Detection and hazard assessment of pathogenic microorganisms in medical wastes

Elucidating the role of environmental management of forests, air quality, solid waste and wastewater on the dissemination of SARS-CoV-2

The increasing frequency of zoonotic diseases is amongst several catastrophic repercussions of inadequate environmental management. Emergence, prevalence, and lethality of zoonotic diseases is intrinsically linked to environmental management which are currently at a destructive level globally. The effects of these links are complicated and interdependent, creating an urgent need of elucidating the role of environmental mismanagement to improve our resilience to future pandemics. This review focused on the pertinent role of forests, outdoor air, indoor air, solid waste and wastewater management in COVID-19 dissemination to analyze the opportunities prevailing to control infectious diseases considering relevant data from previous disease outbreaks. Global forest management is currently detrimental and hotspots of forest fragmentation have demonstrated to result in zoonotic disease emergences. Deforestation is reported to increase susceptibility to COVID-19 due to wildfire induced pollution and loss of forest ecosystem services. Detection of SARS-CoV-2 like viruses in multiple animal species also point to the impacts of biodiversity loss and forest fragmentation in relation to COVID-19. Available literature on air quality and COVID-19 have provided insights into the potential of air pollutants acting as plausible virus carrier and aggravating immune responses and expression of ACE2 receptors. SARS-CoV-2 is detected in outdoor air, indoor air, solid waste, wastewater and shown to prevail on solid surfaces and aerosols for prolonged hours. Furthermore, lack of protection measures and safe disposal options in waste management are evoking concerns especially in underdeveloped countries due to high infectivity of SARS-CoV-2. Inadequate legal framework and non-adherence to environmental regulations were observed to aggravate the postulated risks and vulnerability to future waves of pandemics. Our understanding underlines the urgent need to reinforce the fragile status of global environmental management systems through the development of strict legislative frameworks and enforcement by providing institutional, financial and technical supports.

Disposal habits and microbial load of solid medical waste in sub-district healthcare facilities and households in Yilo-Krobo municipality, Ghana

The study aimed to assess disposal practices and quantify the microbial load present in SMW from ten sub-district level healthcare facilities and 385 households in Yilo Krobo municipality, Ghana. Disposal of solid medical waste (SMW) was assessed by questionnaire-based surveys, unstructured interviews and field observations. Microbiological analysis identified species and counts of bacteria present in SMW from both sources. Sociodemographic factors influencing the method of SMW disposal in households were evaluated using logistic regression analysis, with statistical significance set at p<0.05. Open burning (29%), burying (25%) and disposal at a dumpsite (49%) were common methods used by households to discard SMW. SMW disposal at a dumpsite was associated with age of respondents in households. Older people (50+ years) were three times more likely to place SMW in household waste later discarded at a dumpsite, compared to younger persons (20–30 years) [a0R, 95%CI = 3.37, 1.41–8.02]. In sub-district level healthcare facilities, open burning and burying were the most common methods used. Bacillus subtilis, Klebsiella pneumonia, Pseudomonas aeruginosa, Clostridium tetani, Enterococcus faecalis, Acinetobacter spp. Escherichia coli, Bacillus cereus and Enterococcus faecium) were bacteria identified in SMW recovered from both the healthcare facilities and the households. Klebsiella pneumoniae, Acinetobacter spp. and Clostridium tetani were found exclusively in untreated SMW generated in the healthcare facilities. Bacillus spp. and Pseudomonas spp. were found in one sample of treated SMW. The microbial load in SMW from healthcare facilities and households ranged from 0.036 x 10³cfc/mg to 0.167 x 10³ cfc/mg and from 0.118 x 10³cfc/mg to 0.125 x 10³cfc/mg respectively. This highlights the need for institutionalizing appropriate treatment methods in sub-district level facilities or strengthening the linkages with higher level facilities to ensure regular and adequate treatment of SMW. Public guidance on management of SMW generated in households which is context specific should also be provided.

