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With the risks associated with healthcare-associated infections and the rise of antibiotic resistant microorganisms, there is an important need to control the proliferation of these factors in hospitals, retirement homes and other institutions. This work explores the development and application of a novel class of sulfonamide-based quaternary ammonium antimicrobial coatings, anchored to commercially and clinically relevant material surfaces. Synthesized in high yields (60–97%), benzophenone-anchored antimicrobials were spray-coated and UV grafted onto plastic surfaces, while silane-anchored variants were adhered to select textiles via dip-coating. Surface modified samples were characterised by advancing contact angle, anionic dye staining, X-ray photoelectron spectroscopy and atomic force microscopy. After verifying coating quality through the above characterization methods, microbiological testing was performed on batch samples in conditions that simulate the natural inoculation of surfaces and objects (solid/air) and water containers (solid/liquid). Using the previously established Large Drop Inoculum (LDI) protocol at solid/air interfaces, all treated samples showed a full reduction (105–107 CFU) of viable Arthrobacter sp., S. aureus, and E. coli after 3 h of contact time. Additional testing of the walls of plastic LDPE vials treated with a UV-cured sulfonamide antimicrobial at a solid/liquid interface using the newly developed Large Reservoir Inoculum (LRI) protocol under static conditions revealed a complete kill (>106 reduction) of Gram-positive Arthrobacter sp., and a partial kill (>104 reduction) of Gram-negative E. coli within 24–48 h of contact.

The 3.9-Mbp draft genome sequence of Arthrobacter sp. strain 260, which was isolated from a uranium tailings management facility, is reported. The sequence may help determine the bioremediation potential of this strain and facilitate further research aimed at a better understanding of the hypertolerance of this genus to extreme conditions.

With their large, diverse microbial communities chronically exposed to sub-inhibitory antibiotic concentrations, wastewater treatment works (WWTW) have been deemed hotspots for the emergence and dissemination of antimicrobial resistance, with growing concern about the transmission of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) into receiving surface waters. This study explored (1) the prevalence of ARG and ARB in local WWTW, (2) the effect of sub-inhibitory antimicrobial exposure on ARG copy numbers in pure cultures from WWTW, and (3) two WWTW with different treatment configurations. For each WWTW, qPCR determined the prevalence ofmcr3, sul1, sul2, andblaKPCduring the treatment process, and culture methods were used to enumerate and identify ARB. Bacterial colonies isolated from effluent samples were identified by 16S rDNA sequencing and their respective minimum inhibitory concentrations (MIC) were determined. These were compared to the MICs of whole community samples from the influent, return activated sludge, and effluent of each WWTW. Resistance genes were quantified in 11 isolated cultures before and after exposure to sub-MIC concentrations of target antibiotics. The numbers of ARG and ARB in both WWTW effluents were notably reduced compared to the influent.Sul1andsul2gene copies increased in cultures enriched in sub-MIC concentrations of sulfamethoxazole, whileblaKPCdecreased after exposure to amoxicillin. It was concluded, within the parameters of this study, that WWTW assist in reducing ARG and ARB, but that sub-inhibitory exposure to antimicrobials has a varied effect on ARG copy number in pure cultures.

This study extends probiotic cleaning research to a built environment. Through an eight-month cleaning trial, we compared the effect of three cleaning products (disinfectant, plain soap, and a probiotic cleaner containing a patented Bacillus spore consortium), and tap water as the control, on the resident microbiome of three common hospital surfaces (linoleum, ceramic, and stainless steel). Pathogens, Escherichia coli and Staphylococcus aureus, were deposited and desiccated, and competitive exclusion was assessed for each microbiome. Cell survival was shown to be an incomplete tool for measuring microbial competitive exclusion. Biofilm competition offered a fuller understanding of competitive dynamics. A test for culturable cell survival showed that both plain soap and probiotic cleaner regimes established a surface microbiome that outcompeted the two pathogens. A different picture emerged when observing biofilms with a deposited and desiccated GFP-labeled pathogen, Pseudomonas aeruginosa. Competitive exclusion was again demonstrated. On surfaces cleaned with disinfectant the pathogen outcompeted the microbiomes. On surfaces cleaned with plain soap, the microbiomes outcompeted the pathogen. However, on surfaces cleaned with probiotic cleaner, despite the exponentially higher surface microbial loads, the microbiome did not completely outcompete the pathogen. Thus, the standard culturable cell test for survival on a surface confirmed the competitive advantage that is typically reported for probiotic cleaners. However, observation of competition in biofilms showed that the more diverse microbiome (according to alpha and beta indices) established on a surface cleaned with plain soap had a better competitive advantage than the monoculture established by the probiotic cleaner. Therefore, microbial diversity appears to be as critical to the competitive exclusion principle as cell numbers. The study showed that both plain soap and probiotic cleaner fostered competitive exclusion far more effectively than disinfectant. Probiotic cleaners with microbial diversity could be worth considering for hospital cleaning.

