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Prolonged Antibiotic Exposure Within 90 Days of Percutaneous Nephrolithotomy is Not a Risk Factor for Yeast Growth in Renal Stone Culture
Fern Calkins, B.S.¹, Architha Sudhakar, MD², Evelyn James, M.S.², Erin Santos, PA-C², David W. Sobel, MD^2
1Tufts University School of Medicine, Boston, MA, USA, ²Division of Urology, Maine Medical Center, Portland, ME, USA

Background:Sepsis following percutaneous nephrolithotomy (PCNL) is a well-studied postoperative morbidity. While bacterial species are commonly considered in perioperative antimicrobial prophylaxis, yeast is not frequently described as a pathogenic microorganism. We previously demonstrated an increased incidence of Candida growth in renal stone culture (RSC) amongst patients with high sepsis risk criteria undergoing PCNL. A history of sepsis within three months was significantly associated with yeast growth in stone culture. As increased antibiotic exposure has been associated with Candida growth, we examined the association between prolonged antibiotic use with yeast growth in RSC and postoperative sepsis in patients undergoing PCNL.
Methods:An IRB-approved retrospective review was conducted of all PCNLs procedures performed at a single tertiary care institution from October 2016 through February 2023. Antibiotics prescribed within 90 days of procedure were recorded, including number of agents and number of days per agent. Antibiotics were only recorded if confirmed through electronic medical record query, or prescription was noted in provider documentation. We analyzed the association between antibiotic exposure and incidence of yeast growth in RSC and postoperative sepsis.
Results:Of 258 procedures, 91 (35%) demonstrated positive RSC. Analyses showed an association between positive RSC and duration of antibiotic exposure (p<0.01) but did not show an association between positive RSC and number of antibiotics prescribed. Within the population of positive RSC, 23/91 (25%) grew yeast. Neither antibiotic duration nor number of antibiotics prescribed were statistically associated with yeast growth. Eighteen procedures of 258 (7%) resulted in postoperative sepsis. Duration of antibiotic exposure was associated with development of sepsis (p<0.01), while number of antibiotic courses were not.
Conclusion:There is a well characterized link between chronic antibiotic exposure and Candida growth. Patients with a history of sepsis may be at risk for prolonged antibiotic exposure while awaiting PCNL. We found significant correlations between total days of antibiotics in the 90 days leading up to PCNL and positive RSC and postoperative sepsis. However, yeast growth in RSC was not associated with antibiotic duration or number of antibiotics prescribed. Our results support efforts to improve antibiotic stewardship and minimize delay to definitive stone surgery to lower sepsis risk.
Table 1:
Positive Renal Stone Culture (RSC) and duration and number of antibiotics prescribed:

		Negative RSC(N=167)	Positive RSC(N=91)	Overall(N=258)
Total days of antibiotics
Median [IQR]		8.00 [12.0]	14.0 [23.5]	10.0 [15.3]	P <0.01*
Number of antibiotics prescribed
Median [IQR]		2.00 [2.00]	2.00 [1.00]	2.00 [2.00]	P = 0.63

Postoperative Sepsis and duration and number of antibiotics prescribed:

	No sepsis(N=240)	Sepsis(N=18)	Overall(N=258)
Total days of antibiotics
Median [IQR]	10.0 [14.0]	26.5 [33.0]	10.0 [14.0]	P <0.01*
Number of antibiotics prescribed
Median [IQR]	2.00 [2.00]	2.00 [1.50]	2.00 [2.00]	P = 0.25

Presence of Yeast in renal stone culture and duration and number of antibiotics prescribed:

	No Yeast in RSC(N=68)		Yeast in RSC(N=23)	Overall(N=91)
Total days of antibiotics
Median [IQR]	12.5 [21.0]		23.0 [23.0]	14.0 [23.5]	P = 0.19
Number of antibiotics prescribed
Median [IQR]	2.00 [1.25]		2.00 [2.00]	2.00 [2.00]	P = 0.38

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