Bacterial resistance to antibiotics in Acinetobacter isolates from wastewater treatment plants in Croatia

Abstract

Cilj ovog istraživanja bio je ispitati fenotipsku osjetljivost izolata roda Acinetobacter na različite antibiotike. Uzorci vode su prikupljeni u uređajima za pročišćavanje otpadnih voda (UPOV) Katalinića brig i Stupe u Splitu, te na pripadajućim podmorskim ispustima. Ukupno je identificiran 91 izolat, među kojima su najzastupljeniji bili A. baumannii i A. pittii, dok su ostale vrste bile manje prisutne. Rezultati su pokazali značajnu razinu rezistencije na karbapeneme (meropenem, imipenem) i peniciline s inhibitorima β-laktamaze (piperacilin/tazobaktam, tikarcilin/klavulanska kiselina). A. baumannii je pokazao najveću učestalost rezistencije, dok je A. sichuaensis bio najosjetljiviji na testirane antibiotike. Najviša stopa rezistencije zabilježena je kod izolata iz influenta UPOV-a Katalinića brig, što može biti posljedica ulijevanja bolničkih otpadnih voda u ovaj UPOV. Naime, prethodne studije su pokazale da značajan selekcijski pritisak u takvim uvjetima povećava udio višestruko rezistentnih sojeva. Ovo istraživanje naglašava ulogu otpadnih voda kao rezervoara rezistentnih oportunističkih patogena, uključujući patogena kritičnog prioriteta, karbapenem-rezistentnog A. baumannii, kao i potrebu njihovog rigoroznog praćenja u cilju smanjenja javnozdravstvene prijetnje.The aim of this study was to examine the phenotypic sensitivity of isolates of the genus Acinetobacter to different antibiotics. Samples were collected from wastewater treatment plants (WWTP) of Katalinić brig and Stupe in Split, including their submarine outfalls. A total of 91 isolates were identified, among which A. baumannii and A. pittii were the most abundant, while other species were less present. Results showed a significant level of resistance to carbapenems (meropenem, imipenem) and penicillins with β-lactamase inhibitors (piperacillin/tazobactam, ticarcillin/clavulanic acid). A. baumannii showed the highest resistance rate whereas A. sichuaensis was the most sensitive to the antibiotics used. The highest resistance rate was recorded for isolates from the influent of UPOV Katalinić brig, which could be attributed to the presence of hospital wastewater. It was previously found that the selection pressure under such conditions increases the proportion of multiple resistant strains. The study highlights the role of wastewater as a reservoir of antibiotic-resistant opportunistic pathogens, including the WHO critical-priority pathogens, the carbapenem-resistant A. baumannii, as well as the need for their rigorous monitoring to reduce the public health threat