Diagnosis of Enterococcus hirae infection in association with piglet diarrhea

Abstract

Various viral and bacterial pathogens interact with environmental factors to cause diarrhea in piglets. Enterococcus spp. are Gram-positive anaerobic bacteria that are commonly found in the gastrointestinal tract of several animal species, including pigs. Enterococcus spp. have been reported to infect several animal species as a pathogen. However, gastrointestinal infection by Enterococcus hirae is rare in pigs; only a few cases have been reported worldwide. Four piglets with diarrhea were examined in the diagnostic laboratory of Optipharm Inc. (Cheongju, Korea). During the initial post-mortem examination, no disease lesions were observed. Upon microscopic examination, we found numerous Gram-positive cocci that were adhered to epithelial villi in the jejunum and ileum. However, the villi did not exhibit significant structural damage. Cultured bacteria were identified as E. hirae using the VITEK 2 system and polymerase chain reaction (PCR). Using PCR, we also confirmed that viruses and protozoa that can potentially infect piglet intestines were absent. In antibiotic susceptibility test, the bacteria were resistant to most types of antibiotics. This study presents rare cases of E. hirae infection of the piglet small intestine, which can occur in association with diarrhea possibly by the continuous use of antibiotics.