Detection of antibiotic resistance genes in wastewater treatment plant – molecular and classical approach

Abstract

Antibiotics are a group of substances potentially harmful to the environment. They can play a role in bacterial resistance transfer among pathogenic and non-pathogenic bacteria. In this experiment three representatives of medically important chemotherapeutics, confi rmed to be present in high concentrations in wastewater treatment plants with HPLC analysis were used: erythromycin, sulfamethoxazole and trimethoprim. Erythromycin concentration in activated sludge was not higher than 20 ng L , respectively in winter and summer. Due to a wide variety of PCR-detectable resistance mechanisms towards these substances, the most common found in literature was chosen. For erythromycin: erm and mef genes, for sulfamethoxazole: sul1, sul2, sul3 genes, in the case of trimethoprim resistance dhfrA1 and dhfr14 were used in this study. The presence of resistance genes were analyzed in pure strains isolated from activated sludge and in the activated sludge sample itself. The research revealed that the value of minimal inhibitory concentration (MIC) did not correspond with the expected presence of more than one resistance mechanisms. Most of the isolates possessed only one of the genes responsible for a particular chemotherapeutic resistance. It was confi rmed that it is possible to monitor the presence of resistance genes directly in activated sludge using PCR. Due to the limited isolates number used in the experiment these results should be regarded as preliminary.

Resistance genes to sulphonamide in commensal Escherichia coli isolated from stool of patients in Mansoura University Children Hospital

“…In the same year, Grape et al (2003) detected this gene in E. coli recovered (Perreten and Boerlin, 2003). According to the studies of Wu et al (2010) and Ziembińska-Buczyńska et al (2015), sul3 gene is the least prevalent one in E. coli strains recovered from human and animal resources, this data is in parallel with the present results. Although, sul3 gene was rarely detected in the studied isolates (4% only), this small percentage should be considered as it may be a warning sign revealing that its existence can be widespread in the locality.…”

The occurrence of antibiotic-resistant bacteria, including Escherichia coli, in municipal wastewater and river water

“…In a study by Ziembińska-Buczyńska et al, [17] total bacterial counts in activated sludge fluctuated between 12x10 9 CFU/mL in samples collected in summer and 42x10 9 CFU/mL in winter, and they increased steadily between winter and spring months. The cited authors also reported higher counts of bacteria resistant to erythromycin and sulfamethoxazole/trimethoprim in samples from winter.…”

“…The presence in the aquatic ecosystems of intestinal bacteria, originating from WWTPs, may have a negative impact on public health because of these bacteria can be characterized by multi-drug resistance and they frequently possess ARGs or virulence genes [11,28]. Additionally, these ARB can transmit resistance to native bacteria from the environment, including both pathogenic or non-pathogenic bacteria, mediated by mobile genetic elements, such as plasmids (conjugation), bacteriophages (transduction), or free DNA from the environment (transformation) [11,17]. The obtained results indicate the presence of ARB also in river water before and after the inflow of WWTPs, which may pose a threat to human health and animals using water resources.…”

Isolation and antibiotic resistance profiles of bacteria from influent, effluent and downstream: A study in Botswana

“…The results are consistent with other studies conducted globally. For example, in a study by Ziembińska-Buczyńska et al (2015) on communal WWTP in Zabrze (Poland), dfr and sul1 genes were detected in most of the sample tested from influent, effluent and downstream. In another study, sul1 together with int1 were also detected in samples from WWTP and the downstream environments (Sayah et al, 2005).…”