# The Emergence of Antibioticstics Resistance Genes, Bacteria, and Micropollutants in Grey Wastewater
## 1 Introduction
### Prevalence of Antibiotic-Resistant Bacteria and Antibiotic-Resistance Genes in GW  
[PERSON] et al. [20] analyzed 79 samples of untreated urban sewage in 60 countries, concluding that the dominant bacterial genera were typically fecal, including _Escherichia_, _Bacteroides_, _Bifidobacterium_, _Streptococcus_, and _Faecalibacterium_. Pathogens including _Klebsiella pneumoniae_, _Pseudomonas aeruginosa_, _Salmonella_ spp., _Enterovirus_, _Escherichia coli_, _Giardia_, _Staphylococcus aureus_, _Clostridia_, and _Legionella_ sp. were detected in untreated domestic greywater in England, Australia, U. S., Hungary, Israel, Uganda, and France [21; 22; 23; 24]. In addition, many studies have revealed pathogenic bacteria in treated domestic wastewater worldwide, such as _Salmonella enterica_, _Listeria monocytogenes_[25], _E. Coli_[26], _Aeromonas hydrophilia_, and _Aeromonas veronii_[27].  
Great interest has been explicitly aroused about antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) in greywater [28; 29; 30]. Many studies monitored the occurrence of ARGs and ARBs in wastewater [27; 31; 32; 33]. For example, [PERSON] et al. [32] report the occurrence of resistance genes to macrolide, aminoglycososide, b-lactam, chloramphenicol, tetracycline, fluoroquinoline, sulfonamide, trimethoprim, and rifampicin, including multidrug resistance (MDR) genes. The article summarizes 140 clinically relevant ARGs in wastewater treatment plants. [PERSON] et al. [34] report ARGs in strains of _Salmonella enterica_, including genes such as _aadA1_, _aadA2_, _aadB_, _aphAI-IAB_, _bla(Tem)_,bla(Carb2), cat1, cat2, dhfr1, floR, strA, sul1, sul2, tetA(B) tetA(A),_ and tetA(G). Another example is the research of [PERSON] et al. [35], detecting 44 ARGs in _Aeromonas_ strains. Thus far, 211 isolates were resistant to colistin, quinolones, florfenicol, oxytetracycline, and trimethoprim-sulfamethoxazole. Alongside that, several studies have reported the occurrence of ARGs in small-scale GW reuse systems, including _tet39_, _blaCTX-M-32, qnrS_, and _sul1_ resistance genes [23; 36; 37]. [PERSON] et al. [36] identified _Pseudomonas putida_ in treated greywater, which is clinically resistant to cephens and carbapenems. [PERSON] et al. [38] reported that resistance genes of _P. putida_ were transferable by transformation or conjugation to recipient strains of _Pseudomonas aeruginosa_. Overall, it is recognized that wastewater treatment facilities are potential hotspots for the spread of ARGs [39].  
In wastewater treatment, the risk of conventional pathogens and common pollutants from the reuse of GW has been widely reviewed. The prevalence of ARBs in greywater, mitigation of ARGs, and potential risk to humans and the environment by greywater-reuse practices should be given more attention. Moreover, understanding the possible effect of emerging micropollutants (EMPs) on the multidrug resistance of bacteria and cross-resistance, and the dissemination of antimicrobial chemicals in the environment is crucial. In addition, we tried to summarize the effect of emerging micropollutants on bacteria and their fate in the soil microbiome. Therefore, this review surveys research focused on the most occurring EMPs in GW, and the risk of greywater reuse practices on the environment.