UPLC-MS/MS analysis of antibiotics in pharmaceutical effluent in Tunisia: ecotoxicological impact and multi-resistant bacteria dissemination

VirBR, a transcription regulator, promotes IncX3 plasmid transmission, and persistence of blaNDM-5 in zoonotic bacteria

IncX3 plasmids carrying the New Delhi metallo-β-lactamase-encoding gene, blaNDM-5, are rapidly spreading globally in both humans and animals. Given that carbapenems are listed on the WHO AWaRe watch group and are prohibited for use in animals, the drivers for the successful dissemination of Carbapenem-Resistant Enterobacterales (CRE) carrying blaNDM-5-IncX3 plasmids still remain unknown. We observe that E. coli carrying blaNDM-5-IncX3 can persist in chicken intestines either under the administration of amoxicillin, one of the largest veterinary β-lactams used in livestock, or without any antibiotic pressure. We therefore characterise the blaNDM-5-IncX3 plasmid and identify a transcription regulator, VirBR, that binds to the promoter of the regulator gene actX enhancing the transcription of Type IV secretion systems (T4SS); thereby, promoting conjugation of IncX3 plasmids, increasing pili adhesion capacity and enhancing the colonisation of blaNDM-5-IncX3 transconjugants in animal digestive tracts. Our mechanistic and in-vivo studies identify VirBR as a major factor in the successful spread of blaNDM-5-IncX3 across one-health AMR sectors. Furthermore, VirBR enhances the plasmid conjugation and T4SS expression by the presence of copper and zinc ions, thereby having profound ramifications on the use of universal animal feeds.

Occurrence of contaminants of emerging concern and pesticides and relative risk assessment in Tunisian groundwater

Groundwater is an important source for drinking water supply, agricultural irrigation and industrial uses in the Middle East and North Africa region. Due to the growing need for groundwater use, groundwater quality studies on the presence of contaminants of emerging concern (CECs) and pesticides have gained attention. The Wadi El Bey is one of the most polluted areas in Tunisia. However, very limited data on CECs infiltration into aquifers has been described, in comparison to industrialized countries where groundwater contamination has been comprehensively addressed. To gain early insight into potential contamination, groundwater wells in northeast Tunisia, an area with high population density and intensive agricultural activity were sampled during two seasons and were analyzed with two high resolution mass spectrometry approaches: target and suspect screening. The latter was used for screening banned pesticides. A selection of 116 CECs of which 19 are transformation products (TPs) and 20 pesticides previously prioritized by suspect screening were screened in the groundwater samples. The results showed the presence of 69 CECs and 1 TP and 20 pesticides at concentrations per well, ranging between 43 and 7384 ng L-1 and 7.3 and 80 ng L-1, respectively. CECs concentrations in Tunisian groundwater do not differ from those in industrialized countries. WWTPs were considered the main source of pollution, where the main classes detected were analgesics, antihypertensives and artificial sweeteners and especially caffeine, salicylic acid and ibuprofen were found to be ubiquitous. Regarding pesticides, triazines herbicides and carbamates insecticides pose the highest concern due to their ubiquitous presence, high leachability potential for most of them and high toxicity. The environmental risk assessment (ERA) highlighted the high risk that caffeine, ibuprofen, and propoxur may pose to the environment, and consequently, to non-target organisms. This study provides occurrence and ERA analysis of CECs and pesticides in Tunisian groundwater.

Antibiotic, Heavy Metal, and Biocide Concentrations in a Wastewater Treatment Plant and Its Receiving Water Body Exceed PNEC Limits: Potential for Antimicrobial Resistance Selective Pressure

Although the rise in antimicrobial resistance has been attributed mainly to the extensive and indiscriminate use of antimicrobials such as antibiotics and biocides in humans, animals and on plants, studies investigating the impact of this use on water environments in Africa are minimal. This study quantified selected antibiotics, heavy metals, and biocides in an urban wastewater treatment plant (WWTP) and its receiving water body in Kwazulu-Natal, South Africa, in the context of the predicted no-effect concentrations (PNEC) for the selection of antimicrobial resistance (AMR). Water samples were collected from the WWTP effluent discharge point and upstream and downstream from this point. Heavy metals were identified and quantified using the United States Environmental Protection Agency (US EPA) method 200.7. Biocides and antibiotic residues were determined using validated ultra-high-performance liquid chromatography with tandem mass spectrometry-based methods. The overall highest mean antibiotic, metal and biocide concentrations were observed for sulfamethoxazole (286.180 µg/L), neodymium (Nd; 27.734 mg/L), and benzalkonium chloride (BAC 12) (7.805 µg/L), respectively. In decreasing order per sampling site, the pollutant concentrations were effluent > downstream > upstream. This implies that the WWTP significantly contributed to the observed pollution in the receiving water. Furthermore, most of the pollutants measured recorded values exceeding the recommended predicted no-effect concentration (PNEC) values, suggesting that the microbes in such water environments were at risk of developing resistance due to the selection pressure exerted by these antimicrobials. Further studies are required to establish such a relationship.

