What are the criteria for diagnosing sepsis in a patient with a urinary tract infection, chronic kidney disease (CKD), and a history of alcoholism?

Sepsis Diagnostic Criteria

Sepsis is diagnosed when there is documented or suspected infection PLUS life-threatening organ dysfunction, defined as an increase in the Sequential Organ Failure Assessment (SOFA) score of 2 or more points, which correlates with in-hospital mortality exceeding 10%. 1

Core Diagnostic Framework

The SOFA score is the gold standard for identifying sepsis-related organ dysfunction and evaluates six organ systems 1:

• Respiratory dysfunction: PaO2/FiO2 ratio <300 or SpO2 ≤90% 1
• Cardiovascular dysfunction: Systolic blood pressure <90 mmHg, mean arterial pressure <70 mmHg, or vasopressor requirement 1
• Renal dysfunction: Creatinine >2.0 mg/dL (176.8 μmol/L) or urine output <0.5 mL/kg/h for ≥2 hours 1
• Hepatic dysfunction: Bilirubin >2 mg/dL (34.2 μmol/L) 1
• Coagulation dysfunction: Platelets <100,000/μL or INR >1.5 1
• Neurological dysfunction: Altered mental status or decreased Glasgow Coma Scale 1

Alternative Diagnostic Criteria (When SOFA Unavailable)

The Surviving Sepsis Campaign criteria require documented or suspected infection PLUS any of the following 1:

• Temperature >38.3°C or <36°C 1
• Heart rate >90/min or >2 standard deviations above normal for age 1
• Tachypnea 1
• Altered mental status 1
• Significant edema or positive fluid balance (>20 mL/kg over 24 hours) 1
• Hyperglycemia (>140 mg/dL or 7.7 mmol/L) without diabetes 1
• Leukocytosis (WBC >12,000/μL) or leukopenia (WBC <4,000/μL) 1
• Normal WBC with >10% immature forms (bandemia) 1
• Elevated C-reactive protein or procalcitonin (>2 standard deviations above normal) 1

Initial Risk Stratification

Use the NEWS2 scoring system immediately for all patients aged 16 and over with suspected infection to determine urgency of intervention. 2 The NEWS2 assigns points based on seven physiological parameters: respiratory rate, oxygen saturation, supplemental oxygen use, systolic blood pressure, heart rate, level of consciousness, and temperature 2:

• NEWS2 ≥7: High risk of severe illness or death—administer antibiotics within 1 hour, monitor every 30 minutes 2
• NEWS2 5-6: Moderate risk—administer antibiotics within 3 hours, monitor every hour 2
• NEWS2 1-4: Low risk—administer antibiotics within 6 hours, monitor every 4-6 hours 2
• NEWS2 0: Very low risk 2

Essential Laboratory Evaluation

Immediately obtain the following tests when sepsis is suspected 3:

• Serum lactate: Elevated lactate ≥4 mmol/L defines sepsis-induced tissue hypoperfusion requiring aggressive resuscitation; recheck every 2-6 hours during acute resuscitation with target of normalization 3
• Blood cultures: At least 2 sets (aerobic and anaerobic bottles) before antimicrobials if this causes no substantial delay (>45 minutes), with at least one percutaneously and one through each vascular access device unless recently inserted (<48 hours) 3
• Complete blood count: Check for leukocytosis, left-shift, or neutropenia 3
• Comprehensive metabolic panel: Essential to assess baseline renal function (creatinine, eGFR), electrolytes (particularly sodium), and albumin (hypoalbuminemia correlates with bacteremia) 3

Blood Culture Indications

Obtain blood cultures when any of the following are present 4:

• Fever, chills, or hypothermia 4
• Leukocytosis, left-shift of neutrophils, or neutropenia 4
• Hypoalbuminemia 4
• Development of renal failure 4
• Signs of hemodynamic compromise 4
• Diagnosis of urinary tract infection 4

Blood cultures should be taken as soon as possible after onset of fever or chills, ideally immediately before a regular dose of antibiotic to minimize blood levels 4.

