Reservoir Of Pathogenic Bacteria Research Articles

Effect of Bacteriophages against Biofilms of Escherichia coli on Food Processing Surfaces.

The bacterial adhesion to food processing surfaces is a threat to human health, as these surfaces can serve as reservoirs of pathogenic bacteria. Escherichia coli is an easily biofilm-forming bacterium involved in surface contamination that can lead to the cross-contamination of food. Despite the application of disinfection protocols, contamination through food processing surfaces continues to occur. Hence, new, effective, and sustainable alternative approaches are needed. Bacteriophages (or simply phages), viruses that only infect bacteria, have proven to be effective in reducing biofilms. Here, phage phT4A was applied to prevent and reduce E. coli biofilm on plastic and stainless steel surfaces at 25 °C. The biofilm formation capacity of phage-resistant and sensitive bacteria, after treatment, was also evaluated. The inactivation effectiveness of phage phT4A was surface-dependent, showing higher inactivation on plastic surfaces. Maximum reductions in E. coli biofilm of 5.5 and 4.0 log colony-forming units (CFU)/cm2 after 6 h of incubation on plastic and stainless steel, respectively, were observed. In the prevention assays, phage prevented biofilm formation in 3.2 log CFU/cm2 after 12 h. Although the emergence of phage-resistant bacteria has been observed during phage treatment, phage-resistant bacteria had a lower biofilm formation capacity compared to phage-sensitive bacteria. Overall, the results suggest that phages may have applicability as surface disinfectants against pathogenic bacteria, but further studies are needed to validate these findings using phT4A under different environmental conditions and on different materials.

The microbiome: an integral player in immune homeostasis and inflammation in the respiratory tract.

The last decade of microbiome research has highlighted its fundamental role in systemic immune and metabolic homeostasis. The microbiome plays a prominent role during gestation and into early life, when maternal lifestyle factors shape immune development of the newborn. Breast milk further shapes gut colonization, supporting the development of tolerance to commensal bacteria and harmless antigens while preventing outgrowth of pathogens. Environmental microbial and lifestyle factors that disrupt this process can dysregulate immune homeostasis, predisposing infants to atopic disease and childhood asthma. In health, the low-biomass lung microbiome, together with inhaled environmental microbial constituents, establishes the immunological set point that is necessary to maintain pulmonary immune defense. However, in disease perturbations to immunological and physiological processes allow the upper respiratory tract to act as a reservoir of pathogenic bacteria, which can colonize the diseased lung and cause severe inflammation. Studying these host-microbe interactions in respiratory diseases holds great promise to stratify patients for suitable treatment regimens and biomarker discovery to predict disease progression. Preclinical studies show that commensal gut microbes are in a constant flux of cell division and death, releasing microbial constituents, metabolic by-products, and vesicles that shape the immune system and can protect against respiratory diseases. The next major advances may come from testing and utilizing these microbial factors for clinical benefit and exploiting the predictive power of the microbiome by employing multiomics analysis approaches.

Biodegradation and valorization of feather waste using the keratinase-producing bacteria and their application in environmentally hazardous industrial processes

Poultry feathers are widely discarded as waste worldwide and are considered an environmental pollutant and a reservoir of pathogenic bacteria. Therefore, developing sustainable and environmentally friendly methods for managing feather waste is one of the important environmental protection requirements. In this study, we investigated a rapid and eco–friendly method for the degradation and valorization of feather waste using keratinase–producing Pseudomonas geniculata H10, and evaluated the applicability of keratinase in environmentally hazardous chemical processes. Strain H10 completely degraded chicken feathers within 48 h by producing keratinase using them as sources of carbon, nitrogen, and sulfur. The culture contained a total of 402.8 μM amino acids, including 8 essential amino acids, which was higher than the chemical treatment. Keratinase was a serine-type metalloprotease with optimal temperature and pH of 30 °C and 9, respectively, and showed relatively high stability at 10–40 °C and pH 3–10. Keratinase was also able to degrade various insoluble keratins such as duck feathers, wool, human hair, and nails. Furthermore, keratinase exhibited more efficient depilation and wool modification than chemical treatment, as well as novel functionalities such as nematicidal and exfoliating activities. This suggests that strain H10 is a promising candidate for the efficient degradation and valorization of feather waste, as well as the improvement of current industrial processes that use hazardous chemicals.