The tools used to study biofilms generally involve either destructive, end-point analyses or periodic measurements. The advent of the internet of things (IoT) era allows circumvention of these limitations. Here we introduce and detail the development of the BioSpec; a modular, nondestructive, real-time monitoring system, which accurately and reliably track changes in biofilm biomass over time. The performance of the system was validated using a commercial spectrophotometer and produced comparable results for variations in planktonic and sessile biomass. BioSpec was combined with the previously developed carbon dioxide evolution measurement system (CEMS) to allow simultaneous measurement of biofilm biomass and metabolic activity and revealed a differential response of these interrelated parameters to changing environmental conditions. The application of this system can facilitate a greater understanding of biofilm mass–function relationships and aid in the development of biofilm control strategies.

Water from the Blyderiver dam in the Mpumalanga province, South Africa is used for gravity-fed irrigation. Biofilm development in the pipelines causes an increase in pipeline surface roughness, reduced hydraulic capacity, and water delivery below design capacity. The role of manganese (Mn) concentration on biofilm development is of interest, since the water is currently extracted at depth near the bottom of the reservoir (45–50 m when full) where high Mn levels were measured during four sampling events over 2 years. In the water body, dissolved oxygen (DO) and Mn concentrations showed a strong, inverse correlation, with rapid decrease in DO at increased depth, mirrored by an increase in total and soluble Mn. The depth of this inflection point correlated with the reservoir's water level. DO concentrations typically remained constant between 8 and 9 mg l−1 in the upper regions of the water column, followed by a rapid decline to lower than 2 mg l−1 at deeper zones. Similarly, Mn concentrations remained constant with increasing depth, ranging between 10 and 100 μg l−1, followed by a rapid increase once the depth is reached where DO levels started to decline, to 8,631 μg l−1 near the bottom. In the main, 1.5 m diameter pipeline, Mn concentrations decreased with distance; from 8,631 μg l−1 at the extraction point to 134 μg l−1 at 23 km downstream in the bulk aqueous phase, while in the biofilm biomass, Mn concentrations decreased from 30105.4 mg kg−1 at 4.5 km to 23501.9 mg kg−1 at 12.5 km, and 13727.7 mg kg−1 at 28.4 km downstream. This decrease in Mn concentration with distance suggests that biofilm accumulation has not yet reached a steady state. The aesthetic and operational problems caused by manganese in drinking water systems is well-documented, with biological removal gaining increasing interest as alternative to physical and chemical removal strategies. This study showed that the microbial processes that are being harnessed in drinking water treatment, i.e., Mn accumulation through biofilm formation supported by Mn cycling in sand filters, may have undesirable consequences in bulk water distribution systems by causing notable reduction in flow.

South Africa’s rivers are frequently used by communities lacking proper sanitation infrastructure for domestic purposes; however, these surface waters may pose a health risk to immunocompromised individuals due to the presence of opportunistic pathogenic fungi in the polluted water. Although only a few studies have focused on the presence of clinically relevant fungal species in South African rivers, many known opportunistic pathogenic species were found to be predominant in these waters. Furthermore, strong evidence exists that increased numbers of clinically relevant species may be observed in future due to fungi acquiring thermotolerance in response to the global increase in temperature. Thermotolerance is a major factor contributing to pathogenesis in fungi, due to the generally low tolerance of most fungi toward mammalian body temperatures. It is therefore contended that combinatorial effects of water pollution and rising environmental temperatures could lead to an increase in the incidence of mycoses in South Africa. This is especially concerning since a relatively large population of immunocompromised individuals, represente mostly by HIV-infected people, resides in the country.

