*Review* **Biogenic Nanosilver against Multidrug-Resistant Bacteria (MDRB)**

#### **Caio H. N. Barros †, Stephanie Fulaz †, Danijela Stanisic and Ljubica Tasic \***

Laboratory of Chemical Biology, Institute of Chemistry, State University of Campinas, Campinas 13083-970, Brazil; caionasibarros@gmail.com (C.H.N.B.); ste.fulaz@gmail.com (S.F.);

danijela.stanisic@iqm.unicamp.br (D.S.)


Received: 28 June 2018; Accepted: 31 July 2018; Published: 2 August 2018

**Abstract:** Multidrug-resistant bacteria (MDRB) are extremely dangerous and bring a serious threat to health care systems as they can survive an attack from almost any drug. The bacteria's adaptive way of living with the use of antimicrobials and antibiotics caused them to modify and prevail in hostile conditions by creating resistance to known antibiotics or their combinations. The emergence of nanomaterials as new antimicrobials introduces a new paradigm for antibiotic use in various fields. For example, silver nanoparticles (AgNPs) are the oldest nanomaterial used for bactericide and bacteriostatic purposes. However, for just a few decades these have been produced in a biogenic or bio-based fashion. This review brings the latest reports on biogenic AgNPs in the combat against MDRB. Some antimicrobial mechanisms and possible silver resistance traits acquired by bacteria are also presented. Hopefully, novel AgNPs-containing products might be designed against MDR bacterial infections.

**Keywords:** silver nanoparticles; biological synthesis; multidrug-resistant bacteria
