© Hong Kong Academy of Medicine. CC BY-NC-ND 4.0
LETTER TO THE EDITOR
Streptococcus gallolyticus endocarditis—an
uncommon but serious complication of constipation management
John SM Leung, FCSHK, FHKAM (Surgery)
Department of Cardiothoracic Surgery, St Paul’s
Hospital, Causeway Bay, Hong Kong
Corresponding author: Dr John SM Leung (leungsiumanjohn@yahoo.com.hk)
To the Editor—I deeply appreciate the timely
publication of the Consensus Statement on Chronic Idiopathic Constipation
in the current issue of the Hong Kong Medical Journal (April
2019).1 It addressed many important
issues, including advising caution on the popular use of fibre-rich
supplements and lactulose. These compounds are indigestible for humans and
serve as osmotic bulk expanders to facilitate faecal transit and
expulsion. They are fermented by intestinal bacteria, often but not always
favouring beneficial bacteria such as bifidobacteria over unfavourable
bacteria such as clostridia and bacteroides. For decades, health food
advocates focused on their value and seldom cautioned against any risks.2 However, the survival advantage
might change, and allow opportunistic pathogens to thrive.3 Streptococcus gallolyticus is an example of
such an opportunist. First, it is capable of digesting a wide range of
plant cellulose and disaccharides, including lactulose. Second, it creates
a highly acidic local environment deleterious to many other organisms but
not to itself, having developed various pathways to survive such acidity.
Third, it attains virulence with Pil-3 and other molecules, which enable
it to infect intestinal mucosal cells, to evade host innate immunity, and
to enter the bloodstream, whereupon it readily attaches to collagen-rich
tissues such as heart valves resulting in endocarditis.4 For a patient with chronic constipation, the long-term
intake of a high-fibre diet and lactulose has been found associated with Streptococcus
gallolyticus endocarditis.5
Author contributions
The author had full access to the data, contributed
to the study, approved the final version for publication, and take
responsibility for its accuracy and integrity.
Conflicts of interest
The author has no conflicts of interest to disclose.
Funding/support
This letter received no specific grant from any
funding agency in the public, commercial, or not-for-profit sectors.
References
1. Wu JC, Chan AO, Cheung TK, et al.
Consensus statement on diagnosis and management of chronic idiopathic
constipation in adults in Hong Kong. Hong Kong Med J 2019;25:142-8. Crossref
2. Simpson HL, Campbell BJ. Review article:
dietary fibre-microbiota interactions. Aliment Pharmacol Ther
2015;42:158-79. Crossref
3. Montagne L, Pluske JR, Hampston DJ. A
review of interactions between dietary fibre and the intestinal mucosa,
and their consequences on digestive health in young, non-ruminant animals.
Anim Feed Sci Technol 2003;108:95-117. Crossref
4. Hensler ME. Streptococcus
gallolyticus, infective endocarditis, and colon carcinoma: new light
on an intriguing coincidence. J Infect Dis 2011;203:1040-2. Crossref
5. Rusniok C, Couvé E, Da Cunha V, et al.
Genome sequence of Streptococcus gallolyticus: insights into its
adaptation to the bovine rumen and its ability to cause endocarditis. J
Bacteriol 2010;192:2266-76. Crossref