An Unusual Cause of Peritonitis in Peritoneal Dialysis Patients: Pantoea Agglomerans

Peritonitis is a serious infection and early diagnosis and treatment is mandatory. A variety of microorganisms are identified in these cases and during recent years a new one was included, Pantoea agglomerans. In this case report, a female patient on continuous ambulatory peritoneal dialysis therapy with a peritonitis episode caused by this organism is described. The source of infection was thought to be due to contact of catheter with non-sterile surfaces. In microbiologic culture, this organism was identified and the patient successfully treated with a three week course of gentamicin therapy. The number of reported cases with this organism has increased in last years and various infection localizations and clinical progress patterns have been identified. In peritoneal dialysis patients presenting with peritonitis, this organism must be kept in mind. Introduction Peritonitis is a common and serious complication in patients on peritoneal dialysis (PD) [1]. Gram-positive and aerobic gram-negative bacteria are commonly isolated from peritoneal fluid in this group of patients. One of these gram-negative organisms is Pantoea agglomerans. The earliest reports regarding this organism were published in 1972 and it was formerly named Enterobacter agglomerans and Erwinia herbicola [2]. It belongs to the family Enterobacteriaceae and is responsible for infection diseases ranging from plant-thorn arthritis, osteoitis, osteomyelitis and traumatic wound infections to bacteremia. Until now a number of clinical cases caused by this organism have been described. In this report we present a patient on continuous ambulatory peritoneal dialysis (CAPD) infected with P. agglomerans and we reviewed the literature for infections caused by this organism, including peritonitis.


Introduction
Peritonitis is a common and serious complication in patients on peritoneal dialysis (PD) [1].Grampositive and aerobic gram-negative bacteria are commonly isolated from peritoneal fluid in this group of patients.One of these gram-negative organisms is Pantoea agglomerans.The earliest reports regarding this organism were published in 1972 and it was formerly named Enterobacter agglomerans and Erwinia herbicola [2].It belongs to the family Enterobacteriaceae and is responsible for infection diseases ranging from plant-thorn arthritis, osteoitis, osteomyelitis and traumatic wound infections to bacteremia.Until now a number of clinical cases caused by this organism have been described.
In this report we present a patient on continuous ambulatory peritoneal dialysis (CAPD) infected with P. agglomerans and we reviewed the literature for infections caused by this organism, including peritonitis.

Case Report
A 63 years old female patient receiving CAPD for a year presented with abdominal, inguinal pain and cloudy peritoneal fluid.Two days prior to presentation she had completed two weeks intraperitoneal vancomycin and ceftazidime treatment for a peritonitis attack which was assumed to have developed after a non-sterile surface contact of the PD catheter.Her past medical history consisted of hypertension.Four exchanges of two liters per day were her PD prescription.She was a house wife and had not traveled recently.On physical examination, her temperature was 37˚C and blood pressure was 150/100 mmHg.There was minimal pretibial edema, mild generalized abdominal tenderness with no rebound and normal bowel sounds.Catheter exit-site was clean and without erythema.In laboratory studies, white blood cell count (WBC) was 5.88×10 3 /µL.The haemoglobin level was 10.8 g/dl and the platelet count was 168×10 3 /µL.C-reactive protein was 0.1 mg/dl.The serum blood urea nitrogen and creatinine were detected as 36 mg/dl and 4.3 mg/dl respectively.Dialysate WBC count was 810/µL.For microbiologic evaluation, 10 ml dialysate was inoculated in a BACTEC Plus Aerobic/F and Plus Anaerobic/F broth (Becton Dickinson Franklin Lakes, USA) and incubated at 37°C in a BACTEC 9120 (Becton Dickinson, Franklin Lakes, USA) automatised blood culture system.Meanwhile, intraperitoneal (IP) 1 gr cefazolin sodium and 80 mg gentamicin per day were started.Bacterial growth developed in aerobic bottle after 24 hours of incubation.Inoculation was applied on solid culture from positive bottles.In gram staining of dialysate from positive bottles, gram negative bacilli were detected (Figure 1.) On blood and chocolate agar plates, the colonies displayed yellow pigmentation (Figures 2 and 3).The isolate was identified as P. agglomerans by Vitek-2 automatized system (bioMerieux, Marcy l'Etoile, France).Identification was confirmed by conventional microbiological methods (Citrate-, urease-, TSI Alk/A hydrogen sulfide -, indole-, voges-proskauer+, motility+, yellow pigment+, oxidase-, catalase+).It was sensitive to ampicillin, gentamicin, amikacin, ciprofloxacin, trimethoprim-sulfamethoxazole, piperacillin, ceftazidime and tigecycline.The initially administered 1 gr cefazolin sodium was stopped and 80 mg gentamicin per day IP was continued for 21 days.In clinical follow-up, patients' complaints completely resolved and dialysate WBC count decreased to normal levels within a few days.The patient is currently still on CAPD with no complaint.

