Salmonella enteritidis in Antarctica: zoonosis in man or humanosis in penguins?

Occurrences of UV filters, endocrine disruptive chemicals, alkyl phenolic compounds, fragrances, and hormones in the wastewater and coastal waters of the Antarctica

We present a simplified status description of the prevalence and occurrences of organic micropollutants including endocrine disruptive chemicals (EDCs), therapeutic drugs, hormones, fragrances and ultraviolet (UV) filters in the wastewaters and the adjacent coastal oceans in the Northern and Southern Antarctica. Different treatment technologies adopted in the research stations and their efficacy in removing pharmaceuticals and personal care products (PPCPs) are reviewed. Till date, 56 PPCPs are reported in the wastewaters of Antarctic research stations, and 23 in the adjacent coastal waters and sea ice. The reported concentrations in the wastewaters are at the levels of μg L^-1 for UV filters, plasticizer Bisphenol A, metabolites, antibiotics, alkyl phenolic compounds, and stimulants. Concentrations in the coastal waters and sea ice are two orders of magnitude lower than the wastewaters because of dilution and degradation. It is apparent however, that the PPCP-laden effluents discharged from the research stations contaminate them. If left unchecked, pollution of the coastal waters and sea-ice can lead to toxic levels. Through this review, we have established widespread occurrence of PPCPs in the polar coastal oceans; this study will also provide the status quo for the researchers and policymakers to seriously consider the issue and initiate remedial action in the near future. The existing substantial gaps in understanding of the impact of PPCPs on the flora and fauna of Antarctica, and the ineffectiveness of the current treatment technologies adopted by the research stations are highly evident. Future-oriented polar research should focus on protecting the pristine ecosystem by utilizing climate-sensitive, cost-effective treatment technologies.

Antimicrobial resistance in Antarctica: is it still a pristine environment?

Although the rapid spread of antimicrobial resistance (AMR), particularly in relation to clinical settings, is causing concern in many regions of the globe, remote, extreme environments, such as Antarctica, are thought to be relatively free from the negative impact of human activities. In fact, Antarctica is often perceived as the last pristine continent on Earth. Such remote regions, which are assumed to have very low levels of AMR due to limited human activity, represent potential model environments to understand the mechanisms and interactions underpinning the early stages of evolution, de novo development, acquisition and transmission of AMR. Antarctica, with its defined zones of human colonisation (centred around scientific research stations) and large populations of migratory birds and animals, also has great potential with regard to mapping and understanding the spread of early-stage zoonotic interactions. However, to date, studies of AMR in Antarctica are limited. Here, we survey the current literature focussing on the following: i) Dissection of human-introduced AMR versus naturally occurring AMR, based on the premise that multiple drug resistance and resistance to synthetic antibiotics not yet found in nature are the results of human contamination ii) The potential role of endemic wildlife in AMR spread There is clear evidence for greater concentrations of AMR around research stations, and although data show reverse zoonosis of the characteristic human gut bacteria to endemic wildlife, AMR within birds and seals appears to be very low, albeit on limited samplings. Furthermore, areas where there is little, to no, human activity still appear to be free from anthropogenically introduced AMR. However, a comprehensive assessment of AMR levels in Antarctica is virtually impossible on current data due to the wide variation in reporting standards and methodologies used and poor geographical coverage. Thus, future studies should engage directly with policymakers to promote the implementation of continent-wide AMR reporting standards. The development of such standards alongside a centralised reporting system would provide baseline data to feedback directly into wastewater treatment policies for the Antarctic Treaty Area to help preserve this relatively pristine environment. Video Abstract.

