European Journal of Cardiovascular Medicine

Sepsis is a life-threatening condition characterized by a dysregulated host response to infection, leading to organ dysfunction and, in many cases, death^1,2. Globally, sepsis affects approximately 30 million people annually and is responsible for up to 6 million deaths¹. Early identification and appropriate antimicrobial therapy are critical for improving survival rates.

Blood and body fluid cultures remain the gold standard of microbial diagnosis in sepsis⁶. However, 30–65% of patients with sepsis may have negative culture results, leading to uncertainty in treatment decisions³. Culture-negative sepsis is often attributed to prior antibiotic use, fastidious organisms, or inadequate sampling. Comparatively, culture-positive sepsis has been associated with more severe illness and worse outcomes in several studies^3,4.

This study aims to compare the clinical outcomes of culture-positive and culture-negative sepsis admitted to the medicine ward of Assam Medical College and Hospital (AMCH), Dibrugarh.

Study Site: Department of General Medicine, Assam Medical College and Hospital.

Study Design: A hospital-based observational study.

Study Duration: 6 months (January 2024 to June 2024)

Study population: Considering the prevalence (P) of sepsis cases in India⁵ to be 28.3% and taking absolute error (d) of 10% with 95% confidence interval, the sample size calculated is 78 which is then rounded off to obtain the final sample size of 80. The purpose of the study was explained and informed consent was obtained from parents or patients in vernacular language.

Inclusion Criteria:

1. Adults (>18 years) diagnosed with sepsis based on Sepsis-3 criteria
2. Patients admitted to the medicine ward

Exclusion Criteria:

1. Patients < 18 years of age.
2. Patients refuse to give consent.
3. Patients with pre-existing organ dysfunction
4. Malignancy on chemotherapy
5. Pulmonary thromboembolism
6. Pregnant or postpartum women.
7. Patients transferred from MICU after more than 24 hours

Data Collection: Patients fulfilling the inclusion criteria were included in the study. Demographic data with detailed history and clinical examination were done along with routine investigations.

The following investigations were performed within 24 hours of admission-

• complete blood count with ESR
• serum electrolytes,
• renal and liver function tests,
• serum electrolytes
• viral markers for hepatitis B, C and HIV
• routine urine examination
• urine culture and sensitivity
• arterial blood gas analysis,
• Hs-CRP.

Blood samples collected under aseptic conditions were inoculated immediately into the blood culture bottle (aerobic blood culture bottle). Once received in the microbiology laboratory, the blood culture bottles were loaded into the BACTALERT-480 Automated blood culture system. The bacterial isolates were identified from the positive vial by gram stain, colony morphology on blood agar, chocolate agar, and MacConkey agar, and by standard biochemical tests⁷

Ethical statement: Ethical clearance was obtained from the Institutional Ethics Committee (IEC) of Assam Medical College and Hospital (Human)

Statistical Analysis: Data were analysed using SPSS v20. Continuous variables were expressed as mean ± SD and compared using the Students’ t-test. Categorical variables were expressed as numbers and percentages and compared using the chi-square test. A p-value <0.05 was considered statistically significant.

Table -1: Gender Distribution

Table -2: Age wise distribution

Table–3: Status of Body Fluid Cultures

Table–4: Positive Culture

Table–5: Causative organism in cultures

Table 6: Comparison of clinical outcomes between culture positive and culture negative

In the present study, majority of patients were male i.e, 49 (61.25%) and 31 (38.75%) were female.

The mean age of the population was 48±13 years. Out of 80 cases, majority were in the 41-50 age group i.e, 29 (36.25%) followed by 51-60 age group i.e, 18 (22.50%). There were 15 (18.75%) patients above the age of 60 and 18 (22.5%) below the age of 40.

33 (41.25%) were culture-positive and 47 (58.75%) were culture-negative.

Positive cultures were mainly from urine and sputum (30.3% each), followed by blood (15.15%) and wounds/others (12.12% each).

Escherichia coli was the most frequently isolated organism in 13 cases (39.4%). This was followed by Staphylococcus aureus in 6 cases (18.18%), Klebsiella in 5 cases (15.2%), Pneumococci in 5 cases (15.1%), and Pseudomonas in 4 cases (12.12%). Overall, gram-negative organisms predominated with E. coli leading as the primary causative organism.

The need for ICU care was high in both groups (84.8% vs. 78.7%). Similarly, the requirement for mechanical ventilation was comparable (60.6% vs. 61.7%) as was the use of vasopressors (57.6% vs. 61.7%). However, mortality was notably higher in the culture-positive group (75.8%) compared to the culture-negative group (42.5%) suggesting a potentially worse prognosis in culture-positive sepsis.

The worse outcomes in culture-positive sepsis could be due to higher bacterial burden, delayed antimicrobial initiation or resistant organisms.

Culture-negative sepsis may represent cases where the infection was partially treated or where non-bacterial pathogens were involved.

Interestingly, there was no significant difference in ICU admission, need for mechanical ventilation and inotropic support between the groups, suggesting that even culture-negative sepsis carries a substantial burden of illness.

The predominance of gram-negative pathogens calls for heightened vigilance and appropriate empirical antimicrobial therapy. Future research should focus on improving diagnostic yield in culture-negative sepsis and exploring rapid molecular diagnostics to optimize care.

Limitations:

1. Single-Center Study: The research was conducted in a single tertiary care hospital, which may limit the generalizability of findings to other settings or populations.
2. Short Study Duration: A six-month period may not capture seasonal variations in microbial patterns or sepsis incidence.
3. Small Sample Size: With only 80 patients included, subgroup analysis and broader conclusions may be constrained by limited statistical power.
4. Lack of Advanced Diagnostic Methods: Only conventional culture techniques were used, which may have failed to identify fastidious or non-bacterial pathogens, leading to a high rate (58.75%) of culture-negative cases.
5. No Follow-Up Beyond Hospital Stay: Long-term outcomes such as 30-day or 90-day mortality, readmission rates, or recovery trajectory were not assessed.

Declaration of Interests: There are no conflicts of interest.

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