Bacteria and antimicrobial resistance profile during the composting process of wastes from animal production.

Livestock waste is widely used in agriculture. Although they provide benefits to the soil, and consequently to plants, they have the potential to contaminate the environment, as they contain pathogenic microorganisms and determinants of antimicrobial resistance, if not properly managed. Therefore, this study aims to evaluate the effect of composting horse bedding and poultry litter in organic and conventional production systems on the occurrence of bacteria in the Enterobacteriales order and to identify their antimicrobial resistance profiles. Bacterial strains were isolated from Salmonella-Shigella and eosin methylene blue solid media from animal waste during the composting process that was conducted for 125days. After isolation, the strains were identified by the MALDI-TOF technique; the disk diffusion test was then performed for phenotypic detection of antimicrobial resistance. A total of 158 bacterial strains were isolated during composting of three wastes. The Enterobacteriaceae family was the most abundant, whereas Proteus mirabilis and Escherichia coli were the species with the highest percentage in the wastes, which also exhibited a multi-resistance profile. Poultry litter showed a greater abundance of resistant bacteria than horse bedding did. Similarly, a greater number of resistant bacteria was detected in conventional poultry litter than in organic poultry litter. The results obtained reinforce that animal wastes are reservoirs of pathogenic bacteria that are resistant to antimicrobials and highlight the importance of developing management strategies that aim to reduce and/or eliminate these contaminants to guarantee their safe use in agriculture.

Antibiotic use during coronavirus disease 2019 intensive care unit shape multidrug resistance bacteriuria: A Swedish longitudinal prospective study.

High frequency of antimicrobial prescription and the nature of prolonged illness in COVID-19 increases risk for complicated bacteriuria and antibiotic resistance. We investigated risk factors for bacteriuria in the ICU and the correlation between antibiotic treatment and persistent bacteria. We conducted a prospective longitudinal study with urine from indwelling catheters of 101 ICU patients from Uppsala University Hospital, Sweden. Samples were screened and isolates confirmed with MALDI-TOF and whole genome sequencing. Isolates were analyzed for AMR using broth microdilution. Clinical data were assessed for correlation with bacteriuria. Length of stay linearly correlated with bacteriuria (R2 = 0.99, p ≤ 0.0001). 90% of patients received antibiotics, primarily the beta-lactams (76%) cefotaxime, piperacillin-tazobactam, and meropenem. We found high prevalence of Enterococcus (42%) being associated with increased cefotaxime prescription. Antibiotic-susceptible E. coli were found to cause bacteriuria despite concurrent antibiotic treatment when found in co-culture with Enterococcus. Longer stays in ICUs increase the risk for bacteriuria in a predictable manner. Likely, high use of cefotaxime drives Enterococcus prevalence, which in turn permit co-colonizing Gram-negative bacteria. Our results suggest biofilms in urinary catheters as a reservoir of pathogenic bacteria with the potential to develop and disseminate AMR.

Bacterial Biofilm And Role In The Pathogenesis Of Disease

Background: Bacterial biofilms may play a role in pathogenesis which has led to increased focus on identifying diseases that may be associated with biofilms. Chronic biofilm infections are usually chronic in nature, as the bacteria that live in biofilms can be resilient to both the immune system and antibiotics and other treatments. Current knowledge of how biofilms contribute to disease pathogenesis suggests a number of different mechanisms. This extends from biofilms being merely a reservoir of pathogenic bacteria, to playing a more active role, for example, by contributing to inflammation. This knowledge is important for developing effective treatment strategies for such infections.

