Impact of Hospital Wastewater on the Occurrence and Diversity of Beta-Lactamase Genes During Wastewater Treatment with an Emphasis on Carbapenemase Genes: A Metagenomic Approach

Abstract

The diversity of beta-lactam antibiotic resistance genes, with particular emphasis on carbapenemase genes, during the treatment process at two wastewater treatment plants (WWTPs) with different levels of hospital wastewater inflow was investigated using high-throughput sequencing. An additional aspect of the study was to determine the taxonomic diversity of microorganisms in the studied samples. The obtained results suggest that bacteria of the Fusobacteriaceae family, not associated to date with this phenomenon, may be involved in the spread of antibiotic resistance in the environment. In samples from both wastewater treatment plants, the dominant beta-lactamase genes included blaOXA, blaGES, blaBEL, blaCfxA, and blaTEM. It is worth noting that the blaKPC and blaNDM genes were only found in untreated municipal wastewater with a higher hospital wastewater content. Moreover, an increase in the abundance of the blaIMP gene after the biological treatment stage in the studied treatment plants was found. In wastewater characterized by a higher proportion of hospital wastewater, 94 correlations were observed, while in wastewater with its lower proportion, 41 correlations were noted. Considering the above, the current research indicates that the inflow of hospital wastewater contributes to the spread of antibiotic resistance in the aquatic environment.

The Resistome of ESKAPEE Pathogens in Untreated and Treated Wastewater: A Polish Case Study

“…An analysis of integrase genes (MGEs) revealed that int I1 was more prevalent in wastewater samples (78.17–2911.29 ppm) than int I2 (0.37–34.41 ppm) and int I3 (0.15–10.03 ppm) ( Figure 4 and Table S11 ). Similar results were noted in our previous study [ 33 ], where int I1 was the most abundant integrase gene (166.59–2883.91 ppm), whereas int I2 (0.02–29.87 ppm) and int I3 (0.09–2.46 ppm) were determined in smaller quantities. The concentrations of integrase genes followed a similar pattern in other studies [ 69 , 70 ].…”

“…The activated sludge process in the WWTP equipped with a biological and mechanical wastewater treatment system reduced the abundance of ESKAPEE genera and species by 80% on average (UWW vs. TWW) ( Table S4 ). In other studies, biological and mechanical wastewater treatment systems led to a similar reduction in microbial levels (80–99%) [ 33 , 50 ]. According to the literature, the effectiveness of wastewater treatment can be significantly affected by the type of wastewater inflow and fluctuations in a plant’s performance [ 51 , 52 , 53 ].…”

“…The plant also receives wastewater from four hospitals, which accounts for 2% of the treated wastewater. Detailed information about the examined WWTP was previously provided by Hubeny et al [ 33 ].…”

Clinically Relevant β-Lactam Resistance Genes in Wastewater Treatment Plants

“…In some studies, bla TEM was predominant, e.g., in an Irish study [ 86 ], as well as in Colombia [ 87 ], Poland and Portugal [ 9 , 88 ], Belgium [ 89 ], the US [ 90 ], and Africa [ 91 ]. Another significant group representing the KPC family encoded by bla KPC genes was detected in numerous WWTPs from European [ 65 , 69 , 89 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 ], as well as from American [ 90 , 102 , 103 , 104 ], African [ 72 , 91 , 105 ], and Asian countries [ 106 , 107 ]. Moreover, analysis of reviewed articles, especially those using developed techniques as high-throughput qPCR, whole-genome sequencing, or metagenomics, shows a high variety of detected genes of the discussed β-lactamases, not only representing bla CTX-M , bla SHV , bla TEM , and bla KPC families, but also others less frequently associated with public health, i.e., BEL, cfxA, GES, PER, SME, VEB, and others [ 65 , 92 , 96 , 102 , 107 , 108 , 109 , 110 , 111 ].…”

“…Finally, the removal efficiency of ARGs was the least for bla GES (94.8%) and bla CTX-M (95.3%), while for other genes, it was >98% [ 69 ]. In another study, the presence of bla KPC was completely eliminated even after the first mechanical procedure [ 93 ]. In a Chinese survey comparing bacteria carrying bla CTX-M , bla SHV , and bla TEM , isolated from influent and effluent, higher prevalence was noted in influent samples, except for bla CTX-M , which was more frequently detected in effluent samples [ 129 ].…”