*3.2.2 Nanoparticles as a drug delivery vehicle*

Nano-particles based drug delivery system provides increased drug retention time in blood. Reduced non-specific distribution at targeted site of infections, Opsonin proteins in blood rapidly attach to Nanoparticles, promoting macrophages to bind and remove NPs from blood circulation [68].

### *3.2.3 Bacterial resistance to NPS*

Bacterial cells acquire resistant towards NPs by multiple mutations. NPs resistance to bacteria is a clinical concern but it is rare. Some studies suggest that bacteria develop resistance to Ag, Au, and Cu NPs after continuous exposure. For example: CU++ NPs sowed reduced susceptibility to TiO2 NPS after continuous exposure to *Schewanella oneidensis* [69]*.*

Increased use of Ag NPS in clinical application raises the NP bacterial drug resistance to *K.pneumoniae and Enterobacter cloacae.* Hemeg et al. showed, Al2O3 NPs increased the expression of conjugation-promoting genes and are responsible for horizontal gene transfer of resistant genes [70].

#### **3.3 Probiotics**

Probiotics are living Microorganisms that confers a health benefit to the host when administered in adequate amount. For example, *Lactobacilli and bifidobacteria*. Probiotics bacteria have many beneficial properties:


### *3.3.1 Spread of antibiotic resistant*

Gastrointestinal bacteria act as a major reservoir for resistance genes that can be acquired from ingested bacteria and it is responsible for transfer of resistant gene from one bacteria cell to another by plasmid mediated conjugation. Intrinsic resistance of probiotic bacteria is a major concern. Vancomycin, Tetracycline and Chloramphenicol antibiotic resistance have been reported in lactobacillus spp. intrinsically [71].
