Obusan, M. C. | bioRxiv Science

bioRxiv2024

Resistance profiles and genes of Enterobacteriaceae from cetaceans stranded in Philippine waters from 2018-2019 provide clues on the extent of antimicrobial resistance in the marine environment

With the premise that cetaceans are sentinels for understanding the extent of antimicrobial resistance in the marine environment, we determined the phenotypic and genotypic antibiotic resistance profiles of the Enterobacteriaceae isolated from cetaceans (representing twelve cetacean species) that stranded in Philippine waters from 2018-2019. The phenotypic identifications and antibiotic susceptibility profiles of the isolates were determined through VITEK 2 system while their genotypic identifications were confirmed through 16S rRNA gene sequencing. Targeted antibiotics for profiling phenotypic resistance include penicillins, cephalosporins, carbapenems, quinolones, polymyxins and folate pathway inhibitors while detected antibiotic resistance genes (ARGs) for evaluating genotypic resistance include: (1) ampicillins (blaAmpC); (2) cephalosporins (blaAmpC blaTEM, blaSHV, and blaCTX-M); (4) carbapenem (blaKPC); (4) polymyxins (mcr-1) and (5) sulphonamides (sul1, and sul2). Percent resistances (% R), percent susceptibilities (% S) and multiple antibiotic resistance (MAR) index values were computed. Eighty-six Enterobacteriaceae were isolated from the exhaled breath condensate and swab samples of 19 stranded cetaceans. These isolates were confirmed to belong to the following genera: Escherichia (39.53%), Enterobacter (26.74%), Klebsiella (24.41%), Citrobacter (5.81%), Morganella (1.16%), Pantoea (1.16%) and Providencia (1.16%). Overall, 35/86 (40.70%) of the isolates exhibited acquired resistances against cephalosporins (i.e., cefuroxime, 26/86 or 30.23%), polymyxins (i.e., colistin, 6/86 or 6.97%), folate-pathway inhibitors (i.e., trimethoprim-sulfamethoxazole,5/86 or 5.82%), ampicillin (3/86 or 3.49%), and cefoxitin (2/86 or 2.32%), while the lowest resistance (1.16% of isolates) were resistant against amoxicillin-clavulanic acid, piperacillin and imipenem. Moreover, 40.70% of the isolates were characterized as multidrug-resistant (2.33%) and extensively drug-resistant (38.37%) while 5/86 (5.81%) of the isolates had MAR indices greater than 0.2. Six out of seven (85.71%) of the targeted ARGs responsible for the resistance types for ampicillins, cephalosporins, polymyxins and sulphonamides (i.e., blaAmpC, blaSHV blaTEM, mcr-1, sul1 and sul2, respectively) were detected in 48.57% of isolates. Antibiotic susceptibility testing revealed that a considerable portion of the isolates exhibited acquired resistance to selected antibiotics and were categorized as multidrug-resistant (MDR) or extremely drug-resistant (XDR). As for genotypic resistance, six out of seven target antibiotic resistance genes (ARGs) responsible for resistance to ampicillins, cephalosporins, polymyxins, and sulfonamides were detected in nearly half of the isolates with acquired resistance. Considering the habitat ranges of the source animals, this indicates the extent of reach of antibiotics and/or ARGs in the marine environment, and pelagic migratory cetaceans may play an important role in their dissemination.

microbiology↗

bioRxiv2020

Bacteriological and histopathological findings in cetaceansthat stranded in the Philippines from 2017 to 2018

The relatively high frequency of marine mammal stranding events in the Philippines provide many research opportunities. A select set of stranders (n=21) from 2017 to 2018 were sampled for bacteriology and histopathology. Pertinent tissues and bacteria were collected from eight species (i.e. Feresa attenuata, Kogia breviceps, Globicephala macrorhynchus, Grampus griseus, Lagenodelphis hosei, Peponocephala electra, Stenella attenuata and Stenella longirostris) and were subjected to histopathological examination and antibiotic resistance screening, respectively. Lesions that were observed in tissues of 19 cetaceans include congestion, hemorrhage, edema, hemosiderosis, glomerulopathy, Zenkers necrosis, atrophy, atelectasis, and parasitic cysts. These lesions may be associated with factors possibly contributing to the death, debility, and stress of the animals during their strandings. On the other hand, the resistance profiles of 24 bacteria (belonging to genera Escherichia, Enterobacter, Klebsiella, Proteus, and Shigella) that were isolated from four cetaceans were determined using 18 antibiotics. All 24 isolates were resistant to at least one antibiotic class, and 79.17% were classified as multiple antibiotic resistant (MAR). The MAR index values of isolates ranged from 0.06 to 0.39 with all the isolates resistant to erythromycin (100%; n=24) and susceptible to imipenem, doripenem, ciprofloxacin, chloramphenicol, and gentamicin (100%; n=24). The resistance profiles of these bacteria can be used as basis for selecting antibiotics needed in the medical management of stranded cetaceans that need to be rehabilitated. Overall, the histopathological and bacteriological findings of the study demonstrate the challenges faced by cetacean species in the wild, such as but not limited to, biological pollution through land-sea movement of effluents, fisheries interactions, and anthropogenic activities.

zoology↗