Essay: Microbial Infections

Microbial infections are considered as the major causes of morbidity and mortality. However, among the causative microbes, bacterial infection is the most prevalent one. Although various antibiotics discovered time to time rescued mankind from different dreadful diseases, the extensive and uncontrolled use of broad-spectrum antibiotics resulted in the development of antibiotic resistance in microbes. Thus, multi-drug resistance (MDR) is increasing at an alarming rate, and now it is one of the major concerns worldwide (Rai et al. 2012). Moreover, biofilms are increasingly recognized as the important source of pathogens (Jamal et al. 2018). They pose significant clinical dilemma because sessile bacterial cells are inherently recalcitrant to antibiotics (Lebeaux et al. 2014). Several factors are responsible for the biofilm-associated resistance including the density and physiological state of the cells, and physical structure of the biofilm. The cells within biofilm are generally less metabolically active, and therefore, significantly less sensitive to antimicrobials targeting synthesis of macromolecules or metabolic pathways such as beta-lactams and quinolones (Ali et al. 2018). The recurrence of biofilms in spite of treatment with various antimicrobial agents was attributed to the impedance created by the biofilm matrix (Al-Fattani 2006). Although water channels are present in biofilms, the deep-lying organisms escape the treatment as the matrix deters diffusion of the drug. Besides, exopolysaccharide slime formed due to biofilm reduces the susceptibility of the organism to the administered drug.
Considering such global health threats, development of novel therapeutic agents, drugs or materials having significant efficacy in management of microbial infections including infections caused by MDR pathogens and inhibition of biofilm formation are needed. Moreover, it is believed that nanotechnology can serve as a prominent solution to all these problems because nanoparticles possess broad-spectrum antimicrobial potential (Rai et al. 2014).
There are various physical, chemical and biological approaches proposed for the synthesis of different nanoparticles. In biological synthesis, a variety of biological agents including plants (Ingle et al. 2017a, 2017b; Padma et al. 2018; Shaik et al. 2018; Sur et al. 2018; Suresh et al. 2018), bacteria (Jayaseelana et al. 2012; Shantkriti and Rani 2014), fungi (Din and Rehan 2017; Elamawi et al. 2018; Venkatesh et al. 2013), actinomycetes (Manimaran and Kannabiran 2017; Wypij et al. 2018), algae and blue green algae (Abdel-Raouf et al. 2018; Mahdieh et al. 2012; Patel et al. 2015) have been successfully exploited. However, among these biological agents, plants have attracted a great deal of attention by researchers around the globe for their use in the synthesis of metal and metal oxide nanoparticles because this approach is simple, easy and eco-friendly. Plant metabolites present in the extract act as reducing agents, which reduce the metal ions in respective nanoparticles, and also serve as stabilizing agents (Jain and Mehata 2017; Oluwaniyi et al. 2016; Shaik et al. 2018).