Enterobacteria associated with houseflies (Musca domestica) as an infection risk indicator in swine production farms

Turmeric shortens lifespan in houseflies

Climate change poses a significant threat to food security and global public health with the increasing likelihood of insect pest outbreaks. Alternative ways to control insect populations, preferably using environmental-friendly compounds, are needed. Turmeric has been suggested as a natural insecticide with toxicity properties in some insect groups. However, empirical evidence of the effects of turmeric - and their interaction with other ecological factors such as diet - on insect survival has been limited. Here, we tested the effects of turmeric and its interactions with diets differing in protein source in the common housefly, Musca domestica. We found that turmeric shortened lifespan independent of diet and sex. Females in turmeric diets were heavier at death, which was likely driven by a combination of relatively lower rates of body mass loss during their lifetime and a higher percentage of water content at death. Each sex responded differently to the protein source in the diet, and the magnitude of the difference in lifespan between sexes were greatest in diets in which protein source was hydrolysed yeast; individuals from both sexes lived longest in sucrose-milk diets and shortest in diets with hydrolysed yeast. There was no evidence of an interaction between turmeric and diet, suggesting that the toxicity effects are independent of protein source in the diet. Given the seemingly opposing effects of turmeric in insects and mammals being uncovered in the literature, our findings provide further evidence in support of turmeric as a potential natural insecticide.

House Flies Are Underappreciated Yet Important Reservoirs and Vectors of Microbial Threats to Animal and Human Health

House flies are well recognized as filth-associated organisms and public nuisances. House flies create sanitation issues when they bridge the gap between microbe-rich breeding environments and animal/human habitations. Numerous scientific surveys have demonstrated that house flies harbor bacterial pathogens that pose a threat to humans and animals. More extensive and informative surveys incorporating next-generation sequencing technologies have shown that house fly carriage of pathogens and harmful genetic elements, such as antimicrobial resistance genes, is more widespread and dangerous than previously thought. Further, there is a strong body of research confirming that flies not only harbor but also transmit viable, and presumably infectious, bacterial pathogens. Some pathogens replicate and persist in the fly, permitting prolonged shedding and dissemination. Finally, although the drivers still have yet to be firmly determined, the potential range of dissemination of flies and their associated pathogens can be extensive. Despite this evidence, the house flies’ role as reservoirs, disseminators, and true, yet facultative, vectors for pathogens have been greatly underestimated and underappreciated. In this review, we present key studies that bolster the house fly’s role both an important player in microbial ecology and population biology and as transmitters of microbial threats to animal and human health.

House Flies (Musca domestica) from Swine and Poultry Farms Carrying Antimicrobial Resistant Enterobacteriaceae and Salmonella

The house fly (Musca domestica) is a very common insect, abundantly present in farm settings. These insects are attracted by organic substrates and can easily be contaminated by several pathogenic and nonpathogenic bacteria. The aim of this survey was to evaluate the presence of Salmonella spp. and other Enterobacteriaceae in house flies captured in small-medium size farms, located in Northwest Tuscany, Central Italy, and to evaluate their antimicrobial resistance; furthermore, isolates were tested for extended spectrum β-lactamase and carbapenems resistance, considering the importance these antimicrobials have in human therapy. A total of 35 traps were placed in seven poultry and 15 swine farms; three different kinds of samples were analyzed from each trap, representing attractant substrate, insect body surface, and insect whole bodies. Enterobacteriaceae were isolated from 86.36% of farms, 82.87% of traps, and 60.95% of samples; high levels of resistance were detected for ampicillin (61.25% of resistant isolates) and tetracycline (42.5% of resistant isolates). One extended spectrum β-lactamase producer strain was isolated, carrying the blaTEM-1 gene. Salmonella spp. was detected in 36.36% of farms, 25.71% of traps, and 15.24% of samples. Five different serovars were identified: Kentucky, Kisarawe, London, Napoli, and Rubislaw; some isolates were in R phase. Resistance was detected mainly for ampicillin (31.21%) and tetracycline (31.21%). House flies could represent a serious hazard for biosecurity plans at the farm level, carrying and sharing relevant pathogenic and antimicrobial resistant bacteria.

