Antibiotic Resistance and Prevalence of Class 1 and 2 Integrons in Escherichia coli Isolated from Two Wastewater Treatment Plants, and Their Receiving Waters (Gulf of Gdansk, Baltic Sea, Poland)

EWA KOTLARSKA, ANETA ŁUCZKIEWICZ, MARTA PISOWACKA, AND ARTUR BURZYŃSKI

4.1 INTRODUCTION

Safe and economical way of wastewater disposal is an important problem requiring proper receiver-oriented management. Nowadays, wastewater treatment focuses mainly on parameters that may cause oxygen depletion and eutrophication of the receiving waters: organic matter, nitrogen, and phosphorus. Health aspects are considered only in terms of fecal contamination and evaluated only in bathing areas by monitoring fecal indicators (Escherichia coli and Enterococcus species). However, other important

aspects of wastewater discharge are currently under debate. It is suspected that clinically relevant bacteria and mobile genetic elements can survive the wastewater treatment plant processes (Reinthaler et al. 2003; D’Costa et al. 2006; Łuczkiewicz et al. 2010) and be disseminated in the receiving waters (Iwane et al. 2001; Li et al. 2009; Czekalski et al. 2012). Additionally, human-associated bacteria are regarded as important vectors of gene transmission (D’Costa et al. 2006). Thus, domestic and municipal wastewater should be considered in global antibiotic resistance gene dissemination.