Relapsing peritonitis with Bacillus cereus in a patient on continuous ambulatory peritoneal dialysis

Abstract

We present a case where Bacillus cereus was determined to be the causative agent of relapsing peritonitis in a patient on continuous ambulatory peritoneal dialysis (CAPD). The patient, a 70-year-old man from the Faroe Islands, was admitted with relapsing peritonitis four times over a 3-month period. Peritoneal cultures were positive for growth of B. cereus, a rare bacterial cause of peritonitis. The cultures demonstrated susceptibility to vancomycin, and therefore the patient was treated with intraperitoneal vancomycin, intraperitoneal gentamycin and oral ciprofloxacin. As a result of the relapsing B. cereus peritonitis diagnosis and a CT scan showing contraction of the peritoneum after longstanding inflammation, the peritoneal catheter was removed and the patient converted to haemodialysis. To date, the patient has not been readmitted due to peritonitis. A lack of proper hygiene when changing the dialysis bag was the suspected source of infection with B. cereus.

Background

Peritonitis is the most common complication associated with peritoneal dialysis.¹ However, only nine cases of peritonitis with Bacillus cereus in patients on peritoneal dialysis have been reported in the literature.^2–9 In this report, we use peritoneal dialysis to refer to patients who have received continuous ambulatory peritoneal dialysis (CAPD), intermittent peritoneal dialysis as well as automated peritoneal dialysis. Our new report from the Faroe Islands adds to the critical knowledge about this rare infection, and shares clinically useful information regarding treatment and potential sources of infection.

Case presentation

A 70-year-old Caucasian man on CAPD since 2010 was hospitalised on 21 September 2012, reporting of abdominal pain. The patient had known heart disease and was on CAPD due to terminal kidney disease caused by membranous glomerulonephritis, which was diagnosed in 2005. The patient had a history of hospitalisation due to peritonitis (table 1).

Table 1.

Peritonitis episodes prior to September 2012

Date	Bacterial aetiology
19 May 2010	Enterococcus faecalis
3 June 2010	*
19 July 2010	Pseudomonas oryzihabitans Enterococcus faecalis
15 February 2011	Enterococcus faecalis
21 February 2011	Enterococcus faecalis
19 March 2011	No growth
1 June 2011	Enterobacter cloacae
22 August 2011	Gram-positive rods*
7 October 2011	Enterococcus faecalis
26 November 2011	Enterococcus faecalis
9 February 2012	Gram-positive rods*
8 March 2012	Klebsiella pneumonia
5 April 2012	Staphylococcus epidermidis
8 June 2012	Pseudomonas fluorescens
11 July 2012	Staphylococcus epidermidis

*Unavailable.

It is important to note that the patient refused to have his catheter removed at an early stage of his CAPD treatment and insisted on CAPD as renal replacement therapy. The peritoneal catheter in place at his 2012 hospital admission was the original catheter from 2010 and he had never been on haemodialysis. The procedure he routinely used with his CAPD was: four exchanges a day using Gambrosol, TRIO three times daily and Extraneal (Baxter) overnight. Inflow volume was 2 L per bag.

Peritonitis was suspected at this admission as well. Peritoneal fluid was cultured and empirical antibiotics vancomycin (2 g, 1 dose) and Gentamycin (80 mg, 1 dose) were administered intraperitoneally. The patient's dry body weight was 98 kgs. Results from the peritoneal fluid culture showed growth of B. cereus, a Gram-positive rod, susceptible to vancomycin. The patient reported that, preceding symptom onset, he had handled two plants received as a gift and then proceeded to change his dialysis bag. It is possible that this lack of proper hygiene was responsible for the infection with the atypical pathogen B. cereus.

The empirical antibiotic regimen successfully relieved the abdominal pain and the patient was in good condition. Therefore, it was decided to treat him on an outpatient basis. On discharge, the patient received gentamycin (80 mg, once daily for 1 week) and vancomycin (2 g, 1 dose administered 1 week after discharge) to be administered intraperitoneally. In addition, oral treatment with ciprofloxacin (500 mg, twice daily for 10 days) was prescribed as prophylaxis against Gram-negative bacteria.

