Detection of Salmonella enterica Serovar Montevideo and Newport in Free-ranging Sea Turtles and Beach Sand in the Caribbean and Persistence in Sand and Seawater Microcosms

Epidemiology of Salmonella enterica subspecies enterica serotypes, isolated from imported, farmed and feral poultry in the Cayman Islands

Non-typhoidal Salmonellae (NTS) are common foodborne pathogens throughout the world causing acute gastroenteritis. Compared to North America and Europe, there is little information on NTS in the Caribbean. Here we investigated the prevalence and characteristics of NTS present in the local poultry of the Cayman Islands to determine the public health risk. In total, we collected 156 samples. These were made up of boot swabs of 31 broiler farms and 31 layer farms (62 samples), paper bedding from 45 imported chick boxes, and 49 pooled cecum samples from feral chickens, each sample representing 10 individual chickens. Salmonella was isolated using the ISO 6579 protocol and isolates were characterized using Whole Genome Sequencing (WGS) analysis. Eighteen Salmonella isolates were obtained and comprised six S. enterica subspecies enterica serotypes and one subspecies houtenae serotype. Serotypes were: S. Kentucky (n = 9), S. Saintpaul (n = 5), S. Javiana (n = 1), S. Senftenberg (n = 1), S. Poona (n = 1) and S. Agona (n = 1). S. Kentucky strains were all ST152 and clonally related to poultry strains from the United states. S. Saintpaul ST50 strains showed clonality to North American strains. Over half of the strains (n = 11) contained resistance genes to at least two antibiotic groups and five strains were MDR, mainly those from imported day-old chicks. The blaCMY-2 gene was found in S. Kentucky from day-old chicks. Strains from feral poultry had no acquired AMR genes. While serotypes from feral poultry have been identified in human infections, they pose minimal risk due to their low virulence.

Bacterial Infections in Sea Turtles

Sea turtles are important for the maintenance of marine and beach ecosystems, but they are seriously endangered due to factors mainly related to human activities and climate change such as pollution, temperature increase, and predation. Infectious and parasitic diseases may contribute to reducing the number of sea turtles. Bacteria are widespread in marine environments and, depending on the species, may act as primary or opportunistic pathogens. Most of them are able to infect other animal species, including humans, in which they can cause mild or severe diseases. Therefore, direct or indirect contact of humans with sea turtles, their products, and environment where they live represent a One Health threat. Chlamydiae, Mycobacteria, and Salmonellae are known zoonotic agents able to cause mild or severe diseases in sea turtles, other animals, and humans. However, other bacteria that are potentially zoonotic, including those that are antimicrobially resistant, are involved in different pathologies of marine turtles.

Heavy Rainfall, Sewer Overflows, and Salmonellosis in Black Skimmers (Rynchops niger)

Extreme weather events, particularly heavy rainfall, are occurring at greater frequency with climate change. Although adverse human health effects from heavy rainfall are often publicized, impacts to free-ranging wildlife populations are less well known. We first summarize documented associations of heavy rainfall on wildlife health. We then report a novel investigation of a salmonellosis outbreak in a colony of black skimmers (Rynchops niger) in Florida, USA. During June-September 2016, heavy rainfall resulted in the discharge of millions of gallons of untreated wastewater into the Tampa Bay system, contaminating the water body, where adult skimmers foraged. At least 48 fledglings died, comprising 39% of the colony's nesting season's offspring. Of eight examined deceased birds from the colony, six had a systemic salmonellosis infection. Isolates were identified as Salmonella enterica serotype Typhimurium. Their pulsed-field gel electrophoresis patterns were identical to each other and matched those from several human Salmonella sp. infections. Differences among whole-genome sequences were negligible. These findings and the outbreak's epidemic curve suggest propagated transmission occurred within the colony. A multidisciplinary and One Health approach is recommended to mitigate any adverse effects of climate change-driven stochastic events, especially when they place already imperiled wildlife at further risk.