Discussion
In this report, we present a patient with PD.In this group of patients, peritonitis is a serious complication and one of the major reasons for drop-out from PD. Treatment of infections is very important and this requires proper microbiological evaluation.One of the microorganisms with increased incidence over the last years is P. agglomerans.Various sources of infection and transmission patterns have been identified.In this study, we considered that a simple contact of the PD catheter with a non-sterile surface was responsible for transmission.For PD patients, compliance with sterilization procedures is very important for preventing contamination with this organism along with other pathogens.Presentation of infection is generally the same as that with other pathogens, as in our case.Microbiological evaluation is essential for identification.The course of the infection shows variability but response to treatment is satisfactory.In our case, the isolate was highly susceptible to antibiotics and gentamicin treatment was sufficient to resolve the episode.
This organism is found especially in plants, fruits, vegetables and also human and animal feces [2].Its transmission is generally associated with plant thorn injuries, intravenous anaesthetic catheters, contaminated parenteral nutrition and subgingival sites with periodontal diseases [3,4].Clinical reflections are listed from osteoitis, osteomyelitis, arthritis to systemic infections and severe septicemia.Peritonitis is a rare presentation of this organism.For diagnosis, microbiological specimens obtained from proper localizations according to patients' complaints and presentationare generally sufficient.The symptoms of P. agglomerans-associated peritonitis are not different from those with other pathogens, including fever, nausea, vomiting and abdominal pain.P. agglomerans is commonly considered an environmental pathogen, but it can cause symptomatic peritonitis with a fatal outcome.Therefore, microbiological evaluation and antibiotic susceptibility tests should be required for every peritonitis episode as suggested by International Society for Peritoneal Dialysis (ISPD) guidelines [5].P. agglomerans peritonitis shows good response to antibiotics such as ciprofloxacin and aminoglycoside.Also in our case, the isolate was highly susceptible to antibiotics, and gentamycin was sufficient to resolve the episode.
In the literature, infections with P. agglomerans have generally been presented as case reports.We detected an increase the number of reports with this organism in recent years.In 2007, Cruz et al. reported 53 pediatric cases with isolates from varied sites including blood culture, abscesses, joints, urinary tract, and peritoneum [6].In immunosuppressed patients, presentation with sepsis was also reported [7].In 2010, a rare presentation of P. agglomerans -endophtalmitis -was observed and a good response with systemic and local antibiotics was reported [8].Another case report, authored by Kurşun et al. described a ventilatorassociated pneumonia in a male patient with chronic renal failure in intensive care unit [9].In 2012, Boszczowski et al. identified a nosocomial outbreak with P. agglomerans in patients treated with hemodialysis and plasmapheresis.In that study, a possible environmental contamination was considered and continuous education for good quality hand hygiene and rigorous observation of environmental transmission were advised [10].In another study, high association between bacteremia and gastroesophageal reflux disease was identified [11].
Among PD patients, peritonitis attacks with this organism have increased in recent years.The, mode of infection and pathogenesis of this disease in this patients' group remained unclear.There is no proven better diagnostic technique for more easily identification.The incubation period is uncertain and inappropriate growth media and identification methods could be the reason for negative results.Different contamination patterns were identified like rose-thorn injury and teething on a catheter in these reports also [12][13][14].However, some patients proposed etiologies were unknown [14,15].Our patient did not report any injury or skin trauma but complained of a previous contact of the catheter on nonsterile surfaces.We think this contamination was responsible for bacterial infection.
In peritonitis attacks of PD patients, this micoorganism must be keep in mind.Response to treatment is favorable and early treatment modification according to antibiogram is essential.In PD patients, peritoneal function tests may be affected after this infection.Ultrafiltration failure has been observed in some cases and peritoneal calcification and thickening were considered as possible pathologies [16].

Conclusion
Peritonitis is a serious complication of PD treatment.P. agglomerans is one of the causative organisms with rising incidence in recent years and must be kept in mind.Although early diagnosis and therapy provides satisfactory outcomes, studies regarding transmission patterns are still required.