An updated min-review on environmental route of the SARS-CoV-2 transmission

The risk of newly emerging diseases is constantly present in a world where changes occur significantly in climatic, commercial, and ecological conditions, in addition to the development of biomedical investigations in new situations. An epidemic respiratory disease instigated by a new coronavirus was initially identified in and has resulted in the current global dissemination. This viral strain and its related disease has been termed "SARS-CoV-2" and "coronavirus disease 2019" (abbreviated "COVID-19" or "2019-nCoV"), respectively, which is transmitted simply between individuals. The World Health Organization (WHO) announced the COVID-19 outburst as a pandemic on March 11, which necessitates a cooperative endeavour globally for mitigating the spread of COVID-19. The absence of previous, and minimum present-day information, particularly concerning the path of contagion have precluded the control of this disease. The present article, therefore, describes the SARS-CoV-2 paths of contagion such as drinking water, solid waste, sewer water, ambient air, and the rest of emerging likely paths.

Vitrified medical wastes bottom ash in cement clinkerization. Microstructural, hydration and leaching characteristics

The present investigation focuses on the utilization of medical wastes incineration bottom ash (MBA), vitrified with soda lime recycled glass (SLRG), as an alternative raw material in cement clinkerization. Bottom ash is recovered from the bottom of the medical wastes incineration chamber, after being cooled down through quenching. It corresponds to 10-15 wt% of the initial medical wastes weight and since it has been classified in the category of hazardous wastes, its safe management has become a major environmental concern worldwide. MBA glasses of various syntheses were initially obtained during the MBA vitrification simultaneously with various amounts of silica scrap (20, 25 and 30 wt% correspondingly). The produced MBA glasses were in turn used for the production of Portland cement clinker, after sintering at 1400 °C, thus substituting traditional raw materials. Both evaluation of vitrification and sintering products was carried out by chemical and mineralogical analyses along with microstructure examination. The final cements were prepared by clinkers co-grinding in a laboratory ball mill with appropriate amounts of gypsum (≈5.0 wt%) and the evaluation of their quality was carried out by determining setting times, standard consistency, expansibility and compressive strength at 2, 7, 28 and 90 days. Finally, the leaching behaviour of the vitrified MBA and hydrated cements, together with the corresponding of the "as received" MBA, was further examined using the standard leaching tests of the Toxicity Characteristic Leaching Procedure (TCLP) and the EN 12457-2. According to the obtained results, the quality of the produced cement clinkers was not affected by the addition of the vitrified MBA in the raw meal, with the trace elements detected in all leachates measured well below the corresponding regulatory limits.

Clothing as a transport vector for airborne particles: Chamber study

Strong evidence suggests that clothing serves as a reservoir of chemical pollutants and particles, including bioaerosols, which may have health significance. However, little is known about the role that clothing may play as a transport vector for inhaled airborne particles. Here, we contribute toward bridging the knowledge gap by conducting experiments to investigate clothing release fraction (CRF), determined as the size-dependent ratio of released to deposited particulate matter in the diameter range 0.5-10 μm. In a fully controlled chamber with low background particle levels, we deployed a programmable robot to reproducibly quantify the size-dependent CRF as a function of motion type and intensity, dust loadings, and activity duration. On average, 0.3%-3% of deposited particles were subsequently released with fabric motion, confirming that clothing can act as a vehicle for transporting airborne particles. The CRF increased with the vigor of movement and with dust loading. Rubbing and shaking the fabric were more effective than fabric stretching in resuspending particles. We also found that most of the release happened quickly after the onset of the resuspension activity. Particle size substantially influenced the CRF, with larger particles exhibiting higher values.

Pathogenic features of heterotrophic plate count bacteria from drinking-water boreholes

Evidence suggests that heterotrophic plate count (HPC) bacteria may be hazardous to humans with weakened health. We investigated the pathogenic potential of HPC bacteria from untreated borehole water, consumed by humans, for: their haemolytic properties, the production of extracellular enzymes such as DNase, proteinase, lipase, lecithinase, hyaluronidase and chondroitinase, the effect simulated gastric fluid has on their survival, as well as the bacteria's antibiotic-susceptible profile. HuTu-80 cells acted as model for the human intestine and were exposed to the HPC isolates to determine their effects on the viability of the cells. Several HPC isolates were α- or β-haemolytic, produced two or more extracellular enzymes, survived the SGF treatment, and showed resistance against selected antibiotics. The isolates were also harmful to the human intestinal cells to varying degrees. A novel pathogen score was calculated for each isolate. Bacillus cereus had the highest pathogen index: the pathogenicity of the other bacteria declined as follows: Aeromonas taiwanensis > Aeromonas hydrophila > Bacillus thuringiensis > Alcaligenes faecalis > Pseudomonas sp. > Bacillus pumilus > Brevibacillus sp. > Bacillus subtilis > Bacillus sp. These results demonstrated that the prevailing standards for HPCs in drinking water may expose humans with compromised immune systems to undue risk.