On 3 November 2012, the patient was rehospitalised with abdominal pain and fever. Peritoneal fluid was again examined and cultured. The peritoneal fluid was turbid and cloudy; taken together with the patient’s history, peritonitis was again suspected. The patient was then treated with vancomycin and gentamycin intraperitoneally as in the previous hospitalisation. Treatment with antibiotics again caused the abdominal pain to resolve. Results of the peritoneal fluid culture showed a recurrence of B. cereus with the same antibiotic susceptibility found previously. Gentamycin was discontinued and vancomycin prescribed intraperitoneally once a week for 4 weeks in total.

Five days later, on 8 November 2012, the patient presented with increased abdominal pain, fever and reduced appetite. He was readmitted to the hospital for the third time since September 2012. The peritoneal fluid was clear this time. However, B. cereus peritonitis was again identified by culturing. The patient was treated with vancomycin (2 g, once a week for 4 weeks) and gentamycin (80 mg, once daily for 6 days) intraperitoneally. Oral treatment with ciprofloxacin (500 mg, twice daily for 10 days) was repeated. Unlike the two previous episodes of peritonitis, the abdominal pain persisted and a CT scan showed displacement of the peritoneal catheter, with neither abscess formation nor intestinal perforation. Displacement of the dialysis catheter was from the fossa rectovesicalis to the space in front of the bladder just behind the symphysis pubica. The catheter was determined to still be functional and an attempt was made to replace the catheter under X-ray guidance, but failed. Since the catheter still functioned and the abdominal pain was relieved, the patient was discharged after 6 days.

On 29 December 2012, a new episode of peritonitis with B. cereus was diagnosed for this patient. A new CT scan with contrast injected through the peritoneal catheter showed inflammation along the catheter and contrast accumulation in a limited cavity in the right abdominal cavity (figures 1 and 2). It was not possible to continue peritoneal dialysis under these circumstances. Therefore, the patient was sent to a tertiary centre where the dialysis catheter was removed and the patient converted to haemodialysis. A cultured sample taken from the exit site showed growth of Staphylococcus haemolyticum. Unfortunately, no sample was taken from the catheter itself when it was removed.

Figure 1.

Abdominal CT (axial slice) with contrast injected through the peritoneal dialysis catheter with the arrow indicating inflammatory changes subcutaneously along the peritoneal catheter and air bubbles along the catheter also indicating inflammation.

Figure 2.

Abdominal CT (axial slice) showing accumulation of contrast fluid in a limited 10×14×17 cm cavity in the right abdominal cavity, marked with an arrow, caused by inflammatory contraction of the peritoneum after longstanding inflammation.

Since the cluster of B. cereus-positive peritonitis at the end of 2012, the patient has not been hospitalised again for peritonitis. He has, however, been hospitalised twice since 2012 for issues unrelated to the peritonitis—once because of pneumonia and once because of a secondary skin infection related to itching and high plasma phosphate levels.

Discussion

Peritonitis caused by B. cereus is very rare. There are 13 previously reported cases of B. cereus peritonitis. In 2 of the 13 cases, B. cereus caused peritonitis after caesarean section in otherwise healthy women.¹⁰ Patients in 2 of the 13 cases had chronic liver disease and developed spontaneous B. cereus peritonitis.^{11 12} The remaining nine cases were patients on peritoneal dialysis (table 2). B. cereus caused relapsing peritonitis in six cases on peritoneal dialysis. All six patients with CAPD presented with abdominal pain. The discovery of B. cereus resulted in replacement of the dialysis catheter in three of the six reports and conversion to haemodialysis in one of the cases.^{5 6 9} One of the cases was a paediatric patient who underwent a kidney transplantation, while the other three cases responded well to empirical antibiotic treatment.^{2 3 7 8}

Table 2.