Reduced immune responsiveness contributes to winter energy conservation in an Arctic bird

Animals in seasonal environments must prudently manage energy expenditure to survive the winter. This may be achieved through reductions in the allocation of energy for various purposes (e.g. thermoregulation, locomotion, etc.). We studied whether such trade-offs also include suppression of the innate immune response, by subjecting captive male Svalbard ptarmigan (Lagopus muta hyperborea) to bacterial lipopolysaccharide (LPS) during exposure to either mild temperature (0°C) or cold snaps (acute exposure to −20°C), in constant winter darkness when birds were in energy-conserving mode, and in constant daylight in spring. The innate immune response was mostly unaffected by temperature. However, energy expenditure was below baseline when birds were immune challenged in winter, but significantly above baseline in spring. This suggests that the energetic component of the innate immune response was reduced in winter, possibly contributing to energy conservation. Immunological parameters decreased (agglutination, lysis, bacteriostatic capacity) or did not change (haptoglobin/PIT54) after the challenge, and behavioural modifications (anorexia, mass loss) were lengthy (9 days). While we did not study the mechanisms explaining these weak, or slow, responses, it is tempting to speculate they may reflect the consequences of having evolved in an environment where pathogen transmission rate is presumably low for most of the year. This is an important consideration if climate change and increased exploitation of the Arctic would alter pathogen communities at a pace outwith counter-adaption in wildlife.

Evidence of the role of free-living birds as disseminators of Salmonella spp

ABSTRACT This study aimed to review aspects of Salmonella spp. in free-living birds and their potential as disseminators for domestic animals, man, and the environment. Isolation of Salmonella spp. have been reported in several species of wild birds from Passeridae and Fringillidae, among other avian families, captured in countries of North America and Europe, where Salmonella ser. Typhimurium is the most frequently reported serotype. The presence of pathogens, including Salmonella, may be influenced by several factors, such as diet, environment, exposure to antibiotics, infection by pathogenic organisms and migration patterns. Researches with wild birds that live in urbanized environment are important, considering that birds may participate in the transmission of zoonotic pathogens, which are more prevalent in cities due to the human activity. Based on the information collected, this article concludes that wild birds are still important disseminators of pathogens in several geographic regions and may affect man, domestic animals, and other birds.

Do humans spread zoonotic enteric bacteria in Antarctica?

Reports of enteric bacteria in Antarctic wildlife have suggested its spread from people to seabirds and seals, but evidence is scarce and fragmentary. We investigated the occurrence of zoonotic enteric bacteria in seabirds across the Antarctic and subantarctic region; for comparison purposes, in addition to seabirds, poultry in a subantarctic island was also sampled. Three findings suggest reverse zoonosis from humans to seabirds: the detection of a zoonotic Salmonella serovar (ser. Enteritidis) and Campylobacter species (e.g. C. jejuni), typical of human infections; the resistance of C. lari isolates to ciprofloxacin and enrofloxacin, antibiotics commonly used in human and veterinary medicine; and most importantly, the presence of C. jejuni genotypes mostly found in humans and domestic animals but rarely or never found in wild birds so far. We also show further spread of zoonotic agents among Antarctic wildlife is facilitated by substantial connectivity among populations of opportunistic seabirds, notably skuas (Stercorarius). Our results highlight the need for even stricter biosecurity measures to limit human impacts in Antarctica.

Characterization of Campylobacter spp. isolated from wild birds in the Antarctic and Sub-Antarctic

A lack of knowledge of naturally occurring pathogens is limiting our ability to use the Antarctic to study the impact human-mediated introduction of infectious microorganisms have on this relatively uncontaminated environment. As no large-scale coordinated effort to remedy this lack of knowledge has taken place, we rely on smaller targeted efforts to both study present microorganisms and monitor the environment for introductions. In one such effort, we isolated Campylobacter species from fecal samples collected from wild birds in the Antarctic Peninsula and the sub-Antarctic island of South Georgia. Indeed, in South Georgia, we found Campylobacter lari and the closely related Campylobacter peloridis, but also distantly related human-associated multilocus sequence types of Campylobacter jejuni. In contrast, in the Antarctic Peninsula, we found C. lari and two closely related species, Campylobacter subantarcticus and Campylobacter volucris, but no signs of human introduction. In fact, our finding of human-associated sequence types of C. jejuni in South Georgia, but not in the Antarctic Peninsula, suggests that efforts to limit the spread of infectious microorganisms to the Antarctic have so far been successful in preventing the introduction of C. jejuni. However, we do not know how it came to South Georgia and whether the same mode of introduction could spread it from there to the Antarctic Peninsula.