Investigating public support for biosecurity measures to mitigate pathogen transmission through the herpetological trade

The expanding global trade in herpetofauna has contributed to new infectious disease dynamics and pathways that allow for the rapid spread of pathogens geographically. Improved biosecurity is needed to mitigate adverse biodiversity, economic and human health impacts associated with pathogen transmission through the herpetological trade. However, general lack of knowledge of the pathogen transmission risks associated with the global trade in herpetofauna and public opposition to biosecurity measures are critical obstacles to successfully preventing pathogen transmission. In 2019 we administered a survey to 2,007 members of the public in the United States of America to ascertain their support for interventions to prevent the spread of Batrachochytrium dendrobatidis (Bd), Batrachochytrium salamandrivorans (Bsal), ranaviruses, and Salmonella through the herpetological trade. We presented survey respondents with different potential hazards associated with pathogen transmission through this trade, namely ecological, economic, and human health impacts. We used structural equation models to determine how these different hazards and respondents’ characteristics influenced respondents’ support for quarantine and veterinary observation of herpetofauna imported into the United States, mandatory tests for diseases of concern, and best practices to reduce stress and improve the care of live herpetofauna during transport to the United States. Respondents’ values and their perceived susceptibility and sensitivity to different hazards associated with pathogen transmission were key determinants of their support for biosecurity. Respondents with strong biospheric and altruistic values demonstrated sensitivity to ecological and human health impacts associated with pathogen transmission, whereas respondents with strong egoistic values demonstrated sensitivity to economic impacts. Respondents had limited knowledge of Bd, Bsal or ranaviruses, the size of the herpetological trade, or how this trade may contribute to pathogen transmission. Improved outreach and education on pathogen transmission through the herpetological trade is required, but it is important that messages are tailored to people with different values to elicit their support for biosecurity.

Prevalence and phenotypic characterization of Salmonella enterica isolates from three species of wild marine turtles in Grenada, West Indies

BACKGROUND AND AIM

Salmonella enterica causes enteric disease in mammals and may potentially be transmitted from marine turtles that shed the pathogen in the environment. Marine turtle-associated human salmonellosis is a potential public health concern in Grenada, as the island supports populations of leatherback turtles (Dermochelys coriacea), hawksbill turtles (Eretmochelys imbricata), and green turtles (Chelonia mydas) that interface with veterinarians and conservation workers, the local population, and the thousands of visitors that frequent the island yearly. To date, the prevalence of S. enterica has only been examined in a small subset of marine turtles in the Caribbean and no studies have been conducted in Grenada. The aim of this study was to quantify the prevalence of S. enterica in leatherback, hawksbill and green turtles in Grenada, characterize phenotypes and DNA profiles, and explore the potential risk to human health in the region.

MATERIALS AND METHODS

A total of 102 cloacal swabs were obtained from nesting leatherback turtles and foraging hawksbill and green turtles. Samples were cultured on enrichment and selective media and isolates were phenotypically characterized using serotyping, pulsed-phase gel electrophoresis, and antibiotic susceptibility. Enrichment broths were additionally screened by polymerase chain reaction (PCR) using S. enterica-specific primers.

RESULTS

S. enterica was cultured from 15/57 (26.3%) leatherback turtles, 0/28 hawksbill, and 0/17 green turtles. This included S. enterica serovars Montevideo, S. I:4,5,12:i:-, Salmonella Typhimurium, Salmonella Newport, S. I:6,7:-:-, and S. I:4,5,12:-:-. Five/15 leatherback turtles carried multiple serovars. Eight pulsotype groups were identified with multiple clustering; however, there was no clear association between pulsotype group and serotype profile. Five/71 isolates showed resistance to streptomycin or ampicillin. Twenty-one/57 leatherback turtles, 14/28 hawksbill turtles, and 8/17 green turtles tested positive for S. enterica by quantitative PCR.

CONCLUSION

Nesting leatherback turtles actively shed S. enterica and poses a risk for zoonosis; however, the presence of viable pathogen in green and hawksbill species is unclear. These findings help elucidate the role of marine turtles as potential sources of zoonotic S. enterica and provide baseline data for one health research in Grenada and the wider Caribbean region.

