A potential role of extracellular DNA in biofilm and ciprofloxacin resistance


  • Hind Tahseen Ibrahim Department of Medical laboratory techniques, College of Medical (Technology), Al-Farahidi University, Baghdad, Iraq.
  • Ali A. Mussa Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq.
  • Harith Jabbar Fahad Al-Mathkhury Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq.




eDNA, Biofilm, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa


Objectives: This study aims to broaden our knowledge of the role of eDNA in bacterial biofilms and antibiotic-resistance gene transfer among isolates.

Methods: Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa were isolated from different non-repeated 170 specimens. The bacterial isolates were identified using morphological and molecular methods. Different concentrations of genomic DNA were tested for their potential role in biofilms formed by study isolates employing microtiter plate assay. Ciprofloxacin resistance was identified by detecting a mutation in gyrA and parC.

Results: The biofilm intensity significantly decreased (P < 0.05) concerning S. aureus isolates and insignificantly (P > 0.05) concerning E. coli isolates. Yet, one E. coli isolate's biofilm was significantly decreased (P < 0.05) linearly with increasing eDNA. Of considerable interest, the addition of eDNA led to a significant increase (P < 0.05) in the biofilm of the two-tested P. aeruginosa isolates. Moreover, eDNA participated in transferring Ciprofloxacin resistance to the sensitive isolate when it presents in its biofilm.

Conclusion: eDNA has a dual effect on bacterial biofilms either supportive or suppressive following bacterial species per se. Also, it seems to play an important role in antibiotic resistance within the biofilm.


Akmatov, M. K., Mehraj, J., Gatzemeier, A., Strompl, J., Witte, W., Krause, G., et al., Serial home-based self-collection of anterior nasal swabs to detect Staphylococcus aureus carriage in a randomized population-based study in Germany. Int J Infect Dis. 2014; 25: 4-10. doi:10.1016/j.ijid.2014.01.021

Junie, L. M., Simon, L. M., Pandrea, S. L. Resistance to the chemotherapeutic agents of Staphylococcus aureus strains isolated from hospitalized patients. International Journal of Infectious Diseases. 2014; 21: 79-80. doi:10.1016/j.ijid.2014.03.593

Rossi, E., Cimdins, A., Luthje, P., Brauner, A., Sjoling, A., Landini, P., et al., "It's a gut feeling" - Escherichia coli biofilm formation in the gastrointestinal tract environment. Crit Rev Microbiol. 2018; 44(1): 1-30. doi:10.1080/1040841X.2017.1303660

Bettelheim, K. A., Goldwater, P. N. Escherichia coli and Sudden Infant Death Syndrome. Front Immunol. 2015; 6: 343. doi:10.3389/fimmu.2015.00343

Blount, Z. D. The unexhausted potential of E. coli. Elife. 2015; 4. doi:10.7554/eLife.05826

Soukarieh, F., Vico Oton, E., Dubern, J. F., Gomes, J., Halliday, N., de Pilar Crespo, M., et al., In Silico and in Vitro-Guided Identification of Inhibitors of Alkylquinolone-Dependent Quorum Sensing in Pseudomonas aeruginosa. Molecules. 2018; 23(2). doi:10.3390/molecules23020257

Markou, P., Apidianakis, Y. Pathogenesis of intestinal Pseudomonas aeruginosa infection in patients with cancer. Front Cell Infect Microbiol. 2014; 3: 115. doi:10.3389/fcimb.2013.00115

Flemming, H. C., Wingender, J., Szewzyk, U., Steinberg, P., Rice, S. A., Kjelleberg, S. Biofilms: an emergent form of bacterial life. Nat Rev Microbiol. 2016; 14(9): 563-575. doi:10.1038/nrmicro.2016.94

Liu, Y., Ren, Z., Hwang, G., Koo, H. Therapeutic Strategies Targeting Cariogenic Biofilm Microenvironment. Adv Dent Res. 2018; 29(1): 86-92. doi:10.1177/0022034517736497