Assessment of relevant fungal species in clinical solid wastes

The study aimed to determine the fungal diversity in clinical waste samples from a healthcare facility in Penang Malaysia. Different fungi species were detected in 83.75 % of the 92 clinical waste samples that were screened from different sections of the healthcare facility. One hundred fifty fungal isolates comprising of 8 genera and 36 species were obtained. They were purified by using single spore isolation technique. Subsequently, the isolates were identified by phenotypic method based on morphological and culture characteristics on different culture media. Among all fungal isolates, Aspergillus spp. in section Nigri 10.2 %, Aspergillus niger 9.5 %, Aspergillus fumigatus 8.8 %, Penicillium. simplicissium 8 %, Aspergillus tubingensis 7.3 %, Aspergillus terreus var. terreus 6.6 %, Penicillium waksmanii 5.9 % and Curvularia lunata 6.5 % were the most frequent. Among five sections of the Wellness Centre, the clinical wastes collected from the diagnostic labs of haematology section had the highest numbers of fungal species (29 species). Glove wastes had the highest numbers of fungal species (19 species) among 17 types of clinical wastes screened. Among all fungal species, Aspergillus spp. exhibited higher growth at 37 °C than at 28 °C, indicating the potential of these opportunistic fungi to cause diseases in human. These results indicated the potential of hospital wastes as reservoirs for fungal species.

Retrospection-Simulation-Revision: Approach to the Analysis of the Composition and Characteristics of Medical Waste at a Disaster Relief Site

A large amount of medical waste is produced during disaster relief, posing a potential hazard to the habitat and the environment. A comprehensive understanding of the composition and characteristics of medical waste that requires management is one of the most basic steps in the development of a plan for medical waste management. Unfortunately, limited reliable information is available in the open literature on the characteristics of the medical waste that is generated at disaster relief sites. This paper discusses the analysis of the composition and characteristics of medical waste at a disaster relief site using the retrospection-simulation-revision method. For this study, we obtained 35 medical relief records of the Wenchuan Earthquake, Sichuan, May 2008 from a field cabin hospital. We first present a retrospective analysis of the relief medical records, and then, we simulate the medical waste generated in the affected areas. We ultimately determine the composition and characteristics of medical waste in the affected areas using untreated medical waste to revise the composition of the simulated medical waste. The results from 35 cases showed that the medical waste generated from disaster relief consists of the following: plastic (43.2%), biomass (26.3%), synthetic fiber (15.3%), rubber (6.6%), liquid (6.6%), inorganic salts (0.3%) and metals (1.7%). The bulk density of medical relief waste is 249 kg/m3, and the moisture content is 44.75%. The data should be provided to assist the collection, segregation, storage, transportation, disposal and contamination control of medical waste in affected areas. In this paper, we wish to introduce this research method of restoring the medical waste generated in disaster relief to readers and researchers. In addition, we hope more disaster relief agencies will become aware of the significance of medical case recording and storing. This may be very important for the environmental evaluation of medical waste in disaster areas, as well as for medical waste management and disposal.

