Escherichia coli infection in ducks in the Mekong Delta: Bacterial isolation, serogroup distribution and antibiotic resistance

Abstract

An investigation on duck Escherichia coli infection was carried out by examination of 241 suspicious colibacillosis outbreaks from 5 city and provinces in the Mekong delta. The study procedure involves several steps,including bacterial isolation and identification, O sero-group typing and antibiotic resistant determination. The results showed that 990 from 994 ducks were confirmed to be infected by E. coli. E. coli bacteria were found from feces in almost diseased ducks (99.0%) and many organ samples, the highest rate of positive isolates was reported from livers (78.3%), followed by lungs (71.8%), spleens (67.4%), and the lowest one was in bone marrows (58.9%). The typing of 300 E. coli isolates with 10 important groups of mono O antisera revealed that 265 isolates were identified and belonged to 10 O sero-groups. The most commonly isolated O group was O2 (16.7%), followed by O78 (15.0%), O81 (9.7%), O35 (9.3%), O1 (8.0%), O36 (7.0%), O111 (7.7%), O92 (5.7%), O18 (5.3%) and the lowest one was O93 (4.0%). A total of 659 E. coli isolates were tested for their sensitivity to commonly used antibiotics, these APEC isolates demonstrated moderate to high resistances (20.2 % to 67.4 %) to 7/15 antibiotics tested, and very little amikacin and fosfomycin resistances (3.0 and 6.4%). It is imperative that susceptibility tests should be carried out on infecting pathogen prior to treatment of ducks colibacillosis in field in order to avoid treatment failure and reduce selective pressure that could result in spreading avian pathogenic E. coli in the environment.Keywords: antibiotic, duck, E. coli, resistance, sero-group