Molecular detection and expression of virulence factor encoding genes of Pseudomonas aeruginosa isolated from clinical samples


  • Alyaa Ghaffar Husain
  • Bahaa Abdullah Laftaah Alrubaii



Pseudomonas aeruginosa,, MIC, virulence factor genes, gene expression, real time- PCR, Lactobacillus acidophilus


Introduction and Aim: Pseudomonas aeruginosa virulence factors genes are a growing concern as they are involved not only in its pathogenicity, but also cause bacterial resistance to multiple classes of antibiotics. Laboratory identification of clinical isolates carrying the virulence genes would be critical in limiting the bacteria's spread and reducing its pathogenicity. The purpose of this study was to investigate a simple and inexpensive real-time PCR test to find the level of expression of Pseudomonas aeruginosa virulence genes before and after treatment with specific concentration of Lactobacillus acidophilus cell-free supernatants (CFSs). 


Materials and Methods: Between December 2021 and June 2022, 350 clinical samples collected from Baghdad hospitals, Iraq, were tested for the presence of P. aeruginosa. The P. aeruginosa isolated were tested for their antimicrobial susceptibility using the Kirby-Bauer disk diffusion method. P. aeruginosa virulence genes were detected by using the reverse transcription-PCR method. The expression levels of these genes before and after treatment with Lactobacillus acidophilus cell-free supernatants were measured by real-time PCR.


Results: Out of 350 samples tested, 60 isolates were positive for the presence of P. aeruginosa. Antibiotic susceptibility tests revealed a high level of antibiotic resistance, while genetic techniques identified the presence of several virulence genes that exhibited variable expression under the influence of Lactobacillus acidophilus supernatants.


Conclusion: The study findings showed that L. acidophilus supernatants had an effect on reducing the expression of certain virulence genes of P. aeruginosa, implying that L. acidophilus could be used as an option in treating P. aeruginosa infection.

Author Biographies

Alyaa Ghaffar Husain

Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq

Bahaa Abdullah Laftaah Alrubaii

Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq


Jawher, I.M., Hasan, M.G. Hassan. Antibiotics resistance patterns of Pseudomonas aeruginosa isolated from meat at Mosul city. Iraqi Journal of Veterinary Sciences. 2023; 37(2): 363-367.

Streeter, K., Katouli, M. Pseudomonas aeruginosa: A review of their pathogenesis and prevalence in clinical settings and the environment. J Infect Epidemiol Med. 2016;2(1):25-32.

Al-lateef, B.A., Al-shukri, M.S.,Judi, M.R. Expression of circulatory interleukin-6 concentration associated with Pseudomonas aeruginosa persistence in recurrent urinary tract infections Medical Journal of Babylon. 2023;20(1):201-205.

Al Hashimy, S.K., Ismaeel, Z.A.L., Abdulrazaq, M.A. Investigate Pseudomonas aeruginosa resistant to antibiotics and study the antibacterial effect of rosemary oils at different concentrations. Journal of Education and Scientific Studies. 2021;3(17): 209-218.

Almutairi, A.A., Abdulla, A.A. Occurrence of Class 1, 2, and 3 integrons among multi-drug resistant Pseudomonas aeruginosa in Babylon Province, Iraq. Medical Journal of Babylon.2023;20(1):181-187.

Macin, S., Akyon, Y. Phenotypic and genotypic virulence factors in Pseudomonas aeruginosa strains according to pigment presence. Acta Medica Mediterranea.2017; 33(6):1033-1038.

Sweedan, E.G. The antimicrobial effects of alcoholic leaves of Salvia officinalis against multidrug resistance Pseudomonas aeruginosa. Iraqi Journal of Science. 2021;62(2):441-448.

Yaseen, N.N., Ahmed D.A. Detection of mexB multidrug efflux gene in some local isolates of Pseudomonas aeruginosa. Iraqi Journal of Science. 2003; 64 (1):111-118.

Al-Asadi, H.M., Luti, K.J. Antibacterial activity of Lactobacillus plantarum bacteriocin as a dermal probiotic against Pseudomonas aeruginosa isolated from diabetic foot ulcer. Journal of Madinat Al Ilam College. 2023;15 (1):38-46.

Jasim, N.A. Using Saccharomyces cerevisiae and Lactobacillus acidophilus as probiotic against Salmonella Enterica Serovar Typhimurium isolated from poultry. Al-Anbar Journal of Veterinary Sciences. 2020;13 (2):109-117.

