Mini Review

Antibiotic Resistance Genes in Various Environments

Hyun Min Janga and Eunsung Kan^1,2*

¹ Texas A&M AgriLife Research Center, USA

² Office of Sponsored Projects, Tarleton State University, USA

Submission: September 04, 2018; Published: September 18, 2018

*Corresponding author: Eunsung Kan, Texas A&M AgriLife Research Center, 1229 North US Highway 281, Stephenville, TX 76401, USA; Tel: +1-254-968-4144; Fax: +1-254-968-3759; Email: eunsung.kan@ag.tamu.edu

How to cite this article: Hyun M J, Eunsung K. Antibiotic Resistance Genes in Various Environments. Agri Res & Tech :Open Access J. 2018; 17(5): 556037. DOI:10.19080/ARTOAJ.2018.17.556037

Abstract

This mini-review addresses occurrence, fate, mechanisms and possible remediation of antibiotic resistant genes in various environments. While antibiotic resistant genes are widely spread via multiple mechanisms, they often causes various diseases and significantly influence on human health. Wastewater treatment plants among various environmental matrices are considered as the main reservoir of antibiotic resistant genes. Current wastewater treatment technologies have revealed limitations for effective treatment of antibiotic resistance at wastewater treatment plants. Thus, innovative and cost-effective means to reduce antibiotic resistance in wastewater needs to be developed.

Keywords: Antibiotics; Antibiotic resistance genes; Human health; Human bacterial pathogens

Abbrevations:ARGs: Antibiotic Resistance Genes; HGT: Horizontal Gene Transfer; WWTPs: Wastewater Treatment Plants

Introduction

Since the penicillin was discovered by Fleming [1], over 250 different antibiotics have been registered for treatment of human and veterinary diseases [2]. Unlike other pharmaceutical compounds, antibiotics selectively act on bacteria via various mechanisms [3]. For example, antibiotics can inhibit synthesis of cell wall and enzyme as well as protein [4]. However, some bacteria can be intrinsically resistant to one or multiple antibiotics through following molecular mechanisms [5]:

a. Changes in antibiotic targets by mutation

b. Modification of targets

c. Direct modification of antibiotics

d. Prevention of access to target (e.g., efflux pump).

All genes related to the antibiotic resistance are called “Antibiotic resistance genes (ARGs)”.

In ecosystems, ARGs can persist over many generations and be enable to proliferate by not only vertical transfer but also horizontal gene transfer (HGT) such as conjugation and transduction [6]. Accordingly, recent attention has focused on the fate of ARGs in environments since it directly threatens human and animal health [7,8]. For instance, in US, at least 23,000 people die each year as a direct result of these antibiotic-resistant infections [9].

Several extensive literatures have reported the fate of ARGs in various environment matrices such as soil [10-13], ocean [14,15], river [16,17], and wastewater treatment plants (WWTPs) [18,19]. Among them, WWTPs is one of the largest reservoirs of ARGs and plays a significant role in the proliferation of ARGs to the environment [20-22]. Especially, environmental conditions including high microbial density and diversity in WWTPs may promote the HGT of ARGs with abundant mobile genetic elements [23]. Recent studies have revealed the negative effects of effluents from WWTPs on received environments [24,25].

For this reason, tertiary processes could be an effective opportunity to minimize the expose of ARGs to the environment and ultimately reduce the risk of antibiotic-resistant infections in human health [6,24,26]. Up to date, a few technologies such as UV [26], ozone [27], chlorination [28], and biological treatment [29], have been applied, but further studies are needed to develop more suitable and efficient treatment options for reduction of ARGs in effluents of WWTPs.

Discussion

A growing evidence indicate the importance of proper control of ARGs in WWTPs. However, there is still insufficient information available regarding the tertiary processes which can effectively remove the ARGs in effluent of WWTPs. In addition, long-term tracing of ARGs in the received environments (e.g., river and soil) after tertiary processes should be conducted since the regulation of level of ARGs is still questionable.

Conclusion

A lot of antibiotics have been released to various environments and led to develop antibiotic resistance causing serious health problems. Particularly, antibiotic resistant genes (ARGs) are widely spread over soil, water and air via multiple mechanisms while negatively influencing on human health. Since wastewater treatment plants are the major sink of ARGs, various remediation technologies such as ultraviolet light, ozone, chlorination and biological treatment have been applied to reduction of ARGs in wastewater. However, these technologies have shown limitations to effectively remove ARGs in wastewater. Therefore, innovative and cost-effective technologies for reduction of ARGs in wastewater need to be developed.

Acknowledgement

This work was supported by Texas A&M University Chancellor Research Initiative Fund.

