Sepsis After Kidney Stone Removal: Risks and Pathways

Kidney stone removal is a common procedure, but it carries risks, including post-operative infections that can lead to sepsis. This life-threatening response to infection can cause organ failure and death if not promptly treated. Patients with kidney stones are particularly vulnerable due to bacteria in the urinary tract and complications from surgical interventions.

Common Routes Of Infection

Infections following kidney stone removal typically arise from bacterial entry into the urinary tract during or after the procedure. The most common pathway involves contamination from surgical instruments such as catheters and ureteroscopes. Despite strict sterilization protocols, biofilms on medical devices can serve as persistent reservoirs for pathogens. Biofilms on urinary catheters can develop within 24 hours, significantly increasing infection risk (Tenke et al., 2017, World Journal of Urology).

Residual stone fragments left in the urinary tract can also promote bacterial colonization. Incomplete stone clearance, particularly after extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrolithotomy (PCNL), creates environments where bacteria thrive. Research indicates that patients with retained fragments have a 23% infection rate postoperatively, compared to 8% in those with complete clearance (Mariappan et al., 2005, Journal of Urology).

Reflux of infected urine is another major route of infection, particularly in individuals with vesicoureteral reflux or obstructive uropathy. When bacteria-laden urine is forced back into the kidney due to increased intrarenal pressure during ureteroscopy, it can lead to pyelonephritis and bacteremia. A retrospective analysis found that patients with high intrarenal pressures during ureteroscopy had a 3.5-fold increased risk of febrile UTIs (Traxer et al., 2020, European Urology).

Microbial Factors

The development of sepsis after kidney stone removal is closely linked to bacterial colonization in the urinary tract. Certain microbes pose higher risks due to their virulence, antibiotic resistance, and ability to form biofilms.

Gram-Negative Bacteria

Gram-negative bacteria are the most common pathogens in post-kidney stone removal infections, with Escherichia coli being the leading cause. These bacteria possess lipopolysaccharides (LPS) in their outer membrane, triggering strong inflammatory responses when they enter the bloodstream. Other common gram-negative species include Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa. Proteus mirabilis produces urease, which promotes struvite stone formation and increases the likelihood of persistent infection post-surgery (Armbruster et al., 2018, Nature Reviews Microbiology).

Biofilm formation enhances antibiotic resistance and persistence. Pseudomonas aeruginosa biofilms can survive antibiotic treatment, leading to recurrent infections and increased sepsis risk (Macleod & Stickler, 2021, Journal of Medical Microbiology). Multidrug-resistant Klebsiella pneumoniae strains are increasingly reported in post-surgical infections, sometimes requiring last-resort antibiotics such as carbapenems (Pitout et al., 2022, Clinical Microbiology Reviews).

Gram-Positive Bacteria

Though less common, gram-positive bacteria also contribute to infections after kidney stone removal. Enterococcus faecalis is frequently implicated, particularly in patients with prior antibiotic exposure or prolonged catheterization. It exhibits intrinsic resistance to many antibiotics, complicating treatment (Hollenbeck & Rice, 2012, Clinical Infectious Diseases).

Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA), can cause post-operative infections, particularly via hematogenous spread. While not a typical urinary pathogen, S. aureus can enter the bloodstream through surgical wounds or catheter-related infections, leading to bacteremia and sepsis. Bloodstream infections involving S. aureus are associated with higher mortality rates (Tong et al., 2015, Clinical Microbiology Reviews).

Emerging Resistant Strains

Antibiotic resistance is a growing concern in post-kidney stone removal infections. Extended-spectrum beta-lactamase (ESBL)-producing E. coli and Klebsiella pneumoniae limit the effectiveness of fluoroquinolones and cephalosporins. A multicenter study found ESBL-producing E. coli in 18% of post-ureteroscopy infections, often requiring carbapenems or combination therapy (Tamma et al., 2021, JAMA Network Open).

Carbapenem-resistant Enterobacterales (CRE) and vancomycin-resistant Enterococcus (VRE) further complicate treatment. CRE infections have higher mortality rates due to limited therapeutic options, often necessitating colistin or tigecycline (Bonomo et al., 2018, Clinical Microbiology Reviews). The rise of multidrug-resistant organisms underscores the need for routine preoperative screening and strict infection control measures.