Exploring the nature of interaction between shiga toxin producing Escherichia coli (STEC) and free-living amoeba - Acanthamoeba sp

Free-living amoebae (FLA) are widely distributed protozoa in nature, known to cause severe eye infections and central nervous system disorders. There is growing attention to the potential role that these protozoa could act as reservoirs of pathogenic bacteria and, consequently, to the possibility that, the persistence and spread of the latter may be facilitated, by exploiting internalization into amoebae. Shiga toxin-producing strains of Escherichia coli (STEC) are zoonotic agents capable of causing serious diseases, such as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). Cattle represent the main natural reservoir of STEC, which are frequently found also in other domestic and wild ruminants, often without causing any evident symptoms of disease. The aspects related to the ecology of STEC strains in animal reservoirs and the environment are poorly known, including the persistence of these microorganisms within niches unfavorable to survival, such as soils or waters. In this study we investigated the interaction between STEC strains of serotype O157: H7 with different virulence gene profiles, and a genus of a wild free-living amoeba, Acanthamoeba sp. Our results confirm the ability of STEC strains to survive up to 20 days within a wild Acanthamoeba sp., in a quiescent state persisting in a non-cultivable form, until they reactivate following some stimulus of an unknown nature. Furthermore, our findings show that during their internalization, the E. coli O157 kept the set of the main virulence genes intact, preserving their pathogenetic potential. These observations suggest that the internalization in free-living amoebae may represent a means for STEC to resist in environments with non-permissive growth conditions. Moreover, by staying within the protozoa, STEC could escape their detection in the vehicles of infections and resist to the treatments used for the disinfection of the livestock environment.

Prevalence and investigations of bacterial contamination in dental healthcare associated environment

Microbial contamination of medical substrate surface of dental parts touched or exposed to blood and saliva of patients can act as a reservoir for pathogenic bacteria, resulting in cross-contamination. For this reason, presence of oral microorganisms in dental clinics is a major source of dental contamination and infection worldwide. The work described here aimed to determine the presence of bacteria on variety of dental clinic surfaces including a dental chair arm rest, a sink/faucet, the floor beneath a dental chair; a towel dispenser, handles connected to a light and to an instrument table; dental record paper; an X-ray viewer and finally, a bench and head-rest in five separate departments (pediatric dentistry, implant, dental prosthetics, oral medicine and restorative dentistry) of the King Saud University Dental Hospital, both before and after patient treatment. The isolation and identification of bacterial colonies was achieved using a range of methods such as using a Vitek2 automated system. The results showed that all surfaces in different departments were contaminated with bacteria, most notably in the Implant Department, while much less bacterial contamination was reported in the Department of Oral Medicine. The most commonly isolated bacteria were species of, Staphylococcus, Streptococcus, Pseudomonas, Bacillus and Micrococcus.

Diverse antibiotic resistance genes and potential pathogens inhabit in the phyllosphere of fresh vegetables

Fresh vegetables are considered as a reservoir of pathogenic bacteria and antibiotic resistance genes (ARGs), which are the emerging environmental contaminants, posing increasing concerned risk to human health. However, the prevalence of pathogens in phyllosphere of fresh vegetables, as well as the association of ARGs with pathogenic bacteria, have not been well elaborated. In this study, we explored the structure of microbial communities and ARGs through high-throughput quantitative PCR and 16S rRNA gene Illumina sequencing, and characterized the microorganisms resisting to antibiotics by pure culture. From phyllosphere of six different kinds of vegetables, 205 ARGs were detected and genes for multidrug resistance was the most abundant. The predominant potential pathogens were classified to Pseudomonas, Klebsiella, and Acinetobacter genera, which carried various ARGs such as multidrug and beta-lactam resistance genes presumedly. Among six kinds of vegetables, Lactuca sativa var. asparagina carried the highest abundance of potential pathogens and ARGs, while Allium sativum L harbored the lowest abundance of pathogens and ARGs. In addition, various culturable bacteria resisting to colistin or meropenem could be isolated from all vegetables, remarkably, all the isolates resistant to both antibiotics are potential pathogens. Our study highlighted the risks of pathogens and ARGs from raw vegetables to consumers, characterized their structure patterns among different vegetables, and analyzed the potential mechanisms regulating phyllosphere pathogens and resistome of fresh vegetables, which would be helpful for reducing the microbial risk from vegetable ingestion.

High Rate of Bacterial Contamination on Healthcare Worker's Mobile Phone and Potential Role in Dissemination of Healthcare-Associated Infection at Debre Berhan Referral Hospital, North Shoa Zone, Ethiopia.

