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Antibiotics are one of the most important emerging contaminants as they have been detected in several environmental compartments including soil. Compared to the wide literature on the effects of antibiotics on aquatic organisms, knowledge and understanding of their potential effects on terrestrial environment is still scarce, especially when mixtures are taken into consideration. In this study, a screening-level phytotoxicity assay was used to evaluate the effects of three antibiotics (Oxytetracycline, Levofloxacin, Ampicillin) individually and in mixtures, on seed germination, root and shoot elongation of Egyptian clover (Trifolium alexandrinum L.) After five days exposure time, the acute effects of individual antibiotics and their binary and ternary mixtures were assessed using three endpoints, namely percentage of seed germination, shoot length and root elongation. The results of the study indicated that plant germination was insensitive to the individually tested antibiotics, with no significant decreases up to the highest treatment concentration of 100 mg L-1. Root elongation was observed as the most sensitive end point in individual antibiotics. However, increase in the root and shoot elongation was observed in mixtures relative to the individual antibiotics. The results show the importance of evaluating the toxicity of antibiotic mixtures, since they might have distinct effects when compared to the individual compounds.

Bacteria from wastewater discharged to the sewerage near three hospitals of Islamabad, Rawalpindi, and Faisalabad were examined for resistance to the most commonly prescribed antibiotics in Pakistan. From the selected sites, a total of 109 isolates from 40 different species were identified based on 16S rRNA gene sequence and phylogeny. The isolates were tested for their resistance to ciprofloxacin, levofloxacin, ofloxacin, amoxicillin, and ampicillin. The results indicated that the isolates were resistant with the highest percentage to ampicillin and the lowest percentage to ciprofloxacin. Among the resistant isolates, 91.7% were found resistant to ampicillin, 83.5% to amoxicillin, 67.0% to ofloxacin, whereas only 27.5% to ciprofloxacin and 21.1% to levofloxacin. Among three sampled locations, the most of resistance was observed in Escherichia and Acinetobacter species. More than 30% isolated microorganisms were found resistant to more than three antibiotics. These findings concluded the presence of predominant microbial population resistant to antibiotics in wastewater channels near hospitals and its surroundings, which requires further investigation regarding their existence and spread in other environmental media having potential community health implications.

Antibiotic resistance is a global public health issue and it is even more daunting in developing countries. The main objective of present study was to investigate molecular responses of antibiotic-resistant bacteria. The 48 bacterial strains, which were previously isolated and identified were subjected to disc diffusion and MIC (minimum inhibitory concentration) determination, followed by investigating the production of the three beta-lactamases (ESBLs (Extended-spectrum Beta-lactamases), MBLs (Metallo Beta-lactamases), AmpCs) and exploring prevalence of the two antibiotic-resistant genes (ARGs); blaTEM and qnrS. Higher MIC values were observed for penicillin(s) than that for fluoroquinolones (ampicillin > amoxicillin > ofloxacin > ciprofloxacin > levofloxacin). Resistance rates were high (58–89%) for all of the tested beta-lactams. Among the tested strains, 5 were ESBL producers (4 Aeromonas spp. and 1 Escherichia sp.), 2 were MBL producers (1 Stenotrophomonas sp. and 1 Citrobacter sp.) and 3 were AmpC producers (2 Pseudomonas spp. and 1 Morganella sp.). The ARGs qnrS2 and blaTEM were detected in Aeromonas spp. and Escherichia sp. The results highlighted the role of Aeromonas as a vector. The study reports bacteria of multidrug resistance nature in the wastewater environment of Pakistan, which harbor ARGs of clinical relevance and could present a public health concern. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-020-02366-3) contains supplementary material, which is available to authorized users.

Antibiotic resistance is a worldwide problem and is wreaking havoc in many developed and developing countries. Investigations are being carried out in this field but special attention needs to be paid to antibiotic resistance in environmental matrices. Studies have proven that the environment plays a significant part in spreading antibiotic resistance. Aquatic environment provides ideal conditions for genetic recombination and emergence of antibiotic resistance because of the presence of selective pressure and opportunities for genetic material exchange. Scientific evidence suggests that resistant bacteria and genes are pervasive in the environment, and horizontal gene transfer (HGT) mechanism in particular, with integrons as most common for environmental dissemination of resistance. A number of studies have found correlation of high level of integrons with anthropogenically affected locations, promoting resistance in environment. These locations, contaminated by human activities, act as hotspots for antibiotic resistance development and dissemination. High concentrations of antibiotics in environment are another major concern that is directly promoting selection of bacterial resistance in environment. These sublethal concentrations are promoting resistance and facilitating HGT. To combat and curb this issue, in-depth knowledge and understanding of antibiotics in environment are essential.