Occurrence of pharmaceutical, recreational and psychotropic drug residues in surface water on the northern Antarctic Peninsula region

Human presence in the Antarctic is increasing due to research activities and the rise in tourism. These activities contribute a number of potentially hazardous substances. The aim of this study is to conduct the first characterisation of the pharmaceuticals and recreational drugs present in the northern Antarctic Peninsula region, and to assess the potential environmental risk they pose to the environment. The study consisted of a single sampling of ten water samples from different sources, including streams, ponds, glacier drains, and a wastewater discharge into the sea. Twenty-five selected pharmaceuticals and 21 recreational drugs were analysed. The highest concentrations were found for the analgesics acetaminophen (48.74 μg L^-1), diclofenac (15.09 μg L^-1) and ibuprofen (10.05 μg L^-1), and for the stimulant caffeine (71.33 μg L^-1). All these substances were detected in waters that were discharged directly into the ocean without any prior purification processes. The hazard quotient (HQ) values for ibuprofen, diclofenac and acetaminophen were far in excess of 10 at several sampling points. The concentrations of each substance measured and used as measured environmental concentration values for the HQ calculations are based on a one-time sampling. The Toxic Unit values indicate that analgesics and anti-inflammatories are the therapeutic group responsible for the highest toxic burden. This study is the first to analyse a wide range of substances and to determine the presence of pharmaceuticals and psychotropic drugs in the Antarctic Peninsula region. We believe it can serve as a starting point to focus attention on the need for continued environmental monitoring of these substances in the water cycle, especially in protected regions such as the Antarctic. This will determine whether pharmaceuticals and recreational drugs are hazardous to the environment and, if so, can be used as the basis for risk-assessment studies to prioritise the exposure to risk.

Diverse and highly recombinant anelloviruses associated with Weddell seals in Antarctica

The viruses circulating among Antarctic wildlife remain largely unknown. In an effort to identify viruses associated with Weddell seals (Leptonychotes weddellii) inhabiting the Ross Sea, vaginal and nasal swabs, and faecal samples were collected between November 2014 and February 2015. In addition, a Weddell seal kidney and South Polar skua (Stercorarius maccormicki) faeces were opportunistically sampled. Using high throughput sequencing, we identified and recovered 152 anellovirus genomes that share 63–70% genome-wide identities with other pinniped anelloviruses. Genome-wide pairwise comparisons coupled with phylogenetic analysis revealed two novel anellovirus species, tentatively named torque teno Leptonychotes weddellii virus (TTLwV) -1 and -2. TTLwV-1 (n = 133, genomes encompassing 40 genotypes) is highly recombinant, whereas TTLwV-2 (n = 19, genomes encompassing three genotypes) is relatively less recombinant. This study documents ubiquitous TTLwVs among Weddell seals in Antarctica with frequent co-infection by multiple genotypes, however, the role these anelloviruses play in seal health remains unknown.

Isolation of Campylobacter spp. from Three Species of Antarctic Penguins in Different Geographic Locations

