Patients with kidney stones that need surgical treatment are at risk of urinary tract infection, and sometimes sepsis. Stones often have bacteria attached to them, and these bacteria can be hard to eliminate. A recent study from Tel Aviv University looked at post-operative infection in patients undergoing percutaneous nephrolithotomy (PCNL).
Stone samples retrieved during surgery were sent for culture, to see if there were bacteria associated with the kidney stones.
Urinary sepsis (an infection that spreads from urine into the bloodstream and causes a patient to be unwell) occurred in 31% of patients who had a positive stone culture, compared to 5.9% of those patients who had a negative stone culture. E coli (gram negative bacteria) and Enterococcus sp. (gram positive bacteria) were the most common organisms found.
The problem is that it takes a number of days for the culture to come back, and the patient will have developed sepsis by that time. However, what it does highlight is that doing a urine culture 1 to 2 weeks before PCNL surgery can help the situation. If the urine culture is positive, the patient should have a course of antibiotics for 7 days to try to sterilise the urine, and then intravenous antibiotics at the time of surgery. If the urine is sterile pre-operatively, then intravenous antibiotics at the time of surgery are sufficient.
Two other interesting points were raised. First, that resistance to ciprofloxacin and norfloxacin was high, and this is something that is of concern. These antibiotics may be overused in the general population, causing resistance. This is something we are also seeing in patients who need a prostate biopsy for a raised PSA.
Second, we know that some patients cannot reach a point where the urine is sterile (free of bacteria) if they have stones, because the stones themselves are colonised with bacteria, and antibiotics cannot get into stones. These patients pose a specific problem and are at higher risk of infection.
Reference - Ohad Shoshany et al. Percutaneous nephrolithotomy for infection stones: what is the risk for postoperative sepsis? A retrospective cohort study. Urolithiasis (online) 01 Jan 2015
You can read more about kidney stone surgery and the risk of infection by following this link to an article by Michael Wong.