Phage research group

The phage research group at Rīga Stradiņš University (RSU) is composed of various specialists who conduct daily research on the possible use of bacteriophages in the prevention and treatment of resistant bacterial infections.

The focus of group's research activity is on multidrug resistant bacteria such as K.pneumoniae, P. aeruginosa, E. coli, MRSA, and others. The group assesses the phage lytic effect in bacterial biofilms as well as the possible application strategies of bacteriophages to limit biofilm-associated infections. One of the directions of the group's scientific activity is to study and evaluate bacteriophage interactions with antibiotics. To prevent infections associated with biomaterials, solutions are being studied to impregnate bacteriophages in biomaterials.

Head of the group

Asst. Prof., Dr. med. Kārlis Rācenis – Vice-Dean for research at the faculty of medicine of Rīga Stradiņš University (RSU), an internist and a nephrologist. He coordinates interdisciplinary research and assesses patients’ clinical situations and the potential for bacteriophage therapy in individual cases. He also takes part in interdisciplinary case reviews and is directly involved in developing individualised bacteriophage therapy solutions. In December 2023 he defended his doctoral thesis on bacteriophages. It was the first comprehensive study in Latvia of the antibacterial activity of bacteriophages against multidrug-resistant and biofilm-forming infections. K. Rācenis leads and takes part in several research projects and supervises four doctoral students.

Lead researcher

Prof. Juta Kroiča, PhD, is a clinical microbiologist with many years of experience in organizing and leading research. She helps develop the group’s new research ideas and directions and contributes to analysing and interpreting results. In the group’s work she focuses on identifying, analysing and assessing the risks of bacteriophage use, supporting the development of evidence-based and safe strategies for applying bacteriophages.

Researchers

Dr. biol. Nikita Zrelovs – a researcher with a wide range of skills, starting from traditional micro- and molecular biology to bioinformatics. Using multidisciplinary approaches, Zrelovs has already participated in the isolation of several dozen unknown tailed bacteriophages and has described their properties with the aim of expanding the known diversity of phages. Within the group, he determines and analyses the full genome sequences of phages and their hosts isolated in our laboratory. In February 2024, Zrelovs defended his doctoral thesis, “Expansion of the Known Tailed Bacteriophage Diversity One Phage at a Time”.

Dr Dace Eglīte – is a clinical microbiologist and PhD candidate. Her research focuses on the impregnation of biomaterials with bacteriophages as antimicrobial agents. Such modified or newly synthesised impregnated biomaterials are intended for the prevention and treatment of biomaterial-associated infections - a field in which rising antimicrobial resistance and biofilm formation limit the efficacy of conventional antibacterial therapy. Dace contributes expertise in clinical microbiology to the group's research activities, bridging biomaterial development and its clinical application.

Laima Sevastjanova, MPharm, MSc Clin. Pharm. is a pharmacist. In the group, her main tasks are to study and evaluate the efficacy of antibiotics, bacteriophages and their combinations, and to refine the laboratory methods used. Laima is interested in finding new ways to improve treatment, so her current research focuses on incorporating bacteriophages into various dosage forms.

Lïse Berentsen, MSc Biomedical Sciences – researcher with international experience in both microbiology and molecular biology. She has always had a broad interest in multiple fields of biology and gained extensive research experience with various microbes since her bachelor studies. Her main research interest is combating biofilm producing and multi-resistant bacteria.

Dr Sandis Mauriņš – is a neurology resident. He is interested in ways to reduce antimicrobial resistance, which has become a global problem. He sees bacteriophage therapy as a potential alternative for treating multidrug-resistant bacterial infections in modern medicine.

Nikola Brauča – works in bacteriophage research, specialising in isolating bacteriophages from environmental samples and characterising them. Her research interests include bacteriophage diversity, biological properties and potential applications. Nikola is particularly interested in developing bacteriophage research in Latvia and exploring new possibilities for their use in medicine.

Dr Renāte Rūta Apse has a particular interest in the use and efficacy of bacteriophages in treating patients infected with various resistant bacterial strains.

Kitija Straumane – biomedical and research laboratory technician who prepares resistant bacteria sensitivity tests daily and contributes to the biobank's stock for further phage isolation. Works at a clinical university hospital and is also studying to become a physician assistant at RSU Red Cross Medical College.

Jānis Tikmers is a student at the Faculty of Medicine who is interested in ways to reduce antimicrobial resistance. He sees bacteriophage therapy as a potential alternative for treating multidrug-resistant bacterial infections.

Māra Aleksandra Kariņa is a student at the Faculty of Medicine with a strong interest in the potential use of bacteriophages to treat multidrug-resistant bacterial infections.

Phage research group during the RSU Research Week 2025 (left to right): Ņikita Zrelovs, Laima Sevastjanova, Renāte Rūta Apse, Prof. Juta Kroiča, Asst. Prof. Kārlis Rācenis, Lise Berentsen, Līga Stīpniece, Dace Rezevska and Sandis Mauriņš

