Co-occurrence of free-living protozoa and foodborne pathogens on dishcloths: Implications for food safety

Reliable and specific detection of Acanthamoeba spp. in dishcloths using quantitative real-time PCR assay

Acanthamoeba spp., are ubiquitous protist which belongs to Free-Living Amoeba (FLA) group, is considered as causal agent of side-threatening keratitis or fatal encephalitis among other human infections. Besides, this parasite has been reported as host for other microorganisms important to human health such as Campylobacter spp. or Vibrio spp. among others. This role of Acanthamoeba as pathogen and environmental phagocyte has increased the reports confirming its presence in human related environments, acting as a water quality indicator. Considering the tide relationship between water and kitchen environments, and the high prevalence of Acanthamoeba in water sources, the present study aims to establish a quick and accurate protocol based on DNA extraction and a real time qPCR assay to detect Acanthamoeba spp. in dishcloths. The procedure has been validated by processing 17 used dishcloths. Our findings demonstrated the high sensitivity of the qPCR assay used which was capable of detecting up to one Acanthamoeba from an in vitro contaminated dishcloth. The protocol accurately detected 64.7% of positive samples for Acanthamoeba spp, (in 4 samples DNA concentrations corresponded to 1-102 amoebae). Our findings demonstrate the importance of FLA surveillance by efficient and sensitive methods since one amoeba is capable of colonizing human related food environments such as kitchens sinks and could be a potential source of infection.

Cross-contamination in the kitchen: A model for quantitative microbiological risk assessment

A quantitative microbiological risk assessment model for the cross-contamination transmission route in the kitchen (KCC) is presented. Bacteria are transmitted from contaminated (chicken) meat to hands, kitchen utensils, and other surfaces, subsequently contaminating a salad. The model aims to estimate the fraction of bacteria on the meat that is ingested due to cross-contamination, determine the importance of the different transmission routes, and assess the effect of scenarios (interventions) on the fraction ingested. The cross-contamination routes defined, bacterial source-to-recipient transfer fractions as available and derived from literature, and important characteristics (e.g., washing in cold water vs. hot water with soap) shaped the KCC model. With this model, 32 scenarios of an eight-step preparation of a "meat and salad" meal in a domestic kitchen were stochastically simulated. The "cutting board-salad" route proved dominant and the salad plays a major role in the final exposure. A realistic scenario (washing hands, cutting board, and knife with cold water after cutting the meat) estimates that a mean fraction of 3.2E - 3 of the bacteria on the meat is ingested. In the case of "hand washing with hot water and soap" and "cutting board and knife replacement," the mean fraction ingested is 3.6E - 6. For a subsequent meal, where the contaminated sources were kitchen fomites, the estimated mean fraction is 4.3E - 4. In case of hamburger, part of the bacteria is unavailable for cross-contamination, resulting in a mean fraction ingested of about 5.4E - 5. The role of the dishcloth in cross-contamination transmission proved to be minor.

Contamination of fresh vegetables in municipal stores with pathogenic Acanthamoeba genotypes; a public health concern

Acanthamoeba spp. cause keratitis and encephalitis, and are a proper carrier of foodborne pathogens. A total of 70 samples including garden cress, chives, mint, parsley, and basil were collected. Samples were cultured onto a 2% non-nutrient agar medium. The cultures were analyzed using morphological and molecular techniques. In total, 18 (25.7%) out of 70 samples were positive including garden cress 10/22 (45.45%), chives 3/12 (25%), mint 2/13 (15.38%), basil 2/13 (15.38%), and parsley 1/10 (10%). The diagnostic fragment 3 was successfully sequenced in 15 samples and represented 11 (73.3%) T4, three (20%) T5, and one T9 genotypes. In addition, three, two, and one strains, belonging to the genotypes T4, T5, and T9 were ranked highly pathogenic. This is the first study reporting contamination of the most commonly consumed fresh vegetables with pathogenic Acanthamoeba genotypes. Our findings signify the public health concerns due the contamination of vegetables in municipal public markets.

Prevalence and Antimicrobial Resistance Profile of Diarrheagenic Escherichia coli from Fomites in Rural Households in South Africa