Mulcahy, H., Charron-Mazenod, L., Lewenza, S. Pseudomonas aeruginosa produces an extracellular deoxyribonuclease that is required for utilization of DNA as a nutrient source. Environ Microbiol. 2010; 12(6): 1621-1629. doi:10.1111/j.1462-2920.2010.02208.x

Wang, H., Huang, Y., Wu, S., Li, Y., Ye, Y., Zheng, Y., et al., Extracellular DNA inhibits Salmonella enterica Serovar Typhimurium and S. enterica Serovar Typhi biofilm development on abiotic surfaces. Curr Microbiol. 2014; 68(2): 262-268. doi:10.1007/s00284-013-0468-5

Harley, J. B. Laboratory Exercises in Microbiology. 10 ed: McGraw- Hill Education; 2016.

Jennifer, M. A. Determination of minimum inhibitory concentrations. J Antimicrob Chemother. 2001; 48: 5–16.

Martineau, F., Picard, F. J., Roy, P. H., Ouellette, M., Bergeron, M. G. Species-specific and ubiquitous-DNA-based assays for rapid identification of Staphylococcus aureus. J Clin Microbiol. 1998; 36(3): 618-623.

McClure, J. A., Conly, J. M., Lau, V., Elsayed, S., Louie, T., Hutchins, W., et al., Novel multiplex PCR assay for detection of the staphylococcal virulence marker Panton-Valentine leukocidin genes and simultaneous discrimination of methicillin-susceptible from -resistant staphylococci. J Clin Microbiol. 2006; 44(3): 1141-1144. doi:10.1128/JCM.44.3.1141-1144.2006

Anastasi, E. M., Matthews, B., Gundogdu, A., Vollmerhausen, T. L., Ramos, N. L., Stratton, H., et al., Prevalence and persistence of Escherichia coli strains with uropathogenic virulence characteristics in sewage treatment plants. Appl Environ Microbiol. 2010; 76(17): 5882-5886. doi:10.1128/AEM.00141-10

Gomig, F., Galvao, C. W., Freitas, D. L., Labas, L., Etto, R. M., Esmerino, L. A., et al., Quinolone resistance and ornithine decarboxylation activity in lactose-negative Escherichia coli. Braz J Microbiol. 2015; 46(3): 753-757. doi:10.1590/S1517-838246320131291

Pakzad, I., Zayyen Karin, M., Taherikalani, M., Boustanshenas, M., Lari, A. R. Contribution of AcrAB efflux pump to Ciprofloxacin resistance in Klebsiella pneumoniae isolated from burn patients. GMS Hyg Infect Control. 2013; 8(2): Doc15. doi:10.3205/dgkh000215

Nakao, R., Ramstedt, M., Wai, S. N., Uhlin, B. E. Enhanced biofilm formation by Escherichia coli LPS mutants defective in Hep biosynthesis. PLoS One. 2012; 7(12): e51241. doi:10.1371/journal.pone.0051241

Darbani, R., Farshadfar, C., Tavana, S., Saljoughi, H., Zonouri, S. S. Identification of DNA gyrase Subunit a Mutations Associated with Ciprofloxacin Resistance in Staphylococcus aureus Isolated from Nasal Infection in Kurdistan-Iran. J Mol Biol Res. 2017; 7(1): 186. doi:10.5539/jmbr.v7n1p186

Mathur, T., Singhal, S., Khan, S., Upadhyay, D., Fatma, T., Rattan, A. Detection of biofilm formation among the clinical isolates of staphylococci: an evaluation of three different screening methods. Indian Journal Medical Microbiology. 2006; 24: 25-29.

Mohammed, M. K., Rasheed, M. N., Nadeer, M. I. Detection of biofilm -associated genes in clinical Staphylococcus aureus isolates from iraqi patient. Iraqi J Sci Nat 2015; 6: 19-22.