BackgroundMobile Phone (MP) handling by healthcare workers (HCWs) in hospital is an open breeding place for the transmission of bacteria and healthcare-associated infection (HCAI). This HCAI is a huge problem to the healthcare system worldwide.MethodsA laboratory-based cross-sectional study design was conducted from January 2020 to January 2021 in Debre Berhan Referral Hospital, North Shoa Zone, Ethiopia. A total of 65 swab samples were collected from HCWs mobiles phone. Other important data were collected using a self-administered questionnaire. The collected samples were processed for bacteriological identification and drug susceptibility testing. Data obtained were entered and cleaned into MS Excel spreadsheet and analyzed using SPSS version 21.ResultsFrom the total of 65 swab sample, 84 bacterial isolates were detected. Of these bacterial isolates, 46.4% were Gram-positive bacteria while 53.6% were Gram-negative bacteria. The overall MDR prevalence was found to be 42.9%. The proportion of MP contamination was higher in males (67.9%) and the age groups of 20–35 years (50%). All the MP carried by HCWs was contaminated with at least one bacterial pathogen. The high rate of MP contamination was observed in the intensive care unit (ICU) (22.6%) followed by surgical ward (17.8) and laboratory rooms (17.8%). The rate of bacterial contamination of MP was higher among HCWs working in ICU, who did not disinfect or clean their phone regularly and who did not wash their hands regularly.ConclusionHealthcare worker’s MP was contaminated with pathogenic bacteria. Since MP could serve as a vehicle and a reservoir for pathogenic bacteria, HCWs should be aware of the public health risks of HCAI, and appropriate intervention mechanisms should be practiced to reduce the burden and cross-transmission.

Hospitals Surfaces and Sites as a Reservoir for Pathogenic Bacteria That Play a Role in Transmission of Infectious Diseases

The key to success of healthcare quality is the control of hospital environment. Challenge of infection prevention and epidemiology practice continues to be an increasing emergence and spread of pathogenic bacteria is of great concern. The study is about the prevalence and isolation of bacteria from hospital surfaces environment in Kenya. About 246 samples of the two hospitals was obtained using sterile cotton swabs from random sampling of hospital different surfaces, drainages, hands of healthcare givers and hospital waste dump site among others. The samples were aseptically collected, transported and processed following standard procedures. Bacteria were isolated and identified using various biochemical tests and confirmed using API 20E. Door handle surfaces had the highest percentage of isolated bacteria (13%) while the least was cupboard surfaces (3%) in both hospitals. Kenyatta National Hospital (KNH) had the most isolated bacteria as compared to Kikuyu Mission Hospital (KMH) in most swabbed surfaces; the difference however was not significant. Various bacteria were isolated where the most abundant bacteria in both hospitals was Providencia species, while the least was Enterobacter species. There is therefore, high bacteria contamination of objects of hospitals frequently touched sites and surfaces act as a source of infectious diseases as they harbor potential pathogens.

Pharyngeal Carriage of Beta-Haemolytic Streptococcus Species and Seroprevalence of Anti-Streptococcal Antibodies in Children in Bouaké, Côte d'Ivoire.

The pharynx of the child may serve as a reservoir of pathogenic bacteria, including beta-haemolytic group A streptococci (GAS), which can give rise to upper airway infections and post-streptococcal diseases. The objective of this study was to determine the prevalence of beta-haemolytic Streptococcus spp. in pharyngeal samples stemming from children aged 3–14 years in Bouaké, central Côte d’Ivoire. Oropharyngeal throat swabs for microbiological culture and venous blood samples to determine the seroprevalence of antistreptolysin O antibodies (ASO) were obtained from 400 children in March 2017. Identification was carried out using conventional bacteriological methods. Serogrouping was performed with a latex agglutination test, while an immunological agglutination assay was employed for ASO titres. The mean age of participating children was 9 years (standard deviation 2.5 years). In total, we detected 190 bacteria in culture, with 109 beta-haemolytic Streptococcus isolates, resulting in an oropharyngeal carriage rate of 27.2%. Group C streptococci accounted for 82.6% of all isolates, whereas GAS were rarely found (4.6%). The ASO seroprevalence was 17.3%. There was no correlation between serology and prevalence of streptococci (p = 0.722). In conclusion, there is a high pharyngeal carriage rate of non-GAS strains in children from Bouaké, warranting further investigation.