Positive biofilms to guide surface microbial ecology in livestock buildings

The increase in human consumption of animal proteins implies changes in the management of meat production. This is followed by increasingly restrictive regulations on antimicrobial products such as chemical biocides and antibiotics, used in particular to control pathogens that can spread zoonotic diseases. Aligned with the One Health concept, alternative biological solutions are under development and are starting to be used in animal production. Beneficial bacteria able to form positive biofilms and guide surface microbial ecology to limit microbial pathogen settlement are promising tools that could complement existing biosecurity practices to maintain the hygiene of livestock buildings. Although the benefits of positive biofilms have already been documented, the associated fundamental mechanisms and the rationale of the microbial composition of these new products are still sparce. This review provides an overview of the envisioned modes of action of positive biofilms used on livestock building surfaces and the resulting criteria for the selection of the appropriate microorganisms for this specific application. Limits and advantages of this biosecurity approach are discussed as well as the impact of such practices along the food chain, from farm to fork.

Different creep compound feed formulations for new born piglets: influence on growth performance and health parameters

The aim of this study was to compare the influence of different compositions of creep compound feed (CCF) (C-I – control group; TG-II – a CCF containing wheat bran extruded and fermented with L. paracasei; TG-III – a creep compound feed containing sugar beet pulp) on the piglets' growth performance, blood parameters, fecal microbial profile and physicochemical characteristics. Moreover, the fecal volatile compound (VC) profile was analyzed as a possible chemical marker related to changes in the fecal microbial profile and physicochemical characteristics. A 21-day experiment was conducted using 1-day-old 300 Large White/Norwegian Landrace piglets. The highest body weight (at the 21st day) was found in piglets of the TG-III group, and both treated groups showed lower feed conversion ratios. At the end of the experiment, significantly higher lactobacillus counts in the feces of both treated groups were found, and a correlation between fecal textural hardness and the lactobacillus count was established (r = 0.475). Significant correlations of piglets' individual fecal VC with microbiological parameters and fecal pH were established [lactobacilli with 3-n-nonadecanol-1; enterobacteria with butyric acid <2-methyl->; pentanoic acid, 4-methyl-; eicosene(E)-, etc.]. It can be concluded that local material could be successfully incorporated into CCF preparation without impairing animal metabolism.

ERIC-PCR based molecular typing of multidrug resistant Escherichia coli isolated from houseflies (Musca domestica) in the environment of milk and meat shops

The emergence and spread of antimicrobial resistance has become a major global public health concern. A component of this problem is the spread of the antibiotic resistant bacteria. Flies move freely between habitats of food-producing animals and human beings and thus have great potential for dissemination of antimicrobial resistant bacteria from a contaminated environment to milk and meat markets, posing potential hazards for the consumers. During the present study, a total of 150 houseflies were captured from milk and meat shops located in Durg and Raipur city of Chhattisgarh, India. The E. coli were isolated from houseflies and characterized on the basis of cultural and molecular tests. Further, the isolates were subjected to antimicrobial susceptibility testing against frequently used antibiotics using disk diffusion method. The antibiotic resistance genes and int1 gene were detected using polymerase chain reaction (PCR). A total of 45 E. coli isolates were obtained from the fly samples with overall prevalence rate of 30.0%. Antibiogram results confirmed that E. coli isolates were resistant to multiple antibiotics. Out of the (45) isolates of E. coli, 17 (37.8%) isolates were extended spectrum beta-lactamase (ESBL) producer and multi-drug resistant (MDR). Out of the ESBL and MDR E.coli isolates, bla_CTX-M (24.4%), bla_TEM (11.1%), tetA (28.8%), tetB (26.7%), gyrA (26.7%), parC (31. 1%) and int1 genes (15.5%) were detected but none of the isolates were found positive for bla_SHV gene. Findings of the present study confirm that MDR E. coli are widely distributed in houseflies and play an important role in transmission of antibiotic-resistant bacteria from contaminated environment to milk and meat shop environment.

Antimicrobial Resistance in Rural Settings in Latin America: A Scoping Review with a One Health Lens

