909 Review article doi: 10.1016/S2222-1808(16)61155-6 ©2016 by the Asian Pacific Journal of Tropical Disease. All rights reserved. Role of microbial fora in female genital tract: A comprehensive review Subramanyam Dasari 1,2 , Suresh Karanam Anandan 1 , Wudayagiri Rajendra 3 , Lokanatha Valluru 1* 1 Department of Biotechnology, Dravidian University, Kuppam, 517426, Andhra Pradesh, India 2 Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, 61107, Illinois, USA 3 Department of Zoology, Sri Venkateswara University, Tirupati, 517502, Andhra Pradesh, India Asian Pac J Trop Dis 2016; 6(11): 909-917 Asian Pacific Journal of Tropical Disease journal homepage: www.elsevier.com/locate/apjtd *Corresponding author: Dr. Lokanatha Valluru, Department of Biotechnology, Dravidian University, Kuppam, 517426, Andhra Pradesh, India. Tel: +91 9652840923 Fax: +91-08570278230 E-mail: lokanath.valluru@gmail.com The journal implements double-blind peer review practiced by specially invited international editorial board members. 1. Introduction A diverse group of microorganisms is associated with different parts of the human body from birth to death. The human body routinely harbours about 1 014 bacteria which are collectively called normal or indigenous microbial species. They are widely distributed in various parts of the body, including eyes, skin, nails, oropharynx, gastrointestinal and genital tracts. These microbial florae are stable during normal conditions and do not cause any harmful effects to the human body[1]. Anatomically, the female genital tract is a very favourable atmosphere for the occurrence of a number of microorganisms. Most of these normal microorganisms play a significant role in the defense mechanism for maintaining the healthy environment to that particular part or organ especially in female genital tract[2]. In 1892, Albert Doderlein first reported that the vaginal microbial flora was colonized with Gram-positive rods, popularly known as “Doderlein’s bacilli”. These bacteria are popularly known as Lactobacillus species and are predominant species of the genital microflora along with some aerobic and anaerobic bacterial species[3]. It is well established that lactobacilli are one of the defense mechanism against pathogenic organisms. Although several means of protection have been suggested, their mechanism of interaction is not fully understood. The improvement in the number and metabolic activity of lactobacilli plays an essential role in the prevention and treatment of different infectious diseases along with already available therapeutic interventions[4]. Historical data indicate that the majority (70%) of genital tract infections (GTIs) are caused by the abnormal microbial population[5]. Furthermore, abnormal microbial flora of the vagina and cervix causes various infectious diseases, such as bacterial vaginosis (BV) and sexually transmitted viral infections (human simplex virus and human papilloma virus), which can lead from moderate to severe infectious conditions, and sometimes they may also cause death[6]. The major cause of GTIs in females is bacterial infections, formerly known as nonspecific vaginitis which is defined ARTICLE INFO ABSTRACT The female genital tract is a complex of microbial colonization, which shows a prominent role in the development of either a healthy or diseased condition. The aim of the present review is to describe the diverse components of both the protective and defective mechanisms induced by microbial species present in the female genital tract. The protective mechanism was induced by indigenous microbial flora colonized in the female genital tract, which includes innate immunity, secretions containing cytokines, antimicrobial peptides and inhibitory substances like organic acids, H 2 O 2 , bacteriosin and toll-like receptors. On the other hand, abnormal microorganisms produce virulence factors and enzymes, which cause life-threatening infectious diseases including cancer. The review summarizes that depending upon the presence and/or absence of normal and abnormal microorganisms, the female genital tract shows either a healthy and/or infectious condition. Contents lists available at ScienceDirect Article history: Received 1 Jul 2016 Received in revised form 8 Aug, 2nd Revised form 19 Aug 2016 Accepted 23 Sep 2016 Available online 27 Sep 2016 Keywords: Antimicrobial compounds Bacteriocin Cervical cancer Female genital tract Mucinase Nitrosamines