Mathur, T., Singhal, S., Khan, S., Upadhyay, D. J., Fatma, T., Rattan, A. Detection of Biofilm Formation among the clinical isolates of staphylococci: an evaluation of three different screening methods. Indian J Med Microbiol. 2006; 24: 25-29.

Saeed, E. A., Bnyan, I. A., AL Saadi, M. A. K. Quorum sensing and Biofilm formation by Bacterial Isolates from Hemodialysis Patients. Research in Pharmacy. 2013; 3: 33-40.

Fattahi, S., Kafil, H. S., Nahai, M. R., Asgharzadeh, M., Nori, R., Aghazadeh, M. Relationship of biofilm formation and different virulence genes in uropathogenic Escherichia coli isolates from Northwest Iran. GMS Hyg Infect Control. 2015; 10: Doc11. doi:10.3205/dgkh000254

Ghafil, J. A. Assessment the effect of non-thermal plasma on Escherichia coli and Staphylococcus aureus biofilm formtion in vitro. Iraqi J Sci. 2018; 59: 25-29.

Archer, N. K., Mazaitis, M. J., Costerton, J. W., Leid, J. G., Powers, M. E., Shirtliff, M. E. Staphylococcus aureus biofilms: properties, regulation, and roles in human disease. Virulence. 2011; 2(5): 445-459. doi:10.4161/viru.2.5.17724

Barrett, L., Atkins, B. The clinical presentation of prosthetic joint infection. J Antimicrob Chemother. 2014; 69 Suppl 1: i25-27. doi:10.1093/jac/dku250

Chatterjee, S., Maiti, P., Dey, R., Kundu, A., Dey, R. Biofilms on indwelling urologic devices: microbes and antimicrobial management prospect. Ann Med Health Sci Res. 2014; 4(1): 100-104. doi:10.4103/2141-9248.126612

Kiedrowski, M. R., Horswill, A. R. New approaches for treating staphylococcal biofilm infections. Ann N Y Acad Sci. 2011; 1241: 104-121. doi:10.1111/j.1749-6632.2011.06281.x

Moormeier, D. E., Bayles, K. W. Staphylococcus aureus biofilm: a complex developmental organism. Mol Microbiol. 2017; 104(3): 365-376. doi:10.1111/mmi.13634

Lister, J. L., Horswill, A. R. Staphylococcus aureus biofilms: recent developments in biofilm dispersal. Front Cell Infect Microbiol. 2014; 4: 178. doi:10.3389/fcimb.2014.00178

Sharma, G., Sharma, S., Sharma, P., Chandola, D., Dang, S., Gupta, S., et al., Escherichia coli biofilm: development and therapeutic strategies. J Appl Microbiol. 2016; 121(2): 309-319. doi:10.1111/jam.13078

Berne, C., Kysela, D. T., Brun, Y. V. A bacterial extracellular DNA inhibits settling of motile progeny cells within a biofilm. Mol Microbiol. 2010; 77(4): 815-829. doi:10.1111/j.1365-2958.2010.07267.x

Özdemir, C., Karaca, B., Akçelik, N. The role of extracellular DNA in Salmonella biofilms: is it in intimate relationship with matrix or initial adhesion? 25th ECCMID Conference; Copenhagen, Denmark.2015.

Harmsen, M., Lappann, M., Knochel, S., Molin, S. Role of extracellular DNA during biofilm formation by Listeria monocytogenes. Appl Environ Microbiol. 2010; 76(7): 2271-2279. doi:10.1128/AEM.02361-09

Lappann, M., Claus, H., van Alen, T., Harmsen, M., Elias, J., Molin, S., et al., A dual role of extracellular DNA during biofilm formation of Neisseria meningitidis. Mol Microbiol. 2010; 75(6): 1355-1371. doi:10.1111/j.1365-2958.2010.07054.x

Mohamed, T. J., Rabeea, I. S., Abd, A. H., Abdulkhaleq, M. A. Efficacy of Combination of Meropenem with Ciprofloxacin, and Nitrofurantoin Against Resistant E. coli Isolated from Patients with Urinary Tract Infections: in vitro Study. AL-Yarmouk Journal. 2011; special volume: 61-75.

