Pet turtles are well-known to harbor an array of bacterial pathogens which can cause zoonotic infections in humans as well as opportunistic infections in the turtles itself. Essential oils are the natural plant extracts which have been traditionally used for disease treatment. In the present study, the essential oil of lavender (EOL) was examined for its antibacterial activity against thirty-eight strains of turtle-borne pathogenic bacteria belonging to seven species; Aeromonas hydrophila, A. caviae, A. dhakensis, Citrobacter freundii, Proteus mirabilis, Salmonella enterica and Pseudomonas aeruginosa. Antibacterial activity of EOL was tested by means of disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests. In addition, the antimicrobial susceptibility pattern of 11 commonly used antimicrobials was examined and the multiple antibiotic resistance (MAR) index was calculated. The results revealed that EOL was active against all tested turtle-borne pathogenic bacteria except P. aeruginosa. The range of MIC and MBC values of EOL against isolates except P. aeruginosa were recorded as 0.5-1% (V/V) and 0.5-2% (V/V), respectively. The MBC/MIC ratio was detected as <4, revealing that the tested EOL was bactericidal. Besides, most of the isolates were resistant to different antimicrobials in antimicrobial disk diffusion test. MAR index values of the tested strains were ranging from 0.27 to 0.91. The outcomes indicate that EOL has a potential to be used as an antibacterial agent against pathogenic bacteria isolated from pet turtles.

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We evaluated 44 strains of Aeromonas spp. consisting of five species; A. hydrophila, A. veronii, A. caviae, A. enteropelogenes, and A. media isolated from frozen white‐leg shrimp marketed in Korea. All the isolates were positive in DNase, protease, gelatinase, and lipase tests whereas 29 isolates (66%) were positive for slime production. Ten virulence genes were detected by PCR in which the prevalence of act, alt, ast, aerA, lip, ahyB, ser, fla, gcat, and ascV were 50%, 77%, 72%, 82%, 84%, 93%, 80%, 64%, 84%, and 23%, respectively. As observed in antibiogram, 100% resistance was detected in ampicillin and clindamycin while nalidixic acid, tetracycline, cephalothin, erythromycin, and trimethoprim‐sulfamethoxazole were resisted by 95%, 89%, 86%, 68%, and 66% of the isolates, respectively. Multiple antibiotic resistance index was >0.20 in 42/44 (95%) of the isolates. Overall, our results indicated that these aeromonads are indicative of a serious public health risk due to their virulence potential and the multiple‐antimicrobial resistance.Practical applicationsSimilar to other seafood, shrimp have been identified as vehicles of Aeromonas spp. which are the etiological agents of many foodborne infections. The gyrB gene sequencing and phylogenetic analysis confirmed the occurrence of five species of Aeromonas in frozen white‐leg shrimp marketed in Korea. Putative virulence properties were examined by both phenotypic tests and PCR assays whereby majority of the isolates exhibited the virulence both phenotypically and genetically. Besides, the disc diffusion test was carried out to assess the antibiotic susceptibility of the isolates. Following the results, the MAR index was calculated for each strain thereby suggested their high risk owing to MAR indices higher than 0.20. With our results, frozen white‐leg shrimp associated Aeromonas spp., exhibiting potential virulence and antimicrobial resistance, can be considered as a potential public health risk. Moreover, it is noteworthy that freezing the shrimp may not reduce the incidence of pathogenic Aeromonas.

The usage of essential oils as antimicrobial agents is gaining attention. Besides, pet turtles were known to harbor a range of pathogenic bacteria while the turtle keeping is a growing trend worldwide.The current study examined the antimicrobial activity of lemon grass oil (LGO) against seven species of Gram negative bacteria namely; Aeromonas hydrophila, A. caviae, Citrobacter freundii, Salmonella enterica, Edwardsiella tarda, Pseudomonas aeruginosa, and Proteus mirabilis isolated from three popular species of pet turtles. Along with the results of disc diffusion, minimum inhibitory and minimum bactericidal concentration (MIC and MBC) tests, LGO was detected as effective against 6 species of bacteria excluding P. aeruginosa. MIC of LGO for the strains except P. aeruginosa ranged from 0.016 to 0.5% (V/V). The lowest MIC recorded in the E. tarda strain followed by A. hydrophilla, C. freundii, P. mirabilis, and S. enterica. Interestingly, all the bacterial species except E. tarda were showing high multiple antimicrobial resistance (MAR) index values ranging from 0.36 to 0.91 upon the 11 antibiotics tested although they were sensitive to LGO.

Antibacterial activity of cinnamon (Cinnamomum zeylanicum) essential oil (CEO) and cinnamaldehyde was tested against seven Gram negative and nine Gram positive fish pathogenic bacteria isolated from cultured olive flounder (Paralichthys olivaceus) in Korea. Disk diffusion assay, MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) tests were done. Cinnamon and cinnamaldehyde inhibited the growth of both Gram negative and Gram positive bacteria. Cinnamaldehyde showed lower MIC values than CEO which ranged from 0.001 to 0.015% (V/V). CEO (MBC/MIC 2-4) was bactericidal for all tested strains while cinnamaldehyde was bactericidal for all except 6 strains. For all fish pathogenic bacteria, the inhibition zone diameter (IZD) increased in proportion to the oil concentration and the maximum effect was found at 100% (V/V) concentration of CEO and cinnamaldehyde.  The antibiogram pattern indicated that all the bacterial strains excluding three strains of Streptococcus iniae(S186, S530 and S131) showed resistance to one or more antibiotics. Higher percentages of relative inhibition zone diameter (RIZD %) were exhibited at higher concentrations of CEO and cinnamaldehyde. Since antibacterial activities of CEO and cinnamaldehyde were considerably effective against fish pathogenic bacteria, these could be used as alternatives to treat bacterial infections in aquaculture.