Overview of case reports describing Bacillus cereus peritonitis in patients on peritoneal dialysis

Sex	Age	Treatment	Outcome	References
M	73	IV vancomycin+IV netilmicin	Complete cure	2
F	11	IP vancomycin+IP ceftazidime IP cephalothin+IP ceftazidime+PO ciprofloxacin+PO nystatin	Relapse, change of antibiotic treatment, then complete cure	3
M	71	IP cefotaxime IP gentamicin	Relapse, then death after cardiac arrest	4
F	63	IP gentamicin+IP vancomycin IP vancomycin IV vancomycin	Relapse twice, catheter removed, then complete cure	5
M	69	IP cefuroxime+IP ceftazidime IP tobramycin IP vancomycin+IV ciprofloxacin	Relapse, converted to haemodialysis	6
M	65	IV vancomycin+IV gentamicin	Complete cure	7
M	67	IP teicoplanin+IP aztreonam	Complete cure	8
F	60	IP gentamicin+cefuroxim IP gentamicin+IP vancomycin PO cotrimoxazole Vancomycin for 6 weeks*	Relapse twice, catheter removed, then complete cure	Case 19
F	62	IP gentamicin+IP cefuroxim IP vancomycin PO ciprofloxacin	Relapse twice, catheter removed, then complete cure	Case 29

*Route of administration not reported.

IP, intraperitoneal; IV, intravenous; PO, peroral.

B. cereus is a Gram-positive endospore forming rod of which the natural reservoir is rotten organic material, salt water and fresh water, vegetables and the bowels of invertebrates.¹³ It produces β lactamases and is therefore often resistant to β-lactam antibiotics.¹³ The most frequent source of infection is food and soil.¹³ B. cereus causes food poisoning through rice, milk and pasta that are not correctly prepared or not heated properly.^{7 13} The spores are resistant to cold, heat, radiation and desiccation.^{3 13} Besides gastrointestinal symptoms, B. cereus has in some cases been shown to cause more severe conditions such as central nervous system infections, sepsis, severe pneumonia, panophthalmitis and severe skin infections. Severe infections are more common in immunocompromised patients, patients with implanted medical equipment and intravenous drug abusers.^{5 12 13} B. cereus has hydrophobic properties, which facilitate adherence to different surfaces, such as catheters. B. cereus also produces biofilm, a matrix of polysaccharide, which surrounds bacteria and drastically reduces the ability of antibiotics to penetrate.

In the case we report here, as well as in four other cases, there was suspicion of contamination from the surrounding environment.^{2 3 5} In one of these studies,⁵ of a B. cereus infected patient who lived on a farm, the authors hypothesised that soil and dust could have been contributory factors to the infection. In another study,³ bad hygiene in the home was reported, potentially leading to colonisation of the catheter. In a third study,² the patient admitted he had not used correct changing techniques and may have touched the catheter connector. In a further study,⁸ the patient admitted he did not wash his hands after preparing a ‘roll-up’ cigarette before changing the dialysis bag.

In the case we report here, the patient indicated that he had handled plants he had received as a gift and changed the dialysis bag shortly thereafter. The precedent from the cases reported in the literature suggests that contamination from the soil, combined with suboptimal hygiene when changing the dialysis bag, could be responsible for the B. cereus peritonitis in our case as well. No data are available to prove if B. cereus exists naturally in Faroese soil. All plants for indoor use in the Faroe Islands are imported from abroad, and there is no local Faroese production of houseplants.

Learning points.

• In most cases, identification of Bacillus cereus is considered to be a sampling contamination because of its wide distribution in the environment. However, as seen in the case above, it can cause opportunistic infections.

• Production of biofilm by B. cereus makes antibiotic treatment of peritonitis challenging. In many cases, treatment success requires changing the dialysis catheter.

• The importance of proper hygiene when changing the dialysis catheter and maintaining an acceptable level of hygiene in the patient's environment should be discussed with the patient to avoid contaminating the dialysis catheter during routine use.

• Clinicians treating patients on peritoneal dialysis should be aware of the possibility that B. cereus can cause peritonitis in patients on peritoneal dialysis. In addition, clinicians should be especially aware of contamination from soil originating from houseplants.