Culture of dialysate in suspected CAPD associated peritonitis using the BacT/Alert system

Comparison of Peritoneal Fluid Culture Results from Adults and Children Undergoing Capd

Background

Peritonitis is a common complication in patients with end-stage renal disease treated by continuous ambulatory peritoneal dialysis (CAPD). Empirical treatment is based on the organisms that are most frequently isolated and their susceptibilities.

Objective

To analyze and then compare peritoneal fluid culture results from adult and pediatric patients on CAPD, with respect to micro-organisms and antimicrobial susceptibilities.

Design

Three-year retrospective review of peritoneal fluid cultures from adults and children on CAPD.

Results

We isolated 481 organisms from 378 peritoneal fluid specimens, collected from 135 patients (45 children, 90 adults). There were 191 episodes of peritonitis in children (mean 4.2 ± 3.5, range 1 – 15) compared to 187 in adults (2.1 ± 1.9, range 1 – 10) ( p < 0.001). Two or more episodes occurred in 30 of 45 children (67%) compared to 33 of 90 adults (37%) ( p < 0.001). The number of different organisms/patient as well as the total number of isolates/patient were significantly greater in children (respectively, 2.8 ± 2.3, range 1 – 12; and 5.3 ± 5.2, range 1 – 27) than in adults (2.0 ± 1.3, range 1 – 6; and 2.7 ± 2.4, range 1 – 10) ( p < 0.005). After Staphylococcus epidermidis, S. aureus was the most frequently isolated organism, occurring in 18% of episodes in adults and 12% of episodes in children ( p < 0.01). Twenty-two of 33 fungal isolates (67%) in children were Candida parapsilosis compared to 3 of 24 (12%) in adults ( p < 0.001). Subanalysis of multiple episodes revealed that Pseudomonas and Candida occurred significantly more often in children ( p < 0.01), whereas S. aureus occurred more often in adults ( p < 0.001). In polymicrobial episodes S. epidermidis occurred more often in adults ( p < 0.05). Significant differences in susceptibilities to ampicillin, ceftriaxone, chloramphenicol, and gentamicin were found between children and adults ( p < 0.05 – 0.001).

Conclusions

CAPD-associated peritonitis occurs significantly more often in children than adults. Significant differences in microbial etiology and susceptibilities were found between pediatric and adult patients. Each dialysis unit should periodically analyze peritoneal fluid culture results from its CAPD patients. These data can then be used for optimization of empirical antimicrobial therapy of peritonitis.

Time to Positivity of Bacteria Cultures in Peritoneal Dialysis Fluid: Evaluation of Different Laboratory Techniques

Patients with chronic kidney disease on peritoneal dialysis (PD) are susceptible to infections, with peritonitis being the primary cause of dropout. Peritoneal fluid culture is one of the essential elements for proper diagnosis and peritonitis treatment. The aim of this study was to compare the time required to obtain a positive culture using different laboratory methods. An in vitro cross-sectional study was conducted comparing different techniques for preparation and culture of bacteria in peritoneal fluid. The research was carried out with 21 sterile dialysis bags and 21 PD bags containing peritoneal fluid drained from patients without peritonitis. Fluids from the 42 PD bags were contaminated by injecting a coagulase-negative Staphylococcus suspension and then prepared for culture using 4 distinct techniques: A - direct culture; B - post-centrifugation culture; C - direct culture after 4 h sedimentation; and D - culture after 4 h sedimentation and centrifugation. This was followed by seeding. In the 21 contaminated sterile bags, mean times to obtain a positive culture with techniques D (19.6 h ± 2.6) and C (19.1 h ± 2.3) were longer than with technique A (15.8 h ± 3.0; p < 0.01), but not statistically different from group B (19.0 h ± 3.2). The same occurred in the 21 bags drained from patients, with mean times for techniques D (14.0 h ± 1.9) and C (14.5 h ± 1.7) being longer than technique A (12.22 h ± 1.94; p < 0.05) but not statistically different from technique B (13.2 h ± 1.3). The sedimentation and centrifugation steps seem to be unnecessary and may delay antibiotic sensitivity test results by approximately 8 hours.

Epidemiology of culture isolates from peritoneal dialysis peritonitis patients in southern India using an automated blood culture system to culture peritoneal dialysate

AIM

Continuous ambulatory peritoneal dialysis (CAPD) is a major form of therapy for chronic end stage renal disease patients, which may lead to CAPD-associated peritonitis. The spectrum of organisms associated with CAPD peritonitis varies geographically. Not much data is available regarding this from southern India. The aim of this study was to characterize the spectrum of organisms associated with CAPD peritonitis in this region and observe the utility of automated blood culture systems to culture peritoneal dialysate.

METHODS

Ninety episodes of peritonitis were cultured over a span of 3 years using an automated blood culture system.

