A rare case of urinary balantidiasis in an elderly renal failure patient.

Balantidium coli is the largest ciliated protozoa infecting humans by the feco-oral transmission from pigs. Large gut is the most common site of involvement. Symptomatology varies from asymptomatic carrier to invasive dysentery. Extra-intestinal infections can occur in liver, lung and urogenital tract. There are very few case reports of urinary balantidiasis. We present a case of urinary balantidiasis in an elderly farmer having diabetes and chronic kidney disease. This case is reported for its rarity and future references.

INTRODUCTION

Balantidium coli is a ciliated protozoan parasite which causes dysentery in humans. It is the only ciliate to infect humans and also the largest human protozoan. B. coli inhabits the large intestine of humans, pigs and monkeys. The parasite exists in two stages; trophozoite stage found in dysenteric stool and encysted stage found in chronic cases and carriers. B. coli passes its life cycle in two stages, but in one host only. Pig is the natural host and man is an accidental host. Cyst is the infective stage of the parasite and the route of transmission is feco-oral. The pig serves as the usual source of infection. Transmission occurs through the ingestion of food or water contaminated by cysts obtained from the feces of a pig or man. The infection is found world-wide. Most human cases have been reported from South and Central America, China, Iran, Indonesia, Philippines, New Guinea and Pacific Islands.[1]

B. coli infection is uncommon in humans. The organism, though pathogenic, is of low virulence. The following three clinical manifestations of balantidiasis can occur (i) mild infections-causing intermittent diarrhea alternating with constipation (ii) acute infection-with stool containing blood and mucus similar to those of amoebic dysentery. There may be headache, fever, nausea, vomiting, abdominal pain and intestinal colic. In a few cases, fulminant ulceration with perforation of intestine may be occuring giving rise to hemorrhage, shock and even death (iii) chronic infection-presenting with intermittent diarrhea alternating with constipation. Stool contains a lot of mucus, but rarely any blood.[1]

Although intestine is the most common site of balantidiasis, there are rare extra-intestinal sites of infection. These include the liver, lung and genitourinary tract.[12] Genitourinary sites of infection, including uterine infection, vaginitis and cystitis are thought to occur via direct spread from the anal area or secondary to rectovaginal fistula created from infection with B. coli.[3] Only three cases of urinary balantidiasis have been reported so far (from Italy, USA and India). We present this case because of its rarity and for the purpose of documentation.

STUDY

A 68-year-old man, farmer by profession who was suffering from diabetes for 10 years and chronic kidney disease for the last 4 years presented with fever and dysuria for 7 days. At the time of admission temperature was 102°F, pulse 110/min, blood pressure-150/110 mm Hg and respiratory rate was 18/min. Examination of the chest and heart did not reveal any specific abnormality. Abdominal examination revealed suprapubic tenderness. Patient was confused without any focal neurological deficit. A provisional diagnosis of type 2 diabetes mellitus, chronic kidney disease and urosepsis was made and the patient was shifted to intensive care unit. The initial laboratory investigation revealed hemoglobin 7.6 g/dl, total leukocyte count-8.8 cm × 103/cm, differential count-P68%, L26%, E4% and absolute eosinophil count-380/cm, total platelet count 220 cm × 103/cm. Erythrocytes sedimentation rate-46 1st h. Random plasma glucose was 180 mg/dl, blood urea nitrogen-58 mg/dl, serum creatinine-5.2, serum Na+-126 mmol/l, serum K+-5.6 mmol/l. Urine routine and microscopic examination revealed tubular cast, 10-12 red blood cells/low power field (LPF) and pus cell 15-20/LPF. The urine sample showed 10-15 large, ovoid, ciliate parasites measuring 200 μm × 80 μm [Figures 1–3]. They had a rotary, boring motion and were moving very rapidly across the field of view suggesting trophozoites of B. coli [Video Clips 1 and 2]. Cystic forms of B. coli measuring 50-60 μm in diameter were seen in some of the fields of same urine sample [Figure 4]. Blood and midstream urine samples were sent for aerobic culture. Arterial blood gas examination revealed pH-7.28, PaCO2-35 mm Hg, PaO2-97 mm Hg, bicarbonate-19 mEq/l (metabolic acidosis). Chest X-ray revealed bilateral minimal pleural effusion. Ultrasonography of the pelvis revealed features of chronic kidney disease and thickened bladder mucosa indicating cystitis. Medication on admission included piperacillin-tazobactum, regular insulin, iron and erythropoietin. Repeated urine samples were also positive for the similar trophozoite. The stool samples were collected on two consecutive days and were negative for B. coli trophozoites or cysts. Patient's condition deteriorated and he had to undergo hemodialysis. The blood culture did not grow any organism and the urine sample showed insignificant growth of candida species. Patient was given tetracycline and metronidazole according to the level of glomerular filtration rate for total 7 days and the patient gradually improved.

Figure 1

Trophozoite of Balantidium coli in urine

Figure 3

Macronucleus, micronucleus and food vacuoles of ciliate trophozoite of Balantidium coli

Figure 4

Cystic form of Balantidium coli with micronucleus, macronucleus and food vacuoles from urine sample

3-4 trophozoites of Balantidium coli in urinary sediment

DISCUSSION

B. coli primarily infects the large intestine after ingestion of food contaminated by the cysts producing inflammation, ulceration and necrosis of the bowel mucosa.[4] Very few cases of extra-intestinal balantidiasis have been documented from liver, lung and genitourinary tract. Genitourinary tract is affected predominantly by retrograde transmission of the trophozoites. Only three cases of urinary balantidiasis have been documented until now. Among these, two cases (a 56-year-old man from Italy having non-Hodgkin's lymphoma[5] and the other from India, a 29 year immunocompetent lady)[3] were having urinary balantidiasis in the absence of B. coli in stool. We describe a similar case of urinary balantidiasis in a farmer having diabetes and chronic kidney disease. We postulate that trophozoites residing in the large gut, could invade the mucosa, enter the blood stream and finally “metastasize” to the urinary bladder to cause infection.

CONCLUSION

Humans are infected accidentally from pigs. Large intestine is the most common site to be involved. Extra-intestinal infections include liver, lungs and urogenital tract. Urogenital tract is affected commonly by retrograde transmission of the trophozoites from the anus to urinary tract (predominantly in females). The trophozoites can also invade the gut mucosa to enter into the circulation and finally metastasize to the urinary bladder. Prompt diagnosis by fresh urine sediment study by a Microbiologist is of immense help for treatment.