Analysis of Pathogens and Calculus Components in Patients with Urolithiasis Complicated with Urosepsis

Abstract

Objective: The incidence of urolithiasis is high in Yingde Area, and the incidence of urolithiasis complicated with urinary tract infection (UTI), especially urosepsis, is also high, which poses great challenges to clinical treatment. In addition, the negative rate of pathogen detection for this disease is high, and the composition of pathogens and calculus components has not been reported yet. Methods: This study retrospectively analyzed 450 patients with urolithiasis complicated by urinary tract infection who were admitted to the People’s Hospital of Yingde City between 2015 and 2024. The study population included 199 patients in the uncomplicated UTI group, 127 in the preoperative urosepsis group, 72 in the pyonephrosis group, and 31 in the non-infection group. Patient sex distribution, pathogen profiles from urine cultures, pathogen distribution associated with urinary nitrite positivity, stone composition, and pathogen distribution from blood cultures were systematically analyzed.  Results: The distributions of sex, urinary pathogen profiles, urinary nitrite status, stone composition, and blood culture results across different patient groups are summarized in Tables 1–5. A female predominance was observed among patients with severe infections. In the pre-hospital urosepsis group, females accounted for 74.8% of the cases, while all patients in the postoperative urosepsis group were female. Urine culture results showed that the proportion of culture-negative cases decreased with increasing infection severity. The urine culture negative rate was 78.6% in the uncomplicated UTI group, 55.6% in the pyonephrosis group (60 of 72 patients underwent urine culture), 63.0% in the pre-hospital urosepsis group, and 38.1% in the postoperative urosepsis group. Among culture-positive urine samples, Escherichia coli was the most frequently identified pathogen across all groups. Blood culture analysis in patients with urosepsis revealed similar negative rates between the pre-hospital and postoperative groups (52.9% and 52.4%, respectively). Among culture-positive blood samples, E. coli was the predominant pathogen in both groups, while Enterococcus faecium was identified only in the postoperative urosepsis group. Urinary nitrite positivity increased with infection severity. The positive rates were 0% in the non-infection group, 8.5% in the uncomplicated UTI group, 29.2% in the pyonephrosis group, 24.4% in the pre-hospital urosepsis group, and 33.3% in the postoperative urosepsis group. Analysis of stone composition revealed that calcium oxalate–based calculi were the most common type in all groups. Calcium oxalate monohydrate combined with calcium oxalate dihydrate was the predominant component in the non-infection group (58.1%), uncomplicated UTI group (43.4%), pyonephrosis group (33.3%), and pre-hospital urosepsis group (33.1%). In both urosepsis groups, a subset of cases contained carbonate apatite (14.3% in the postoperative group and 12.6% in the pre-hospital group). Notably, L-cystine and pure calcium oxalate monohydrate were observed only in the pre-hospital urosepsis group (1.6% and 0.8%, respectively).  Conclusion: Escherichia coli was the most frequently identified pathogen in patients with urolithiasis complicated by urosepsis. Notably, Enterococcus faecium was detected exclusively in patients with postoperative urosepsis, indicating that Gram-positive coccal infections in this population should not be overlooked. The predominant calculus components in both urosepsis groups were calcium oxalate–based stones, with a subset of cases containing carbonate apatite. In addition, struvite calculi were rarely observed, whereas carbonate apatite was present in a considerable proportion of cases, warranting clinical attention.