The colistin-dependent A. baumannii H08-391D strain was isolated from a patient, and target gene-inactivation mutants were constructed. We investigated the effects of target gene on colistin dependence with quantitative real-time PCR and endotoxin assay. Also, we observed the change of cell morphology by electron microscopy. Results: The expression of ACICU_02898, encoding a soluble lytic transglycosylase associated with cell-wall degradation and recycling, was increased by eight-to 42-fold in colistin-dependent mutants, and deletion of ACICU_02898 in a colistin-dependent strain led to colistin susceptibility (MIC = 8 mg/L). Endotoxin activity was significantly low in a colistin-dependent derivative ACICU_02898-inactivated mutant and a complemented mutant. In addition, the ACICU_02898-inactivated mutant showed a highly reduced growth rate. The colistin-dependent derivative and ACICU_02898-inactivated mutant showed clearly distinguished absorption profiles in the red/green fluorescence dot blot with regard to their membrane potential. Electron microscopy revealed that the deletion mutant cells were elongated compared to the colistin-susceptible wild-type strain and colistin-dependent strain. Conclusions: A colistin-dependent A. baumannii strain exhibited a deficiency in its outer membrane integrity and high expression of lytic transglycosylase was required for survival. This study reveals why the colistin-dependent mutant can tolerate high antibiotic concentrations. © 2019 European Society of Clinical Microbiology and Infectious Diseases
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Collections - College of Biotechnology & Natural Resource > Department of Systems Biotechnology > 1. Journal Articles
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