Testudines as sentinels for monitoring the dissemination of antibiotic resistance in marine environments: an integrative review

Dissemination of antibiotic resistance (AR) in marine environments is a global concern with a propensity to affect public health and many ecosystems worldwide. We evaluated the use of sea turtles as sentinel species for monitoring AR in marine environments. In this field, antibiotic resistant bacteria have been commonly identified by using standard culture and sensitivity tests, leading to an overrepresentation of specific, culturable bacterial classes in the available literature. AR was detected against all major antibiotic classes, but the highest cumulative global frequency of resistance in all represented geographical sites was against the beta-lactam class by a two-fold difference compared to all other antibiotics. Wastewater facilities and turtle rehabilitation centres were associated with higher incidences of multidrug-resistant bacteria (MDRB) accounting for an average of 58% and 49% of resistant isolates, respectively. Furthermore, a relatively similar prevalence of MDRB was seen in all studied locations. These data suggest that anthropogenically driven selection pressures for the development of AR in sea turtles and marine environments are relatively similar worldwide. There is a need, however, to establish direct demonstrable associations between AR in sea turtles in their respective marine environments with wastewater facilities and other anthropogenic activities worldwide

Cutaneous lesions in freshwater turtles (Emydura macquarii krefftii and Myuchelys latisternum) in a rainforest creek in North Queensland, Australia

Freshwater turtles inhabit most rivers and creeks on the east coast of Australia, but some species are only found in specific catchments, which makes them vulnerable to extinction. During annual fieldtrips to Alligator Creek, North Queensland, the resident population of Myuchelys latisternum and Emydura macquarii krefftii in a natural pond, just outside Bowling Green National Park, have been surveyed for a number of years and demographic data recorded against tagged turtles. Rounded, cutaneous lesions on individual animals were first noted in August 2016, three years after the first survey of the population. Turtles living in the upstream sections of the creek were not affected. An initial investigation into the cause of the lesions ruled out pollutants and although the bacterial communities appeared to be different on turtles with lesions, a causative agent was not identified. Attempts to isolate virus in culture was not successful and specific PCRs for ranavirus, papillomavirus, adenovirus and herpesvirus did not identify their presence. Blood biochemical parameters, body condition and activity levels were not significantly different between affected turtles and those without lesions. The turtles in this pond were monitored regularly over the following three years with 249 M. latisternum and 192 E. m. krefftii captured, tagged and released. The prevalence of the lesions fluctuated with season from 0 to 77 and 68% respectively, but did not vary significantly between species or sex in adults. There was a tendency for larger animals to be more likely to have lesions. The position of the lesions on the turtles was mostly on dorsal surfaces, distally on the legs and proximal on the tales of males, indicating that the initial lesion may have been associated with a behaviourally induced trauma. Recaptured animals (n = 43) during this period, provided records of lesion progression over time and while some healed up between capture events, others persisted for up to 24 months. Some turtles were repeatedly captured without lesions. Intra-species aggression associated with seasonal behaviours could potentially be the primary cause of skin trauma, followed by a secondary invasion of an unusual pathogen present in the environment

Using Green sea turtles (Chelonia mydas) as essential bio-indicators for monitoring antibiotic resistance in marine environments worldwide: a critical appraisal

The development and environmental transmission of antibiotic resistance (ABR) pathogens is of global public health concern. In marine environments, this problem is associated at least in part, with pollution due to anthropogenic activities such as discharging wastewater and industrial waste run-off. Herein we systematically reviewed and evaluated the incidence of ABR identified in Green sea turtles and their propensity to be used as bio-indicators for monitoring ABR in marine environments because of their highly migratory nature and reliance on sea vegetation. ABR was identified using standard culture and sensitivity tests; quantitatively represented as percentages of confirmed bacterial isolates. Studied sites to date are represented by clusters in the Arabian Sea and the Pacific and Atlantic oceans; frequencies of identified multidrug resistant bacteria (MDRB) were: 78 ± 16%, 42 ± 13% and 16% respectively. Antimicrobials of the beta-lactam class were associated with the highest cumulative frequency of resistance (103%) compared to quinonolones (31%) and aminoglycosides (30%) across all sites. This data seems to reflect concerted, global efforts to reserve and minimise the use of aminoglycosides and quinolones. These ABR patterns mirror trends in the use of antibiotics in anthropogenic activities generally. However, there is a need to establish direct associations between ABR in sea turtles with wastewater and other anthropogenic activities in marine environments worldwide