Global Advanced Research Journal of Medicine and Medical Sciences (ISSN: 2315-5159) Vol. 8(1) pp. 001-008, January, 2019 Available online http://garj.org/garjmms Copyright © 2019 Global Advanced Research Journals Full Length Research Article Study of the side effects of Docetaxel as chemotherapy medicine on changing the expression of genes of Enterococcus faecalis isolated from patients with breast cancer Farnaz Rahbarzare 1,2 , Elham Eslahi 3 , Nazafarin Hatami-Mazinani 4 , Elham Magharehabed 5 , Mahsa Aliqanbari 6 , Niloofar Ahmadi 3 , Shabnam Naderifar 8 , Mona Mirgeloybayat 3 , Hamed Hojatian 6 , Mojdeh Naeima 9 and Soha Sadeghi 6,7* 1 Department of Genetics and Molecular Biology, Institute of Biological Science, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia. 2 Department of microbial biotechnology, North Tehran Branch, Islamic Azad University, Tehran, Iran 3 Department of Microbiology, Research and Science branch, Islamic Azad University, Tehran, Iran 4 Department of Clinical Pharmacy, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran 5 Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran 6 Department of Cellular and Molecular Biology, NourDanesh Institute of Higher Education, Isfahan, Iran 7 Department of Molecular genetics, Research Institute of NikanRoyesh Gene, Karaj, Iran 8 Department of Microbiology, Karaj Branch, Islamic Azad University, Karaj, Iran 9 Faculty of Pharmacy, First Moscow State Medical University, IM. Sechenov Moscow, Russia Corresponding Author E-mail: sadeghi.soha@gmail.com; Tel and Fax: +98 26 34557220 Accepted 15 January, 2019 The present study strived to ascertain the side effects of chemotherapy on the pathogenic potential of Enterococcus faecalis (a natural microflora bacteria) isolated from patients with breast cancer. Participants included 400 female sufferers from breast cancer before and after the period of chemotherapy and 400 healthy people living with patients.After RNA extracted from the stool of all the participants, cDNA was constructed. Nineteen virulent genes (vanB, vanA, VanC-3,VanC-2, VanC-1, aac(6′)-Ie-aph(2″)-Ia, Tet(L), Erm(B), gelE, esp, gyrA,slyA, cylA,cylB,cylM, asa1, aggA, efaA and enlA) of E. faecalis were assessed by Real-Time qPCR. The findings revealed a statistically significant correlation between the expression level of fourteen virulence genes(vanA(p = 0.033), vanB(p = 0.003), VanC-3(p = 0.003), aac(6′)-Ie-aph(2″)-Ia(p = 0.005), Erm(B) (p = 0.008), gelE(p = 0.002), esp(p = 0.0005), gyrA(p = 0.003), slyA(p = 0.001), cylA(p = 0.003), cylB(p = 0.0002), asa1(p = 0.003), aggA(p = 0.003), efaA(p = 0.003))in the group of the sufferers after chemotherapy and the other two groups (P<0.05).Additionally, the observation of patient group after chemotherapy showed an outstanding association between overexpression ofantibiotic resistance genes (vanA, vanB, VanC-3, Erm(B), aac(6′)-Ie-aph(2″)-Ia) and observation of the antibiotic resistance (vancomycin, erythromycin, gentamicin in respectively). Interestingly, while Docetaxel seems to be a suitable medicine to treat breast cancer, it may change the balance of mRNA expression of microflora. These could trigger infections during the cancer chemotherapy. Keywords: Breast cancer, Docetaxel, antibiotic resistance, Enterococcus faecalis