The presence of Campylobacter species was studied in three Antarctic penguin species, Adélie (Pygoscelis adeliae), chinstrap (Pygoscelis antarctica) and gentoo (Pygoscelis papua). A total of 390 penguins were captured in 12 different rookeries along the Antarctic Peninsula with differences in the amount of human visitation: six colonies were highly visited [Stranger Point, King George Island (P. papua and P. adeliae); Hannah Point, Livingston Island (P. papua and P. antarctica); Deception Island (P. antarctica); and Paradise Bay, Antarctic Peninsula (P. papua)], and six colonies were rarely visited [Devil's Point, Byers Peninsula, Livingston Island (P. papua); Cierva Cove, Antarctic Peninsula (P. papua); Rongé Island (P. papua and P. antarctica); Yalour Island (P. adeliae); and Avian Island (P. adeliae)]. A total of 23 strains were isolated from penguins from nine different rookeries. Campylobacter lari subsp. lari was isolated from eight samples (seven from P. papua and one from P. adeliae); C. lari subsp. concheus from 13 (ten from P. adeliae and three from P. antarctica) and C. volucris from two samples (both from P. papua). We did not find any significant differences in the prevalence of Campylobacter spp. between the populations in highly and rarely visited areas. This is the first report of C. lari subsp. concheus and C. volucris isolation from penguins in the Antarctic region.

Anthropogenic antibiotic resistance genes mobilization to the polar regions

Anthropogenic influences in the southern polar region have been rare, but lately microorganisms associated with humans have reached Antarctica, possibly from military bases, fishing boats, scientific expeditions, and/or ship-borne tourism. Studies of seawater in areas of human intervention and proximal to fresh penguin feces revealed the presence of Escherichia coli strains least resistant to antibiotics in penguins, whereas E. coli from seawater elsewhere showed resistance to one or more of the following antibiotics: ampicillin, tetracycline, streptomycin, and trim-sulfa. In seawater samples, bacteria were found carrying extended-spectrum β-lactamase (ESBL)-type CTX-M genes in which multilocus sequencing typing (MLST) showed different sequence types (STs), previously reported in humans. In the Arctic, on the contrary, people have been present for a long time, and the presence of antibiotic resistance genes (ARGs) appears to be much more wide-spread than was previously reported. Studies of E coli from Arctic birds (Bering Strait) revealed reduced susceptibility to antibiotics, but one globally spreading clone of E. coli genotype O25b-ST131, carrying genes of ESBL-type CTX-M, was identified. In the few years between sample collections in the same area, differences in resistance pattern were observed, with E. coli from birds showing resistance to a maximum of five different antibiotics. Presence of resistance-type ESBLs (TEM, SHV, and CTX-M) in E. coli and Klebsiella pneumoniae was also confirmed by specified PCR methods. MLST revealed that those bacteria carried STs that connect them to previously described strains in humans. In conclusion, bacteria previously related to humans could be found in relatively pristine environments, and presently human-associated, antibiotic-resistant bacteria have reached a high global level of distribution that they are now found even in the polar regions.

Detection of Salmonella enterica in Magellanic penguins (Spheniscus magellanicus) of Chilean Patagonia: evidences of inter-species transmission

Patagonia in southern South America is among the few world regions where direct human impact is still limited but progressively increasing, mainly represented by tourism, farming, fishing and mining activities. The sanitary condition of Patagonian wildlife is unknown, in spite of being critical for the assessment of anthropogenic effects there. The aim of this study was the characterization of Salmonella enterica strains isolated from wild colonies of Magellanic penguins (Spheniscus magellanicus) located in Magdalena Island and Otway Sound, in Chilean Patagonia. Eight isolates of Salmonella were found, belonging to Agona and Enteritidis serotypes, with an infection rate of 0·38%. Resistance to ampicillin, cefotaxime, ceftiofur and tetracycline antimicrobials were detected, and some of these strains showed genotypic similarity with Salmonella strains isolated from humans and gulls, suggesting inter-species transmission cycles and strengthening the role of penguins as sanitary sentinels in the Patagonian ecosystem.

