Table 1. Drugs and Therapeutic Schemes available for Blastocystis Infections Drug Metronidazol
Dosage Adult
750 mg t.d.s. 6 10 days 500 mg t.d.s. 6 10 days 1.5 g/day single dose 6 10 days
Pediatric
15 mg/kg/day 6 7 days 20–30 mg/kg/day 6 10 days
Trimethoprim–sulfametoxazol (TMP–SMX)
Adult
320 mg TMP and 1600 mg SMX daily in two equal doses 6 7 days
Nitazoxanide
Pediatric Adult
6 mg/kg TMP and 30 mg/kg SMX daily in two equal doses 6 7 days 500 mg b.d. 6 3 days
Pediatric
Paramomycin
1–3 years
100 mg b.d. 6 3 days
4–11 years
200 mg b.d. 6 3 days
25 mg/kg t.d.s. 6 10 days
PUBLISHED EXPERIENCE IN THE HEMOPHILIA SETTING
observed in the stools any more and a fecal occult blood test was negative.
The relevance of symptomatic B. hominis infection in the hemophilic setting remains scarce. Actually only two cases of hemophiliacs diagnosed with Blastocystisrelated enterocolitis have been reported in the international English language literature for the time being; both had different presentation patterns. One of them [23] was a hemophiliac suffering from advanced HIV infection who presented with gastrointestinal symptoms and was found to have a high density of B. hominis in his duodenal secretions and stools. No gastrointestinal bleeding complicated the infection. Furazolidone therapy was successful in achieving clinical improvement and eradication of the organism. The patient died 6 weeks after the infection was treated from AIDS-related complications. The authors raised the issue that B. hominis might behave as an opportunistic pathogen in immunocompromised patients; this issue remains unclear two decades later, but Tan [1] points out that there is an increasing body of evidence supporting this approach.
There are some issues in the case reported that deserve some more detailed discussion. First, bleeding from enteric injuries caused by Blastocystis has not been reported before because of the non-invasive nature of the infection as mentioned above, and the existence of inflammatory diarrhea always makes exclusion of inflammatory bowel disease mandatory even though, for unknown reasons, the association of this condition with congenital bleeding disorders has very rarely been reported; a possible contribution of thrombosis to the pathogenesis of this condition has been claimed as a reason for this somewhat protective role [25]. It has been reported that B. hominis can induce the production of interleukin (IL)-8 and granulocyte–macrophage colony-stimulating factor (GM-CSF) in epithelial cells mediated by the activation of cell surface receptors by cysteine proteases without direct invasion of the intestinal epithelium; this results in an influx of inflammatory cells into the intestinal mucosa leading to tissue damage, barrier compromise, and gastrointestinal disturbances [26]. Surprisingly, our patient presented with endoscopic signs of mucosal disruption, which was most likely a triggering factor for the bleeding; the high density of parasites found in stools or undiagnosed associated infections might have had an influence on clinical presentation.
We also reported [24] a second case of an HIVnegative mild hemophilia A patient who presented with a 6-week history of watery-type diarrhea associated with colic-type central abdominal pain, flatulence, and rectal tenesmus, which became complicated by hemorrhagic rectal discharge. Regular stool cultures and a Clostridium difficile toxin test were negative. A colonoscopy showed generalized edema and hyperemia of the colic mucosa as well as colonic ulcerations. Treatment with recombinant factor VIII concentrate (two doses of 30 IU/kg each) rapidly stopped the bleeding but not the rest of the intestinal symptoms, which were just slightly milder 4 weeks later. Further microbiological investigations revealed the presence of abundant vacuolar forms of B. hominis in stool samples. The patient was started on metronidazol (500 mg t.d.s. p.o. for 10 days) with rapid and full improvement in his symptoms. Four weeks after the antibiotic had been stopped, B. hominis could not be www.slm-hematology.com
The role that hemophilia might play in bleeding in this setting is uncertain but probably limited. There are no reports about specific infection rates by B. hominis in hemophiliacs, but we can easily assume that such rates are similar to those reported for the general population living in the same geographical areas and overall high (especially for hemophilic subjects from developing countries); however, cases of bleeding following this infection have not been reported to date. This means that, should intestinal bleeding arise, local injuries might be responsible, and hemophilia might at most contribute to exacerbating 45
JCD 2009; 1:(1). OCTOBER 2009