A Review of the Public Health Challenges of Salmonella and Turtles

Non-typhoidal Salmonella serovars are recognized as zoonotic pathogens. Although human salmonellosis is frequently associated with ingestion of contaminated foods of animal origin, contact with animals may also be a significant source of Salmonella infection, especially contact with turtles, which have shown to be an important reservoir of Salmonella, specifically through their intestinal tracts. Turtles are among the most common reptiles kept as house pets that may pose a public health risk associated with Salmonella exposure, especially among infants and young children. This review discusses the literature reporting the link between turtles and Salmonella as well as turtle-associated human salmonellosis in the last ten years. In most outbreaks, a high proportion of patients are children under five years of age, which indicates that children are at the greatest risk of turtle-associated salmonellosis. Therefore, turtles should not be preferred as recommended pets for children under five years of age. Reducing turtle stress to minimise Salmonella shedding as well as providing client education handouts at the points of sale of these animals may reduce the risk of transmitting such significant pathogen to humans. Further studies are required to investigate the role of both direct contact with turtles as well as indirect contact through cross-contamination in the transmission of turtles-associated Salmonella to humans.

Febrile illness after a beach day: a case of salmonella bacteremia from oral exposure to a sand dollar

This case report discusses a rare presentation of salmonella bacteremia after an oral exposure to a sand dollar in a pediatric patient. A 2-year-old Hispanic male presented to the emergency department with a chief complaint of diarrhea and fever for 8 days after a family trip to Destin beach, Florida, during the sea turtle nesting season. The symptoms began a day after the patient took a bite on a sand dollar found on the beach that caused a small wound inside his cheek. The laboratory testing done in the emergency department was remarkable for blood and stool culture testing positive for non-typhoid salmonella. The sand dollar is a type of a sea urchin commonly found on sandy beaches and consists of an anatomical filtration system to consume sandy water. It could be inferred that the increased presence of sea turtles during the time of the patient's visit to Destin beach could have led to higher levels of salmonella in the seawater and consequently in the sand dollar, possibly leading to the inoculation of salmonella in this patient. To the best of our knowledge, this is a first case report that links oral exposure of the sand dollar to invasive salmonellosis.

Loggerhead sea turtles as sentinels in the western Mediterranean: antibiotic resistance and environment-related modifications of Gram-negative bacteria

Sea turtles possess relevant characteristics to serve as sentinel species for monitoring the health of marine ecosystems, which is currently threatened. This study examined 35 loggerhead turtles from the western Mediterranean, focusing on the oral and cloacal prevalence of aerobic Gram-negative bacteria, their antibiotic resistance and the influence of several variables linked both to the animal and the environment (i.e. estimated life stage; area, season and cause of recovery; plastic ingestion). Conventional bacteriology methods led to the isolation of bacterial families commonly regarded as opportunistic pathogens (i.e. Aeromonadaceae; Enterobacteriaceae; Pseudomonadaceae; Shewanellaceae; Vibrionaceae), but pointing out sea turtles as carriers of potential zoonotic agents. The high rates of antibiotic resistance, here detected, raise important concerns on the dissemination of this phenomenon in marine environments. Moreover, several of the examined variables showed a significant influence on the prevalence of bacterial families, strengthening the role of sea turtles as mirrors of their ecosystems.

Sources of human infection by Salmonella enterica serotype Javiana: A systematic review

Non-typhoidal Salmonella (NTS) infection is one of the major causes of diarrheal disease throughout the world. In recent years, an increase in human S. Javiana infection has been reported from the southern part of the United States. However, the sources and routes of transmission of this Salmonella serotype are not well understood. The objective of this study was to perform a systematic review of the literature to identify risk factors for human S. Javiana infection. Using PRISMA guidelines, we conducted a systematic search in Web of Science, PubMed, and the Morbidity and Mortality Weekly Report (MMWR). Searches returned 63 potential articles, of which 12 articles met all eligibility criteria and were included in this review. A review of the literature indicated that both food and non-food (such as animal contact) exposures are responsible for the transmission of S. Javiana infection to humans. Consumption of fresh produce (tomatoes and watermelons), herbs (paprika-spice), dairy products (cheese), drinking contaminated well water and animal contact were associated with human S. Javiana infections. Based on the findings of this study, control of human S. Javiana infection should include three factors, (a) consumption of drinking water after treatment, (b) safe animal contact, and (c) safe food processing and handling procedures. The risk factors of S. Javiana infections identified in the current study provide helpful insight into the major vehicles of transmission of S. Javiana. Eventually, this will help to improve the risk management of this Salmonella serotype to reduce the overall burden of NTS infection in humans.