Lytic P. aeruginosa bacteriophage on double layer TSA plates

Presence of Siphovirus in Transmission Electron Microscopy

Lytic effect of eleven different bacteriophages in uropathogenic E. coli

Latest scientific publications and results

Green S, Niazi M, Kazmirchuk A, Rubchuk O, Sanko O, Tretiakov V, Carattoli A, Bogaerts P, Tournebize R, Lannoy V, Eckert C, D’Aliesio E, Ceyssens PJ, Costescu Strachinaru DI, Steurs G, Cochez C, Griselain J, Merabishvili M, Stoefs A, Racenis K, Alt V, Wagemans J, Lê TL, Vriens E, Lavigne R, Pirnay JP. Genomic epidemiology of conflict-associated Klebsiella pneumoniae in Ukraine reveals a high-risk clone with a hybrid plasmid vulnerable to phages. bioRxiv [Preprint]. 2026 Jan 21;2026.01.21.700813. doi: 10.64898/2026.01.21.700813
Walter N, Amanatullah DF, Debarbieux L, Doub JB, Ferry T, Groß J, Międzybrodzki R, Mirzaei MK, Deng L, Racenis K, Suh GA, Que YA, Górski A, Rupp M. Performance of large language models as a source of clinical information on bacteriophage therapy. npj Viruses. 2026;4:41. doi: 10.1038/s44298-026-00224-2
Eglīte D, Chen YH, Mauriņš S, Rācenis K, Kroiča J, Stīpniece L. Toward Phage Delivery: Metal Ions Effect on Stability and Encapsulation in Alginate Hydrogels. In: Abstract Book: Viruses of Microbes 2026. Prague, Czech Republic; 2026. p. 875–876. Abstract WE73
Classen AY, Clokie MRJ, Giske CG, Paz RN, Pirnay JP, Resch G, Laurent F; EUCAST Phage Susceptibility Testing Subcommittee. Towards a reference methodology for bacteriophage susceptibility testing - position paper of the EUCAST Phage Susceptibility Testing Subcommittee. Clin Microbiol Infect. 2026 Nov;32(11):1817-1822. doi: 10.1016/j.cmi.2026.06.005
Brauča, N., Rezevska, D., Jansons, J., Svanberga, K., Rācenis, K., Kroiča, J., & Zrelovs, Ņ. (2025). Isolation and Characterization of a Novel Klebsiella michiganensis Bacteriophage RSU-F4K5. PHAGE: Therapy, Applications, and Research. https://doi.org/10.1089/phage.2025.0009
Rezevska, D., Stipniece, L., Rubene, L., Sceglova, M., Maurins, S., Vasiljevs, R., Racenis, K., & Kroica, J. (2025). Zinc-substituted hydroxyapatite–bacteriophage complexes for complementary antibacterial properties. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 720, 137114. https://doi.org/10.1016/j.colsurfa.2025.137114
Rīga Stradiņš University Phage Group. 2024. Klebsiella spp. strains from Latvia and their phages (BioProject PRJNA1199463). National Center for Biotechnology Information.
Pirnay JP, Djebara S, Steurs G, Griselain J, Cochez C, De Soir S, Glonti T, Spiessens A, Vanden Berghe E, Green S, Wagemans J, Lood C, Schrevens E, Chanishvili N, Kutateladze M, de Jode M, Ceyssens PJ, Draye JP, Verbeken G, De Vos D, Rose T, Onsea J, Van Nieuwenhuyse B; Bacteriophage Therapy Providers; Bacteriophage Donors; Soentjens P, Lavigne R, Merabishvili M. Personalized bacteriophage therapy outcomes for 100 consecutive cases: a multicentre, multinational, retrospective observational study. Nat Microbiol. 2024 Jun;9(6):1434-1453
doi: 10.1038/s41564-024-01705-x. Epub 2024 Jun 4. PMID: 38834776; PMCID: PMC11153159
Mauriņš, S., Rezevska, D., Sevastjanova, L., Kroiča, J., & Rācenis, K. (2023). Perspektīvas antimikrobiālās rezistences pārvarēšanā: bakteriofāgu potenciāla izmantošana mūsdienu medicīnā. Latvijas Ārsts, (Nr.9/12), 94-100
Grase L, Onufrijevs P, Rezevska D, et al. "Effect of Femtosecond Laser-Irradiated Titanium Plates on Enhanced Antibacterial Activity and Preservation of Bacteriophage Stability." Nanomaterials (Basel). 2023;13(14):2032. Published 2023 Jul 9.
doi:10.3390/nano13142032
Racenis K, Lacis J, Rezevska D, et al. "Successful Bacteriophage-Antibiotic Combination Therapy against Multidrug-Resistant Pseudomonas aeruginosa Left Ventricular Assist Device Driveline Infection." Viruses. 2023;15(5):1210. Published 2023 May 20.
doi:10.3390/v15051210
Mukane L, Racenis K, Rezevska D, Petersons A, Kroica J. "Anti-Biofilm Effect of Bacteriophages and Antibiotics against Uropathogenic Escherichia coli." Antibiotics (Basel). 2022;11(12):1706. Published 2022 Nov 26.
doi:10.3390/antibiotics11121706
Racenis K, Rezevska D, Madelane M, et al. "Use of Phage Cocktail BFC 1.10 in Combination With Ceftazidime-Avibactam in the Treatment of Multidrug-Resistant Pseudomonas aeruginosa Femur Osteomyelitis-A Case Report." Front Med (Lausanne). 2022;9:851310. Published 2022 Apr 25.
doi:10.3389/fmed.2022.851310
Stipniece L, Rezevska D, Kroica J, Racenis K. "Effect of the Biopolymer Carrier on Staphylococcus aureus Bacteriophage Lytic Activity." Biomolecules. 2022;12(12):1875. Published 2022 Dec 14.
doi:10.3390/biom12121875
Racenis K, Kroica J, Rezevska D, et al. "S. aureus Colonization, Biofilm Production, and Phage Susceptibility in Peritoneal Dialysis Patients." Antibiotics (Basel). 2020;9(9):582. Published 2020 Sep 7.
doi:10.3390/antibiotics9090582