A five-year study of the microbiologic results of exit site infections and peritonitis in continuous ambulatory peritoneal dialysis

We studied the culture results from 321 continuous ambulatory peritoneal dialysis (CAPD) related infections (exit site, tunnel infections, and peritonitis) in 137 patients over a 5-year period to determine the contribution of exit site and tunnel infections to peritonitis and catheter loss. Seventeen percent of peritonitis episodes were associated temporally and by microbiologic results with exit site or tunnel infections. Twenty-one percent of exit site and tunnel infections and 20% of peritonitis episodes resulted in catheter loss. Peritonitis due to Staphylococcus aureus was more likely to be associated with an exit site or tunnel infection and was more likely to result in loss of the catheter than peritonitis due to Staphylococcus epidermidis. Peritonitis and exit site infections due to Pseudomonas sp also frequently resulted in catheter removal. We found that exit site infections cause significant morbidity in CAPD patients. Further studies in this area are needed.     

Use of pulsed-field gel electrophoresis in the analysis of recurrent Staphylococcus aureus infections in patients on continuous ambulatory peritoneal dialysis

BACKGROUND/AIM: The purpose of this study was to evaluate pulsed-field gel electrophoresis (PFGE) for distinguishing between relapse and reinfection of Staphylococcus aureus infections in patients on continuous ambulatory peritoneal dialysis (CAPD). METHODS: Between July 1993 and May 1997, 4 patients with recurrent CAPD-associated infections caused by S. aureus we enrolled in this study. There were nine episodes of peritonitis, one episode of temporary double lumen catheter infection, and one episode of Hickman catheter infection. A total of eleven S. aureus isolates were collected from peritoneal fluid (n = 9) and blood (n = 2). PFGE typing was applied. RESULTS: In our study, from PFGE typing, the 11 S. aureus isolates were classified into seven patterns. Antibiogram profiling classified only four patterns. Patient A had a reinfection by another strain of S. aureus, and patient B had three episodes of peritonitis caused by the same strain of S. aureus due to exit site infections. Patient C had two episodes of CAPD peritonitis caused by two different strains, respectively. Patient D had four episodes of S. aureus infection (three CAPD peritonitis and one bacteremia); the first two episodes of peritonitis were caused by an identical strain of S. aureus, whereas the subsequent two infections were caused by other organisms. CONCLUSION: PFGE has a high discriminatory power and can be an assistant method to antibiogram profiling for distinguishing relapse from reinfection in CAPD-associated peritonitis.     

Peritonitis in continuous ambulatory peritoneal dialysis: impact of a compulsory switch from a standard to a Y-connector system in a single North American Center.

One hundred one continuous ambulatory peritoneal dialysis (CAPD) patients from a single North American center were analyzed in a retrospective and cross-over study for peritonitis rates using a standard system (Travenol System II) or a Y-shaped disconnect-disinfectant system (Travenol O-set). Twenty-one of 34 patients using the standard set (group I) had 53 episodes of peritonitis in 508 patient-months or one episode per 9.6 patient-months. Nine of 17 patients switching from the standard to the disconnect-disinfectant system (group II) experienced 22 episodes of peritonitis in 275 patient-months or one episode per 12.5 patient-months on the standard set, while six patients had 10 episodes of peritonitis in 275 patient-months or one episode per 27.5 patient-months on the disconnect-disinfectant system (P less than 0.04). Twenty-eight of 67 new CAPD patients starting on the disconnect-disinfectant system (group III) had 37 episodes of peritonitis in 1,086 patient-months or one episode per 29.4 patient-months (P less than 0.01 v group I). Exit-site infections (ESI) occurred in 35.3% of patients using the standard set versus 34.3% of those using the O-set. The presence of an ESI was not associated with a higher risk of peritonitis, but modified the bacteriological profile of subsequent peritonitis episodes in patients using the O-set, favoring the organisms isolated from the exit site. Decreases in peritonitis rates with the O-set were due to a reduction of peritonitis episodes secondary to most bacterial agents and not only to skin organisms. Diabetics using intraperitoneal insulin had similar peritonitis and ESI rates as nondiabetics.(ABSTRACT TRUNCATED AT 250 WORDS)     

Successful prophylaxis for fungal peritonitis in patients on continuous ambulatory peritoneal dialysis: six years' experience