The abundance of endocrine-disrupting chemicals (EDCs) in downstream of the Bengawan Solo and Brantas rivers located in Indonesia

Numerous chemical substances are used for daily life activities have an effect on the endocrine system and are frequently classed as endocrine-disrupting chemicals (EDCs). The present study investigated the fact and distribution of EDCs type (estrogen, plasticizer, and preservative). In particular, EDCs such as estriol, 1,2,4 triazole, 17α-ethinylestradiol, methyl paraben, estrone, 3,4,4 trichlorocarbanilide, 17β-estradiol, and bisphenol A (BPA) were selected as the target EDCs for the detection in the Bengawan Solo and Brantas rivers located in Indonesia. Among the targeted EDCs, BPA is found to be highest in the water samples of Bengawan Solo (1070 ng/L and mean at 219 ng/L) and Brantas (556 ng/L and mean at 222 ng/L) rivers. The EDCs concentration is higher in both rivers during the dry season compared to the wet season due to the dilution effect caused by heavy rainfall. The entry of municipal wastewater is the primary sources of EDCs contamination in both rivers. Finally, this study suggests that the contamination level of EDCs in river water could pose an environmental threat, particularly during dry seasons.

Functional Up-Conversion Nanoparticle-Based Immunochromatography Assay for Simultaneous and Sensitive Detection of Residues of Four Tetracycline Antibiotics in Milk

An ultrahigh-sensitivity lateral flow immunochromatography (LFIC) assay based on up-converting nanoparticles (UCNPs) was developed to carry out a multi-residue detection of tetracycline in milk. The sensitivity of the immunoassay was greatly improved by the use of a broad-spectrum monoclonal antibody attached to UCNPs to form a signal probe. Under the optimal conditions, the UCNP-LFIC assay enabled sensitive detection of tetracycline (TC) as well as of oxytetracycline (OTC), chlortetracycline (CTC), and doxycycline (DOX) within 10 min, with IC ₅₀ values of 0.32, 0.32, 0.26, 0.22 ng/mL, respectively. There was no cross-reactivity with ten other antibiotics. Similarly, we evaluated the experimental results for matrix effects. Experiments involving spiking showed the four tetracycline antibiotics displaying mean recoveries ranging from 93.95 to 111.90% with relative standard deviations (RSDs) of < 9.95%. The detection results of actual samples using the developed method showed a good correlation (R ² ≥ 0.98) with the results using high-performance liquid chromatography (HPLC). Thus, the assay can achieve an ultrahighly sensitive detection of antibiotics in milk, and can hence promote human health and provides promising applications in the bio-detection field.

Analysis, occurrence and removal of pharmaceuticals in African water resources: A current status

Pharmaceuticals are organic compounds used in medicines for alleviation of pain. Since 2017, there has been a steady increase on the availability of information on contamination of water resources caused by pharmaceuticals in some African countries. Thus far, most environmental monitoring studies of pharmaceuticals are conducted in South Africa while there is still no available data in majority of the African countries. Therefore, the knowledge on the presence of pharmaceuticals in African water resources is still lacking. In an attempt to provide more information in this aspect, this review article seeks to critically evaluate the progress made thus far by the African scientists in the environmental monitoring and assessment of pharmaceuticals. The most studied groups of pharmaceuticals in Africa are non-steroidal anti-inflammatory drugs, antibiotics, antiretroviral drugs and steroid hormones. Various remediation studies for selected pharmaceuticals in Africa are documented in literature. In the present review, the challenges facing the African researchers or countries on providing more scientific data on the occurrence of pharmaceuticals in water are discussed. Furthermore, the gaps and recommendations for future work are given.

Bacterial community structures and biodegradation kinetic of Tiamulin antibiotic degrading enriched consortia from swine wastewater

The antibiotic tiamulin (TIA) is common and widely used medication for dysentery eradication in swine productions. Tiamulin persists in livestock manure, and its residues have been found in various environment. This work obtained four tiamulin-degrading enriched bacterial consortia from a covered anaerobic lagoon system and a stabilized pond system of swine farms. Tiamulin was efficiently removed by the enriched cultures at the concentrations between 2.5 and 200 mg/L, with a removal of 60.1-99.9% during 16 h and a degradation half-life of 4.5-15.7 h. The stabilized pond system cultured with taimulin solely could eliminate tiamulin at the highest rates. The logistic substrate degradation model fit most of the experimental data. Next-generation amplicon sequencing was conducted, and it was found that the bacterial community was significantly impacted by the inoculum source, nutrient addition, and high tiamulin concentrations. Principal coordinate analysis (PCoA) indicated the similarity of bacterial communities in the original enriched samples and the 2.5 mg/L tiamulin-removed cultures. The 200 mg/L consortia were rather different and became similar to the other 200 mg/L consortia from different sources and cultures without nutrient supplementation. Shannon and Simpson indices suggested a reduction in bacterial diversity at high concentrations. The microbes that had high growth in the most efficient enriched culture, or which were abundant in all samples, or which increased with higher tiamulin concentrations were likely to be the major tiamulin-degrading bacteria. This is the first report suggested the possible roles of Achromobacter, Delftia, Flavobacterium, Pseudomonas, and Stenotrophomonas in tiamulin degradation.