References

1. Fleming A (1944) The Discovery of Penicillin. British Medical Bulletin 2(1): 4-5.
2. Kümmerer K, Henninger A (2003) Promoting resistance by the emission of antibiotics from hospitals and households into effluent. Clin Microbiol Infect 9(12): 1203-1214.
3. Sköld O (2011) Antibiotics and antibiotic resistance. John Wiley & Sons.
4. Madigan MT, Martinko JM, Parker J (1997) Brock biology of microorganisms. Prentice hall Upper Saddle River, New Jersey, USA.
5. Blair JM, Webber MA, Baylay AJ, Ogbolu DO, Piddock LJ (2015) Molecular mechanisms of antibiotic resistance. Nat Rev Microbiol 13(1): 42-51
6. Dodd MC (2012) Potential impacts of disinfection processes on elimination and deactivation of antibiotic resistance genes during water and wastewater treatment. J Environ Monit 14(7): 1754-1771.
7. Pruden A, Larsson DJ, Amézquita A, Collignon P, Brandt KK, et al. (2013) Management options for reducing the release of antibiotics and antibiotic resistance genes to the environment. Environ Health Perspect 121(8): 878-885.
8. Wright GD (2010) Antibiotic resistance in the environment: a link to the clinic? Curr Opin Microbiol 13(5): 589-594.
9. CDC (2013) Antibiotic resistance threats in the United States, 2013. US Department of Health Human Services.
10. Donato JJ, Moe LA, Converse BJ, Smart KD, Berklein FC, et al. (2010) Metagenomic analysis of apple orchard soil reveals antibiotic resistance genes encoding predicted bifunctional proteins. Appl Environ Microbiol 76(13): 4396-4401.
11. Esiobu N, Armenta L, Ike J (2002) Antibiotic resistance in soil and water environments. Int J Environ Health Res 12(2): 133-144.
12. Heuer H, Schmitt H, Smalla K (2011) Antibiotic resistance gene spread due to manure application on agricultural fields. Curr Opin Microbiol 14(3): 236-243.
13. Knapp CW, Dolfing J, Ehlert PA, Graham DW (2009) Evidence of increasing antibiotic resistance gene abundances in archived soils since 1940. Environmental science & technology 44(2): 580-587.
14. Chen B, Yang Y, Liang X, Yu K, Zhang T, et al. (2013) Metagenomic profiles of antibiotic resistance genes (ARGs) between human impacted estuary and deep ocean sediments. Environ Sci Technol 47(22): 12753-12760.
15. Hatosy SM, Martiny AC (2015) The ocean as a global reservoir of antibiotic resistance genes. Applied and environmental microbiology.
16. Graham DW, Olivares-Rieumont S, Knapp CW, Lima L, Werner D, et al. (2010) Antibiotic resistance gene abundances associated with waste discharges to the Almendares River near Havana, Cuba. Environ Sci Technol 45(2): 418-424.
17. Rodriguez-Mozaz S, Chamorro S, Marti E, Huerta B, Gros M, et al. (2015) Occurrence of antibiotics and antibiotic resistance genes in hospital and urban wastewaters and their impact on the receiving river. Water Res 69: 234-242.
18. Rizzo L, Manaia C, Merlin C, Schwartz T, Dagot C, et al. (2013) Urban wastewater treatment plants as hotspots for antibiotic resistant bacteria and genes spread into the environment: A review. Sci Total Environ 447: 345-360.
19. Tennstedt T, Szczepanowski R, Braun S, Pühler A, Schlüter A (2003) Occurrence of integron-associated resistance gene cassettes located on antibiotic resistance plasmids isolated from a wastewater treatment plant. FEMS Microbiol Ecol 45(3): 239-252.
20. LaPara TM, Burch TR, McNamara PJ, Tan DT, Yan M, et al. (2011) Tertiarytreated municipal wastewater is a significant point source of antibiotic resistance genes into Duluth-Superior Harbor. Environmental science & technology 45(22): 9543-9549.
21. Lee J, Shin SG, Jang HM, Kim YB, Lee J, et al. (2017) Characterization of antibiotic resistance genes in representative organic solid wastes: Food waste-recycling wastewater, manure, and sewage sludge. Science of the Total Environment 579: 1692-1698.
22. Zhang T, Zhang XX, Ye L (2011) Plasmid metagenome reveals high levels of antibiotic resistance genes and mobile genetic elements in activated sludge. PloS one 6(10): e26041.
23. Schlüter A, Szczepanowski R, Pühler A, Top EM (2007) Genomics of IncP-1 antibiotic resistance plasmids isolated from wastewater treatment plants provides evidence for a widely accessible drug resistance gene pool. FEMS Microbiol Rev 31(4): 449-477
24. Pruden A, Arabi M, Storteboom HN (2012) Correlation between upstream human activities and riverine antibiotic resistance genes. Environ Sci Technol 46(21): 11541-11549.
25. Storteboom H, Arabi M, Davis JG, Crimi B, Pruden A (2010) Tracking antibiotic resistance genes in the South Platte River basin using molecular signatures of urban, agricultural, and pristine sources. Environmental science & technology 44(19): 7397-7404.
26. McKinney CW, Pruden A (2012) Ultraviolet disinfection of antibiotic resistant bacteria and their antibiotic resistance genes in water and wastewater. Environ Sci Technol 46(24): 13393-13400.
27. Alexander J, Knopp G, Dötsch A, Wieland A, Schwartz T (2016) Ozone treatment of conditioned wastewater selects antibiotic resistance genes, opportunistic bacteria, and induce strong population shifts. Sci Total Environ 559: 103-112.
28. Yuan QB, Guo MT, Yang J (2015) Fate of antibiotic resistant bacteria and genes during wastewater chlorination: implication for antibiotic resistance control. PloS one 10(3): e0119403.
29. Christgen B, Yang Y, Ahammad S, Li B, Rodriquez DC, et al. (2015) Metagenomics shows that low-energy anaerobic−aerobic treatment reactors reduce antibiotic resistance gene levels from domestic wastewater. Environ Sci Technol 49(4): 2577-2584.