Abstract
Acinetobacter baumannii is an opportunistic bacterial pathogen associated with hospital-acquired infections, including pneumonia, meningitis, bacteremia, urinary tract infection, and wound infections. Recognition of host cell surface carbohydrates plays a crucial role in adhesion and enables microbes to colonize different host niches. Here the potential glycosphingolipid receptors of A. baumannii were examined by binding of 35S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. Thereby a selective interaction with two non-acid glycosphingolipids of human and rabbit small intestine was found. The binding-active glycosphingolipids were isolated and, on the basis of mass spectrometry, identified as neolactotetraosylceramide (Galβ4GlcNAcβ3Galβ4Glcβ1Cer) and lactotetraosylceramide (Galβ3GlcNAcβ3Galβ4Glcβ1Cer). Further binding assays using reference glycosphingolipids showed that A. baumannii also bound to lactotriaosylceramide (GlcNAcβ3Galβ4Glcβ1Cer) demonstrating that GlcNAc was the basic element recognized. In addition, the bacteria occasionally bound to galactosylceramide, lactosylceramide with phytosphingosine and/or hydroxy fatty acids, isoglobotriaosylceramide, gangliotriaosylceramide, and gangliotetraosylceramide, in analogy with binding patterns that previously have been described for other bacteria classified as “lactosylceramide-binding”. Finally, by isolation and characterization of glycosphingolipids from human skin, the presence of neolactotetraosylceramide was demonstrated in this A. baumannii target tissue.
Highlights
Acinetobacter baumannii is emerging as a worldwide problem as a nosocomial pathogen in hospitalized patients
Hboinwdeivnegr,oinf mA.osbtanuomna-nanciidi tgolyacnoyspahcinidgoglliypcidosfprahcitniognosliapibdins.dinHgoowf ethveerb,aicntemriaost ndoigntFnlo-yioagccncuoo-irdamseycgpild1cloye,ufcrrlnaoaamsdncptseiihdsominen1isggr–eroo4aglf)it.ipironaIinndgbsbifwanirtdatacsdhstmieitooiambnollsnsoei,nanrovatbe-eisnndatndui(ndimenexd,gbeiremogarflbpytobclhfiiotfeismetbyhdaloyccriemtnereaurFsimsial,goitruwdoare-tecmroi1enmig,gtelirpaosaontntiuiesnnsnewgd,1a–asgsn4mlo)yd.bcigIhosnreusarpamtvhdienaiddngnigt(isieonomxlnitepah,mliealdpmisnnliuotfieimnnesodtbti-nheianreenodf mowreesrelodwis-mtinigctrlaytirnegcogglyncizoesdphbiyngthoelipbiadcsteirniath(Feingounre-a1c,idlanfreasct1i–o4n)s. of rabbit small intestine, rabbit thymus, rat intestine, and human small intestine were distinctly recognized by the bacteria (Figure 1, lanes 1–4)
Thereby we found that A. baumannii bound to lactotriaosylceramide (Figure 4E,F, lane 2), in addition to neolactotetraosylceramide and lactotetraosylceramide
Summary
Acinetobacter baumannii is emerging as a worldwide problem as a nosocomial pathogen in hospitalized patients. These bacteria primarily cause pneumonia, but they are frequent causes of wound and burn infections, bacteremia, meningitis, urinary tract infections, and skin and soft tissue infections. A. baumannii has been classified as highest priority on the recently published WHO list of pathogens needing research and development of new antibiotics [1]. The ability of A. baumannii to survive for an extended period of time on artificial surfaces allows it to persist in the hospital environment. This is due to its ability to form biofilms [2].
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