Fungal peritonitis as a serious complication of continuous ambulatory peritoneal dialysis (CAPD) is often associated with severe morbidity, CAPD "drop-out" and, occasionally, death. Most episodes of fungal peritonitis occur during or after a period of antibiotic treatment of various bacterial infections, usually bacterial peritonitis. From April 1979 to December 1982 (period I), 10 episodes of fungal peritonitis occurred during 415 patient-months, ie, 10.5% of all peritonitis episodes recorded in our CAPD program. After the introduction of oral prophylaxis with 3 x 500,000 IU [corrected] nystatin during every course of antibiotic treatment, only four episodes of fungal peritonitis occurred during 2,102 patient-months, ie, 3.1% of all peritonitis episodes from January 1983 to March 1989 (period II). This difference between the first and second periods is significant (P less than 0.05). Moreover, none of the four patients who contracted fungal peritonitis in the second period received nystatin prophylaxis. Thus, the simple measure of oral prophylaxis using this nonabsorbable antifungal agent in every case of an antibiotic treatment largely eliminates the risk of fungal peritonitis in patients on CAPD.     

An analysis of ten-year trends in infections in adults on continuous ambulatory peritoneal dialysis (CAPD)

Infectious complications are the Achilles heel of CAPD. To determine trends in these events, we analyzed the CAPD related infections of 303 adults on CAPD at a single university center between 1979 and 1989. During this decade the percentage of insulin-dependent diabetics increased from 14% to 39% (p less than 0.005). Peritonitis rates fell from 2.4 episodes/y in 1979 to 0.8 episodes/y in 1989. The proportion of patients with multiple episodes of peritonitis decreased (40% of the patients in 1979-1982 vs 15% in 1983-1989, p = 0.0001) while the proportion of patients with no episodes of peritonitis increased during the same periods (29% vs 49%, p = 0.005). The proportion of peritonitis episodes due to S. aureus rose over the 10-year period (p = 0.005), while those due to S. epidermidis decreased (p less than 0.10). The overall incidence of S. aureus peritonitis remained unchanged. Catheter infection rates initially increased and then fell during the decade; S. aureus remained the predominant cause. The proportion of peritonitis episodes associated with catheter infection rose (13% in 1982 vs 24% in 1989, p = 0.025), and in 1989, 80% of these episodes were caused by S. aureus. Catheter loss was also primarily due to S. aureus infections in 1989 (80%). Infections due to P. aeruginosa were a persistent problem. The proportion of patients transferring to hemodialysis each year paralleled catheter loss rates, which in turn appeared to be more related to catheter infection rates than to peritonitis rates. We conclude that control of S. aureus and P. aeruginosa will be the key to future reductions in the infectious complications of CAPD patients.     

A randomized prospective comparison of oral versus intraperitoneal ofloxacin as the primary treatment of CAPD peritonitis

Summary: Oral ofloxacin has been successfully used in our centres for the primary treatment of peritonitis complicating continous ambulatory peritoneal dialysis (CAPD). In view of the progressive rise in the resistance rate to ofloxacin among peritoneal bacterial isolates, a study was conducted to determine if oral ofloxacin remains a viable first line treatment for CAPD peritonitis in our centres and if the result can be improved by changing from an oral to an intraperitoneal (i.p.) route. In patients on three 2 L daily CAPD exchanges, ofloxacin given at the i.p. dosage of 200 mg loading followed by 25 mg/L of peritoneal dialysate achieved overnight trough peritoneal levels which are at least four times the minimal 90% inhibitory concentration (MIC90) of most bacterial pathogens without significant accumulation in the systemic circulation. This i.p. dosage was therefore chosen for the clinical study and the result was compared to that using ofloxacin given in the oral dosage of 400 mg loading followed by 300 mg once daily as maintenance. of all the recruited episodes, 35 were eligible for analysis. the overall primary cure rate including primary failures and relapses was 55.6% (10/18) in the oral treatment group and 70.6% (12/17) in the i.p. treatment group. the corresponding figures for gram positive bacterial (g +) infections were 36.4% and 50%, for gram negative bacterial (g -) infections were 66.7 and 80% and for culture negative infections were 75 and 80%. In culture positive cases, all treatment failures were due to resistant infections which were observed in 42.3% of all bacterial isolates, 47.1% of g + isolates and 33.3% of g - isolates. Due to the high background level of bacterial resistance among our CAPD population, ofloxacin monotherapy given either by the oral or the i.p. route can no longer be recommended for the primary treatment of CAPD peritonitis.     

