Objective: To evaluate the bacteriological features in non-struvite nephrolithiasis and in its associated urinary tract infection, and to establish the relationship between the two pathologies.
Methods: The non-struvite calculi from 132 patients were aseptically extracted by percutaneous nephrolithotomy (PNL). The midstream urine and calculi were bacteriologically and biochemically processed.
Results: Most calculi (78%) were located to renal pelvis, associated with hydronephrosis, the biochemical composition confirming the lack of struvite and revealing the predominance of calcium oxalate. The females presented significantly more colonized calculi (50%) than males (21.9%), with higher bacteriological diversity. There is a significant relation between the presence of colonized calculi and urinary tract infections, 24.2% of calculi and 25.8% of the urine samples presenting positive cultures. In 70.4% of cases, we found the same antibiotic resistance pattern between the pathogens isolated from calculi and urine, thus considering them identical strains. The Enterobacteriaceae represented the most predominant bacteria both from calculi (62.5%) and urine (63.6%), approximatively 30% being resistant to cephalosporins and over 50% resistant to fluoroquinolones, ampicillin and tetracycline. There were 3.8% of cases in which the calculi were colonized but the urine was sterile, the bacteria being sensitive to cephalosporins that are used as prophylaxis.
Conclusions: In all the cases, the same bacterial species was found both in calculi and urine, and 70.4% of them were phenotypically identical. The resistance to the second generation cephalosporins is lower than in the case of other antibiotics, which makes them the most suitable for prophylaxis in PNL.