Diarrheagenic Escherichia coli (DEC) pathotypes are the leading cause of mortality and morbidity in South Asia and sub-Saharan Africa. Daily interaction between people contributes to the spreading of Escherichia coli (E. coli), and fomites are a common source of community-acquired bacterial infections. The spread of bacterial infectious diseases from inanimate objects to the surrounding environment and humans is a serious problem for public health, safety, and development. This study aimed to determine the prevalence and antibiotic resistance of diarrheagenic E. coli found in toilets and kitchen cloths in the Vhembe district, South Africa. One hundred and five samples were cultured to isolate E. coli: thirty-five samples were kitchen cloths and seventy-five samples were toilet swabs. Biochemical tests, API20E, and the VITEK®-2 automated system were used to identify E. coli. Pathotypes of E. coli were characterised using Multiplex Polymerase Chain Reaction (mPCR). Nine amplified gene fragments were sequenced using partial sequencing. A total of eight antibiotics were used for the antibiotic susceptibility testing of E. coli isolates using the Kirby-Bauer disc diffusion method. Among the collected samples, 47% were positive for E. coli. DEC prevalence was high (81%), with ETEC (51%) harboring lt and st genes being the most dominant pathotype found on both kitchen cloths and toilet surfaces. Diarrheagenic E. coli pathotypes were more prevalent in the kitchen cloths (79.6%) compared with the toilet surfaces. Notably, hybrid pathotypes were detected in 44.2% of the isolates, showcasing the co-existence of multiple pathotypes within a single E. coli strain. The antibiotic resistance testing of E. coli isolates from kitchen cloths and toilets showed high resistance to ampicillin (100%) and amoxicillin (100%). Only E. coli isolates with hybrid pathotypes were found to be resistant to more than three antibiotics. This study emphasizes the significance of fomites as potential sources of bacterial contamination in rural settings. The results highlight the importance of implementing proactive measures to improve hygiene practices and antibiotic stewardship in these communities. These measures are essential for reducing the impact of DEC infections and antibiotic resistance, ultimately safeguarding public health.

Antiamoebic properties of Methyltrioctylammonium chloride based deep eutectic solvents

PURPOSE

This aim of this study was to assess anti-parasitic properties of deep eutectic solvents against eye pathogen, Acanthamoeba, often associated with the use of contact lens.

METHODS

Assays were performed to investigate the effects of various Methyltrioctylammonium chloride-based deep eutectic solvents on Acanthamoeba castellanii, comprising amoebicidal assays, encystment assays, excystment assays, cytotoxicity assays by measuring lactate dehydrogenase release from human cells, and cytopathogenicity assays to determine parasite-mediated host cell death.

RESULTS

In a 2 h incubation period, DES-B, DES-C, DES-D, and DES-E exhibited up to 85 % amoebicidal activity at micromolar doses, which was enhanced further following 24 h incubation. When tested in encystment assays, selected deep eutectic solvents abolished cyst formation and were able to block excystment of A. castellanii. All solvents exhibited minimal human cell cytotoxicity except DES-D. Finally, all tested deep eutectic solvents inhibited amoeba-mediated cytopathogenicity, except DES-B.

CONCLUSIONS

Deep eutectic solvents show potent antiamoebic effects. These findings are promising and could lead to the development of novel contact lens disinfectants, as well as opening several avenues to explore the molecular mechanisms, various doses and incubation periods, and use of different bases against Acanthamoeba castellanii.

Antibiotic susceptibility pattern of fish pathogens: A new approach of emerging the bacterial resistance through biofilm formation in in-vitro condition

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Different fishes were collected and were subjected to form an in vitro biofilm.

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Huge array (up to 10⁷ cfu/ml or g) of pathogenic bacteria.

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Few of the isolates were sensitive and few were resistant against the antibiotics but after bio-film formation all the species acquired resistance.

Background

The ability of many bacteria to adhere on the host surfaces and forming biofilms has major implications in a wide variety of industries including the food industry, where biofilms may create a persistent source of contamination. In the same environmental condition, the multiple bacterial species can closely interact with each other and may easily enhance their drug resistance capability, which finally increases the multi-drug resistant (MDR) attribute of the species.

Objective

The present study examined whether the mixed-species biofilm possesses any impact on the enhancement of the antibiotic resistance of the planktonic or single-cell bacterial isolates present in the fish samples.

Methods

In this regard, Cyprinus rubrofuscus (Koi), Heteropneustes fossilis (Shing) and Mystus vittatus (Tengra) fishes were collected and subjected to form an in vitro biofilm by shaking condition into the wise bath. The drug-resistant pattern was determined by the Kirby Bauer technique.

Results

All the samples exhibited a huge array (up to 10⁷ cfu/ml or g) of bacteria such as E. coli, Klebsiella spp., Vibrio spp., Salmonella spp., Proteus spp. and Staphylococcus spp. The isolates from both the bulk samples and their corresponding biofilms were subjected to antibiogram assay using antibiotics such as Ampicillin (10 µg), Erythromycin (15 μg), Streptomycin (STP 10 μg), Oxacillin (10 µg), Nalidixic acid (30 µg). Before biofilm formation, few of the isolates were found to be sensitive and few were resistant against the antibiotics. But when the species were isolated from the biofilm the sensitive one acquired drug resistance and resistant strain unveiled more resistance towards the same antibiotics. The present study revealed extensive bacterial contamination in fish samples among those some were resistant against the supplied drugs.

