Association of Local Unit Sampling and Microbiology Laboratory Culture Practices With the Ability to Identify Causative Pathogens in Peritoneal Dialysis-Associated Peritonitis in Thailand

Abstract

Introduction This describes variations in facility peritoneal dialysis (PD) effluent (PDE) culture techniques and local microbiology laboratory practices, competencies, and quality assurance associated with peritonitis, with a specific emphasis on factors associated with culture-negative peritonitis (CNP). Methods Peritonitis data were prospectively collected from 22 Thai PD centers between May 2016 and October 2017 as part of the Peritoneal Dialysis Outcomes and Practice Patterns Study. The first cloudy PD bags from PD participants with suspected peritonitis were sent to local and central laboratories for comparison of pathogen identification. The associations between these characteristics and CNP were evaluated. Results CNP was significantly more frequent in local laboratories (38%) compared with paired PDE samples sent to the central laboratory (12%, P < 0.05). Marked variations were observed in PD center practices, particularly with respect to specimen collection and processing, which often deviated from International Society for Peritoneal Dialysis Guideline recommendations, and laboratory capacities, capabilities, and certification. Lower rates of CNP were associated with PD nurse specimen collection, centrifugation of PDE, immediate transfer of samples to the laboratory, larger hospital size, larger PD unit size, availability of an on-site nephrologist, higher laboratory capacity, and laboratory ability to perform aerobic cultures, undertake standard operating procedures in antimicrobial susceptibilities, and obtain local accreditation. Conclusion There were large variations in PD center and laboratory capacities, capabilities, and practices, which in turn were associated with the likelihood of culturing and correctly identifying organisms responsible for causing PD-associated peritonitis. Deviations in practice from International Society for Peritoneal Dialysis guideline recommendations were associated with higher CNP rates.

ISPD peritonitis guideline recommendations: 2022 update on prevention and treatment

“…144,145 The specimens should arrive at the laboratory within 6 h. If immediate delivery to the laboratory is not possible, the inoculated culture bottles should ideally be incubated at 37 C. Inoculated bottles should not be refrigerated or frozen, since it may kill or retard the growth of some microorganisms. 146 The solid media should be incubated in aerobic, microaerophilic and anaerobic environments. To fully assess yeast and filamentous fungal pathogens, appropriate fungal media should be selected; incubation of inoculated media under two temperature conditions (room temperature and 35-37 C) can increase the diagnostic yield.…”

“…146 Notably, experience of the centre is important because culture-negative peritonitis rates frequently show an inverse relationship with the PD centre size. 38,146 When cultures remain negative after 3-5 days of incubation, PD effluent should be sent for repeat cell count, differential count, fungal and mycobacterial culture. In addition, subculture on media with aerobic, anaerobic and microaerophilic incubation conditions for a further 3-4 days may help to identify slow-growing fastidious bacteria and yeasts that are undetectable in some automated culture systems.…”

“…To fully assess yeast and filamentous fungal pathogens, appropriate fungal media should be selected; incubation of inoculated media under two temperature conditions (room temperature and 35–37°C) can increase the diagnostic yield. 146…”

Predictors and outcomes of peritoneal dialysis-related infections due to filamentous molds (MycoPDICS)

“…This finding may have reflected a lack of clinician appreciation of the virulence of mold peritonitis in Thailand. Since most Thai PD facilities (91%) have limited ability to culture filamentous mold [ 28 ], the attending nephrologists may also have had limited experience treating fungal peritonitis and limited access to infectious disease specialists. Moreover, some facilities might have had limited facility HD backup support, resulting in a reluctance to remove the PD catheter and subsequent deviation in practice from the ISPD Guideline recommendation.…”

The first human report of Hyphopichia burtonii, initially misdiagnosed as sterile peritonitis in a patient on peritoneal dialysis

“…Cultivation of this specific organism in media with a high water activity (>0.98) or at a higher temperature than 30 °C (maximal temperature of 37 °C) significantly slow its growth [ 16 ]; therefore, traditional bacterial broth (water activity, 0.99) incubated at 37 °C may prevent growth of this rare yeast. Appropriate media should be selected to detect fungal pathogens, and incubation at different temperature conditions are recommended (room temperature and 35–37 °C) [ 19 ].…”