A review of Staphylococcus aureus exit-site and tunnel infections in peritoneal dialysis patients

Staphylococcus aureus peritoneal exit-site and tunnel infections are a source of considerable morbidity for peritoneal dialysis patients. These infections are difficult to resolve, can lead to peritonitis, and often require removal of the peritoneal catheter. Staphylococcal nasal carriage is the major risk factor for S aureus exit-site infections and peritonitis episodes. In the future, the identification of patients who are S aureus nasal carriers and then treatment of the carriage state with rifampin may prove to be a means of decreasing infection rates. The best treatment for S aureus exit-site and tunnel infections has not been established. Treatment regimens in general use include oral antibiotics or intraperitoneal vancomycin. The optimal length of therapy is also unclear. Since the development of the disconnect peritoneal dialysis system, S aureus, rather than the Staphylococcus epidermidis, is the leading cause of peritonitis. To further decrease peritonitis rates, attention must now be directed at catheter-related peritonitis episodes, with S aureus the most common cause of such episodes. Controlled, prospective studies designed to investigate methods of preventing and treating S aureus exit-site infections in peritoneal dialysis patients are needed.     

Increased risk of Staphylococcus epidermidis peritonitis in patients on dialysate containing 1.25 mmol/L calcium.

Peritoneal macrophage function is decreased in vitro in the presence of dialysate with 1.25 mmol/L calcium compared with that containing 1.75 mmol/L calcium. Theoretically, patients using this dialysate may have a higher risk of peritonitis. Nineteen patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) were converted from dialysate with 1.75 mmol/L calcium (mean time, 33 +/- 26 months) to that with 1.25 mmol/L calcium, for some or all exchanges (mean time, 10 +/- 4.7 months). Peritonitis rates were compared with 19 control patients who remained on dialysate with 1.75 mmol/L calcium. The two groups were matched for the proportion of diabetics, sex, age, use of the Y-set, and dialysis modality (CAPD, CCPD). Peritonitis rates were similar in the study patients before conversion to 1.25 mmol/L calcium dialysate and in the control patients (0.49 v 0.58 episodes/patient-year, respectively). After conversion to dialysate with 1.25 mmol/L calcium, the peritonitis rate was 0.82 episodes/patient-year contrasted to 0.58 episodes/patient-year in the control patients (P = 0.09). The peritonitis rate due to Staphylococcus epidermidis was 0.51 episodes/patient-year when 1.25 mmol/L calcium dialysate was used, and 0.19 episodes/patient-year for the comparable period in the control patients on 1.75 mmol/L calcium dialysate (P = 0.005). The proportion of peritonitis episodes due to S epidermidis increased from 20% to 61% after conversion to 1.25 mmol/L calcium (P = 0.01). The increased risk of peritonitis due to S epidermidis in patients using dialysate with 1.25 mmol/L calcium is consistent with a previous study demonstrating that clearance of S epidermidis by peritoneal macrophages is less effective with a decrease in the dialysate calcium content.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of the causative pathogens in uncomplicated CAPD-associated peritonitis: duration of therapy, relapses, and prognosis

We analyzed the frequency with which certain bacteria caused uncomplicated peritonitis in an adult continuous ambulatory peritoneal dialysis (CAPD) program that continued patients on this modality of therapy despite frequent infections. All infections were treated with a commonly employed 10- to 14-day course of narrow spectrum intraperitoneal antibiotics. Although the distribution of bacterial pathogens was similar to previous reports (coagulase-negative staphylococci, 43%; Staphylococcus aureus, 13%), we observed no episodes of fungal peritonitis. Twenty percent of our infections were associated with either "no specimens obtained" or "no growth," a finding similar to the CAPD registry. When the data were available, two thirds of all infections were caused by the same pathogen (genus and species) as in the most immediately preceding infection. Twenty-two of 96 episodes of uncomplicated peritonitis occurred within three weeks of a preceding infection. In all 11 cases where organisms were isolated from both paired episodes, the infecting agent was the same as in the preceding infection and was a staphylococcus. This high rate of apparent relapse and the absence of fungal infections may relate to our treatment protocol and possible explanations are discussed. Lastly, the occurrence of coagulase-negative staphylococcal peritonitis is a harbinger of future episodes of peritonitis caused by a variety of organisms.     