The study evaluated the mass balance of various contaminants of emerging concern (CEC) from a South African wastewater treatment works (WWTW) and surface waters located upstream and downstream from the point of discharge. A total of 45 CECs, that are grouped into 16 drug classes, were quantified during multiple sampling events that spanned over a period of two years in the study area. Daily loads (DL; in g/day) of the target analytes in the WWTW showed persistence of various CECs, along with population-normalised daily loads (PNDL; in mg/day/1000inh) of pharmaceuticals and drugs of abuse (DOA) that were estimated for the first time in the study area, using the wastewater-based epidemiology (WBE) approach. Multiple chemical markers were recorded in river water located upstream of the WWTW discharge, suggesting other urban pollution sources that contribute towards the CEC loading in the surface water environment. Environmental risk characterisation for the WWTW effluent and surface waters was done to calculate multiple risk quotients (RQs) for each CEC spanning over various sentinel trophic levels. High risk profiles (RQ>1.0) with a frequency of exceedance (FoE) larger than 75% were recorded for several CECs in both WWTW effluent and surface water locations that warrants the need for more refined surveillance of pollution hotspots in the urban catchment. These findings highlight the need for developing an urban water profiling (UWP) approach similar to conventional WBE approaches, at least for low- and middle-income countries (LMICs) where some (peri)urban communities are not connected to municipal sewage infrastructure and thus lead to direct discharge of human waste products into the natural environment.

The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic capacity is limited in defined communities, posing a challenge in tracking and tracing new infections. Monitoring student residences, which are considered infection hotspots, with targeted wastewater surveillance is crucial. This study evaluated the efficacy of SARS-CoV-2 targeted wastewater surveillance for outbreak mitigation at Stellenbosch University's student residences in South Africa. Using torpedo-style passive sampling devices, wastewater samples were collected biweekly from manholes at twelve Stellenbosch University Tygerberg (SUT) campus and Stellenbosch University-Main (SUM) campus student residences. The surveillance led to an early warning detection of SARS-CoV-2 presence on campus, followed by an informed management strategy leading to restriction of student activities on campus and a delay in the onset of the third wave that was experienced throughout the country. Moreover, the study highlighted the extent of possible infections at defined locations even when a low number of confirmed coronavirus disease 2019 (COVID-19) cases were reported. The study also tracked the surge of the Delta and Omicron variants in the student residences using the Thermo Fisher TaqMan® RT-qPCR genotyping assay.

Chemical pollution (including chemicals of emerging concern - CECs) continues to gain increasing attention as a global threat to human health and the environment, with numerous reports on the adverse and sometimes devastating effects upon ecosystems the presence of these chemicals can have. Whilst many studies have investigated presence of CECs in aquatic environments, these studies have been often focused on higher income countries, leaving significant knowledge gaps for many low-middle income countries. This study proposes a new integrated powerless, in-situ multi-mode extraction (iMME) sampler for the analysis of chemicals (105 CECs) and biological (5 genes) markers in water in contrasting settings: an urbanized Avon River in the UK and remote Olifants River in Kruger National Park in South Africa. The overarching goal was to develop a sampling device that maintains integrity of a diverse range of analytes via analyte immobilization using polymeric and glass fibre materials, without access to power supply or cold chain (continuous chilled storage) for sample transportation. Chemical analysis was achieved using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Several mobile CECs showed low stability in river water, at room temperature and typical 24 h sampling/transport time. It is therefore recommended that, in the absence of cooling, environmental water samples are spiked with internal standards on site, immediately after collection and analyte immobilization option is considered, in order to allow fully quantitative analysis. iMME has proven effective in immobilization, concentration and increased stability of CECs at room temperature (and at least 7 days storage) allowing for sample collection at remote locations. The results from the River Avon and Olifants River sampling indicate that the pristine environment of Olifants catchment is largely unaffected by CECs common in the urbanized River Avon in the UK with a few exceptions: lifestyle chemicals (e.g., caffeine, nicotine and their metabolites), paracetamol and UV filters due to tourism and carbamazepine due to its persistent nature. iMME equipped with an additional gene extraction capability provides an exciting new opportunity of comprehensive biochemical profiling of aqueous samples with one powerless in-situ device. Further work is required to provide full integration of the device and comprehensive assessment of performance in both chemical and biological targets.

The oxidation of ammonia by autotrophic bacteria is a central part of the nitrogen cycle and a fundamental aspect of biological nutrient removal (BNR) during wastewater treatment. Autotrophic ammonia oxidation produces protons and results in net-CO