Presentation Authors: Michael Liss*, San Antonio, TX, Kelley Reveles, Austin, TX, Allison Wheeler, Azaneth Arellanes, Timothy Tseng, San Antonio, TX
Introduction: Despite antibiotic prophylaxis, we have noted an increase in patients presenting with infectious complications after urologic stone procedures despite negative urine cultures. Herein, we determine if next-generation sequencing (NGS) could identify bacteria in negative urine culture that would alter prophylactic antibiotic selection.
Methods: We performed NGS and PCR for common resistance genes in subjects prior to ureteroscopy. Of the urine being sent for culture, approximately 5-10mL was sent to Microgen Dx for the analysis. NGS results were blinded to the physician and analysis was done after surgery. Surgery, as scheduled per the physician and prophylaxis antibiotics, was prescribed as the standard of care. After the surgery, we made 3 case studies that were reviewed by ten board-certified Urologists to determine if they would change their prophylactic antibiotic regimen and what antibiotic they would prescribe. Two infectious disease pharmacists also reviewed the case reports and provided the ideal antibiotic regimen to be prescribed.
Results: After IRB approval, we obtained samples from urine specimens provided as a preoperative urine culture from twenty patients scheduled for urologic stone surgery. Two culture returned positive with Enterococcus and the NGS result was the same. One sample had two species (enterococcus and coagulase-negative Staphylococcus), in which NGS was able to find both organisms and speciated the staphylococcus to be staphylococcus epidermidus. Of the 18 cultures with no grow 56% (10/18) did show a dominant-bacteria on NGS. Eight urologists returned the three case scenarios and in each of the 3 cases 100%, 88%, and 88% of the physicians would have prescribed a different prophylaxis antibiotic given these results. The ideal antibiotic of choice based on the ID Pharmacist is oral Bactrim for all cases, yet only 50%, 0%, and 0% selected this option in each of the case scenarios. The proportion of physicians instead chose to escalate the antibiotic to vancomycin, piperacillin/tazobactam, or amikacin in conjunction with a second antibiotic in 38%, 25%, and 63%.
Conclusions: NGS identifies a targetable bacterium in up to 50% of negative urine cultures prior to urologic stone surgery. Care should be taken as to not escalate IV antibiotics rather than utilized oral medications. Working with an infectious disease pharmacist may be helpful in guiding selection and operating room antibiotics based on NGS results.