Predictive factors of outcome following staphylococcal peritonitis in continuous ambulatory peritoneal dialysis

BACKGROUND AND AIMS: Staphylococcus epidermidis and other coagulase-negative staphylococci (CoNS) are the most common agents of continuous ambulatory peritoneal dialysis (CAPD) peritonitis. Episodes caused by Staphylococcus aureus evolve with a high method failure rate while CoNS peritonitis is generally benign. The purpose of this study was to compare episodes of peritonitis caused by CoNS species and S. aureus to evaluate the microbiological and host factors that affect outcome. MATERIAL AND METHODS: Microbiological and clinical data were retrospectively studied from 86 new episodes of peritonitis caused by staphylococci species between January 1996 and December 2000 in a university dialysis center. The influence of microbiological and host factors (age, sex, diabetes, use of vancomycin, exchange system and treatment time on CAPD) was analyzed by logistic regression model. The clinical outcome was classified into two results (resolution and non-resolution). RESULTS: The odds of peritonitis resolution were not influenced by host factors. Oxacillin susceptibility was present in 30 of 35 S. aureus lineages and 22 of 51 CoNS (p = 0.001). There were 32 of 52 (61.5%) episodes caused by oxacillin-susceptible and 20 of 34 (58.8%) by oxacillin-resistant lineages resolved (p = 0.9713). Of the 35 cases caused by S. aureus, 17 (48.6%) resolved and among 51 CoNS episodes 40 (78.4%) resolved. Resolution odds were 7.1 times higher for S. epidermidis than S. aureus (p = 0.0278), while other CoNS had 7.6 times higher odds resolution than S. epidermidis cases (p = 0.052). Episodes caused by S. haemolyticus had similar resolution odds to S. epidermidis (p = 0.859). CONCLUSIONS: S. aureus etiology is an independent factor associated with peritonitis non-resolution in CAPD, while S. epidermidis and S. haemolyticus have a lower resolution rate than other CoNS. Possibly the aggressive nature of these agents, particularly S. aureus, can be explained by their recognized pathogenic factors, more than antibiotic resistance.     

Renal histology for the diagnosis of primary hyperoxaluria in patients with end-stage renal disease

In patients utilizing continuous ambulatory peritoneal dialysis (CAPD), Staphylococcus epidermidis is the most prevalent organism isolated from peritoneal and exit site infections [1] although clinically significant systemic infection is unusual. We report 2 patients undergoing CAPD who developed generalized lymphadenopathy following peritonitis and exit site infection with S. epidermidis isolated from the excised lymph nodes. We conclude that catheter-related S. epidermidis infection may result in generalized lymphadenopathy due to dissemination of the infective focus.     

Value of automatized blood culture systems in the diagnosis of continuous ambulatory peritoneal dialysis peritonitis

Peritonitis is a common clinical problem that occurs in patients with end-stage renal disease treated by peritoneal dialysis. The aim of this study was to evaluate the value of blood culture systems for the diagnosis of continuous ambulatory peritoneal dialysis (CAPD) peritonitis among 26 samples of peritoneal fluid obtained from patients with the suspicion of CAPD peritonitis. Significant growth was detected in 12 (70.5%) of 17 bacteria-positive samples. The most striking finding was that 8 (66.6%) of these 12 results were obtained only from blood culture bottles. The identified pathogens were methicillin-sensitive coagulase-negative staphylococci (n = 5), alpha-hemolytic streptococci (n = 2), Corynebacterium spp. (n = 2), Escherichia coli (n = 2), and Enterococcus faecalis (n = 1). Using blood culture bottles inoculated with peritoneal fluid at the bedside, rather than submitting the specimen to the laboratory for later processing, is advocated in the prompt diagnosis of CAPD peritonitis.     

Timing and characteristics of multiple peritonitis episodes: a report of the National CAPD Registry

Patterns of recurrent peritonitis episodes were examined in 6,335 new continuous ambulatory peritoneal dialysis (CAPD) patients entered into the National CAPD Registry. Forty-six percent of all peritonitis episodes were initial occurrences, with 8% of the patients reporting four or more episodes. The proportion of gram-positive and gram-negative infections was constant across episodes. In patients with multiple infections, negative organisms were found to have increased risk of recurring as gram-negative infection. A similar observation was made for fungal infections. Of patients with multiple peritonitis episodes, more than 40% of those who transferred to other maintenance renal replacement therapy identified peritonitis as the reason for transfer. A discrete time logistic model was used to estimate peritonitis risk in 4-month follow-up periods. Patients like those on the registry are estimated to have a 22% risk of developing peritonitis during any 4-month period. This risk was increased 4% for patients aged less than 21 years, 7% for nonwhite patients, and 19% in the period following a peritoneal infection.     

