BERKELEY, CA (UroToday.com) - Laser lithotripsy and percutaneous nephrolithotomy (PCNL) are common endourological procedures performed for the treatment of nephrolithiasis. These procedures carry the risk of postoperative infection affecting up to 1.8% of patients undergoing ureteroscopy and laser lithotripsy, and 35% undergoing PCNL. Several studies have shown that urosepsis can result despite pre-procedural antibiotics. The purpose of this study was to determine if there is a correlation between urine and/or stone cultures with postoperative sepsis in patients treated for renal and ureteral calculi.
Of the 328 patients in this series, 11 patients (3%) developed sepsis: 9 after laser lithotripsy and 2 after PCNL. The only significant difference between the septic and non-septic groups was positive stone culture (73% vs. 28%, p=0.003). There was no difference in rate of sepsis between the laser lithotripsy and PCNL groups (3% vs. 4%, p=1.00). While 73% (8/11) of the patients who developed sepsis had positive stone cultures, none of the 11 had a positive preoperative urine culture within 12 months of the surgery. Overall, 7% (23/328) of patients had a positive preoperative urine culture. Patients with a positive preoperative urine culture were treated for a median duration of 7 days with a culture-determined antibiotic prior to surgery. Positive stone cultures were obtained in 29% of patients (96/328). Eight percent (8/96) of the patients with positive stone cultures developed sepsis, while 1% (3/232) of patients with negative stone cultures developed infection. With regard to association with postoperative sepsis, the sensitivity of the stone culture was 64%, specificity 72%, positive predictive value 7%, and negative predictive value 98% (see table).
The timing of the preoperative urine culture did not correlate with the development of sepsis, nor did it correlate with the stone culture. Of the 11 patients who developed sepsis, 8 had the preoperative culture drawn 1 week prior to surgery while 3 had the preoperative culture drawn the day before surgery (3% vs. 7%, p=0.16).
The urine culture obtained on admission grew the same pathogen as the stone culture in 64% (7/11) of patients compared to 9% (1/11) of preoperative urine cultures (p=0.02). The stone culture changed the antibiotic regimen in 64% (7/11) of admitted patients. Those 7 patients were discharged on a fluoroquinolone and their antibiotic was switched to vancomycin (4 patients), cefepime (1 patient), and fluconazole (2 patients) after readmission. No readmitted patients had positive blood cultures. The most common pathogens obtained from the stone culture were Gram-positive organisms and yeast. Two of the admitted patients grew Gram-negative organisms on admission urine cultures.
The pathogen causing infection had a significantly higher correlation with the organism grown on stone culture than the preoperative urine culture. The patients who developed sepsis did so despite preoperative antibiotics, and the pathogen grown on the preoperative urine culture was different from that seen postoperatively. These results suggest that stone culture is more informative than preoperative urine culture for determining treatment of postoperative sepsis. An intraoperative stone culture is more reliable than a preoperative urine culture in 1) guiding antibiotic therapy in patients who develop sepsis and 2) identifying patients at risk for postoperative sepsis. We, therefore, recommend that an intraoperative stone culture be routinely obtained.
Association of postoperative sepsis with preoperative urine or stone culture
|
|
Urine Culture |
Stone Culture |
|
Sensitivity |
11% |
64% |
|
Specificity |
91% |
72% |
|
PPV |
4% |
7% |
|
NPV |
96% |
98% |
Written by:
Jairam R. Eswara, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Department of Urology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114 USA
Positive stone culture is associated with a higher rate of sepsis after endourological procedures - Abstract
More Information about Beyond the Abstract