Manual emptying of ventilated improved pit latrines and hygiene challenges - a baseline survey in a peri-urban community in KwaZulu-Natal, South Africa.

The presence of Escherichia coli and Staphylococcus spp. was determined on the skin, personal protective equipment, the municipal vehicle, and various surfaces at ten households in a peri-urban community (KwaZulu-Natal, South Africa) before and after manual emptying of ventilated improved pit latrines. Surface samples (n = 14) were collected using sterile wet wipes, and target bacteria were detected using standard procedures. Additionally, E. coli was enumerated in soil samples from an area of open defecation (log10 3.7 MPN/g) and areas where geophagia occurred (log10 2.7 - log10 3.3 MPN/g), using a most probable number (MPN) method. The detection frequency for the target bacteria on household surfaces (e.g., the walkway between the pit latrine and the municipal vehicle) and on municipal workers' hands (which were frequently contaminated before pit emptying), occasionally increased after the pits were emptied, indicating that manual pit emptying might pose a potential health risk to workers and community members.

Silver-gold alloy nanoparticles biofabricated by fungal xylanases exhibited potent biomedical and catalytic activities.

The search for biocompatible nanoparticles with vast applicability has impacted on exploration of various biomaterials for the synthesis of mono and bimetallic nanoparticles. Xylanase is widely regarded as an industrially important enzyme but its potentials in nanotechnological applications are yet to be fully explored. The current study investigates the exploit of xylanases of Aspergillus niger L3 (NE) and Trichoderma longibrachiatum L2 (TE) produced through valorization of corn-cob, to synthesize silver-gold alloy nanoparticles (Ag-AuNPs). Characterization of the Ag-AuNPs involved UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy and transmission electron microscopy, while their prospective use as antimicrobial, antioxidant, catalytic, anticoagulant, and thrombolytic agents were studied. The biosynthesized Ag-AuNPs were ruby red and light purple with surface plasmon resonance at 520 and 534 nm for NEAg-AuNPs and TEAg-AuNPs, respectively; while FTIR showed that protein molecules capped and stabilized the nanoparticles. The Ag-AuNPs were anisotropic with spherical, oval, and irregular shapes having sizes ranging from 6.98 to 52.51 nm. The nanoparticles appreciably inhibited the growth of tested clinical bacteria (23.40-90.70%) and fungi (70.10-89.05%), and also scavenged 2,2-diphenyl-1-picrylhydrazyl (48.51-53.79%) and hydrogen peroxide (80.5-95.50%). Furthermore, the Ag-AuNPs degraded malachite green (91.39%) and methylene blue (47.10%). Moreover, the Ag-AuNPs displayed outstanding anticoagulant and thrombolytic activities using human blood. This study further emphasizes the significance of xylanases in nanobiotechnology as it has established the potential of xylanases to synthesize Ag-AuNPs, which is being reported for the first time.

Characterization, antimicrobial, antioxidant, and anticoagulant activities of silver nanoparticles synthesized from Petiveria alliacea L. leaf extract.

Phytosynthesis of silver nanoparticles (AgNPs) using leaf extract of Petiveria alliacea (PA) was the focus of this research work. The PA-AgNPs were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) study. Studies were made on the AgNPs for antibacterial, antifungal, anticoagulant, free-radical scavenging, and hydrogen peroxide scavenging activities. The crystalline PA-AgNPs were monodispersed, with a size range of 16.70-33.74 nm and maximum absorption at 410 nm. FTIR analysis displayed prominent peaks at 3430.6, 1711.8, and 1165.9/cm, which showed the existence of phenolic compounds and proteins in the synthesis of AgNPs. PA-AgNPs was active against Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus, with 100% inhibition. The PA-AgNPs also displayed good antifungal properties, as the concentrations of 100 and 150 µg/mL had 100% inhibition toward Aspergillus fumigatus and Aspergillus flavus. However, there was 66.67% inhibition of Aspergillus niger. It scavenged both DPPH and H2O2 by 70.69 and 89.02%, respectively. PA-AgNPs also prevented the coagulation of human blood. This study, being the first of its kind to use the leaf extract of PA for the synthesis of AgNPs has shown that PA-AgNPs can find biomedical applications.

Antibiotic resistance profiles of coagulase-positive and coagulase-negative staphylococci from pit latrine fecal sludge in a peri-urban South African community.

The aim of this study was to assess pit latrine samples from a peri-urban community in KwaZulu-Natal (South Africa) for the presence of multidrug-resistant (MDR) Staphylococcus spp. Standard procedures were used to isolate Staphylococcus spp. from pit latrine fecal sludge samples, with confirmation at genus level by polymerase chain reaction (PCR). Sixty-eight randomly selected pit latrine Staphylococcus spp. isolates were further characterized by using established disk diffusion procedures. An average Staphylococcus spp. count of 2.1 × 105 CFU per g fecal material was established using two randomly selected pit latrine samples. Of the 68-selected Staphylococcus spp. pit latrine isolates, 49% were identified as coagulase positive, 51% as coagulase negative and 65% (12 coagulase positive, 32 coagulase negative isolates) were categorized as MDR. The majority (66/68) of Staphylococcus spp. isolates displayed resistance to fusidic acid while only 5/68 isolates displayed resistance to chloramphenicol. The pit latrine samples analyzed in this study are a source of MDR Staphylococcus spp., highlighting the need for proper hygiene and sanitation regimes in rural communities using these facilities.