Al-Jebouri, M. M., Mdish, S. A. Antibiotic Resistance Pattern of Bacteria Isolated from Patients of Urinary Tract Infections in Iraq. Open Journal of Urology. 2013; 03(02): 124-131. doi:10.4236/oju.2013.32024

AL-Marjani, M. F., Kadhim, K. A., A., K. A., Kinani, A. Ciprofloxacin Resistance in Staphylococcus aureus and Pseudomonas aeruginosa Isolated from Patients in Baghdad. International Journal of Pharma Sciences and Research. 2015; 6 382-385.

Abdullah, F. E., Memon, A. A., Bandukda, M. Y., Jamil, M. Increasing Ciprofloxacin resistance of isolates from infected urines of a cross-section of patients in Karachi. BMC Res Notes. 2012; 5: 696. doi:10.1186/1756-0500-5-696

Thomas, C. M., Nielsen, K. M. Mechanisms of, and barriers to, horizontal gene transfer between bacteria. Nat Rev Microbiol. 2005; 3(9): 711-721. doi:10.1038/nrmicro1234

Kaneko, S., Itaya, M. Stable extracellular DNA: a novel substrate for genetic engineering that mimics horizontal gene transfer in nature In: Kikuchi, Y., Rykova, E. Y., editors. Extracellular Nucleic Acids. Nucleic Acids and Molecular Biology Series. 25 ed. Berlin, Heidelberg: Springer-Verlag; 2010. p. 3953.

Bjorklof, K., Nurmiaho-Lassila, E. L., Klinger, N., Haahtela, K., Romantschuk, M. Colonization strategies and conjugal gene transfer of inoculated Pseudomonas syringae on the leaf surface. J Appl Microbiol. 2000; 89(3): 423-432. doi:10.1046/j.1365-2672.2000.01130.x

Springael, D., Peys, K., Ryngaert, A., Van Roy, S., Hooyberghs, L., Ravatn, R., et al., Community shifts in a seeded 3‐chlorobenzoate degrading membrane biofilm reactor: indications for involvement of in situ horizontal transfer of the clc‐element from inoculum to contaminant bacteria. Environ Microbiol. 2002; 4: 70-80.

Molin, S., Tolker-Nielsen, T. Gene transfer occurs with enhanced efficiency in biofilms and induces enhanced stabilisation of the biofilm structure. Current Opinion in Biotechnology. 2003; 14(3): 255-261. doi:10.1016/s0958-1669(03)00036-3

Roberts, A. P., Pratten, J., Wilson, M., Mullany, P. Transfer of a conjugative transposon, Tn5397 in a model oral biofilm. FEMS Microbiol Lett. 2006; 177: 63-66.

Spoering, A. L., Gilmore, M. S. Quorum sensing and DNA release in bacterial biofilms. Curr Opin Microbiol. 2006; 9(2): 133-137. doi:10.1016/j.mib.2006.02.004

Sykes, R. The 2009 Garrod lecture: the evolution of antimicrobial resistance: a Darwinian perspective. J Antimicrob Chemother. 2010; 65(9): 1842-1852. doi:10.1093/jac/dkq217

Dillard, J. P., Seifert, S. A variable genetic island specific for Neisseria gonorrhoeae is involved in providing DNA for natural transformation and is found more often in disseminated infection isolates. Mol Microbiol. 2001; 41: 263-277. doi:10.1046/j.1365-2958.2001.02520.x




How to Cite

Tahseen Ibrahim, H. ., A. Mussa, A. ., & Jabbar Fahad Al-Mathkhury, H. (2023). A potential role of extracellular DNA in biofilm and ciprofloxacin resistance. Journal of Contemporary Medical Sciences, 9(2). https://doi.org/10.22317/jcms.v9i2.1338