Evaluation of physicochemical, microbiological, and energetic characteristics of four agricultural wastes for use in the production of green energy in Moroccan farms

BackgroundAnimal husbandry is one of the agricultural activities that generates economic benefits for agriculture. We detected significant development of these activities in Morocco. Currently, it is stuck between the increase of organic waste polluting the farm environment and the energy needed to ensure the activities. Faced with this challenge, we determined all physical, chemical, and microbiological characteristics for livestock wastes most spread in Morocco. We evaluated also their ability to be used as bioresources for the anaerobic digestion and incineration ways for energy production to agricultural units.MethodsWe worked on four organic wastes (cow dung, horse manure, broiler droppings, and the excrement of laboratory mouse). The physical, chemical, and microbiological characteristics: moisture, total solids, volatile solids, organic carbon, nitrogen, ions and heavy metals, staphylococci, coliforms, yeasts and fungi and total aerobic mesophilic bacteria are determined by standard methods. The determination of lower heating value is performed with calorimetric bomb. The biogas production is determined by four batch types of digesters. All digesters are incubated at 35 ± 1 ℃ for 40 days. The volumes of biogas produced are corrected under standard pressure and temperature conditions.ResultsWe noticed that the four agricultural wastes have a lower heating value closer to each other. When comparing the physicochemical composition of our wastes with that of Tanner’s theoretical waste, we have found that the valorization of these organic wastes by incineration is without energy and economic benefits. The microbiological content reflects the presence of a reservoir of pathogenic bacteria. On the other hand, the biogas potential shows that cow waste produces the largest amount of biogas. The co-digestion is necessary for horse manure, chicken manure, and excrement of laboratory mouse in order to increase their biogas potential. The mineral composition shows the possibility of using digestate of these wastes as an organic amendment to plants.ConclusionsThe comparison of the physicochemical and microbiological characteristics of the four organic wastes in Morocco reflects some important points. Firstly, there is an urgency to intervene to treat and valorize these wastes before putting them in the open air. Secondly, the incineration of this waste is inadequate from an energy point of view. In the third position, these wastes present a great ability to be used as feed substrates of farm digesters. Finally, the biogas potential and the mineral composition of these wastes demonstrates the ability to use them as bioresources capable of producing green energy and an organic amendment to Moroccan farms.

Molecular Identification and Characterization of Smartphone Screen Associated Pathogenic Bacteria

Mobile phone is a device that keeps in contact with our sensitive body parts including faces, hands, nose, ears, and lips, etc. most of the time. Although we know many bad aspects of mobile phones; we are indifferent to its bacterial contamination. Smartphone screen is an endless reservoir of pathogenic bacteria and works as an object in spreading those bacteria. The purpose of the study was to identify pathogenic bacteria from smartphone screen and finding some common causes of bacterial contamination. So, a public survey was conducted among 100 students from the Dept. of Genetic Engineering & Biotechnology, University of Rajshahi to know the uses pattern of their particular smartphone. Then, for the lab-based work samples were collected from the smartphone screen of the students by sterile swabs moistened with normal saline water. Among the samples, four strains were selected based on bacterial concentration for further analysis. Out of four, two strains were gram-positive and two were gram-negative. Biochemical tests indicated that all of them were pathogenic and the selected gram-positive bacteria were coagulase-positive Staphylococcus species and coagulase-negative Staphylococcus species.16S-rRNA gene sequencing identified the selected two-gram negative strains as Stenotrophomonas maltophilia and Klebsiella pneumoniae. The antibiotic sensitivity test referred that all the bacteria were multidrug-resistant and may be dangerous for compromised immune patients.