Microbial aerosol liberation from soiled textiles isolated during routine residuals handling in a modern health care setting

BACKGROUND

A wide variety of specialty textiles are used in health care settings for bedding, clothing, and privacy. The ability of textiles to host or otherwise sequester microbes has been well documented; however, their reciprocal potential for liberating airborne bacteria remains poorly characterized. In response, a multi-season survey of bacterial bioaerosols was conducted in the origin and terminus of residual paths which are specifically designed to isolate soiled hospital textiles as they are moved to laundering. This survey used conventional optical particle counting which incorporated multi-channel fluorescence in conjunction with molecular phylogenetic analyses to characterize the bioaerosols liberated during soiled textile storage--immediately before and after the occupation of a modern hospital. Although outfitted with a HEPA filtration system, the number of airborne particles presenting fluorescing optical signatures consistent with airborne bacteria and fungi significantly increased in textile holding rooms soon after the hospital's commissioning, even though these isolated residual areas rarely host personnel. The bioaerosol liberated during textile storage was characterized using Illumina MiSeq sequencing of bacterial 16S ribosomal ribonucleic acid (rRNA) genes. Gene copies recovered by quantitative PCR from aerosol collected in co-located impingers were consistent with fluorescence gated optical particle counting.

RESULTS

The relative abundance patterns of proximal bacterial bioaerosol were such that the air in the origin and terminus of textile storage rooms could not be differentiated once the hospital began processing soiled linens. Genes from microbes typically associating with human skin, feces, and hair--Staphylococcus, Propionibacteria, Corynebacteria, Lactobacillus, and Streptococcus spp.--dominated the aerosol abundance profiles in textile holding rooms, which were generally far less diverse than communities recovered from surfaces in patient rooms.

CONCLUSIONS

These results suggest that aerosol partitioning from the routine handling of soiled textiles can contribute to airborne exposures in the health care environment.

Optimizing supercritical carbon dioxide in the inactivation of bacteria in clinical solid waste by using response surface methodology

Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO2) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO2 sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO2-treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO2 exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials.

Virus occupational exposure in solid waste processing facilities

It is well known that workers involved in the management of solid waste are at risk of exposure to bioaerosol, which is generally studied in relation to bacteria, fungi, and endotoxins. However, to date, there have been no reports on the incidence of work-related infectious diseases. To determine if occupational exposure to viruses occurs upon exposure to waste-related activities, monitoring was carried out in a landfill, a waste recycling plant, an incineration plant, and a waste collection vehicles. Air and surfaces were sampled and analyzed for torque teno virus (TTV), human adenovirus (HAdV), norovirus, rotavirus, and enterovirus using polymerase chain reaction (PCR)-based techniques. Positivity was confirmed by sequencing and quantification with real-time PCR; infectivity was also tested for culturable viruses. Samples were analyzed in parallel for mean total bacterial and fungi counts in both the summer and winter. In total, 30% (12/40) of air and 13.5% (5/37) of surface samples collected in plants were positive for HAdV and TTV. Among the eight HAdV-positive samples, six (75%), revealed in landfill and recycling plant air and in incinerator and waste vehicles surfaces, were able to replicate in cell culture and were subsequently confirmed as infective. The frequency of detection of virus-positive samples was similar in both seasons, but with evident differences in the type of virus detected: TTV and HAdV were more frequently detected in the summer and winter, respectively. The area of highest viral contamination was the paper selection landfill. Fungi and bacterial contamination did not correlate with viral presence or concentration. In conclusion, we evidence that working with solid and liquid waste can lead to infectious viruses, included in Group 2 of the European Directive 90/679/CEE pathogens list; thus, further investigation on the sources and routes of contamination is needed in order to assess the occupational risk.

Infectious risk assessment of unsafe handling practices and management of clinical solid waste

The present study was undertaken to determine the bacterial agents present in various clinical solid wastes, general waste and clinical sharp waste. The waste was collected from different wards/units in a healthcare facility in Penang Island, Malaysia. The presence of bacterial agents in clinical and general waste was determined using the conventional bacteria identification methods. Several pathogenic bacteria including opportunistic bacterial agent such as Pseudomonas aeruginosa, Salmonella spp., Klebsiella pneumoniae, Serratia marcescens, Acinetobacter baumannii, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pyogenes were detected in clinical solid wastes. The presence of specific pathogenic bacterial strains in clinical sharp waste was determined using 16s rDNA analysis. In this study, several nosocomial pathogenic bacteria strains of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Lysinibacillus sphaericus, Serratia marcescens, and Staphylococcus aureus were detected in clinical sharp waste. The present study suggests that waste generated from healthcare facilities should be sterilized at the point of generation in order to eliminate nosocomial infections from the general waste or either of the clinical wastes.

