Occurrence and Fate of Macrolide Antibiotics in Wastewater Treatment Plants and in the Glatt Valley Watershed, Switzerland

Abstract

An analytical method was developed for determining macrolide antibiotics in treated wastewater effluents and in ambient water based on solid-phase extraction and LC/MS analysis as well as on LC/MS/MS for structural confirmation. In wastewater treatment plants (WWTPs) macrolides are only partly eliminated and can therefore reach the aquatic environment. In treated effluents from three WWTPs in Switzerland, clarithromycin, roxithromycin, and erythromycin-H2O, the main degradation product of erythromycin, were found. The most abundant, clarithromycin, reflects the consumption pattern of macrolide antibiotics. Summer concentrations of clarithromycin varied between 57 and 330 ng/L in treated WWTP effluents. In the WWTP Kloten-Opfikon seasonal differences revealed a load two times higher in winter than in summer. The higher abundance of erythromycin-H2O in the effluent of WWTP Kloten-Opfikon can be explained by distinct consumption patterns due to the main international airport of Switzerland in the catchment area. In the Glatt River clarithromycin reached concentrations of up to 75 ng/L. Mass flux determinations in treated effluents and in river water in the Glatt Valley watershed showed that elimination of clarithromycin along the river stretch of 36 km is insignificant (<20%). Investigations in the Glatt River before and after the diversion of the largest WWTP revealed an observable decrease in clarithromycin loads.

An overview of analytical methodologies for the determination of antibiotics in environmental waters

“…It is recommended as it was shown that MLs can bind divalent and polyvalent cations although they bind not so strong as TCs or FQs. The extraction was performed with polymeric Oasis HLB columns except one study using LiChrolute RP-18 sorbent [5].…”

“…The washing step was performed with water in three studies. The other study does not report the washing step although WWTPs effluents were analyzed [5]. It can be seen from recovery achieved that washing step was necessary.…”

“…The precursor ion chosen for the quantitation was [M+H] + in almost all studies, except of ERY-H 2 O, for which [M+H-H 2 O] + was used as a precursor ion [5,9,17,30].…”

“…Structurally related compounds e.g., kitasamycin [17], spiramycin [9], josamycin [5,7,24] or oleandomycin [5] were also employed. Table 8 HPLC analytical methods for the determination of MLs.…”

“…Therefore, the occurrence of antibiotics in the environment has received considerable attention. They are generally poorly absorbed by the human body and thus excreted either unchanged or transformed, via urine and faeces [5]. There is a growing interest about their presence, persistence and fate in the environment because low levels of antibiotics can favor the proliferation of antibiotic resistant bacteria.…”