A preliminary assessment of bacteria in “ranched” ball pythons (Python regius), Togo, West Africa

Captive reptiles are routinely identified as reservoirs of pathogenic bacteria and reports of reptile-associated infections relating to some species are well documented (e.g., salmonellosis). Currently, relatively little is known about the epidemiology and bacteria of ball pythons. We carried out a survey of ball python farms in Togo, West Africa to assess the presence of any potentially pathogenic bacterial taxa that have been identified in recent scientific literature relating to this species. The presence of bacteria belonging to the genera Acinetobacter, Bacteroides, Citrobacter, Enterobacter, Lysobacter, Proteus, Pseudomonas, Staphylococcus, and Tsukamurella in oral and cloacal samples taken from five individual ball pythons is of potential concern for horizontal transmission given that pathogenic species belonging to these genera have been previously documented. The presence of bacteria belonging to the genera Clostridium, Escherichia, Moraxella, and Stenotrophomonas in the oral and rectal samples taken from five mice used to feed ball pythons suggests that they represent a potential reservoir of infection for wild caught ball pythons and their progeny. Furthermore, possible sources of environmental contamination include other captive amphibians, birds, reptiles and mammals, as well as free ranging birds and small mammals. Additional surveillance of ball pythons in the wild and in captivity at python farms in West Africa will shed light on whether or not this type of commercial activity is increasing pathogen exposure and lowering barriers to transmission. Meanwhile, as a precautionary measure, it is recommended that python farms should immediately establish biosecurity and disease surveillance practices to minimize potential horizontal and vertical bacterial transfer.

English

A wide variety of opportunistic pathogens has been detected in hospital surfaces. Medical center surfaces can serve as reservoirs of pathogenic bacteria. Among this pathogens, Pseudomonas species are one of the leading causes of nosocomial infections, frequently found in hospital environments. Polymerase chain amplification system remains one of the best methods for the rapid detection of low numbers of pathogenic bacteria with core references to nucleic Acid content. However, there is a limited researches focusing on these techniques to examine the molecular content of nosocomial bacteria. The present investigation examines types and strains of bacteria present in indoor air of wards, fomites and surgical tools of three prominent hospitals namely, Ahmadu Bello University Teaching Hospital Zaria, Hajiya Gambo Sawaba Hospital Zaria City and Barau Dikko Teaching Hospital Kaduna using standard methods. Preliminary Grams reaction and biochemical characterization was done according to standard methods, DNA extraction precede PCR amplification, probable organisms include Pseudomonas aeruginosa, Corynebacterium sp., P. aeruginosa, Bacillus sp., Klebsiella pneumonia, Neisseria sp., Staphylococcus aureus and Staphylococcus epidermidis. Out of all the isolates that were of public health concern, Neisseria sp., S. aureus and P. aeruginosa are the most prevailing isolates. A strain of P. aeruginosa was observed to give a DNA sequence. P. aeruginosa was the bacteria isolates sequenced and it showed 100% similarity having the id query: 86603, when blast using National Center for Biotechnology Information (NCBI). In general, patterns were specific at either the genus level or the species level. This research has been able to show that PCR is a promising fast method for the identification of nosocomial microorganisms. Key words: Polymerase chain reaction, nosocomial bacterial, hospital and DNA.

Enumeration of potential pathogenic bacteria collected from university elevators

Community settings can become mechanical transmitter of pathogenic bacteria. Elevator can be reservoir of pathogenic bacteria. Current study aims to understand the possibilities of bacteria cross-contamination that harbors elevators buttons at a university. Qualitative examination of microbes isolated discovered a great quantity of Bacilli spp of gram negative as predominant biotic followed by Gram Positive Bacilli, Gram Negative Cocci and Gram Positive Cocci. The presence of potential pathogenic bacteria that contaminated the elevators indicates the elevator could potentially become reservoir for transmission of pathogenic bacteria strains in the campus.

Isolation of Vibrionaceae from wild blue mussel (Mytilus edulis) adults and their impact on blue mussel larviculture.