Biomarker Interpretation

Procalcitonin (PCT) and C-reactive protein (CRP) are valuable adjuncts but cannot alone differentiate sepsis from other causes of systemic inflammatory response syndrome (SIRS). 4

• PCT ≥1.5 ng/mL: 100% sensitivity and 72% specificity for sepsis; rises more quickly at onset and clears more quickly as inflammation resolves; correlates more closely with severity and predicts mortality 4
• CRP ≥50 mg/L: 98.5% sensitivity and 75% specificity for identifying probable or definite sepsis 4

Daily, sequential measurement of inflammatory markers is more valuable than single measurements 4.

Special Considerations for Your Patient Population

Urinary Tract Infection as Source

In suspected urosepsis, obtain abdominal ultrasound as the first imaging modality due to portability and rapid acquisition. 4 In a retrospective review of 221 patients with first-time bacteremia suspected to be urosepsis, major abnormalities (most commonly pyonephrosis and renal calculi) were found in 32% of patients, with 13% requiring urological intervention 4.

However, if ultrasound is negative or equivocal, proceed immediately to CT abdomen/pelvis with IV contrast, which has an 81.82% positive predictive value for identifying septic foci 4. The genitourinary tract accounts for 20.5% of septic foci in emergency department patients with suspected sepsis 4.

Chronic Kidney Disease Considerations

CKD patients are at significantly increased risk for UTI and urosepsis due to chronic inflammation, metabolic disturbance, and impaired immunocompetence. 5 In this population:

• Pyuria (≥10 leucocytes/µL) is more often observed with oligoanuria and low bacterial colony counts 5
• The diagnosis of UTI is based on standard clinical and laboratory criteria, but interpret in context of baseline renal function 5
• Escherichia coli remains the most common pathogen, but a wide variety of other pathogens may be involved 5

Alcoholism Considerations

Alcoholism significantly enhances the frequency and morbidity of UTI due to defects in humoral and cellular immune mechanisms. 6 Critical concerns include:

• Unusually frequent occurrence of renal papillary necrosis (RPN) in conjunction with pyelonephritis (>90% of RPN cases with alcoholism have pyelonephritis as contributing factor) 6
• Proclivity to medullary ischemia and RPN may result from interstitial renal edema secondary to infection and ethanol effects, plus renal arterial vasoconstriction 6
• Death due to sepsis or renal failure occurs frequently in association with UTI in alcoholics, obliging heightened caution in prevention and treatment 6

Imaging for Source Identification

CT imaging with IV contrast should be performed promptly to confirm infection source, with an 81.82% positive predictive value for identifying septic foci and leading to management changes in 45% of cases. 3

The most common septic foci locations are 4:

• Chest (38.6%): Pneumonia most common
• Abdomen (22.0%): Various intra-abdominal sources
• Pelvis/genitourinary tract (20.5%): Including urosepsis

Hemodynamic Targets

Target mean arterial pressure (MAP) ≥65 mmHg with vasopressors if needed. 3 Additional targets include:

• Central venous oxygen saturation ≥70% (superior vena cava) or ≥65% (mixed venous) if available 3
• Use dynamic variables over static measures to predict fluid responsiveness where available 3

Critical Pitfalls to Avoid

• Do not delay blood cultures or antimicrobials for imaging studies—effective IV antimicrobials must be administered within the first hour of recognizing septic shock 3
• Do not rely on chest radiography alone—sensitivity for pneumonia in severe sepsis/septic shock is only 58% 4
• Do not overlook atypical presentations in elderly, immunocompromised, or chronic disease patients—interpret NEWS2 scores in context of baseline physiology 2
• Do not assume negative urine culture excludes urosepsis—neither pre-operative negative urine culture nor antibiotic prophylaxis avoids infectious complications with certainty 7