Antibiotic and heavy metal resistance of Aeromonas hydrophila and Edwardsiella tarda isolated from red hybrid tilapia (Oreochromis spp.) coinfected with motile aeromonas septicemia and edwardsiellosis

Abstract

Aim:The aim of this study is to identify antibiogram and heavy metal resistance pattern of Aeromonas hydrophila and Edwardsiella tarda isolated from red hybrid tilapia (Oreochromis spp.) coinfected with motile aeromonas septicemia and edwardsiellosis in four commercial fish farms.Materials and Methods:A. hydrophila and E. tarda were isolated using glutamate starch phenol red and xylose lysine deoxycholate (Merck, Germany) as a selective medium, respectively. All the suspected bacterial colonies were identified using conventional biochemical tests and commercial identification kit (BBL Crystal, USA). Susceptibility testing of present bacterial isolates to 16 types of antibiotics (nalidixic acid, oxolinic acid, compound sulfonamides, doxycycline, tetracycline, novobiocin, chloramphenicol, kanamycin, sulfamethoxazole, flumequine, erythromycin, ampicillin, spiramycin, oxytetracycline, amoxicillin, and fosfomycin) and four types of heavy metals (mercury, chromium, copper, and zinc) were carried out using disk diffusion and two-fold agar dilution method, respectively.Results:Three hundred isolates of A. hydrophila and E. tarda were successfully identified by biochemical tests. Antibiotic susceptibility testing results showed that 42.2% of the bacterial isolates were sensitive to compound sulfonamides, sulfamethoxazole, flumequine, oxytetracycline, doxycycline, and oxolinic acid. On the other hand, 41.6% of these isolates were resistant to novobiocin, ampicillin, spiramycin, and chloramphenicol, which resulted for multiple antibiotic resistance index values 0.416. Among tested heavy metals, bacterial isolates exhibited resistant pattern of Zn2+ > Cr6+ > Cu2+ > Hg2+.Conclusion:Results from this study indicated that A. hydrophila and E. tarda isolated from coinfected farmed red hybrid tilapia were multi-resistant to antibiotics and heavy metals. These resistant profiles could be useful information to fish farmers to avoid unnecessary use of antimicrobial products in the health management of farmed red hybrid tilapia.

Occurrence of multiple antibiotic resistance and genotypic characterization inEdwardsiella tardaisolated from cage‐cultured hybrid red tilapia (Oreochromissp.) in the Ping River, Northern Thailand

“…Numerous researchers have also reported that E. tarda isolates in fish in various countries are highly resistant to ampicillin and amoxicillin (Lee & Wendy, ; Ogbonne, Ukazu, & Egbe, ; Shetty et al, ; Wimalasena et al, ). Previous studies have demonstrated that E. tarda is sensitive to oxytetracycline and sulpha‐trimethoprim (Castro, Toranzo, Barja, Nunez, & Magarinos, ; Shetty et al, ; Stock & Wiedemann, ), while the appearance in red tilapia, olive flounder, red sea bream and eels of E. tarda which is resistant to oxytetracycline and sulpha‐trimethoprim has been frequently reported (Lee & Wendy, ; Lo et al, ; Wimalasena et al, ). These observations suggest that there is a general trend of increasing resistance to oxytetracycline and sulpha‐trimethoprim of E. tarda isolates in aquaculture.…”

“…The occurrence of multiple antibiotic‐resistant E. tarda in red hybrid tilapia ( Oreochromis spp.) in Malaysia has been reported (Lee & Wendy, ). The emergence of multidrug‐resistant isolates makes the treatment of edwardsiellosis by antibiotics a challenge.…”

The zebrafish as a model for gastrointestinal tract–microbe interactions

“…Major aquaculture and opportunistic human pathogens include members of the Edwardsiella and Aeromonas genera (Lee & Wendy, 2017). The consumption of food contaminated with these bacteria can cause gastroenteritis in healthy persons, and more severe diarrheal disease in elderly and immunocompromised individuals (Clarridge, Musher, Fainstein, & Wallace, 1980;Gracey, Burke, & Robinson, 1982).…”

The nature and consequences of co‐infections in tilapia: A review

“…Similarly, a case of concurrent infection involving A. hydrophila and E. tarda was reported from farmed red hybrid tilapia (Lee & Wendy, 2017). The co‐infected fish showed loss of pigmentation, exophthalmia, corneal opacity and abdominal dropsy with significant mortality.…”

“…Both bacteria were found to be resistant to several antibiotics, including novobiocin, ampicillin, spiramycin and chloramphenicol. However, they remained highly sensitive to sulphamethoxazole, flumequine, oxytetracycline, doxycycline and oxolinic acid (Lee & Wendy, 2017).…”