Coastal sediments in the proximity of wastewater and emergency outfalls are often sinks of pharmaceutical compounds and other organic and inorganic contaminants that are likely to affect the microbial community. The metabolites of these contaminants affect microbial diversity and their metabolic processes, resulting in undesirable effects on ecosystem functioning, thus necessitating the need to understand their composition and functions. In the present investigation, we studied the metagenomes of 12 coastal surface sediments through whole genome shot-gun sequencing. Taxonomic binning of the genes predicted about 86% as bacteria, 1% as archaea, >0.001% as viruses and Eukaryota, and 12% as other communities. The dominant bacterial, archaeal, and fungal genera were Woeseia, Nitrosopumilus, and Rhizophagus, respectively. The most prevalent viral families were Myoviridae and Siphoviridae, and the T4 virus was the most dominant bacteriophage. The unigenes further aligned to 26 clusters of orthologous genes (COGs) and five carbohydrate-active enzymes (CAZy) classes. Glycoside hydrolases (GH) and glycoside transferase (GT) were the highest-recorded CAzymes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) level 3 functions were subjugated by purine metabolism > ABC transporters > oxidative phosphorylation > two-component system > pyrimidine metabolism > pyruvate metabolism > quorum sensing > carbon fixation pathways > ribosomes > and glyoxalate and dicarboxylate metabolism. Sequences allying with plasmids, integrons, insertion sequences and antibiotic-resistance genes were also observed. Both the taxonomies and functional abundances exhibited variation in relative abundances, with limited spatial variability (ANOVA p > 0.05; ANOSIM-0.05, p > 0.05). This study underlines the dominant microbial communities and functional genes in the marine sediments of Kuwait as a baseline for future biomonitoring programs.

Marine sediments are a sink for antibiotic resistance genes (ARGs) and antibiotic-resistant microbes (ARMs). Wastewater discharge into the aquatic environment is the dominant pathway for pharmaceuticals reaching aquatic organisms. Hence, the characterization of ARGs is a priority research area. This baseline study reports the presence of ARGs in 12 coastal sediment samples covering the urban coastline of Kuwait through whole-genome metagenomic sequencing. The presence of 402 antibiotic resistance genes (ARGs) were recorded in these samples; the most prevalent were patA, adeF, ErmE, ErmF, TaeA, tetX, mphD, bcrC, srmB, mtrD, baeS, Erm30, vanTE, VIM-7, AcrF, ANT4-1a, tet33, adeB, efmA, and rpsL, which showed resistance against 34 drug classes. Maximum resistance was detected against the beta-lactams (cephalosporins and penam), and 46% of genes originated from the phylum Proteobacteria. Low abundances of ESKAPEE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumanii, Pseudomonas aeruginosa, Enterobacter sps., and Escherichia coli) were also recorded. Approximately 42% of ARGs exhibited multiple drug resistance. All the ARGs exhibited spatial variations. The major mode of action was antibiotic efflux, followed by antibiotic inactivation, antibiotic target alteration, antibiotic target protection, and antibiotic target replacement. Our findings supported the occurrence of ARGs in coastal marine sediments and the possibility of their dissemination to surrounding ecosystems.

Antimicrobial resistance (AMR) is one of the biggest threats to human health worldwide. The World Health Organization (WHO, Geneva, Switzerland) has launched the “One-Health” approach, which encourages assessment of antibiotic-resistant genes (ARGs) within environments shared by human-animals-plants-microbes to constrain and alleviate the development of AMR. Aerosols as a medium to disseminate ARGs, have received minimal attention. In the present study, we investigated the distribution and abundance of ARGs in indoor and outdoor aerosols collected from an urban location in Kuwait and the interior of three hospitals. The high throughput quantitative polymerase chain reaction (HT-qPCR) approach was used for this purpose. The results demonstrate the presence of aminoglycoside, beta-lactam, fluoroquinolone, tetracycline, macrolide-lincosamide-streptogramin B (MLSB), multidrug-resistant (MDR) and vancomycin-resistant genes in the aerosols. The most dominant drug class was beta-lactam and the genes were IMP-2-group (0.85), Per-2 group (0.65), OXA-54 (0.57), QnrS (0.50) and OXA-55 (0.55) in the urban non-clinical settings. The indoor aerosols possessed a richer diversity (Observed, Chao1, Shannon’s and Pielou’s evenness) of ARGs compared to the outdoors. Seasonal variations (autumn vs. winter) in relative abundances and types of ARGs were also recorded (R² of 0.132 at p < 0.08). The presence of ARGs was found in both the inhalable (2.1 µm, 1.1 µm, 0.7 µm and < 0.3 µm) and respirable (>9.0 µm, 5.8 µm, 4.7 µm and 3.3 µm) size fractions within hospital aerosols. All the ARGs are of pathogenic bacterial origin and are hosted by pathogenic forms. The findings present baseline data and underpin the need for detailed investigations looking at aerosol as a vehicle for ARG dissemination among human and non-human terrestrial biota.

Airborne particles play a significant role in the spread of bacterial communities. The prevalence of both pathogenic and non-pathogenic forms in the inhalable fractions of aerosols is known. The abundance of microorganisms in the aerosols heightens the likely health hazards due to inhalation since they serve as carriers for pathogens and allergens, often acting as a vector for pulmonary/respiratory infections. Not much information is available on the occurrence and prevalence of bacterial communities in different size-fractionated aerosols in Kuwait. A high-volume air sampler with a six-stage cascade impactor was deployed for sample collection at two sites representing a remote and an urban site. A total volume of 815 ± 5 m³ of air was passed through the filters to trap the particulate matter ranging from 0.39 to >10.2 μm in size (Stage 1 to Stage 5 and base filter). Aeromonas dominated all the stages at the urban site and Stage 5 at the remote site, whereas Sphingobium was prevalent at Stages, 2, 3 and 4 at the remote site. Brevundimonas were found at Stages 1 and 5, and the base filter at the remote site. These results show that the bacterial community is altered in different size fractions of aerosols. Stages 1–4 form the respirable fraction, whereas Stage 5 and particles on the base filter are the inhalable fractions. Many species of Aeromonas cause disease, and hence their presence in inhalable fractions is a health concern, meaning that species-level identification is warranted.

Prolonged and excessive use of antibiotics has resulted in the development of antimicrobial resistance (AMR), which is considered an emerging global challenge that warrants a deeper understanding of the antibiotic-resistant gene elements (ARGEs/resistomes) involved in its rapid dissemination. Currently, advanced molecular methods such as high-throughput quantitative polymerase chain reaction (HT-qPCR) and shotgun metagenomic sequencing (SMS) are commonly applied for the surveillance and monitoring of AMR in the environment. Although both methods are considered complementary to each other, there are some appreciable differences that we wish to highlight in this communication. We compared both these approaches to map the ARGEs in the coastal sediments of Kuwait. The study area represents an excellent model as it receives recurrent emergency waste and other anthropogenic contaminants. The HT-qPCR identified about 100 ARGs, 5 integrons, and 18 MGEs (total—122). These ARGs coded for resistance against the drug classes of beta-lactams > aminoglycoside > tetracycline, macrolide lincosamide streptogramin B (MLSB) > phenicol > trimethoprim, quinolone, and sulfonamide. The SMS picked a greater number of ARGs (402), plasmid sequences (1567), and integrons (168). Based on the evidence, we feel the SMS is a better method to undertake ARG assessment to fulfil the WHO mandate of “One Health Approach.” This manuscript is a useful resource for environmental scientists involved in AMR monitoring.