Detection Methods

Early identification of infection is crucial to prevent sepsis. Physicians rely on clinical assessment, laboratory tests, and imaging to confirm bacterial involvement and systemic complications.

Urinalysis and urine culture are primary diagnostic tools. A positive leukocyte esterase or nitrite test suggests infection, while microscopic examination revealing white blood cells and bacteria supports the diagnosis. Urine culture identifies the causative organism and its antibiotic susceptibility. Proper sample collection is essential to avoid contamination.

Blood cultures are critical when systemic infection is suspected. Bacteremia, a precursor to sepsis, is confirmed by culturing blood samples. A study in Clinical Infectious Diseases found that patients with post-kidney stone removal infections and positive blood cultures had a significantly higher risk of septic shock. Elevated inflammatory markers such as C-reactive protein (CRP) and procalcitonin (PCT) can also indicate bacterial infection, with procalcitonin levels above 0.5 ng/mL often signaling sepsis.

Imaging helps identify complications contributing to persistent infection. Computed tomography (CT) scans without contrast are widely used to detect retained stone fragments, abscesses, or urinary obstruction. A retrospective analysis found that 18% of post-percutaneous nephrolithotomy patients with infections had undiagnosed obstructive uropathy visible on CT. Ultrasound, though less sensitive, can help detect hydronephrosis or fluid collections suggesting infection.

Clinical Manifestations

Symptoms of infection after kidney stone removal range from mild discomfort to rapidly progressing sepsis. Early signs mimic urinary tract infections, including dysuria, urgency, and suprapubic pain. As infection spreads, systemic symptoms such as fever, chills, and malaise emerge. Flank pain suggests upper urinary tract involvement, raising concerns for pyelonephritis.

Persistent high fevers above 38.5°C (101.3°F) warrant immediate evaluation for bacteremia. Tachycardia and hypotension may indicate systemic infection. In severe cases, sepsis can lead to altered mental status, a concerning sign of worsening organ dysfunction. A review of hospitalized patients with post-ureteroscopy infections found that those exhibiting confusion or lethargy had a significantly higher risk of ICU admission.

Pathophysiological Mechanisms

Once bacteria enter the urinary tract, they trigger a cascade of pathological processes that can escalate into sepsis. Initially, bacteria adhere to the urothelium, exploiting fimbriae and adhesins to establish infection. If bacteria ascend to the renal parenchyma, they cause pyelonephritis, tissue inflammation, and potential abscess formation. Obstructive uropathy or retained stone fragments facilitate bacterial proliferation by promoting urinary stasis.

Bacterial endotoxins, such as lipopolysaccharides (LPS) from gram-negative organisms and exotoxins from gram-positive bacteria, stimulate a systemic inflammatory response. This leads to the release of cytokines like tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), which disrupt vascular homeostasis. Endothelial dysfunction increases capillary permeability, causing fluid leakage, hypotension, and potential multi-organ failure. Elevated interleukin-10 levels in post-operative sepsis patients correlate with worse outcomes. If untreated, these changes can result in septic shock, characterized by profound circulatory collapse and high mortality rates.

Potential Long-Term Health Consequences

Survivors of sepsis after kidney stone removal may experience lasting health complications. Acute kidney injury (AKI) is common, often resulting from sepsis-induced hypotension and microvascular dysfunction. Reduced renal perfusion can cause ischemic injury, impairing kidney function. Longitudinal studies indicate that up to 30% of patients with sepsis-related AKI progress to chronic kidney disease (CKD) within five years, increasing the risk of end-stage renal failure.

Beyond renal impairment, persistent inflammation and endothelial damage elevate the risk of hypertension and atherosclerosis, leading to cardiovascular complications. Neurologically, post-sepsis syndrome can manifest as cognitive dysfunction, memory deficits, and chronic fatigue. These complications highlight the need for early intervention and long-term monitoring in patients recovering from post-operative sepsis.