Improving peritoneal dialysis fluid culture-positivity yield from 2022 to 2023

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Nephrology

Background:

• Peritonitis diagnosis via microbiological testing of peritoneal dialysis (PD) bags frequently results in culture-negative samples, exceeding the International Society for Peritoneal Dialysis recommended threshold of 15%.

Purpose of the Study:

• To evaluate the impact of implementing a blood culture (B/C) bottle incubation step on the culture-positivity yield and culture-negative percentage in PD bag testing.
• To determine if the revised methodology reduces the incidence of culture-negative results, a critical factor in peritonitis management.

Main Methods:

• A retrospective analysis of data from the National Health Laboratory Services (NHLS) Central Data Warehouse (CDW) was conducted.
• Culture-positive and culture-negative results were compared between two periods: June-December 2022 (non-B/C bottle method) and January-July 2023 (B/C bottle method).

Main Results:

• The implementation of the B/C bottle method significantly increased culture-positivity yield from 23% to 51% compared to the non-B/C bottle method.
• Despite the improved positivity rate, the culture-negative yield remained high at 49% with the B/C bottle method.

Conclusions:

• The addition of the B/C bottle incubation step more than doubled the culture-positivity yield for microbiological testing of PD bags.
• The persistently high percentage of culture-negative results necessitates further modifications to the laboratory methodology to optimize peritonitis diagnosis and patient management.