Chryseobacterium indologenes peritonitis in a peritoneal dialysis patient

Abstract

Peritonitis remains an important complication of peritoneal dialysis. The Gram-negative bacillus Chryseobacterium indologenes causes infection mostly in immunocompromised patients with severe underlying disease, mainly in Asia. Herein, we report the first case in Europe and the second case in an immunocompetent patient of peritoneal dialysis-associated C. indologenes peritonitis. Our patient presented with abdominal pain and a cloudy effluent and was started on intraperitoneal antibiotics. The organism cultured from the peritoneal fluid was later identified as C. indologenes and antibiotic therapy was adjusted accordingly. Despite this, the peritonitis followed a relapsing course, requiring Tenckhoff catheter removal, temporary transfer to haemodialysis and intravenous antibiotics. Subsequently, a new Tenckhoff catheter was inserted and peritoneal dialysis was restarted. The patient remains peritonitis free after 18 months of follow-up. This case highlights the need to consider rare causes of peritonitis in peritoneal dialysis patients as well as the heterogeneous clinical course of C. indologenes peritonitis.

Background

Peritonitis is a common and serious complication of peritoneal dialysis (PD), usually caused by contamination with pathogenic bacteria from the skin. Gram-positive cocci such as Staphylococcus epidermidis and other coagulase-negative staphylococci, Staphylococcus aureus and Streptococcus spp are the most frequent aetiological agents of PD-associated peritonitis worldwide.¹ Gram-negative organisms are less common agents of PD-associated peritonitis, but are associated with a worse prognosis, with higher rates of catheter loss, hospitalisation and death.² Sources of infection include the bowel, skin, urinary tract, contaminated water or animal contact. Escherichia coli, Klebsiella spp and Pseudomonas aeruginosa are the most commonly isolated Gram-negative agents. The presence of multiple Gram-negative or mixed Gram-negative and Gram-positive cultures should raise the suspicion for a surgical intra-abdominal pathology.^{1 3 4} There is no significant difference in causative agents between home and hospital-acquired peritonitis.¹ The diagnosis of PD-associated peritonitis is made by the presence of two of the following: clinical features of peritonitis (abdominal pain and cloudy dialysis effluent); effluent white cell count >0.1x10⁹/L with >50% polymorphonuclears after a dwell time of at least 2 hours; and positive dialysis effluent culture.¹ Mononuclear predominance can sometimes be seen in fungal or mycobacterial peritonitis. Culture-negative peritonitis occurs in about 10%–20% of cases, although these are expected to diminish as novel diagnostic techniques such as PCR become widely available.¹ A new episode of peritonitis caused by the same aetiological agent is classified as a relapse (if it occurs in the following 4 weeks) or a repeat (after 4 weeks), and is associated with lower rate of cure, more ultrafiltration problems and higher rate of technique failure.¹ The Gram-negative, glucose non-fermenting bacillus Chryseobacterium indologenes causes infection mostly in immunocompromised patients with severe underlying disease. It is widely distributed in soil, plants and water sources despite chlorination, and is not infrequently recovered from wet sources in hospitals. It is not part of the normal human flora.^5–8 Herein, we report the first case in Europe and the second case in an immunocompetent patient of PD-associated C. indologenes peritonitis.

Case presentation

A 76-year-old white man with end-stage renal disease due to nephroangiosclerosis and obstructive uropathy, on PD treatment for 5 years, with medical history of atrial fibrillation, arterial hypertension and pulmonary emphysema presented with diffuse abdominal pain. He denied any recent travel and sick contacts and was not under any immunosuppressive drugs. He related doing some agricultural activities as a hobby. He was a former smoker (40 pack-years). There was no history of diabetes mellitus, previous peritonitis episodes or Tenckhoff catheter substitution.

On physical examination there was pain on abdominal palpation with no inflammatory signs of the catheter exit site. The effluent was cloudy. Bloodwork showed a haemoglobin of 108 g/L, slight leukocytosis without neutrophilia (11.8x10⁹/L WBCs with 73.9% neutrophils), normal platelet count (181x10⁹/L) and an elevated C-reactive protein (CRP) (12.4 mg/dL). Cytological analysis of the peritoneal effluent revealed 1.033x10⁹/L WBCs with 90% neutrophils, confirming the diagnosis of peritonitis. Empirical antibiotic therapy with intraperitoneal cefazolin and ceftazidime was started. The organism cultured from the peritoneal fluid was identified a week later as C. indologenes. Antibiotic therapy was adjusted to intraperitoneal ceftazidime and oral ciprofloxacin according to reported data in the literature, as our hospital’s laboratory was not able to perform antimicrobial susceptibility testing on this agent. Abdominal CT scan did not reveal peritoneal thickening, ascites or tissue densification. The patient completed a 21-day antibiotic course with favourable response. The dialysis effluent analysis throughout the clinical course is shown in table 1.

Table 1.

Peritoneal effluent analysis throughout the clinical course of the PD-associated peritonitis

Day	Peritoneal fluid cytology
1	1.033x109/L WBCs, 72% neutrophils, cloudy
3	0.053x109/L WBCs, 15% neutrophils, cloudy
6	0.119x109/L WBCs, 3% neutrophils, slightly cloudy
10	<0.035x109/L WBCs, clean
14	<0.035x109/L WBCs, clean
19	<0.035x109/L WBCs, clean

PD, peritoneal dialysis; WBC, white blood cell.