Al-ani, S.A., Al-Shahwany, A.W. Study of the effect of some methanolic and aqueous traditional plant extracts on probiotic bacteria. Iraqi Journal of Science. 2018; 59(3B):1396-1408.

Mahdi, L.F., AL-Azawi A.H. Synergistic effect of Conocarpus erectus extract and some antibiotics against multi-drug resistance Pseudomonas aeruginosa. Iraqi Journal of Biotechnology. 2022; 21(2):308-325.

Rasheed H.B., Luti K.J., Alaubydi M.A. A probiotic application of Lactobacillus acidophilus HT1 for the treatment of some skin pathogens. Iraqi Journal of Agricultural Sciences. 2020;51(6):1559-1571.

Sarah, N. L., Zainab, F. M. Activity of Marticaria chamomilla crude and total flavonoid extracts as anti-virulence factor for clinically isolated Pseudomonas aeruginosa. Iraqi Journal of Agricultural Sciences. 2023; 54(1):59- 69.

El-Oksh, A.S., Elmasry, D.M., Ibrahim G.A. Effect of garlic oil nanoemulsion against multidrug-resistant Pseudomonas aeruginosa isolated from broilers. Iraqi Journal of Veterinary Sciences. 2022;36(4):877-888.

CLSI. Performance standards for antimicrobial susceptibility testing. 30thed. CLSI supplement M100. Wayne, PA: Clinical and Laboratory Standards Institute.2021.

George-Okafor, U., Ozoani, U., Tasie, F., Mba-Omeje, K. The efficacy of cell-free supernatants from Lactobacillus plantarum Cs and Lactobacillus acidophilus ATCC 314 for the preservation of home-processed tomato-paste. Scientific African. 2020; 8, e00395.

Pang, Z., Raudonis, R., Glick, R. B., Lin, T., Cheng, Z. Antibiotic resistance in Pseudomonas aeruginosa: mechanisms and alternative therapeutic strategies. Biotechnology Advances. 2019; 37(1):177-192.

Al-Sheikhly, M. A.; Musleh, L. N., AlMathkhury, H. J. Gene expression of pelA and pslA in Pseudomonas aeruginosa under gentamicin stress. Iraqi Journal of Science. 2020; 61(2): 295-305.

Vaez, H., Salehi-Abargouei, A., Ghalehnoo, Z. R., Khademi, F. Multidrug resistant Pseudomonas aeruginosa in Iran: A systematic review and meta-analysis. Journal of Global Infectious Diseases.2018;10(4): 212.

Nasser, M., Ogali, M., Kharat, A. S. Prevalence of MDR Pseudomonas aeruginosa of war-related wound and burn ward infections from some conflict areas of Western Yemen. Wound Medicine. 2018; 20:58-61.

Ahmed A.K.S., Rudden M., Smyth T.J., Dooley J.S.G, Marchant R., Banat I.M. Natural quorum sensing inhibitors effectively downregulate gene expression of Pseudomonas aeruginosa virulence factors. Applied Microbiology and Biotechnology. 2019; 103:3521-3535.

Shehab Z.H., AL-Rubaii B.A.L. Effect of D-Mannose on gene expression of neuraminidase produced from different clinical isolates of Pseudomonas aeruginosa. Baghdad Science Journal. 2019;16(2):291-298.

Shehab Z.H., AL-Rubaii B.A.L.Correlation of nan1 (Neuraminidase) and production of some type III secretion system in clinical isolates of Pseudomonas aeruginosa. Bioscience Research. 2018;15(3):1729-1738.

Jalil, I.S., Mohammad, S.Q., Mohsen, A.K., Al-Rubaii, B.A.L. Inhibitory activity of Mentha spicata oils on biofilms of Proteus mirabilis isolated from burns. Biomedicine. 2023; 43(02):748-752.

Al-saidi, M., Al-bana, R.J.A., Hassan, E., AL-Rubaii, B.A.L. Extraction and characterization of nickel oxide nanoparticles from Hibiscus plant using green technology and study of its antibacterial activity. Biomedicine. 2022; 42(6):1290-1295.




How to Cite

Ghaffar Husain A, Abdullah Laftaah Alrubaii B. Molecular detection and expression of virulence factor encoding genes of Pseudomonas aeruginosa isolated from clinical samples. Biomedicine [Internet]. 2023 Nov. 9 [cited 2023 Dec. 2];43(5):1514-9. Available from:



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