In the past few years the increasing incidence of hospital infections with Acinetobacter baumannii, especially in immunocompromised patients, and its proneness to develop multidrug resistance have been raising considerable concern. This study examines the antimicrobial and antibiofilm activity of protegrin 1 (PG-1), an antimicrobial peptide from porcine leukocytes, against A. baumannii strains isolated from surgical wounds. PG-1 was tested both alone and combined with the antibiotics commonly used in clinical settings. Its antimicrobial activity was evaluated by determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), checkerboard assays, and time-kill experiments. Its effects on biofilm inhibition/eradication were tested with crystal violet staining. The strains were grown in subinhibitory or increasing PG-1 concentrations to test the development of resistance. Mammalian cell toxicity was tested by XTT assays. PG-1 MICs and MBCs ranged from 2 to 8 µg/ml. PG-1 was most active and demonstrated a synergistic interaction with colistin, a last resort antibiotic. Interestingly, antagonism was never observed. In time-kill experiments, incubation with 2 × MIC for 30 min suppressed all viable cells. PG-1 did not select resistant strains and showed a limited effect on cell viability, but it did exert a strong activity against multidrug-resistant A. baumannii. In contrast, in our experimental conditions it had no effect on biofilm inhibition/eradication. PG-1 thus seems to be a promising antimicrobial agent against multidrug-resistant Gram-negative infections.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
O’Neill J (2016) Tackling drug-resistant infections globally: final report and recommendations. The review on antimicrobial resistance. http://amr-review.org/sites/default/files/160525_Final%20paper_with%20cover.pdf. Accessed 19 May 2016
Van Duin D, Doi Y (2017) The global epidemiology of carbapenemase-producing Enterobacteriaceae. Virulence 8:460–469. https://doi.org/10.1080/21505594.2016.1222343
Lee C-R, Lee JH, Park M, Park KS, Bae IK, Kim YB, Cha C-J, Jeong CB, Lee SH (2017) Biology of Acinetobacter baumannii: pathogenesis, antibiotic resistance mechanisms, and prospective treatment options. Front Cell Infect Microbiol 7:55. https://doi.org/10.3389/fcimb.2017.00055
Spellberg B, Rex JH (2013) The value of single-pathogen antibacterial agents. Nat Rev Drug Discov 12:963. https://doi.org/10.1038/nrd3957-c1
Qureshi ZA, Hittle LE, O’Hara JA, Rivera JI, Syed A, Shields RK, Pasculle AW, Ernst RK, Doi Y (2015) Colistin-resistant Acinetobacter baumannii: beyond carbapenem resistance. Clin Infect Dis 60:1295–1303. https://doi.org/10.1093/cid/civ048
Navon-Venezia S, Leavitt A, Carmeli Y (2007) High tigecycline resistance in multidrug-resistant Acinetobacter baumannii. J Antimicrob Chemoter 59:772–774. https://doi.org/10.1093/jac/dkm018
Mahlapuu M, Hakansson J, Ringstad L, Bjorn C (2016) Antimicrobial peptides: an emerging category of therapeutic agents. Front Cell Infect Microbiol 6:194. https://doi.org/10.3389/fcimb.2016.00194
Pletzer D, Hancock REW (2016) Antibiofilm peptides: potential as broad-spectrum agents. J Bacteriol 198:2572–2578. https://doi.org/10.1128/JB.00017-16
Rodziewicz-Motowidło S, Mickiewicz B, Greber K, Sikorska E, Szultka L, Kamysz E, Kamysz W (2010) Antimicrobial and conformational studies of the active and inactive analogues of the protegrin-1 peptide. FEBS J 277:1010–1022. https://doi.org/10.1111/j.1742-4658.2009.07544.x
Steinberg DA, Hurst MA, Fujii CA, Kung AHC, Ho JF, Cheng FC, Loury DJ, Fiddes JC (1997) Protegrin-1: a broad spectrum, rapidly microbicidal peptide with in vivo activity. Antimicrob Agents Chemoter 41:1738–1742. https://doi.org/10.1128/AAC.41.8.1738
Yan H, Hancock REW (2001) Synergistic interaction between mammalian antimicrobial defense peptides. Antimicrob Agents Chemoter 45:1558–1560. https://doi.org/10.1128/AAC.45.5.1558-1560.2001