However, a week later there was a recrudescence of abdominal pain and cloudy effluent, with bloodwork showing haemoglobin 98 g/L, leukocytes 8.6x10⁹/L, platelets 165x10⁹/L and CRP 1.11 mg/dL. Cytological analysis of the peritoneal fluid revealed 1.812x10⁹/L WBCs with 99% neutrophils. A relapse episode was diagnosed, again with identification of C. indologenes in the peritoneal fluid. The patient was submitted to another 21-day regimen of intraperitoneal ceftazidime and oral ciprofloxacin combined with a week of oral fluconazole (antifungal prophylaxis). The analysis of the peritoneal effluent throughout the relapse episode is indicated in table 2.

Table 2.

Peritoneal effluent analysis throughout the clinical course of the relapse episode of peritonitis

Day	Peritoneal fluid analysis
1	3.594x109/L WBCs, 99% neutrophils, cloudy
2	1.812x109/L WBCs, 99% neutrophils, cloudy
3	0.552x109/L WBCs, 80% neutrophils, cloudy
7	0.214x109/L WBCs, 45% neutrophils, cloudy
10	0.06x109/L WBCs, 10% neutrophils, slightly cloudy
14	<0.035x109/L WBCs, clean
21	<0.035x109/L WBCs, clean

WBC, white blood cell.

Echography of the catheter subcutaneous tunnel did not reveal inflammation. A week after achieving clean peritoneal effluent the patient was admitted for Tenckhoff catheter removal. Peritoneal biopsy revealed fibrosis and inflammation with numerous eosinophils. Abdominal CT scan was repeated, showing abdominal wall densification consistent with an infectious process (figure 1).

Figure 1.

Abdominal CT scan showing abdominal wall densification (arrow).

Outcome and follow-up

After Tenckhoff catheter removal the patient remained hospitalised under haemodialysis and received a 14-day intravenous course of ceftazidime and ciprofloxacin. A new Tenckhoff catheter was inserted and he was discharged the following day, restarting PD after 14 days. Since then the patient has remained clinically stable and peritonitis free after 18 months of follow-up.

Discussion

C. indologenes is a glucose non-fermenting, oxidase positive, Gram-negative bacillus, with a yellow to orange pigment, widely distributed in soil, plants and water, but not part of the normal human flora.^{6 7} C. indologenes infection is rare but its incidence has increased in recent years, with most cases consisting of pneumonia and bacteraemia in severely sick immunosuppressed patients, mainly in Asia.⁵ Among these patients, C. indologenes is more commonly identified in those under mechanical ventilation and with indwelling catheters.⁸ To our knowledge, there are only three published cases of PD-associated peritonitis caused by C. indologenes, two in South Korea and one in the USA.^8–10 In one of the cases, the peritonitis episode was caused by multiple organisms, including Sphingomonas paucimobilis.¹⁰ Only one of those three patients was immunocompetent.⁸ There are two other reported cases of peritonitis involving this agent, both in Taiwan, but those patients were not on PD.^{6 11} The guidelines of the International Society for Peritoneal Dialysis (ISPD) recommend the initiation of intraperitoneal antibiotics as soon as the diagnosis of peritonitis is suspected. The empirical antibiotic regimen must cover Gram-positive and Gram-negative bacteria and must consider the local history of infections and antimicrobial sensitivities.¹ In our unit the protocol consists of intraperitoneal cefazolin and ceftazidime. The recommended duration of treatment varies between 2 and 3 weeks depending on the causative agent, with Gram-negative bacteria needing at least 3 weeks of antimicrobial therapy.¹

There are currently no specific guidelines published by ISPD for the treatment of C. indologenes infection, although available data suggest that quinolones, piperacillin/tazobactam and co-trimoxazole may be the most effective drugs.¹² In this case, the lack of antimicrobial susceptibility testing presented additional difficulty in treatment selection and may have contributed to the relapsing course of the peritonitis. In the two reported cases of PD-associated peritonitis solely due to this agent, none required removal of the indwelling catheter.^{8 9} In this report, prolonged antibiotic therapy and Tenckhoff catheter removal were necessary, suggesting a heterogeneous evolution of C. indologenes peritonitis. However, Gram-negative peritonitis has previously been associated with a worse prognosis and higher catheter removal and hospitalisation rates, so the data on our report cannot be considered unexpected.²

This patient presented with eosinophils in the peritoneal biopsy performed at the time of Tenckhoff catheter removal. This finding is infrequent but not rare in the context of infectious peritonitis and is not pathognomonic of eosinophilic peritonitis.¹³

The source of the C. indologenes infection in our patient remains unclear, but the probable mechanism of infection was assumed to be touch contamination while doing agricultural activities. Therefore, patients should be cautious when performing activities that involve risk of contamination of the skin and always adhere to prophylactic measures before fluid exchanges to minimise risk of infection. This case also highlights the need to consider rare causes of peritonitis in PD patients.

In conclusion, we report the first case of PD-associated C. indologenes peritonitis in Europe, the second case in an immunocompetent host and the first case of peritonitis caused solely by C. indologenes in which Tenckhoff catheter removal was necessary. The lack of antimicrobial susceptibility data in our case may have contributed to the relapsing course of the peritonitis episode and, when available, these data should be used to guide treatment. Despite the need for catheter removal and temporary transfer to haemodialysis, the patient successfully restarted PD after 2 weeks and remains clinically stable and peritonitis free after 18 months of follow-up and 6½ years of PD treatment.

Learning points.

• Peritonitis remains a common and serious complication of peritoneal dialysis.

• Rare causes of peritonitis, such as Chryseobacterium indologenes, should be considered in peritoneal dialysis patients even if they are immunocompetent.

• Peritoneal dialysis patients with agricultural activities may be at risk for C. indologenes infection.

• Antimicrobial susceptibility data should always be obtained if possible.

• Catheter removal may be necessary for the successful treatment of C. indologenes peritonitis in peritoneal dialysis patients.