Isolation, identification and antibiogram profiling of bacteria isolated from water, seafood, and macroplastic samples from Baseco Beach, Manila Bay

Abstract

Background and Objective: Manila Bay plays an important role both in economics and ecology because it serves as the major economic center of the Philippines and as it harbors different habitats and biodiversity. Unfortunately, it is threatened by various pollutions including the unregulated discharge of wastewater from industrial, agricultural, and household sectors and improper disposal of trash such as macroplastics among others. All these contributes to the current state of Manila Bay. This study identified bacteria isolated from water, seafood and floating macroplastic samples from Baseco Beach, Manila Bay and determined their antibiogram profiles.

Methodology: Bacterial isolates were obtained from water, seafoods and macroplastic samples from Baseco Beach, Manila Bay using conventional culture techniques. Identification of the isolates was done using Vitek-2 Automated System and antibiogram profiling was done using Kirby-Bauer Disk Diffusion Susceptibility Test.

Results and Conclusions: A total of 30 bacterial isolates were obtained from different samples from water, seafood and macroplastic samples from Baseco Beach, Manila Bay. These isolates were identified and found to belong to 13 different bacterial species with Bacillus spp. comprising 33.33% of the isolates (10 out of 30), and Vibrio alginolyticus comprising 23.33% of the isolates (7 out of 30) and the other species comprise the remaining 43.34% (Pseudomonas spp., Vibrio fluvialis, Klebsiella pneumoniae, Shewanella alga, Sphingomonas paucimobilis, Staphylococcus haemolyticus, Chryseobacterium indologenes, Myroides sp. and Aeromonas salmonicida). Of these, six out of 30 isolates (20%) showed susceptibility to all six representative antibiotics used (Cefazolin 30μg, Gentamicin 10 μg, Chloramphenicol 30 μg, ampicillin 10 μg, Cefuroxime 30 μg, Ceftazidime 30 μg) while 7 isolates (23.33%) were resistant to only one class of antibiotic. Moreover, 17 out of 30 isolates (56.66%) were resistant to two or more classes of antibiotic while only one isolate (3.33%) was found to be resistant to gentamicin. All 30 isolates (100%) were susceptible to chloramphenicol.
Interestingly, three antibiotic resistant (AMR) bacteria were isolated from macroplastics namely
Pseudomonas oleovorans (S2), Vibrio alginolyticus (S5), and Pseudomonas alcaligenes (S29) which were all resistant to ampicillin and cefazolin. This is the first study in the Philippines to isolate AMR bacteria from macroplastics from Manila Bay. The presence of AMR bacteria in macroplastics shows that these materials can be a reservoir for its dynamics and distribution. Lastly, with the emergence of antimicrobial resistant bacteria, the elucidation of the antibiogram profile of bacteria is necessary to determine its implication sand threats to public health. This study served as a baseline study of presence of AMR bacteria in macroplastic samples from Manila Bay.