Conclusion

After the formation of multi-species biofilm, the isolates became more resistant against the same drugs that is alarming for consumers and major obstacles to maintain sustainable health.

The Increasing Importance of Vermamoeba vermiformis

Vermamoeba vermiformis are one of the most prevalent free-living amoebae. These amoebae are ubiquitous and also thermotolerant. Of concern, V. vermiformis have been found in hospital water networks. Furthermore, associations between V. vermiformis and pathogenic bacteria have been reported, such as Legionella pneumophila. Moreover, V. vermiformis are well known to host viruses, bacteria, and other microorganisms and cases of keratitis due to V. vermiformis in conjunction with other amoebae have been reported. Despite the preceding, the medical importance of V. vermiformis is still an ongoing discussion and its genome has been only recently sequenced. Herein, we present a review of the current understanding of the biology and pathogenesis pertaining to V. vermiformis, as well as its' role as an etiological agent and trojan horse. An approach known as theranostics which combines both diagnosis and therapy could be utilized to eradicate and diagnose keratitis cases caused by such amoebae. Given the rise in global warming, it is imperative to investigate these rarely studied amoebae and to understand their importance in human health.

Quantitation of Risk Reduction of E. coli Transmission After Using Antimicrobial Hand Soap

Handwashing with soap is an effective and economical means to reduce the likelihood of Escherichia coli infection from indirect contact with contaminated surfaces during food preparation. The purpose of this study was to conduct a quantitative microbial risk assessment (QMRA) to evaluate the risk of infection from indirect contact with fomites contaminated with E. coli after hand washing with antimicrobial hand soaps. A Monte Carlo simulation was done with a total of 10,000 simulations to compare the effectiveness of two antimicrobial and one control (non-antimicrobial) bar soaps in reducing the exposure and infection risk compared to no hand washing. The numbers of E. coli on several fomites commonly found in household kitchens, as well as the transfer rates between fomites and onto fingertips, were collected from the literature and experimental data. The sponsor company provided the E. coli survival on hands after washing with antimicrobial and control soaps. A number of scenarios were evaluated at two different exposure doses (high and low). Exposure scenarios included transfer of E. coli between meat-to-cutting board surface-to-hands, meat-to-knife surface-to-hands, and from a countertop surface-to-hands, kitchen sponge-to-hands, hand towel-to-hands, and dishcloth-to-hands. Results showed that the risks of illness after washing with the control soap was reduced approximately 5-fold compared to no handwashing. Washing with antimicrobial soap reduced the risk of E. coli infection by an average of about 40-fold compared with no handwashing. The antimicrobial soaps ranged from 3 to 32 times more effective than the non-antimicrobial soap, depending on the specific exposure scenario. Importance: The Centers for Disease Control and Prevention indicate the yearly incidence rate of Shiga Toxin producing E. coli infections is about 1.7/100,000, with about 10% of cases leading to life-threatening hemolytic uremic syndrome and 3–5% leading to death. Our findings confirm handwashing with soap reduces the risks associated with indirect transmission of E. coli infection from contact with fomites during food preparation. Further, in these exposure scenarios, antimicrobial soaps were more effective overall than the non-antimicrobial soap in reducing exposure to E. coli and risk of infection.

Vermamoeba vermiformis - A Free-Living Amoeba with Public Health and Environmental Health Significance

Many case reports emphasize the fact that Free-Living Amoebae (FLA) can relatively easily get in contact with humans or animals. The presence of several facultative parasitic FLA in habitats related to human activities supports their public health relevance. While some strains of Acanthamoeba,Naegleria fowleri,Balamuthia mandrillarisand several other FLA have been described as facultative human pathogens, it remains controversial whetherVermamoeba vermiformisstrains may have a pathogenic potential, or whether this FLA is just an incidental contaminant in a range of human cases. However, several cases support its role as a human parasite, either as the only etiological agent, or in combination with other pathogens. Additionally, a wide range of FLA is known as vectors of microorganisms (endocytobionts), hereby emphasizing their environmental significance. Among those FLA serving as hosts for and vectors of (pathogenic) endocytobionts, there are also descriptions ofV. vermiformisas a vehicle and a reservoir of those endocytobionts. The involvement in animal and human health, the role as vector of pathogenic microorganisms and the pathogenicity in cell cultures, led to the assumption thatV. vermiformisshould be considered relevant in terms of public health and environmental health.