Identification and Characterization of Escherichia coli, Salmonella Spp., Clostridium perfringens, and C. difficile Isolates from Reptiles in Brazil

Considering the increasing popularity of reptiles as pets and their possible role as reservoirs of pathogenic microorganisms, the aim of this study was to isolate Escherichia coli, Salmonella spp., Clostridium perfringens, and C. difficile strains from reptiles in Brazil and to characterize the isolated strains. The characterization was based on phylogenetic typing of E. coli, identification of virulence genes of E. coli, C. perfringens, and C. difficile, serotyping of Salmonella spp., ribotyping and MLST of C. difficile and antimicrobial susceptibility test of pathogenic strains. Cloacal swabs were collected from 76 reptiles, of which 15 were lizards, 16 chelonians, and 45 snakes, either living in captivity, in the wild, or as companion animals. E. coli was isolated from 52 (68.4%) reptiles, of which 46 (88.4%) were characterized as phylogroup B1. The virulence factor CNF1 of E. coli was found in seven (9.2%) sampled animals, whereas the gene of EAST1 was found in isolates from two (2.6%) reptiles. Three isolates positive for CNF1 were resistant to cephalothin, one of which was also resistant to ciprofloxacin, trimethoprim/sulfamethoxazole, and chloramphenicol, being then classified as multidrug resistant strain (MDR). Salmonella enterica was identified in 26 (34.2%) reptiles, of which 13 belonged to the subspecies enterica. Serotypes such as S. Mbandaka, S. Panama, S. Infantis, S. Heidelberg, and S. Anatum were identified. One isolate of S. enterica subsp. houtenae was resistant to cephalothin and ciprofloxacin. C. perfringens type A was isolated from six (7.8%) animals. C. difficile was isolated from three (3.9%) reptiles. Two of these isolates were toxigenic and classified into ribotypes/MLST 081/ST9 and 106/ST42, which have been previously reported to infect humans. In conclusion, reptiles in Brazil can harbor toxigenic C. difficile and potentially pathogenic E. coli and Salmonella enterica subsp. enterica, thus representing a risk to human and animal health.

Multiple Food-Animal-Borne Route in Transmission of Antibiotic-Resistant Salmonella Newport to Humans

Characterization of transmission routes of Salmonella among various food-animal reservoirs and their antibiogram is crucial for appropriate intervention and medical treatment. Here, we analyzed 3728 Salmonella enterica serovar Newport (S. Newport) isolates collected from various food-animals, retail meats and humans in the United States between 1996 and 2015, based on their minimum inhibitory concentration (MIC) toward 27 antibiotics. Random Forest and Hierarchical Clustering statistic was used to group the isolates according to their MICs. Classification and Regression Tree (CART) analysis was used to identify the appropriate antibiotic and its cut-off value between human- and animal-population. Two distinct populations were revealed based on the MICs of individual strain by both methods, with the animal population having significantly higher MICs which correlates to antibiotic-resistance (AR) phenotype. Only ∼9.7% (267/2763) human isolates could be attributed to food-animal origins. Furthermore, the isolates of animal origin had less diverse antibiogram than human isolates (P < 0.001), suggesting multiple sources involved in human infections. CART identified trimethoprim-sulfamethoxazole to be the best classifier for differentiating the animal and human isolates. Additionally, two typical AR patterns, MDR-Amp and Tet-SDR dominant in bovine- or turkey-population, were identified, indicating that distinct food-animal sources could be involved in human infections. The AR analysis suggested fluoroquinolones (i.e., ciprofloxacin), but not extended-spectrum cephalosporins (i.e., ceftriaxone, cefoxitin), is the adaptive choice for empirical therapy. Antibiotic-resistant S. Newport from humans has multiple origins, with distinct food-animal-borne route contributing to a significant proportion of heterogeneous isolates.