Treatment of clinical solid waste using a steam autoclave as a possible alternative technology to incineration

A steam autoclave was used to sterilize bacteria in clinical solid waste in order to determine an alternative to incineration technology in clinical solid waste management. The influence of contact time (0, 5, 15, 30 and 60 min) and temperature (111 °C, 121 °C and 131 °C) at automated saturated steam pressure was investigated. Results showed that with increasing contact time and temperature, the number of surviving bacteria decreased. The optimum experimental conditions as measured by degree of inactivation of bacteria were 121 °C for 15 minutes (min) for Gram negative bacteria, 121 °C and 131 °C for 60 and 30 min for Gram positive bacteria, respectively. The re-growth of bacteria in sterilized waste was also evaluated in the present study. It was found that bacterial re-growth started two days after the inactivation. The present study recommends that the steam autoclave cannot be considered as an alternative technology to incineration in clinical solid waste management.

Count, identification and antimicrobial susceptibility of bacteria recovered from dental solid waste in Brazil

In Brazil, few studies on microbial content of dental solid waste and its antibiotic susceptibility are available. An effort has been made through this study to evaluate the hazardous status of dental solid waste, keeping in mind its possible role in cross-infection chain. Six samples of solid waste were collected at different times and seasons from three dental health services. The microbial content was evaluated in different culture media and atmospheric conditions, and the isolates were submitted to antibiotic susceptibility testing. A total of 766 bacterial strains were isolated and identified during the study period. Gram-positive cocci were the most frequent morphotype isolated (48.0%), followed by Gram-negative rods (46.2%), Gram-positive rods (5.0%), Gram-negative-cocci (0.4%), and Gram-positive coccobacillus (0.1%). Only two anaerobic bacteria were isolated (0.3%). The most frequently isolated species was Staphylococcus epidermidis (29.9%), followed by Stenotrophomonas maltophilia (8.2%), and Enterococcus faecalis (6.7%). High resistance rate to ampicillin was observed among Gram-negative rods (59.4%) and Gram-positive cocci (44.4%). For Gram-negative rods, high resistance was also noted to aztreonam (47.7%), cefotaxime (47.4%), ceftriaxone and cefazolin (43.7%), and ticarcillin-clavulanic acid (38.2%). Against Gram-positive cocci penicillin exhibit a higher resistance rate (45.0%), followed by ampicillin, erythromycin (27.2%), and tetracycline (22.0%). The present study demonstrated that several pathogenic bacteria are present in dental solid waste and can survive after 48 h from the waste generation time and harbor resistance profiles against several clinical recommended antibiotics.

Clinical solid waste management practices and its impact on human health and environment--A review

The management of clinical solid waste (CSW) continues to be a major challenge, particularly, in most healthcare facilities of the developing world. Poor conduct and inappropriate disposal methods exercised during handling and disposal of CSW is increasing significant health hazards and environmental pollution due to the infectious nature of the waste. This article summarises a literature review into existing CSW management practices in the healthcare centers. The information gathered in this paper has been derived from the desk study of open literature survey. Numerous researches have been conducted on the management of CSW. Although, significant steps have been taken on matters related to safe handling and disposal of the clinical waste, but improper management practice is evident from the point of initial collection to the final disposal. In most cases, the main reasons of the mismanagement of CSW are the lack of appropriate legislation, lack of specialized clinical staffs, lack of awareness and effective control. Furthermore, most of the healthcare centers of the developing world have faced financial difficulties and therefore looking for cost effective disposal methods of clinical waste. This paper emphasizes to continue the recycle-reuse program of CSW materials after sterilization by using supercritical fluid carbon dioxide (SF-CO2) sterilization technology at the point of initial collection. Emphasis is on the priority to inactivate the infectious micro-organisms in CSW. In that case, waste would not pose any threat to healthcare workers. The recycling-reuse program would be carried out successfully with the non-specialized clinical staffs. Therefore, the adoption of SF-CO2 sterilization technology in management of clinical solid waste can reduce exposure to infectious waste, decrease labor, lower costs, and yield better compliance with regulatory. Thus healthcare facilities can both save money and provide a safe environment for patients, healthcare staffs and clinical staffs.