Impact of pharmaceutical wastewaters on selection and dissemination of antibiotic resistance

Cilj rada bio je istražiti utjecaj ispusta otpadnih voda iz dviju lokalnih farmaceutskih industrija na recipijentni vodeni okoliš, s naglaskom na razvoj i širenje otpornosti na antibiotike te sastav bakterijskih zajednica. Kemijskom analizom potvrđene su relativno visoke koncentracije antibiotika u otpadnim vodama tih industrija te znatno više koncentracije antibiotika u sedimentima recipijentnih voda nizvodno od ispusta u odnosu na referentnu lokaciju uzvodno od ispusta. Funkcionalnom metagenomikom identificirani su poznati i potencijalno novi geni za otpornost na ciljane antibiotike u otpadnim vodama i sedimentima. Kvantifikacijom odabranih gena otpornosti utvrđene su značajno više količine u sedimentima na lokaciji ispusta i nizvodno od ispusta u odnosu na referentnu uzvodnu lokaciju. Egzogenom izolacijom plazmida potvrđeno je povećano horizontalno širenje gena otpornosti na makrolide i/ili tetracikline u sedimentima onečišćenima otpadnim vodama farmaceutskih industrija. Filogenetskom analizom nukleotidnih sekvenci gena ermB potvrđena je njihova visoka sličnost između okolišnih bakterijskih izolata porijeklom iz riječnog sedimenta izrazito onečišćenog makrolidima i kliničkih izolata streptokoka, što ukazuje na mogući prijenos ovog gena između bakterija kliničkog i okolišnog podrijetla. Sekvenciranjem amplikona 16S rRNA gena utvrđene su značajne prostorne i sezonske promjene u sastavu bakterijskih zajednica izloženih sedimenata. Rezultati ovog istraživanja ukazali su na problem onečišćenja okoliša otpadnim vodama farmaceutskih industrija, što može predstavljati potencijalnu opasnost za zdravlje ljudiThe aim of this work was to explore the impact of the wastewater discharge from two local pharmaceutical industries on the recipient freshwater environments, particularly regarding the development and spread of antibiotic resistance and bacterial communities composition. Chemical analyses confirmed relatively high antibiotic concentrations in the wastewater from those industries and considerably higher antibiotic concentrations in recipient sediments downstream from the discharge site when compared with upstream reference site. Functional metagenomics revealed already known and potentially novel genes for resistance to targeted antibiotics in wastewater and sediments. Significantly higher concentrations of selected resistance genes were found in sediments at the disharge site and downstream from the pharmaceutical industries discharge site relative to the upstream reference site. Exogenous plasmid isolation revealed the increased horizontal transfer of macrolide and/or tetracycline resistance genes in antibiotic-polluted sediments. Phylogenetic analysis confirmed high similarity of the nucletiode sequences of the ermB gene between environmental bacterial isolates that originated from highly macrolide-polluted river sediments and clinical streptococcal isolates indicating potential transfer of this gene between bacteria of environmental and clinical origin. Sequencing of 16S rRNA gene amplicons revealed significant spatial and seasonal changes in bacterial communities composition of wastewater-exposed sediments. The results of this study highlight the problem of environmental pollution with pharmaceutical wastewater, which may pose a potential threat to both human and environmental health