title: Perturbations of Phosphatidate Cytidylyltransferase (CdsA) Mediate Daptomycin Resistance in Streptococcus mitis/oralis by a Novel Mechanism.
abstract: Streptococcus mitis/oralisis an important pathogen, causing life-threatening infections such as endocarditis and severe sepsis in immunocompromised patients. The β-lactam antibiotics are the usual therapy of choice for this organism, but their effectiveness is threatened by the frequent emergence of resistance. The lipopeptide daptomycin (DAP) has been suggested for therapy against such resistantS. mitis/oralisstrains due to itsin vitrobactericidal activity and demonstrated efficacy against other Gram-positive pathogens. Unlike other bacteria, however,S. mitis/oralishas the unique ability to rapidly develop stable, high-level resistance to DAP upon exposure to the drug bothin vivoandin vitroUsing isogenic DAP-susceptible and DAP-resistantS. mitis/oralisstrain pairs, we describe a mechanism of resistance to both DAP and cationic antimicrobial peptides that involves loss-of-function mutations incdsA(encoding a phosphatidate cytidylyltransferase). CdsA catalyzes the synthesis of cytidine diphosphate-diacylglycerol, an essential phospholipid intermediate for the production of membrane phosphatidylglycerol and cardiolipin. DAP-resistantS. mitis/oralisstrains demonstrated a total disappearance of phosphatidylglycerol, cardiolipin, and anionic phospholipid microdomains from membranes. In addition, these strains exhibited cross-resistance to cationic antimicrobial peptides from human neutrophils (i.e., hNP-1). Interestingly, CdsA-mediated changes in phospholipid metabolism were associated with DAP hyperaccumulation in a small subset of the bacterial population, without any binding by the remaining larger population. Our results indicate that CdsA is the major mediator of high-level DAP resistance inS. mitis/oralisand suggest a novel mechanism of bacterial survival against attack by antimicrobial peptides of both innate and exogenous origins.
authors.affiliation: LA Biomedical Research Institute, Torrance, California, USA.|Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Nagendra N
authors.initials: NN
authors.lastname: Mishra
authors.affiliation: Center for Antimicrobial Resistance and Microbial Genomics, Division of Infectious Diseases, University of Texas McGovern School of Medicine, Houston, Texas, USA.
authors.forename: Truc T
authors.initials: TT
authors.lastname: Tran
authors.affiliation: University of California, San Francisco, California, USA.|VA Medical Center, San Francisco, California, USA.
authors.forename: Ravin
authors.initials: R
authors.lastname: Seepersaud
authors.affiliation: Hospital Clinic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Garcia-de-la-Maria
authors.affiliation: Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Kym
authors.initials: K
authors.lastname: Faull
authors.affiliation: Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Yoon
authors.affiliation: Departments of Medical Microbiology & Immunology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Proctor
authors.affiliation: Hospital Clinic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Miro
authors.affiliation: Anti-Infective Research Laboratory, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rybak
authors.affiliation: LA Biomedical Research Institute, Torrance, California, USA abayer@labiomed.org cesar.arias@uth.tmc.edu.|Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Arnold S
authors.initials: AS
authors.lastname: Bayer
authors.affiliation: Center for Antimicrobial Resistance and Microbial Genomics, Division of Infectious Diseases, University of Texas McGovern School of Medicine, Houston, Texas, USA abayer@labiomed.org cesar.arias@uth.tmc.edu.|Antimicrobial Resistance Unit and International Center for Microbial Genomics, Universidad El Bosque, Bogota, Colombia.
authors.forename: Cesar A
authors.initials: CA
authors.lastname: Arias
authors.affiliation: University of California, San Francisco, California, USA.|VA Medical Center, San Francisco, California, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Sullam
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003565:Cytidine Diphosphate / Q000378:metabolism; D017576:Daptomycin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D009504:Neutrophils / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000378:metabolism*; D019533:Streptococcus oralis / Q000187:drug effects* / Q000201:enzymology*
chemical_list: D000900:Anti-Bacterial Agents; D003565:Cytidine Diphosphate; D009713:Nucleotidyltransferases; C022348:phosphatidate cytidylyltransferase; D017576:Daptomycin
keywords: Streptococcus mitis/oralis; daptomycin resistance; phosphatidate cytidylyltransferase