Background: Peritoneal dialysis (PD) is an important therapy for patients with end-stage kidney disease and is used in more than 200,000 such patients globally. However, its value is often limited by the development of infections such as peritonitis and exit-site and tunnel infections. Multiple strategies have been developed to reduce the risk of peritonitis including antibiotics, topical disinfectants to the exit site and antifungal agents. However, the effectiveness of these strategies has been variable and are based on a small number of randomised controlled trials (RCTs). The optimal preventive strategies to reduce the occurrence of peritonitis remain unclear. This is an update of a Cochrane review first published in 2004. Objectives: To evaluate the benefits and harms of antimicrobial strategies used to prevent peritonitis in PD patients. Search methods: We searched the Cochrane Kidney and Transplant's Specialised Register to 4 October 2016 through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. Selection criteria: RCTs or quasi-RCTs in patients receiving chronic PD, which evaluated any antimicrobial agents used systemically or locally to prevent peritonitis or exit-site/tunnel infection were included. Data collection and analysis: Two authors independently assessed risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratio (RR) with 95% confidence intervals (CI). Main results: Thirty-nine studies, randomising 4435 patients, were included. Twenty additional studies have been included in this update. The risk of bias domains were often unclear or high; risk of bias was judged to be low in 19 (49%) studies for random sequence generation, 12 (31%) studies for allocation concealment, 22 (56%) studies for incomplete outcome reporting, and in 12 (31%) studies for selective outcome reporting. Blinding of participants and personnel was considered to be at low risk of bias in 8 (21%) and 10 studies (26%) for blinding of outcome assessors. It should be noted that blinding of participants and personnel was not possible in many of the studies because of the nature of the intervention or control treatment. The use of oral or topical antibiotic compared with placebo/no treatment, had uncertain effects on the risk of exit-site/tunnel infection (3 studies, 191 patients, low quality evidence: RR 0.45, 95% CI 0.19 to 1.04) and the risk of peritonitis (5 studies, 395 patients, low quality evidence: RR 0.82, 95% CI 0.57 to 1.19). The use of nasal antibiotic compared with placebo/no treatment had uncertain effects on the risk of exit-site/tunnel infection (3 studies, 338 patients, low quality evidence: RR 1.34, 95% CI 0.62 to 2.87) and the risk of peritonitis (3 studies, 338 patients, low quality evidence: RR 0.94, 95% CI 0.67 to 1.31). Pre/perioperative intravenous vancomycin compared with no treatment may reduce the risk of early peritonitis (1 study, 177 patients, low quality evidence: RR 0.08, 95% CI 0.01 to 0.61) but has an uncertain effect on the risk of exit-site/tunnel infection (1 study, 177 patients, low quality evidence: RR 0.36, 95% CI 0.10 to 1.32). The use of topical disinfectant compared with standard care or other active treatment (antibiotic or other disinfectant) had uncertain effects on the risk of exit-site/tunnel infection (8 studies, 973 patients, low quality evidence, RR 1.00, 95% CI 0.75 to 1.33) and the risk of peritonitis (6 studies, 853 patients, low quality evidence: RR 0.83, 95% CI 0.65 to 1.06). Antifungal prophylaxis with oral nystatin/fluconazole compared with placebo/no treatment may reduce the risk of fungal peritonitis occurring after a patient has had an antibiotic course (2 studies, 817 patients, low quality evidence: RR 0.28, 95% CI 0.12 to 0.63). No intervention reduced the risk of catheter removal or replacement. Most of the available studies were small and of suboptimal quality. Only six studies enrolled 200 or more patients. Authors' conclusions: In this update, we identified limited data from RCTs and quasi-RCTs which evaluated strategies to prevent peritonitis and exit-site/tunnel infections. This review demonstrates that pre/peri-operative intravenous vancomycin may reduce the risk of early peritonitis and that antifungal prophylaxis with oral nystatin or fluconazole reduces the risk of fungal peritonitis following an antibiotic course. However, no other antimicrobial interventions have proven efficacy. In particular, the use of nasal antibiotic to eradicate Staphylococcus aureus, had an uncertain effect on the risk of peritonitis and raises questions about the usefulness of this approach. Given the large number of patients on PD and the importance of peritonitis, the lack of adequately powered and high quality RCTs to inform decision making about strategies to prevent peritonitis is striking.