Clinical and microbiological factors predicting outcomes of nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis

Abstract

Peritonitis due to gram-negative bacilli (GNB), particularly nonfermenting GNB (NF-GNB), is a serious complication of peritoneal dialysis with a low resolution rate. Beyond the patient’s condition, microbiological properties such as antimicrobial resistance, biofilm production and other virulence factors can explain the poor outcomes. This study aimed to evaluate the influence of patient condition, microbiological characteristics, including biofilm production, and treatment on peritonitis outcome. We reviewed the records of 62 index episodes caused by NF-GNB that occurred between 1997 and 2015 in our center. The etiologies were species of Pseudomonas (51.6%), Acinetobacter (32.2%), and other NF-GNB (16.1%). There was a high (72.9%) proportion of biofilm producer lineages. The in vitro susceptibility rate of Pseudomonas spp. to amikacin, ciprofloxacin, and ceftazidime was significantly greater than that of Acinetobacter spp. and other species; however, there was a similar low resolution rate (< 45%) among the episodes attributable to them. Preexisting exit-site infection was independently associated with nonresolution. No other factor, including biofilm production, was associated with the outcome. The higher in vitro susceptibility of Pseudomonas compared to other NF-GNB that presented a similar resolution rate suggests that bacterial virulence factors such as biofilms can act in concert, thereby worsening the outcome.

Phenotypic and Molecular Characterization of Nonfermenting Gram-Negative Bacilli Causing Peritonitis in Peritoneal Dialysis Patients

“…As previously published by our group [19], the results of the present study confirmed the predominance of P. aeruginosa species as etiologic agents of BGNNF peritonitis [10] in patients treated for PD. Pseudomonas peritonitis is usually severe and is often associated with catheter infection.…”

“…A previous study by our group was not able to identify which clinical factors, treatments employed, or microbiological factors of the NF-GNB causing peritonitis on peritoneal dialysis were related to the outcomes of this infection; only exit-site infection (ESI) was identified as an independent predictor of non-resolution of these infections [19]. Then, the pathogenic profile of NF-GNB may explain, at least partially, the bad outcomes of PD-related peritonitis.…”

“…The epidemiology of these isolates in relation to the studied period was varied; we only observed a concentration of episodes caused by P. aeruginosa in the years 1998-1999 (seven cases) and in the year 2006 (seven cases). In relation to the 48 episodes, 50.0% (24 cases) were caused by Pseudomonas spp., 37.5% (18 cases) were caused by Acinetobacter spp., 6.2% (three cases) were caused by Achromobacter spp., 4.2% (two cases) were caused by Burkholderia spp., and one case (2.1%) by Stenotrophomonas maltophilia (date reproduced from Dos Santos et al) [19].…”

“…Two Pseudomonas isolates, seven Acinetobacter isolates, two Achromobacter isolates, B. cepacia, and the B. gladioli isolate were not biofilm producers. Results reproduced from Dos Santos et al [19].…”

“…Non-fermenting Gram-negative bacilli-causing peritoneal dialysis-related peritonitis episodes and their in vitro susceptibility rates by minimal inhibitory concentration, reproduced from Dos Santos et al[19].…”