Frequency and antimicrobial susceptibility of bacterial agents causing peritoneal dialysis-peritonitis in a Brazilian single center over 20 years

Abstract

Peritonitis remains the main complication of peritoneal dialysis (PD). Antimicrobial therapy may be threatened by development of bacterial resistance, demanding continuous surveillance of infectious agents to improve empirical treatment. The aims of this study were to evaluate the bacterial agents causing peritonitis and their antimicrobial susceptibility in patients undergone PD in a Brazilian center, between 1993 and 2013. Strains were recovered from peritoneal fluid, identified by usual methods and submitted to Etest antimicrobial susceptibility. A total of 400 strains were studied, of which 65.8% were Staphylococcus spp.: S. epidermidis, the main species (22.8%), followed by S. aureus (21.3%). Over time, we verified a decrease in overall peritonitis occurrence, and an increase in gram-negative bacteria proportion, attributed, mainly, to a decrease in gram-positive agents. Vancomycin was effective against all Staphylococcus strains, and oxacillin resistance was higher in coagulase-negative Staphylococcus compared to S. aureus (p < 0.01). Regarding gram-negative bacteria, Enterobacteriaceae species accounted for 20.3% of the strains, but P. aeruginosa, Acinetobacter species, S. maltophilia, B. cepacia, P. fluorescens and A. xylosoxidans were also detected (14.3%). Non-fermentative gram-Negative bacilli presented increased antimicrobial resistance compared to Enterobacteriaceae, and imipenem was the most active antimicrobial drug. Over the 20 year period, increasing or decreasing in the antimicrobial susceptibilities were not observed, despite the occurrence of punctual oscillations. In summary, we verified peritonitis occurrence declining over years, gram-positive infections proportion dropping, and, inversely, gram-negative pathogens proportion increasing. Our finding reinforces recommendations regarding retrospective evaluation of antimicrobial susceptibility to define the optimal empirical therapy in each center.

Keywords:

• gram-positive
• gram-negative
• MIC
• peritoneal infection
• peritonitis
• antimicrobial resistance
• gentamicin resistance
• Etest

Public Interest Statement

Patient with chronic kidney disease often progress to renal failure. Peritoneal dialysis (PD) represents an option in treating these cases before hemodialysis or renal transplantation. PD uses peritoneum as a filter, being a practical alternative with comparable survival rates to hemodialysis. Peritonitis is the main cause of PD interruption, with known impact on morbidity and mortality. It is an infection that can be caused by several microorganisms, presenting variable pathogenic capacity and antimicrobial resistance. Serious problems for the practice of rational antibiotic therapy can occur. In this study we investigated, over 20 years (1993–2013), the frequency and the antimicrobial sensibility of 400 bacterial strains isolated from peritonitis, in order to analyze the impact of practice changes adopted in one center and to provide data for improving patient care. Our microbiological data are in accordance to the current international guidelines, which recommends retrospective local results to define the optimal empiric therapy.

Competing Interests

The authors declare no competing interest.

Acknowledgments

The authors are thankful to staff of the Clinical Laboratory Division and of Dialysis Unit of the Botucatu Medical School for their routine procedures. Authors thank Dra. Erica Chimara for the manuscript revision and suggestions.

Additional information

Funding

Funding. The authors received no direct funding for this research.

Notes on contributors

Carlos H. Camargo

After the introduction of peritoneal dialysis in Botucatu Medical School (BMS) on 1990s, a great number of patients presented peritonitis. In 1993, a multidisciplinary team of medicine doctors from BMS and biologists from Botucatu Biosciences Institute, UNESP, was structured to investigate the clinical, epidemiological and microbiological aspects of peritonitis and to reduce the infection rates in our center, composed by clinical nephrologists (Pasqual Barretti, Jacqueline Caramori), clinical pathologists (Augusto Montelli, Alessandro Mondelli), microbiologists (Terue Sadatsune, Maria Cunha) and molecular microbiologist (Carlos Camargo). The ongoing work of the group over the last 20 years generated numerous national and international publications and academic thesis about peritonitis, with microbiological investigations in all of them. In this paper we present a synthesis of all microbiological information obtained from 400 bacterial strains studied from 1993 to 2013, including identification and antimicrobial susceptibility. The use of our results for improving patient care is suggested.