Introduction:
PCNL is the standard surgical procedure for larger renal stones measuring >2cm, and smaller stones not amenable to therapy with other techniques. PCNL is associated with a low injury rate, better efficacy, and faster recovery. Despite improvements in technology, PCNL is still associated with complications such as bleeding, systemic inflammatory response syndrome (SIRS), sepsis, and injury to the renal collecting system. 
Urosepsis is rare but the most common cause of mortality in patients undergoing PCNL and it may occur despite having a negative pre-operative culture and aseptic surgical technique. The identifiable risk factors for infectious complications post PCNL include female gender, diabetes mellitus, preoperative stenting, elevated leukocyte count, hydronephrosis, multiple puncture access, positive preoperative urine culture, pyuria, stone size, intraoperative lavage rate, positive renal pelvis urine culture (RPUC), positive stone culture (SC), infectious stones, longer operative time, postoperative residual stone, and perioperative blood transfusion. Preoperative midstream urine cultures (PMUC) are usually obtained to predict infectious complications post PCNL, still, studies have shown that despite having negative (PMUC) and receiving antibiotic prophylaxis, patients have developed SIRS or sepsis in their postoperative period. 
SIRS Criteria may be defined as two or more of the following: (1) Body temperature >38°C or < 36∘C; (2) Heart rate >90 bpm; (3) Respiratory rate >20 breaths/min or PaCO2 <32mmHg; (4) White blood cell count >12,000/mm3 or <4,000/mm3. Sepsis is defined by the presence of both SIRS and suspicion or confirmation of urinary pathogen. 
Positive PMUC, RPUC, or SC has been linked in several studies to the emergence of post-PCNL SIRS/sepsis but the results are inconsistent. In this study, we aim to evaluate the association of pre-operative midstream urine culture (PMUC), renal pelvis urine culture (RPUC), and stone culture (SC) and their association with postoperative SIRS or sepsis in patients undergoing PCNL.
OBJECTIVE:
To determine the association of pre-operative midstream urine culture (PMUC), renal pelvis urine culture (RPUC), and stone culture (SC) results and to assess their role in the development of SIRS/sepsis in patients undergoing PCNL.

Study Design: Prospective Cohort Study

All the patients diagnosed with renal stones and undergoing PCNL were selected as per inclusion criteria. PUC was obtained from all the patients planned for PCNL. RPUC samples were collected during the puncture for PCNL. Extracted stone fragments were also sent for culture.

A total of 25 patients underwent PCNL. Positive rates of PUC, RPUC, and SC were 12% (3/25), 28% (7/25), and 36% (9/25) respectively. 20% (5/25) of patients had both positive RPUC and SC, similar organism was found in 8% (2/25). Positive PUC demonstrated multidrug-susceptible E.coli, while RPUC showed a variety of organisms including MDR Enterobacter, drug-susceptible E.coli, and Pseudomonas aeruginosa. SC demonstrated MDR Enterobacter, MDR Klebsiella, E.coli, and Proteus mirabilis. The incidence of post-PCNL SIRS and sepsis was 20% (5/25), and all patients had positive cultures. Among them 12% (3/25) had both RPUC and SC positive, 4% (1/25) had RPUC positive, and 4% (1/25) had SC positive.

PUC was obtained from all the patients planned for PCNL. RPUC samples were collected during the puncture for PCNL. Extracted stone fragments were also sent for culture. We analysed the concordance between cultures and association with postoperative SIRS or sepsis.

PUC doesn’t reflect the same microbiological environment found in urine obtained from renal pelvis and stones. Patients who developed SIRS and sepsis had negative PUC with positive RPUC or SC. RPUC and SC can guide appropriate antibiotics for patients developing post-PCNL SIRS or sepsis. Hence, we recommend performing RPUC and SC to better predict and manage SIRS or sepsis.

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