Repeated centrifuging and washing concentrates bacterial samples in peritoneal dialysis for optimal culture: an original article

Abstract

Background: Bacterial cultures allow the identification of infectious disease pathogens. However, obtaining the results of conventional culture methods is time-consuming, taking at least two days. A more efficient alternative is the use of concentrated bacterial samples to accelerate culture growth. Our study focuses on the development of a high-yield sample concentrating technique.

Results: A total of 71 paired samples were obtained from patients on peritoneal dialysis (PD). The peritoneal dialysates were repeat-centrifuged and then washed with saline, namely the centrifuging and washing method (C&W method). The concentrated samples were Gram-stained and inoculated into culture plates. The equivalent unprocessed dialysates were cultured as the reference method. The times until culture results for the two methods were compared. The reference method yielded no positive Gram stain results, but the C&W method immediately gave positive Gram stain results for 28 samples (p < 0.001). The culture-negative rate was lower in the C&W method (5/71) than in the reference method (13/71) (p = 0.044). The average time for bacterial identification achieved with the C&W method (22.0 h) was shorter compared to using the reference method (72.5 h) (p < 0.001).

Conclusions: The C&W method successfully concentrated bacterial samples and superseded blood culture bottles for developing adequate bacterial cultures. The C&W method may decrease the culture report time, thus improving the treatment of infectious diseases.

Keywords: Bacterial culture; Peritoneal dialysis; Peritonitis; Repeat centrifuging and washing.

Fig. 1

The diagram to report the participants and culture results through the study

Fig. 2

The flow chart of the reference culture method and centrifuging and washing (C&W) method. WBC, white blood cells