Antimicrobial resistance (AMR) in rural Latin America is not fully understood. The transmission pathways are partially known since research predominantly focuses on the urban hospital setting. The contribution to AMR from environmental factors is usually only mentioned in large-scale animal production. To understand the state of the literature on AMR in rural LA, we carried out a scoping review using the One Health (OH) perspective. OH recognises the concomitant contributions and interconnectedness of humans, animal, and the environment, thus, we used the OH perspective to select those articles adopting a holistic view of the problem. We searched original articles in English, Spanish, and Portuguese in four peer-reviewed databases and included 21 publications in the analysis. We charted data on bibliometrics, design, data collection sources, and instruments. We identified the human, animal, and environmental contributions to AMR in rural locations, and information gaps on AMR transmission routes and AMR drivers. Intensive and non-intensive animal production systems and agricultural practices were the most frequently found human contributions to AMR. Poultry, swine, cattle, and fish were the most frequent livestock mentioned as sources of AMR bacteria. Animal carriage and/or transfer of AMR determinants or bacteria was recognised as the primary contribution of livestock to the problem, while water, soil, and farming were predominant environmental contributions. We found that only 1 article out of 21 considered the OH approach as a framework for their sampling scheme, whereas 5 out 21 discussed all the three OH components. There were hardly any descriptions of humans or human waste as reservoirs for AMR in rural locations, and rural health centres or hospitals and wildlife were not represented. No studies identified mining as an anthropogenic activity driving AMR. More OH-oriented studies, with emphasis on molecular approaches—for identification and comparison of AMR genes—are sorely needed to understand better the existence of a network of interconnected transmission routes in rural Latin America and provide efficient strategies to prevent further AMR emergence.

Prevalence of Salmonella enterica in Flies on a Diversified Cattle and Fresh Produce Farm across Two Growing Seasons

ABSTRACT

Flies are a vector for spreading foodborne pathogens pertinent to fresh produce, such as Shiga toxigenic Escherichia coli and Salmonella; however, most studies focus on concentrated animal feeding operations, which do not reflect low-density animal farming practices that often adjoin fruit and vegetable acreage. In this study, we determined the prevalence of Salmonella in flies collected biweekly on an integrated animal and produce operation over two growing seasons. Eleven of 889 pooled samples tested positive for Salmonella. Flies from the Calliphoridae, Muscidae, Sarcophagidae, and Tachinidae families were associated with Salmonella carriage, but fly family was not a significant factor for isolation of Salmonella (P = 0.303). Fly species were a significant factor (P = 0.026), with five Pentacricia aldrichii pools testing positive for Salmonella. With the exception of single specimen isolation, prevalence ranged from 2.2 to 15.2%. With the exception of the Tachinidae family, these results reflect a strong association of flies that are commonly associated with feces or are pests of animals. Trap location was not significantly associated with isolation of Salmonella-positive flies (P = 0.236). Overall, the population of flies was not as abundant as studies conducted with produce grown close to concentrated animal feeding operations, indicating a reduced risk of transmission; however, similar to these studies, fly families that are commonly isolated from fecal and decaying matter were most frequently associated with Salmonella isolation. Further work is warranted to elucidate the foodborne pathogen transmission rates to produce and subsequent survival over time.

HIGHLIGHTS

Bacterial pathogens identified from houseflies in different human and animal settings: A systematic review and meta-analysis

Housefly (Musca domestica) is an excellent candidate for the distribution of susceptible and resistant bacterial strains that potentially threaten public health. To date, there is a paucity of information on the global distribution of pathogenic bacteria of medical and veterinary importance from diverse environmental settings. Therefore, this study was undertaken to conduct a systemic review and meta‐analysis to estimate occurrence of various bacterial species of medical and veterinary importance harboured by houseflies around the world. Published articles from 1980 to 2020 were retrieved from electronic databases and assessed for eligibility according to Preferred Reporting Items for Systemic Reviews and Meta‐Analysis guidelines. Seventy‐eight studies were included in the review with only 44 studies being eligible for meta‐analysis. Results indicated that eligible studies used in this review were from four continents, i.e., Asia (47.4%) America (23.1%), Africa (20.5%) and Europe (8.9%). The majority of the studies (56.4%) used the culture method for the identification of bacterial pathogens, while 30.7% used both culture and PCR techniques. For meta‐analysis, we focused on five pathogenic bacterial species including Escherichia coli, Enterococcusfaecium, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. High heterogeneity was found among studies investigating different pathogens including E. coli (Q = 10,739.55; I² = 99.60; Q‐p 0.0001), E. faecium (Q = 317.61; I² = 86.46; Q‐p < 0.0001), K. pneumonia (Q = 1,576.61; I² = 97.27; Q‐p < 0.0001), S. aureus (Q = 2,439.12; I² = 98.24; Q‐p < 0.0001) and P. aeruginosa (Q = 1,283.0; I² = 96.65; Q‐p < 0.0001). Furthermore, it was observed that houseflies carried a considerable number of susceptible and antibiotic‐resistant bacterial strains that pose considerable threats to public health. Findings from this study have provided more insight on the vectoral potential of houseflies in the transmission of significant bacterial pathogens from different regions across the world. Further investigation is required to quantify the bacterial contamination and dissemination by houseflies.

