Introduction
The genus Chromobacterium , consisting of seven recognized
species, is a Gram-negative, rod-shaped bacterium, in which the most
famous specie is Chromobacterium violaceum with red
pigment (Papapanagiotou & Aligizakis, 1959). Chromobacterium is
mainly distributed in tropical and subtropical regions, and it is
frequently isolated in water sources and humid areas (Blackburn et al.,
2019). Chromobacterium haemolyticum was considered as a separate
species, lacking violet pigmentation but demonstrating strong hemolysis
on sheep blood agar. (Han, Han, & Segal, 2008). C .haemolyticum has been isolated in a variety of water
environments, such as rice roots, lakes, rivers, and sewage effluent
(Kanamori et al., 2020; Priya, Sulaiman, How, Yin, & Chan, 2018; Zhou
et al., 2016). There is evidence that C . haemolyticum is
mainly transmitted through water sources, and some reports suggest thatC . haemolyticum can cause pneumonia and sepsis in humans,
and the patients in these cases have a history of wound exposure or
contact with water sources, indicating that Chromobacterium
haemolyticum maybe an opportunistic pathogen (Miki & Okada, 2014;
Takenaka et al., 2015). There have also reports that diarrhea case was
related to C . haemolyticum , but C .haemolyticum causing diarrhea or even death in other animals has
not been reported (Tanpowpong, Charoenmuang, & Apiwattanakul, 2014).
Piglets diarrhea is a very severe disease that is very harmful to the
breeding industry. The intestinal immunity of piglets is not fully
developed, and many pathogens are susceptible to piglets at this stage,
causing acute diarrhea, vomiting, dehydration, and death (Osek &
Truszczynski, 1992; Wang, Vlasova, Kenney, & Saif, 2019). Diarrhea in
piglets can be devastating to pig farms if the main pathogen cannot be
identified and treated accordingly. Some farms use mountain springs or
river water as water sources, and incomplete disinfection of water
sources often leads to infection of some bacterial diseases. C .haemolyticum is usually detected in water sources. Although it is
pathogenic, it has received less attention. It is necessary to conduct
in-depth research on the biological characteristics and genetic
characteristics of the bacteria.
This study found that unexplained diarrhea occurred in many piglet farms
in south China. After excluded some regular pathogens, a novel type ofChromobacterium
haemolyticum was found in the water source and fecal samples of piglets
with diarrhea. Challenge piglets with isolate GDHYZ30 can cause the same
diarrhea symptoms similar to that of the field cases. And the diarrhea
of piglets had been controlled after changing the drinking water source,
indicating that the GDHYZ30 strain is the agents that cause diarrhea and
death in piglets.