Human migration is important in the international spread of exotic Salmonella serovars in animal and human populations

The exposure of indigenous humans and native fauna in Australia and the Wallacea zoogeographical region of Indonesia to exotic Salmonella serovars commenced during the colonial period and has accelerated with urbanization and international travel. In this study, the distribution and prevalence of exotic Salmonella serovars are mapped to assess the extent to which introduced infections are invading native wildlife in areas of high natural biodiversity under threat from expanding human activity. The major exotic Salmonella serovars, Bovismorbificans, Derby, Javiana, Newport, Panama, Saintpaul and Typhimurium, isolated from wildlife on populated coastal islands in southern temperate areas of Western Australia, were mostly absent from reptiles and native mammals in less populated tropical areas of the state. They were also not recorded on the uninhabited Mitchell Plateau or islands of the Bonaparte Archipelago, adjacent to south-eastern Indonesia. Exotic serovars were, however, isolated in wildlife on 14/17 islands sampled in the Wallacea region of Indonesia and several islands off the west coast of Perth. Increases in international tourism, involving islands such as Bali, have resulted in the isolation of a high proportion of exotic serovar infections suggesting that densely populated island resorts in the Asian region are acting as staging posts for the interchange of Salmonella infections between tropical and temperate regions.

Interspecific variations in the gastrointestinal microbiota in penguins

Despite the enormous amount of data available on the importance of the gastrointestinal (GI) microbiota in vertebrate (especially mammals), information on the GI microbiota of seabirds remains incomplete. As with many seabirds, penguins have a unique digestive physiology that enables them to store large reserves of adipose tissue, protein, and lipids. This study used quantitative real-time polymerase chain reaction (qPCR) and 16S rRNA gene pyrosequencing to characterize the interspecific variations of the GI microbiota of four penguin species: the king, gentoo, macaroni, and little penguin. The qPCR results indicated that there were significant differences in the abundance of the major phyla Firmicutes, Bacteroides, Actinobacteria, and Proteobacteria. A total of 132,340, 18,336, 6324, and 4826 near full-length 16S rRNA gene sequences were amplified from fecal samples collected from king, gentoo, macaroni, and little penguins, respectively. A total of 13 phyla were identified with Firmicutes, Bacteroidetes, Proteobacteria, and Fusobacteria dominating the composition; however, there were major differences in the relative abundance of the phyla. In addition, this study documented the presence of known human pathogens, such as Campylobacter, Helicobacter, Prevotella, Veillonella, Erysipelotrichaceae, Neisseria, and Mycoplasma. However, their role in disease in penguins remains unknown. To our knowledge, this is the first study to provide an in-depth investigation of the GI microbiota of penguins.

Sewage Disposal and Wildlife Health in Antarctica

Sewage and its microbiology, treatment and disposal are important to the topic of Antarctic wildlife health because disposal of untreated sewage effluent into the Antarctic marine environment is both allowed and commonplace. Human sewage contains enteric bacteria as normal flora, and has the potential to contain parasites, bacteria and viruses which may prove pathogenic to Antarctic wildlife. Treatment can reduce levels of micro-organisms in sewage effluent, but is not a requirement of the Environmental Protocol to the Antarctic Treaty (the Madrid Protocol). In contrast, the deliberate release of non-native organisms for any other reason is prohibited. Hence, disposal of sewage effluent to the marine environment is the only activity routinely undertaken in Antarctica knowing that it will likely result in the release of large numbers of potentially non-native species.

When the Madrid Protocol was negotiated, the decision to allow release of untreated sewage effluent was considered the only pragmatic option, as a prohibition would have been costly, and may not have been achievable by many Antarctic operators. In addition, at that time the potential for transmission of pathogens to wildlife from sewage was not emphasised as a significant potential risk. Since then, the transmission of disease-causing agents between species is more widely recognised and it is now timely to consider the risks of continued discharge of sewage effluent in Antarctica and whether there are practical alternatives.