The blue mussel (Mytilus edulis) is known as a robust bivalve species, although its larviculture appears to be highly susceptible to diseases. In this study, we isolated 17 strains from induced mortality events in healthy wild-caught blue mussel adults and demonstrated that they caused between 17% and 98% mortality in blue mussel larvae in a newly developed, highly controlled immersion challenge test model. Eight of the isolates belong to the Splendidus clade of vibrios, while the other isolates belong to the genus Photobacterium. The genomes of the most virulent Vibrio isolate and the most virulent Photobacterium isolate were sequenced and contained several genes encoding factors that have previously been linked to virulence towards bivalves. In vitro tests confirmed that all 17 isolates were positive for these virulence factors. The sequenced genomes also contained a remarkably high number of multidrug resistance genes. We therefore assessed the sensitivity of all isolates to a broad range of antibiotics and found that there were indeed many strong positive correlations between the sensitivities of the isolates to different antibiotics. Our data provide an ecological insight into mass mortality in blue mussels as they indicate that wild mussels contain a reservoir of pathogenic bacteria.

Development of a rapid approach for the enumeration of Escherichia coli in riverbed sediment: case study, the Apies River, South Africa

Research in the last few decades has increasingly demonstrated riverbed sediments as reservoirs of pathogenic bacteria, which could be released into water resources when sediments are resuspended. Current methods for enumerating these organisms in sediments could lead to either overestimation or underestimation of the microbial population in sediments. Therefore, an approach was developed based on Archimedes’ principle to accurately determine microbial counts in sediments and enable better comparison of water and sediment microbial counts. Using the common approach (weighing method), 100 g of sediment was accurately weighed and transferred into a graduated 1-l Durham bottle containing 400 ml of 1× phosphate-buffered saline (PBS). This gave a 20 % dilution (g/v). In the proposed approach (water displacement method), 400 ml of 1× PBS was transferred into a graduated Durham bottle, and sediment was gradually added until the 500-ml mark was reached, giving a 20 % dilution (v/v). The bottles containing sediments from both methods were then manually shaken to dislodge the microorganisms, and an appropriate volume was extracted from each bottle for analysis using the Colilert™ 18/Quantitray-2000 system from IDEXX. There was a statistically significant difference between the mean Escherichia coli counts when comparing the weighing method to the water displacement approach. The time required for the proposed (water displacement) approach was significantly lower than that required for the weighing approach. This method was found to be highly reproducible. Application of the water displacement method to samples collected at different points of the Apies River, Gauteng, South Africa, gave a greater microbial yield than the weighing method. Calculating the actual volume of sediment with the water displacement method results in a greater yield when determining microbial counts in the sediment. Furthermore, since sediment and water microbial counts are expressed in the same unit (MPN/100 ml), direct comparison of counts is possible. The water displacement approach to quantifying bacteria in sediment results in a more accurate microbial count is easy to carryout, highly reproducible and time efficient when processing large number of samples. Considering that pathogens such as Vibrio cholerae, Salmonella sp. and Shigella sp. also reside in sediment but in very low infectious doses, the proposed method could be critical for accurate enumeration when determining what public health risk these organisms might pose.

Social and Economic Aspects of the Transmission of Pathogenic Bacteria between Wildlife and Food Animals: A Thematic Analysis of Published Research Knowledge.

Wildlife is a known reservoir of pathogenic bacteria, including Mycobacterium bovis and Brucella spp. Transmission of these pathogens between wildlife and food animals can lead to damaging impacts on the agri-food industry and public health. Several international case studies have highlighted the complex and cross-sectoral challenges involved in preventing and managing these potential transmission risks. The objective of our study was to develop a better understanding of the socio-economic aspects of the transmission of pathogenic bacteria between wildlife and food animals to support more effective and sustainable risk mitigation strategies. We conducted qualitative thematic analysis on a purposive sample of 30/141 articles identified in a complementary scoping review of the literature in this area and identified two key themes. The first related to the framing of this issue as a 'wicked problem' that depends on a complex interaction of social factors and risk perceptions, governance and public policy, and economic implications. The second theme consisted of promising approaches and strategies to prevent and mitigate the potential risks from transmission of pathogenic bacteria between wildlife and food animals. These included participatory, collaborative and multidisciplinary decision-making approaches and the proactive incorporation of credible scientific evidence and local contextual factors into solutions. The integration of these approaches to address 'wicked problems' in this field may assist stakeholders and decision-makers in improving the acceptability and sustainability of future strategies to reduce the transmission of pathogenic bacteria between wildlife and food animals.