Swine diets impact manure characteristics and gas emissions: Part II protein source

Soybean meal is the dominate protein source for swine diets in the world driven largely by economics, nutritive value, and availability; but conditions can change requiring growers to consider more economical and available protein alternatives. A feeding trial was conducted to determine the impact dietary protein source material on manure slurry chemical properties and manure gas emissions. A total of 32 gilts averaging 130 kg BW were fed either a control diet formulated with soybean meal (SB) or an alternative protein source that included corn gluten meal (CG); canola meal (CM); or poultry meal (PM), with all diets containing 176 g protein kg^-1. Diets were fed for 45 d with an average daily feed intake of 2.68 kg/d. Feces and urine were collected twice daily after each feeding and added to animal-specific manure storage containers. At the end of the study, manure slurries were monitored for gas emissions and chemical properties. Dietary protein source had a significant effect (P < 0.05) on manure pH, total solids, total C, protein N, and total S. Pigs fed the diets containing CM had significantly higher levels of sulfide, butanoic acid, and branch chain fatty acids compared to pigs fed SB diets (P < 0.05). Pigs fed CM diets had significantly lower emissions of NH₃ compared to pigs fed SB diets (P < 0.05). There were no significant differences in C or S emissions or in odorant emission as affected by source of dietary protein. Hydrogen sulfide was the most dominate odorants for all dietary treatments.

The Stable Fly (Stomoxys calcitrans) as a Possible Vector Transmitting Pathogens in Austrian Pig Farms

This pilot study aimed to investigate stable flies from Austrian pig farms for the presence of defined swine pathogens, such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus 2 (PCV2), hemotrophic mycoplasmas in ingested blood and/or body parts and bacteria on the surface of the flies. Furthermore, the use of stable flies as a diagnostic matrix for the detection of pathogens in the ingested pig blood should be investigated. In total, 69 different microorganisms could be found on the surface of tested S. calcitrans from 20 different pig farms. Escherichia coli was the most common bacterium and could be found on flies from seven farms. In seven farms, hemotrophic mycoplasmas were detected in stable flies. PRRSV could not be found in any of the samples of these 20 farms but PCV2 was detected in six farms. Whether the stable fly can be used as a matrix to monitor the health status cannot be accurately determined through this study, especially in regard to PRRSV. Nevertheless, it might be possible to use the stable fly as diagnostic material for defined pathogens like Mycoplasma suis and PCV2.

Swine diets impact manure characteristics and gas emissions: Part II sulfur source

Sulfur is a key nutrient in swine diets and is associated with hydrogen sulfide (H₂S) emissions, odor, and respiratory distress of animals. Due to potential increases in S levels in swine diets by using alternative feedstuffs, a feeding trial study was conducted to determine the effect of dietary S source has on manure slurry chemical properties and gas emissions. A total of 24 gilts averaging 139 kg BW were fed a control diet formulated with corn and soybean meal (CSBM) containing 1.80 g S kg^-1 or diets containing 3.50 g S kg^-1 feed as supplied by calcium sulfate (CaSO₄), distillers dried grains with solubles (DDGS), or feather meal (CFM). Diets were fed for 41 d with an ADFI of 2.70 kg/d. Feces and urine were collected twice daily after each feeding and added to the manure storage containers. At the end of the study, manure slurries were monitored for gas emissions and chemical properties. Dietary S source had a significant effect on excretion of DM, C, N, and S in manure. Pigs fed the diets containing DDGS had significantly higher levels of NH₃, VFAs, and phenols in manure compared to pigs fed the CSBM diet. Pigs fed diets with organic S (i.e., DDGS and CFM) had lower emissions of H₂S compared to pigs fed the diet with inorganic sulfur (CaSO₄). In contrast, there were no significant differences in C or N emissions as affected by dietary treatment. Odor and odorant emissions differed by dietary treatment, with pigs fed the CFM diet having the highest odor emissions as compared to pigs fed the control CSBM diet. Pigs fed diets containing CFM and DDGS had a greater percentage of their chemical odor associated with volatile organic compounds while animals fed the CSBM diet or the diet with CaSO₄ had greater percentage associated with H₂S emissions.