Marini E, Magi G, Mingoia M, Pugnaloni A, Facinelli B (2015) Antimicrobial and anti-virulence activity of capsaicin against erythromycin-resistant, cell-invasive group A streptococci. Front Microbiol 6:1281. https://doi.org/10.3389/fmicb.2015.01281
Nhu NTK, Riordan DW, Nhu TDH, Thanh DP, Thwaites G, Lan NPH, Wren BW, Baker S, Stabler RA (2016) The induction and identification of novel colistin resistance mutations in Acinetobacter baumannii and their implications. Sci Rep 6:28291. https://doi.org/10.1038/srep28291
Edwards IA, Elliot AG, Kavanagh AM, Zuegg J, Blaskovich MAT, Cooper MA (2016) Contribution of amphipathicity and hydrophobicity to the antimicrobial activity and cytotoxicity of β-hairpin peptides. ACS Infect Dis 2:442–450. https://doi.org/10.1021/acsinfecdis.6b00045
Vila-Farris X, Garcia de la Maria C, Lopez-Rojas R, Pachon J, Giralt E, Vila J (2011) In vitro activity of several antimicrobial peptides against colistin-susceptible and colistin-resistant Acinetobacter baumannii. Clin Microbiol Infect 18:383–387. https://doi.org/10.1111/j.1469-0691.2011.03581.x
Falagas ME, Kasiakou SK (2005) Colistin: the revival of polymyxins for the management of multi-drug resistant Gram-negative bacterial infections. Clin Infect Dis 42:1333–1341. https://doi.org/10.1086/429323
Lai PK, Kaznessis YN (2018) Insights into membrane translocation of protegrin antimicrobial peptides by multistep molecular dynamics simulations. ACS Omega 3:6056–6065. https://doi.org/10.1021/acsomega.8b00483
Simonetti O, Cirioni O, Ghiselli R, Orlando F, Silvestri C, Mazzoccato S, Kamysz W, Kamysz E, Provinciali M, Giacometti A, Guerrieri M, Offidani A (2014) In vitro activity and in vivo animal model efficacy of IB-367 alone and in combination with imipenem and colistin against Gram-negative bacteria. Peptides 55:17–22. https://doi.org/10.1016/j.peptides.2014.01.029
Cirioni O, Simonetti O, Pierpaoli E, Barucca A, Ghiselli R, Orlando F, Pelloni M, Minardi D, Cappelletti Trombettoni MM, Guerrieri M, Offidani A, Giacometti A, Provinciali M (2016) Enhanced efficacy of combinations of pexiganan with colistin versus Acinetobacter baumannii in experimental sepsis. Shock 46:219–225. https://doi.org/10.1097/SHK.0000000000000584
Nizet V (2006) Antimicrobial peptide resistance mechanism of human bacterial pathogens. Curr Issues Mol Biol 8:11–26
We are grateful to Prof. Gian Maria Rossolini and Dr. Alberto Antonelli for providing the colistin-resistant A. baumannii strains.
This work was supported by “Progetto Strategico di Ateneo 2016 – UNIVPM: Study of new compounds and innovative strategies to control complicated bacterial skin infections”.
Conflict of interest
The authors declare that they have no conflict of interest.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Edited by: Volkhard A. J. Kempf.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Checkerboard assays performed with serial dilutions of colistin (rows) and PG-1 (columns). Red squares: no growth; green squares: growth (TIFF 675 kb)
Quantification of the biofilms formed by the six representative A. baumannii strains. Panel A: biofilm formation assay. Panel B: biofilm reduction assay. Error bars represent ± SD. (TIFF 405 kb)
XTT assays involving HeLa ATCC CCL-2 cells exposed to different PG-1 concentrations. Red histograms, 48 h; blue histograms, 24 h. Concentrations (x-axis) are expressed in µg/ml; cell viability (y-axis) is expressed as percentage compared to control. Error bars represent ± SD. Asterisks indicated significant results vs the control group (p < 0.05) (TIFF 497 kb)
About this article
Cite this article
Morroni, G., Simonetti, O., Brenciani, A. et al. In vitro activity of Protegrin-1, alone and in combination with clinically useful antibiotics, against Acinetobacter baumannii strains isolated from surgical wounds. Med Microbiol Immunol 208, 877–883 (2019). https://doi.org/10.1007/s00430-019-00624-7
- Acinetobacter baumannii
- Antimicrobial peptides
- Checkerboard assay