Assessment of pit latrines in a peri-urban community in KwaZulu-Natal (South Africa) as a source of antibiotic resistant E. coli strains.

Due to the frequent use of antibiotics and recurring illnesses related to multidrug-resistant (MDR) bacteria in South Africa, we determined if MDR Escherichia coli were present in pit latrine fecal sludge samples obtained from a peri-urban community in KwaZulu-Natal, South Africa. The abundance of E. coli in pit latrine samples was established using a most probable number (MPN) method with species confirmation done using biochemical tests and polymerase chain reaction (PCR). Forty-four randomly selected E. coli pit latrine isolates were further characterized, using the European committee on antimicrobial susceptibility testing (EUCAST) disk diffusion method to establish antibiotic resistance profiles for these E. coli isolates. The resulting MPN values for E. coli ranged from one to 6.2 log10 MPN per gram of fresh pit latrine fecal sludge. While only 3 out of 44 E. coli pit latrine isolates showed no resistance to any of the 12 tested antibiotics, most isolates were resistant to two or more antibiotics. The majority of isolates showed resistance to at least one of the two tested aminoglycosides, one isolate showed resistance to the carbapenem ertapenem, and although resistance was not detected for tigecycline four pit latrine E. coli isolates showed intermediate resistance to this antibiotic. However, about 14% of the E. coli pit latrine isolates were categorized as MDR, all of which showed resistance to four or more antibiotics. The presence of MDR E. coli strains in pit latrine samples demonstrates that these facilities are potential sources for MDR bacteria.

Biomedical and Catalytic Applications of Gold and Silver-Gold Alloy Nanoparticles Biosynthesized Using Cell-Free Extract of Bacillus Safensis LAU 13: Antifungal, Dye Degradation, Anti-Coagulant and Thrombolytic Activities.

This study investigated the green biosynthesis of gold (Au) and silver-gold alloy (Ag-Au) nanoparticles using cell-free extract of Bacillus safensis LAU 13 strain (GenBank accession No: KJ461434). The biosynthesized AuNPs and Ag-AuNPs were characterized using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. Evaluation of the antifungal activities, degradation of malachite green, anti-coagulation of blood, and thrombolysis of human blood clot by the biosynthesized nanoparticles were investigated. The AuNPs and Ag-AuNPs had maximum absorbance at 561 and 545 nm, respectively. The FTIR peaks at 3318, 2378, 2114, 1998, 1636, 1287, 446, 421 cm-1 for AuNPs; and 3310, 2345, 2203, 2033, 1636, 1273, 502, 453, 424 cm-1 for Ag-AuNPs indicated that proteins were the capping and stabilization molecules in the biosynthesized nanoparticles. The particles were fairly spherical in shape with size of 10-45 nm for AuNPs and 13-80 nm for Ag-AuNPs. Moreover, energy dispersive X-ray analysis of AuNPs revealed gold as the most prominent metal in the AuNPs solution, while silver and gold were the most prominent in the case of Ag-AuNPs. Selected area electron diffraction showed the biosynthesized nanoparticles as crystal structures with ring shape pattern. AuNPs and Ag-AuNPs displayed growth inhibitions of 66.67-90.78% against strains of Aspergillus fumigatus and A. niger at concentration of 200 µg/ml , and remarkable degradation (> 90%) of malachite green after 48 h. Furthermore, the nanoparticles prevented coagulation of blood, and also completely dissolved blood clots, indicating the biomedical potential of AuNPs and Ag-AuNPs in the management of blood coagulation disorders. This is the first report of the synthesis of AuNPs and Ag-AuNPs using a strain of B. safensis for biomedical and catalytic applications.

Paper wasp nest-mediated biosynthesis of silver nanoparticles for antimicrobial, catalytic, anticoagulant, and thrombolytic applications.

Biosynthesis of silver nanoparticles (AgNPs) using nest extract of paper wasp (Polistes sp) was investigated in this work. The AgNPs were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), and evaluated for antibacterial, antifungal, dye degradation, blood anticoagulation, and blood clot dissolution (thrombolytic) activities. The crystalline polydispersed AgNPs with size range of 12.5-95.55 nm absorbed maximally at 428 nm and showed anisotropic structures of sphere, triangle, hexagon, rod, and rhombus. The FTIR data showed prominent peaks at 3426 and 1641 cm-1, which indicate the involvement of phenolics compounds and proteins in the synthesis of AgNPs. The prominence of Ag in the EDX spectra showed that indeed, AgNPs were formed. The AgNPs showed potent antibacterial activities (12-35 mm) against three multi-drug strains of Pseudomonas aeruginosa and Klebsiella granulomatis. While the growth of Aspergillus flavus and Aspergillus niger was completely suppressed, the AgNPs produced growth inhibition of 75.61 % against Aspergillus fumigatus at 100 µg/ml. Furthermore, the AgNPs degraded malachite green to the tune of 93.1 %. The AgNPs also prevented coagulation of blood, while it completely dissolved preformed blood clots within 5 min showing the potent anticoagulation and thrombolytic activities. This study, which is the first of its kind to use nest extract of paper wasp for the synthesis of nanoparticles, has shown that the biosynthesized AgNPs could be deployed for biomedical and catalytic applications.