Infectious and catheter-related complications in pediatric patients treated with peritoneal dialysis at a single institution

Continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD) are the predominant dialytic modalities for the majority of children while awaiting transplantation. Wide acceptability of peritoneal dialysis is hindered by infectious complications. A retrospective review of 367 pediatric patients treated with CAPD/CCPD for at least 3 months from September 1980 through December 1994 revealed that the peritonitis incidence ranged from 1.7 to 0.78 episodes per patient-year. No differences in peritonitis rates were observed between patients treated with CAPD or CCPD. Gram-positive organisms were responsible for the majority of peritonitis episodes. Age, sex, race, primary renal disease, presence of nephrotic syndrome, and serum albumin level were not associated risk factors. Longer time on treatment and diminished serum IgG level were associated with increased peritonitis incidence. Treatment was successfully completed at home in most cases. Almost half of the catheter losses were caused byStaphylococcus, Pseudomonas, and fungal peritonitis and tunnel/exit-site infections. Infectious complications are still the major causes of morbidity and treatment failure in patients treated with CAPD/CCPD. Thus, controlled studies are needed to assess methods for prevention or improvement of peritonitis rates in this patient population.     

鲎试验在腹膜透析并发革兰氏阴性细菌腹膜炎时的应用

寻求快速诊断腹膜炎的方法，提供选用敏感抗生素的依据。方法应用鲎试验及细菌培养法对５５例次ＣＡＰＤ腹膜炎腹腔引流液标本进行研究，并以非腹膜炎之腹腔引流液标本４０例次作对照。结果Ｇ－细菌腹膜炎１３例，ＬＡＬ全部阳性，敏感性１００％。Ｇ＋细菌性腹膜炎２６例，ＬＡＬ阳性２例（７．６％）。结论ＬＡＬ法是Ｇ－细菌性腹膜炎的快速，简便的诊断方法，为临床早期选用敏感抗生素提供有力证据。     

Coccidioidal peritonitis associated with continuous ambulatory peritoneal dialysis

We report the first three cases of peritonitis due to the fungus Coccidioides immitis occurring during continuous ambulatory peritoneal dialysis (CAPD). At the time of diagnosis, none of the patients had evidence of active infection outside of the peritoneal cavity. Clues suggesting the diagnosis including a previous history of pulmonary coccidioidomycosis, an excess number of eosinophils in the peritoneal fluid, and failure to respond to therapy directed against bacteria. C immitis in peritoneal fluid was more readily isolated on specific fungal culture media than on routine bacterial culture media. In no instances did potassium hydroxide (KOH) preparations of the fluid reveal fungi. Coccidioidal peritonitis during CAPD appears to be a localized form of extrapulmonary coccidioidomycosis that has a relatively benign course once the peritoneal catheter is removed.     

Peritoneal drainage: an important element in host defence against staphylococcal peritonitis in patients on CAPD.

The growth of Staphylococcus aureus and coagulase-negative staphylococci were studied in fresh and effluent peritoneal dialysate from patients on continuous ambulatory peritoneal dialysis (CAPD). Peritoneal drainage during CAPD removes bacterial contaminants from the peritoneal cavity with an efficiency that depends upon the volume of peritoneal fluid remaining after drainage (residual volume). Combination of our data on the growth of coagulase-negative staphylococci in dialysate with a mathematical model of peritoneal drainage during CAPD shows that a residual volume of less than 800 ml (normal = approximately 400 ml) will prevent survival in the peritoneal fluid. A residual volume of less than 200 ml is required to eliminate S. aureus because of its faster rate of growth in dialysate. Previous work has shown that numbers of macrophages are too few to influence bacterial growth in the peritoneal dialysate. Coagulase-negative staphylococci adhere poorly to mesothelial cells in culture. Survival within the peritoneal cavity during CAPD probably depends on colonization of the PD catheter. Coagulase-negative staphylococcal peritonitis is likely to be localized to areas of the peritoneal membrane in close contact with the PD catheter. S. aureus is able to multiply in the peritoneal dialysate during CAPD and thereby causes generalized peritonitis.     

