%0 Journal Article %T Significance and Biological Importance of Pyrimidine in the Microbial World %A Vinita Sharma %A Nitin Chitranshi %A Ajay Kumar Agarwal %J International Journal of Medicinal Chemistry %D 2014 %I Hindawi Publishing Corporation %R 10.1155/2014/202784 %X Microbes are unique creatures that adapt to varying lifestyles and environment resistance in extreme or adverse conditions. The genetic architecture of microbe may bear a significant signature not only in the sequences position, but also in the lifestyle to which it is adapted. It becomes a challenge for the society to find new chemical entities which can treat microbial infections. The present review aims to focus on account of important chemical moiety, that is, pyrimidine and its various derivatives as antimicrobial agents. In the current studies we represent more than 200 pyrimidines as antimicrobial agents with different mono-, di-, tri-, and tetrasubstituted classes along with in vitro antimicrobial activities of pyrimidines derivatives which can facilitate the development of more potent and effective antimicrobial agents. 1. Introduction Resistance to antimicrobial agents has become an increasingly important and pressing global problem. Of the 2 million people who acquire bacterial infection in US hospitals each year, 70% of cases now involve strains that are resistant to at least one drug [1]. In communities and hospitals around the world, the number of patients with antibiotic-resistant infections continues to climb [2]. A major cause for concern in the UK is methicillin-resistant Staphylococcus aureus (MRSA), which was at low levels a decade ago but now accounts for ca. 50% of all S. aureus isolates [3]. Substantial investment and research in the field of anti-infectives are now desperately needed if a public health crisis is to be averted. The causes of antimicrobial resistance are multifactorial. In case of an antibiotic, it has been well documented that resistance is mainly caused by continued overreliance on and imprudent use of these antibacterial agents [4] and increasing evidence is being obtained suggesting that the same may be true for the emergence of biocide resistance [5, 6]. Of particular concern is the possible cross-resistance of antibiotics and biocide due to common resistance mechanism [7, 8]. Metal resistance is being observed as the result of polluted environments [9, 10]. The consequence of continued exposure to antibacterial environment is an enrichment of bacteria that are intrinsically resistant to antimicrobials or have acquired resistance mechanism to these substances [11, 12]. Structural modification of antimicrobial drugs to which resistance has developed has been proven to be an effective means of extending the lifespan of antifungal agents such as the azoles [13], antiviral agents such as the nonnucleoside reverse %U http://www.hindawi.com/journals/ijmc/2014/202784/