International Journal of Aquaculture, 2026, Vol.16, No.3, 184-195 http://www.aquapublisher.com/index.php/ija 189 Table 4 Colony characteristics of isolates from gill, liver and intestine Weeks Isolate code Colony shape Elevation Edge Surface Pigmentation Opacity 0 FGctr Short rod Raised Regular Dull Pink Opaque FGTii Short rod Raised Entire Smooth Pink Opaque FITv Short rod Raised Regular Smooth Pink Opaque Fiiv Short rod Raised Regular Smooth Pink Opaque FLTiii Short rod Raised Irregular Rough Pink Opaque 4 GGTii Short rod Raised Entire Smooth Pink Opaque GGTiii Short rod Raised Regular Smooth Pink Opaque GGTv Short rod Raised Regular Smooth Pink Opaque GGTiv Short rod Raised Entire Smooth Pink Opaque GIctr Short rod Raised Regular Smooth Pink Opaque GITiv Short rod Raised Regular Dull Pink Opaque GITv Short rod Raised Regular Dull Pink Opaque GLctr Short rod Raised Regular Smooth Pink Opaque GLTii Short rod Raised Irregular Rough Pink Opaque GLTv Short rod Raised Regular Smooth Pink Opaque 8 HGTii Short rod Raised Regular Smooth Pink Opaque HGTv Short rod Raised Entire Smooth Pink Opaque HGTvi Short rod Raised Irregular Rough Pink Opaque HITiii Short rod Raised Regular Smooth Pink Opaque HITiv Short rod Raised Regular Smooth Pink Opaque HLctr Short rod Raised Entire Smooth Pink Opaque HLctr Short rod Raised Regular Dull Pink Opaque HLTii Short rod Raised Regular Smooth Pink Opaque HLTiii Short rod Raised Regular Dull Pink Opaque HLTvi Short rod Raised Regular Smooth Pink Opaque FG, fish gills at 0 weeks; FI, fish intestine at 0 weeks; FL, fish liver at 0 weeks; GG, fish gill at 4 weeks; GI, fish intestine at 4 weeks; GL, fish liver at 4 weeks; HG, fish gill at 8 weeks; HI, fish intestine at 8 weeks; HL, fish liver at 8 weeks; Ctr, experimental pond 1; Tii, experimental pond 2; Tiii, experimental pond 3; Tiv, experimental pond 4; Tv, experimental pond 5; Tvi, experimental pond 6 3.5 Antibiotic sensitivity test The antibiotic sensitivity test for presumptive Plesiomonas shigelloides was interpreted using the recommended guidelines by the Clinical Laboratory Standard Institute (CLSI, 2020) and is shown in table 5. Presumptive Plesiomonas shigelloides that were observed showed 100% resistance to cefotaxime, and cefuroxime, which belongs to the antibiotic class of cephems, followed by meropenem 87.5%, which belong to the antibiotic class of Carbapenems, Ceftazidime 77.5%, which belong to the antibiotic class of cephems, Vancomycin 70% which belong to the antibiotic class of glycopeptides tetracycline 40% which belong to the antibiotic class of tetracycline, ceftriaxone 37.5% which belong to the antibiotic class of cephems, chloramphenicol 20% which belong to the antibiotic class of phenicols, ciprofloxacin 20% which belong to a class of fluoroquinolones, cotrimoxazole 17.5% which belong to a class of sulfonamides, gentamicin and amikacin 0% which belong to a class of aminoglycosides (Table 7). 3.6 Multiple antibiotic resistance phenotypes of Plesiomonas shigelloides All presumptive P. shigelloides obtained from this study exhibited resistance to at least one antibiotic. Meanwhile, most of the isolates (85%) showed resistance to three (3) or more classes of antibiotics. Resistant to four (4) classes of antibiotics had the highest frequency of occurrence. Out of the seventeen isolates resisting the effect of four (4) classes of antibiotics, resistance to Tetracycline, Cephalosporins, Carbapenem and Glycopeptides (76.5%) was seen to be the highest compared to other phenotypes (Table 8).
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