Antibiotic Resistance of Gram-Negative Bacteria from Wild Captured Loggerhead Sea Turtles

Abstract

Sea turtles have been proposed as health indicators of marine habitats and carriers of antibiotic-resistant bacterial strains, for their longevity and migratory lifestyle. Up to now, a few studies evaluated the antibacterial resistant flora of Mediterranean loggerhead sea turtles (Caretta caretta) and most of them were carried out on stranded or recovered animals. In this study, the isolation and the antibiotic resistance profile of 90 Gram negative bacteria from cloacal swabs of 33 Mediterranean wild captured loggerhead sea turtles are described. Among sea turtles found in their foraging sites, 23 were in good health and 10 needed recovery for different health problems (hereafter named weak). Isolated cloacal bacteria belonged mainly to Enterobacteriaceae (59%), Shewanellaceae (31%) and Vibrionaceae families (5%). Although slight differences in the bacterial composition, healthy and weak sea turtles shared antibiotic-resistant strains. In total, 74 strains were endowed with one or multi resistance (up to five different drugs) phenotypes, mainly towards ampicillin (~70%) or sulfamethoxazole/trimethoprim (more than 30%). Hence, our results confirmed the presence of antibiotic-resistant strains also in healthy marine animals and the role of the loggerhead sea turtles in spreading antibiotic-resistant bacteria.

Antibiotics and Environment

“…S. aureus is one of the bacterial species with a higher ability to acquire antibiotic resistance determinants and is usually associated with a multidrug-resistant profile. Antibiotic-resistant bacteria and antibiotic resistance genes were also described in marine environments, such as the Mediterranean Sea and its seacoast [8], and in wild marine animals, such as healthy sea turtles [9]. These studies confirmed that Gram-negative bacteria are most frequently found in samples deriving from the marine environment.…”

A New Water-Soluble Bactericidal Agent for the Treatment of Infections Caused by Gram-Positive and Gram-Negative Bacterial Strains

“…Similarly, several new agents for the treatment of methicillin-resistant S. aureus (MRSA) are currently undergoing clinical trials, although these data in real-life terms are limited and require further investigations [ 21 ]. Moreover, the increase in antibiotic-resistant phenotypes and antibiotic resistance genes in different environments [ 22 ] and widely different organisms [ 23 ] requires urgent identification and development, at an industrial level, of new antimicrobial solutions. In this context, highly desirable new anti-pseudomonal and -staphylococcal antimicrobials should not drive superinfection [ 20 ] and be preferably available as oral formulations to allow step-down therapy in the treatment of both Gram-negative and -positive infections [ 24 ].…”

Expression of a Shiga-Like Toxin during Plastic Colonization by Two Multidrug-Resistant Bacteria, Aeromonas hydrophila RIT668 and Citrobacter freundii RIT669, Isolated from Endangered Turtles (Clemmys guttata)

“…Both A. hydrophila and C. freundii are documented pathogens found among both freshwater and marine chelonians, and include antibiotic-resistant forms [ 85 , 86 , 87 ]. The study of antibiotic-resistant bacteria in marine turtles may also be used as a bio-indicator of exposure to effluents and other sources of environmental contamination [ 88 , 89 ]. Thus, turtles are a “sentinel species” for ecosystem health [ 90 , 91 ].…”