Faecal indicator bacteria and antibiotic-resistant β-lactamase producing Escherichia coli in blackwater: a pilot study

The aim of this study was to identify and quantify faecal indicator bacteria in blackwater collected from a source separation unit and determine the amount of E. coli isolates resistant to antimicrobials and their potential to produce extended spectrum β-lactamases (ESβLs) and metallo-β-lactamases (MβLs), which hydrolyse the most important antibiotics used in clinical practice. Most of the isolates were resistant to amoxicillin with clavulanic acid (36.4 %), followed by ticarcillin with clavulanic acid (22.7 %) and tetracycline (18.2 %). ESβL-producing genes blaCTX-M and blaTEM were found in three (13.6 %) and four (18.2 %) E. coli strains, respectively, while MβL genes were found in two (9.1 %). By separating at source, this pilot study clearly shows that gastrointestinal bacteria of healthy people can be an important source of antibiotic resistance released into the environment through wastewaters. One way to prevent that is to treat wastewater with a combination of TiO2, UV light, or ozone, as successful methods to remove resistant bacteria and prevent their spread in the environment.
V vzorcih črne vode, ki je ena od frakcij odpadne vode, smo ugotavljali prisotnost in število fekalnih indikatorskih bakterij, vključno z bakterijo Escherichia coli (E. coli). Pri osamljenih sevih E. coli smo ugotavljali njihovo odpornost proti izbranim antibiotikom in njihov potencial za tvorbo nekaterih β-laktamaz razširjenega spektra in metalo-β-laktamaz. Preizkušeni sevi so bili najpogosteje odporni proti amoksicilinu s klavulansko kislino (36,4 %), tikarcilinu s klavulansko kislino (22,7 %) in tetraciklinu (18,2 %). Nukleotidne sekvence za blaCTX-M in blaTEM smo našli pri treh (13,6 %) in štirih (18,2 %) sevih, medtem ko smo gene za izbrane metalo-β-laktamaze ugotovili pri dveh (9,1 %) sevih E. coli. Pilotna študija, z ločevanjem odpadne vode na viru nastanka, kaže, da so bakterije v prebavnem traktu zdravih ljudi lahko pomemben vir prenosa odpornosti proti antibiotikom v okolju preko odpadne vode. Eden izmed načinov za preprečevanje širjenja odpornosti proti antibiotikom je čiščenje odpadne vode z uporabo kombinacije TiO2, UV svetlobe in ozona, ki so se pokazale kot uspešne metode za odstranjevanje bakterij, odpornih proti antibiotikom.