Kappell Anthony D, DeNies Maxwell S, Ahuja Neha H, Ledeboer Nathan A, Newton Ryan J, Hristova Krassimira R
Department of Biological Sciences, Marquette University Milwaukee, WI, USA.
Department of Pathology, Medical College of Wisconsin Milwaukee, WI, USA ; Dynacare Laboratories, Milwaukee WI, USA.
Front Microbiol. 2015 Apr 29;6:336. doi: 10.3389/fmicb.2015.00336. eCollection 2015.
Urban waterways represent a natural reservoir of antibiotic resistance which may provide a source of transferable genetic elements to human commensal bacteria and pathogens. The objective of this study was to evaluate antibiotic resistance of Escherichia coli isolated from the urban waterways of Milwaukee, WI compared to those from Milwaukee sewage and a clinical setting in Milwaukee. Antibiotics covering 10 different families were utilized to determine the phenotypic antibiotic resistance for all 259 E. coli isolates. All obtained isolates were determined to be multi-drug resistant. The E. coli isolates were also screened for the presence of the genetic determinants of resistance including ermB (macrolide resistance), tet(M) (tetracycline resistance), and β-lactamases (bla OXA, bla SHV, and bla PSE). E. coli from urban waterways showed a greater incidence of antibiotic resistance to 8 of 17 antibiotics tested compared to human derived sources. These E. coli isolates also demonstrated a greater incidence of resistance to higher numbers of antibiotics compared to the human derived isolates. The urban waterways demonstrated a greater abundance of isolates with co-occurrence of antibiotic resistance than human derived sources. When screened for five different antibiotic resistance genes conferring macrolide, tetracycline, and β-lactam resistance, clinical E. coli isolates were more likely to harbor ermB and bla OXA than isolates from urban waterway. These results indicate that Milwaukee's urban waterways may select or allow for a greater incidence of multiple antibiotic resistance organisms and likely harbor a different antibiotic resistance gene pool than clinical sources. The implications of this study are significant to understanding the presence of resistance in urban freshwater environments by supporting the idea that sediment from urban waterways serves as a reservoir of antibiotic resistance.
城市水道是抗生素耐药性的天然储存库，可能为人类共生细菌和病原体提供可转移遗传元件的来源。本研究的目的是评估从威斯康星州密尔沃基市城市水道分离出的大肠杆菌的抗生素耐药性，并与密尔沃基市污水及临床环境中分离出的大肠杆菌进行比较。使用涵盖10个不同类别的抗生素来确定所有259株大肠杆菌分离株的表型抗生素耐药性。所有获得的分离株均被确定为多重耐药。还对大肠杆菌分离株进行了耐药性遗传决定因素的筛查，包括ermB（大环内酯类耐药）、tet(M)（四环素耐药）和β-内酰胺酶（bla OXA、bla SHV和bla PSE）。与人类来源相比，城市水道中的大肠杆菌对17种测试抗生素中的8种表现出更高的抗生素耐药发生率。这些大肠杆菌分离株对更多种类抗生素的耐药发生率也高于人类来源的分离株。与人类来源相比，城市水道中同时存在抗生素耐药性的分离株更为丰富。在筛查赋予大环内酯类、四环素类和β-内酰胺类耐药性的五种不同抗生素耐药基因时，临床大肠杆菌分离株比城市水道分离株更有可能携带ermB和bla OXA。这些结果表明，密尔沃基市的城市水道可能会选择或导致多重抗生素耐药生物的发生率更高，并且可能拥有与临床来源不同的抗生素耐药基因库。本研究的意义在于支持城市水道沉积物作为抗生素耐药性储存库这一观点，从而有助于理解城市淡水环境中耐药性的存在。