Synergistic Interactions within a Multispecies Biofilm Enhance Individual Species Protection against Grazing by a Pelagic Protozoan

Biofilm formation has been shown to confer protection against grazing, but little information is available on the effect of grazing on biofilm formation and protection in multispecies consortia. With most biofilms in nature being composed of multiple bacterial species, the interactions and dynamics of a multispecies bacterial biofilm subject to grazing by a pelagic protozoan predator were investigated. To this end, a mono and multispecies biofilms of four bacterial soil isolates, namely Xanthomonas retroflexus, Stenotrophomonas rhizophila, Microbacterium oxydans and Paenibacillus amylolyticus, were constructed and subjected to grazing by the ciliate Tetrahymena pyriformis. In monocultures, grazing strongly reduced planktonic cell numbers in P. amylolyticus and S. rhizophila and also X. retroflexus. At the same time, cell numbers in the underlying biofilms increased in S. rhizophila and X. retroflexus, but not in P. amylolyticus. This may be due to the fact that while grazing enhanced biofilm formation in the former two species, no biofilm was formed by P. amylolyticus in monoculture, either with or without grazing. In four-species biofilms, biofilm formation was higher than in the best monoculture, a strong biodiversity effect that was even more pronounced in the presence of grazing. While cell numbers of X. retroflexus, S. rhizophila, and P. amylolyticus in the planktonic fraction were greatly reduced in the presence of grazers, cell numbers of all three species strongly increased in the biofilm. Our results show that synergistic interactions between the four-species were important to induce biofilm formation, and suggest that bacterial members that produce more biofilm when exposed to the grazer not only protect themselves but also supported other members which are sensitive to grazing, thereby providing a "shared grazing protection" within the four-species biofilm model. Hence, complex interactions shape the dynamics of the biofilm and enhance overall community fitness under stressful conditions such as grazing. These emerging inter- and intra-species interactions could play a vital role in biofilm dynamics in natural environments like soil or aquatic systems.

Arcobacter: an emerging food-borne zoonotic pathogen, its public health concerns and advances in diagnosis and control - a comprehensive review

Arcobacter has emerged as an important food-borne zoonotic pathogen, causing sometimes serious infections in humans and animals. Newer species of Arcobacter are being incessantly emerging (presently 25 species have been identified) with novel information on the evolutionary mechanisms and genetic diversity among different Arcobacter species. These have been reported from chickens, domestic animals (cattle, pigs, sheep, horses, dogs), reptiles (lizards, snakes and chelonians), meat (poultry, pork, goat, lamb, beef, rabbit), vegetables and from humans in different countries. Arcobacters are implicated as causative agents of diarrhea, mastitis and abortion in animals, while causing bacteremia, endocarditis, peritonitis, gastroenteritis and diarrhea in humans. Three species including A. butzleri, A. cryaerophilus and A. skirrowii are predominantly associated with clinical conditions. Arcobacters are primarily transmitted through contaminated food and water sources. Identification of Arcobacter by biochemical tests is difficult and isolation remains the gold standard method. Current diagnostic advances have provided various molecular methods for efficient detection and differentiation of the Arcobacters at genus and species level. To overcome the emerging antibiotic resistance problem there is an essential need to explore the potential of novel and alternative therapies. Strengthening of the diagnostic aspects is also suggested as in most cases Arcobacters goes unnoticed and hence the exact epidemiological status remains uncertain. This review updates the current knowledge and many aspects of this important food-borne pathogen, namely etiology, evolution and emergence, genetic diversity, epidemiology, the disease in animals and humans, public health concerns, and advances in its diagnosis, prevention and control.

Abundance, diversity and community composition of free-living protozoa on vegetable sprouts

Interactions with free-living protozoa (FLP) have been implicated in the persistence of pathogenic bacteria on food products. In order to assess the potential involvement of FLP in this contamination, detailed knowledge on their occurrence, abundance and diversity on food products is required. In the present study, enrichment and cultivation methods were used to inventory and quantify FLP on eight types of commercial vegetable sprouts (alfalfa, beetroot, cress, green pea, leek, mung bean, red cabbage and rosabi). In parallel, total aerobic bacteria and Escherichia coli counts were performed. The vegetable sprouts harbored diverse communities of FLP, with Tetrahymena (ciliate), Bodo saltans and cercomonads (flagellates), and Acanthamoeba and Vannella (amoebae) as the dominant taxa. Protozoan community composition and abundance significantly differed between the sprout types. Beetroot harbored the most abundant and diverse FLP communities, with many unique species such as Korotnevella sp., Vannella sp., Chilodonella sp., Podophrya sp. and Sphaerophrya sp. In contrast, mung bean sprouts were species-poor and had low FLP numbers. Sampling month and company had no significant influence, suggesting that seasonal and local factors are of minor importance. Likewise, no significant relationship between protozoan community composition and bacterial load was observed.