Health of Antarctic birds: a review of their parasites, pathogens and diseases

Antarctic birds are not beyond the effects of parasites or pathogens. However, potential ecological consequences of wide-spread infections for bird populations in Antarctica have received little attention. In this paper, we review the information published about disease and parasites, and their effects on Antarctic birds. The information on host species, parasites and pathogens, and geographic regions is incomplete and data on ecological effects on the populations, including how birds respond to pathogens and parasites, are almost inexistent. We conclude that more research is needed to establish general patterns of spatial and temporal variation in pathogens and parasites, and to determine how such patterns could influence hosts. This information is crucial to limit the spread of outbreaks and may aid in the decision-making process should they occur.

Salmonella infections in Antarctic fauna and island populations of wildlife exposed to human activities in coastal areas of Australia

Salmonella infections in Antarctic wildlife were first reported in 1970 and in a search for evidence linking isolations with exposure to human activities, a comparison was made of serovars reported from marine fauna in the Antarctic region from 1982-2004 with those from marine mammals in the Northern hemisphere. This revealed that 10 (83%) Salmonella enterica serovars isolated from Antarctic penguins and seals were classifiable in high-frequency (HF) quotients for serovars prevalent in humans and domesticated animals. In Australia, 16 (90%) HF serovars were isolated from marine birds and mammals compared with 12 (86%) HF serovars reported from marine mammals in the Northern hemisphere. In Western Australia, HF serovars from marine species were also recorded in humans, livestock, mussels, effluents and island populations of wildlife in urban coastal areas. Low-frequency S. enterica serovars were rarely detected in humans and not detected in seagulls or marine species. The isolation of S. Enteritidis phage type 4 (PT4), PT8 and PT23 strains from Adélie penguins and a diversity of HF serovars reported from marine fauna in the Antarctic region and coastal areas of Australia, signal the possibility of transient serovars and endemic Salmonella strains recycling back to humans from southern latitudes in marine foodstuffs and feed ingredients.

Biological invasions in the Antarctic: extent, impacts and implications

Alien microbes, fungi, plants and animals occur on most of the sub-Antarctic islands and some parts of the Antarctic continent. These have arrived over approximately the last two centuries, coincident with human activity in the region. Introduction routes have varied, but are largely associated with movement of people and cargo in connection with industrial, national scientific program and tourist operations. The large majority of aliens are European in origin. They have both direct and indirect impacts on the functioning of species-poor Antarctic ecosystems, in particular including substantial loss of local biodiversity and changes to ecosystem processes. With rapid climate change occurring in some parts of Antarctica, elevated numbers of introductions and enhanced success of colonization by aliens are likely, with consequent increases in impacts on ecosystems. Mitigation measures that will substantially reduce the risk of introductions to Antarctica and the sub-Antarctic must focus on reducing propagule loads on humans, and their food, cargo, and transport vessels.

Characterization of a pore-forming cytotoxin expressed by Salmonella enterica serovars typhi and paratyphi A

Cytolysin A (ClyA) is a pore-forming cytotoxic protein encoded by the clyA gene that has been characterized so far only in Escherichia coli. Using DNA sequence analysis and PCR, we established that clyA is conserved in the human-specific typhoid Salmonella enterica serovars Typhi and Paratyphi A and that the entire clyA gene locus is absent in many other S. enterica serovars, including Typhimurium. The gene products, designated ClyA(STy) and ClyA(SPa), show >/=90% amino acid identity to E. coli cytolysin A, ClyA(EC), and they are immunogenically related. The Salmonella proteins showed a pore-forming activity and are hence functional homologues to ClyA(EC). The chromosomal clyA(STy) gene locus was expressed at detectable levels in the serovar Typhi strains S2369/96 and S1112/97. Furthermore, in the serovar Typhi vaccine strain Ty21a, expression of clyA(STy) reached phenotypic levels, as detected on blood agar plates. The hemolytic phenotype was abolished by the introduction of an in-frame deletion in the clyA(STy) chromosomal locus of Ty21a. Transcomplementation of the mutant with a cloned clyA(STy) gene restored the hemolytic phenotype. To our knowledge, Ty21a is the first reported phenotypically hemolytic Salmonella strain in which the genetic determinant has been identified.