Adult and pediatric peritonitis rates in a home dialysis program: comparison of continuous ambulatory and continuous cycling peritoneal dialysis

We reviewed our 115-month experience with continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD) in adult and pediatric patients to determine whether there is a difference in the incidence of peritonitis between patients performing CAPD or CCPD. Peritonitis rates were similar in patients performing CAPD or CCPD in both the adult and pediatric age groups. The overall CAPD peritonitis rate was significantly lower in adult patients when compared with pediatric patients. There was no difference in peritonitis rates for CCPD between adult and pediatric patients. When the data are divided into 3-year subgroups, the incidence of peritonitis is significantly lower in adult patients undergoing either CAPD or CCPD when compared with pediatric patients during the years 1986 to 1988. There is significant improvement over time in the incidence of peritonitis in both adult and pediatric patients performing CCPD; similarly, there is a trend toward improvement in patients performing CAPD. Staphylococcus species organisms remain the most common bacterial cause of peritonitis, except in pediatric patients under the age of 2 years or with nephrostomies, where gram-negative rod infections were more common. Peritonitis resulted in discontinuation of peritoneal dialysis in a greater number of adult patients. These results suggest that the number of catheter manipulations is not important in determining the incidence of peritonitis. Pediatric patients are more likely than adult patients to develop peritonitis with either CAPD or CCPD. Adult patients are more likely than pediatric patients to discontinue peritoneal dialysis secondary to peritonitis.     

Clonal spread of staphylococci among patients with peritonitis associated with continuous ambulatory peritoneal dialysis

BACKGROUND: Peritonitis is the most important complication of continuous ambulatory peritoneal dialysis (CAPD). Coagulase-negative staphylococci (CNS) are the most common causes of peritonitis, only limited information is available regarding the distribution and epidemiology of different CNS species associated with CAPD peritonitis. METHODS: CNS isolated from dialysis effluent from CAPD patients with peritonitis was identified by species and further analyzed with pulsed-field gel electrophoresis (PFGE). RESULTS: A total of 216 microorganisms (206 bacteria and 10 Candida species) were isolated from 196 consecutive culture-positive CAPD samples obtained from 75 patients. One hundred and twenty-one (56%) isolates represented staphylococci. The four most frequently isolated staphylococcal species were Staphylococcus epidermidis (70 isolates), Staphylococcus aureus (31 isolates), Staphylococcus hemolyticus (10 isolates), and Staphylococcus hominis (4 isolates). PFGE analysis revealed the clonal spread among patients of three different clones of S. epidermidis and one clone of S. aureus among the investigated patients. Indistinguishable isolates of either S. epidermidis, S. hominis, or S. aureus were also isolated in repeated samples from several patients. CONCLUSION: PFGE is a useful method for the epidemiological evaluation of staphylococci-associated CAPD infections and should replace older and less accurate methods, such as antibiotic sensitivity patterns. We recommend that CNS isolates from patients with CAPD-associated peritonitis should be saved for future investigations and typing, which would aid in the management of this patient category.     

Use of pure bicarbonate-buffered peritoneal dialysis fluid reduces the incidence of CAPD peritonitis.

BACKGROUND: Advances in bag connection technology have reduced the incidence of peritonitis in CAPD patients but there is little information on the effect of the new peritoneal dialysis fluids. METHODS: We studied the incidence of CAPD peritonitis for about 3 years in 100 incident patients--50 patients dialysed with lactate-buffered solution, pH 5.5 and containing glucose degradation products (GDP) (lactate group), and 50 patients with pure bicarbonate-buffered solution, pH 7.4 and low GDP (bicarbonate group). Patients in both groups were similar in age, sex, length of time on CAPD, connection technology and handling of dialysis. RESULTS: In the lactate group, 74 episodes of peritonitis were recorded compared with 43 in the bicarbonate group, i.e. one episode per 21 patient-months with the lactate dialysis fluid and one episode per 36 patient-months with the bicarbonate dialysis fluid (OR 0.58, 95% CI 0.37-0.91, P = 0.017). A total of 3369 exchanges per episode of peritonitis were recorded for bicarbonate compared with 2004 exchanges per episode of peritonitis in the lactate group. The majority of organisms isolated in both groups were Gram-positive bacteria, with a predominance of the oropharyngeal and cutaneous endogenous flora. Three episodes of fungal peritonitis occurred in the lactate group and none in the bicarbonate group. CONCLUSIONS: Our results suggest that the pure bicarbonate-buffered peritoneal dialysis fluid appears to reduce the frequency of peritonitis in CAPD patients possibly in relation to greater biocompatibility and maintenance of peritoneal membrane structural integrity. Similar results can probably relate to all low-GDP solutions.