RESULTS

The yield of culture positivity was 50%. The most predominant organism was found to be coagulase-negative Staphylococcus spp. (21.1%) followed by Enterobacteriaceae (12.2%). Other organisms isolated were non-fermenting Gram-negative bacilli (4.4%), Pseudomonas aeruginosa (3.3%), α-haemolytic Streptococci (3.3%), Candida spp. (2.2%), Staphylococcus aureus (1.1%), β-haemolytic Streptococci (1.1%) and Micrococci (1.1%). A high degree of resistance to third generation cephalosporins (66.7%) was noted amongst the Gram-negative bacilli. Also, all the Gram-negative bacilli isolated from patients who had prior empirical antibiotic therapy of ceftazidime before arrival at the centre, were resistant to third generation cephalosporins.

CONCLUSION

A varied spectrum of organisms isolated from peritoneal dialysate compared to the global scenario was observed. Also, a high degree of third generation cephalosporin resistance was noted amongst the Gram-negative bacilli. Thus, it is suggested that the empirical therapy should be dependent on the local epidemiology.

Detecting bacterial growth in continuous ambulatory peritoneal dialysis effluent using two culture methods

BACKGROUND/AIMS

The aim of this study was to evaluate the peritonitis-causing bacteria detected in peritoneal fluid using a blood culture bottle in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).

METHODS

One-hundred and eleven dialysates from 43 patients suspected of peritonitis related to CAPD were retrospectively evaluated between May 2000 and February 2008. In all cases, 5 to 10 mL of dialysate was inoculated into a pair of BacT/Alert blood culture bottles, and 50 mL of centrifuged dialysate was simultaneously inoculated into a solid culture media for conventional culture. The results were compared to those of the conventional culture method. Isolated microorganisms were compared between the two methods.

RESULTS

The blood culture method was positive in 78.6% (88 / 112) of dialysate specimens and the conventional culture method in 50% (56 / 112, p < 0.001).

CONCLUSIONS

The blood culture method using the BacT/Alert system is useful for culturing dialysates and improves the positive culture rate in patients with suspected peritonitis compared to the conventional culture method.

Continuous ambulatory peritoneal dialysis peritonitis: broth inoculation culture versus water lysis method

BACKGROUND/AIM

In the setting of empiric antibiotic treatment of peritoneal-dialysis-related peritonitis complications, the speed with which a bacteriological diagnosis can be achieved is of importance. We compare the clinical performance of two culture methods to diagnose the causative microorganisms as suggested by the International Society for Peritoneal Dialysis and the United Kingdom Health Protection Agency.

METHODS

We prospectively evaluated microbiological cultures of peritoneal fluid samples by the direct broth culture versus water lysis. Samples from 17 consecutive patients with dialysis-associated peritonitis were examined.

RESULTS

Of the 17 dialysates cultured, 14 (82.4%) were positive by one of the two methods. The final culture results agreed in 16 of 17 specimens (94.1%). The preliminary organism identification rate by Gram staining with the broth culture method was 70.6%, which was significantly greater than 17.6% by the water lysis method (p = 0.0019). In particular, the broth culture technique demonstrated superior Gram stain performance to identify Gram-positive organisms. Among the 13 dialysate samples positive by both methods, the broth culture method detected organisms faster than the water lysis method (1.3 +/- 0.7 vs. 2.6 +/- 1.6 days, p = 0.005).

CONCLUSIONS

Our results support the routine use of the broth culture technique using BacT/Alert blood culture bottles in order to facilitate early streamlining of empiric antibiotic therapy. Gram staining of sediments after centrifugation is associated with low diagnostic yield. Whether the lysis-centrifugation technique could provide additional value in case of peritonitis with a high likelihood of culture-negative results needs to be evaluated.

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.

Evaluation of the BacT/Alert microbial detection system with FAN aerobic and FAN anaerobic bottles for culturing normally sterile body fluids other than blood

We evaluated the BacT/Alert Microbial Detection System (Organon Teknika Corporation, Durham, NC, USA) by using FAN bottles compared to conventional culture methods for the recovery of microorganisms from normally sterile body fluids other than blood and dialysates. Clinically significant pathogens were isolated from 116 (11%) of 1, 099 consecutive specimens (80 from both conventional media and FAN bottles; 23 from FAN bottles only; 13 from conventional media only). Gram-positive cocci were more likely to be recovered from FAN bottles than from conventional media (p = 0.04). Contaminants were also more likely to have grown in FAN bottles (3%) than on conventional media (1%) (p = 0.04). The mean time to detection of significant pathogens was 20.9 h using FAN bottles as compared to 30. 9 h using conventional media (p = 0.0001). These results indicate that the BacT/Alert Microbial Detection System using FAN blood culture bottles improves the yield of clinically significant Gram-positive isolates from normally sterile body fluids with a reduced time to detection.