The identification of causative microorganisms in sepsis plays a vital role in patient management and prognosis. Sepsis can result from a broad spectrum of bacterial and fungal pathogens, each with varying degrees of antimicrobial resistance. As highlighted in previous studies, including the work by Vendemiato et al⁵ common causative agents include Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and multidrug-resistant organisms such as Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA). Accurate microbiological identification not only facilitates targeted antimicrobial therapy but also helps curb the inappropriate use of broad-spectrum antibiotics, which contributes to resistance. Given that early and appropriate antibiotic intervention significantly reduces mortality in sepsis, microbiological confirmation through blood culture remains an essential diagnostic and therapeutic tool in clinical practice.

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 India⁶ 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 for the diagnosis of sepsis.

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 tests⁴.

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: Distribution of study subjects by types of primary disease on presentation

Table–4: Status of Body Fluid Cultures

Table–4: Positive Culture

Table–5: Causative organism in cultures

The study reveals that respiratory tract infections (27.5%) and urinary tract infections (20%) were the most common presenting illnesses, followed by acute encephalitis syndrome (16.2%) and endocarditis (11.3%). Correspondingly, urine (25.53%) and sputum (21.3%) were the most frequent positive culture sources, reflecting the clinical burden of urinary and respiratory infections. Blood cultures accounted for 19.14%, highlighting the importance of bloodstream infections, while CSF and pleural fluid contributed smaller proportions.

Regarding the cultures, a major proportion of cultures (41.25%) showed no growth, which may reflect prior antibiotic use, inadequate sample collection, or the presence of fastidious organisms not detected by routine culture methods.

Among the positive cultures, Escherichia coli was the most frequently isolated organism (25.53%), consistent with its well-established role as a predominant pathogen in both community-acquired and healthcare-associated infections, particularly urinary tract and bloodstream infections⁷.

Klebsiella pneumoniae (17.02%) and Klebsiella oxytoca (10.64%) were also common isolates, highlighting the increasing clinical significance of Klebsiella species, which are often associated with multidrug resistance and extended-spectrum beta-lactamase (ESBL) production⁸.

The detection of Staphylococcus aureus in 14.9% of cultures, including the possibility of methicillin-resistant strains, highlights its importance in both skin/soft tissue and invasive infections⁸.

Pseudomonas spp. (6.38%) and Acinetobacter baumannii (4.25%), though less frequent, are of particular concern due to their intrinsic resistance mechanisms and their association with nosocomial infections, especially in critically ill patients⁹. The isolation of Pneumococci (12.77%) reflects the burden of community-acquired respiratory infections, while Enterobacter spp. (8.51%) further adds to the complexity of gram-negative infections encountered in clinical practice.

The presence of multidrug-resistant organisms like Acinetobacter baumannii and Pseudomonas spp. is of high concern as it makes treatment a significant challenge. This calls for strict antimicrobial stewardship and infection control measures. The high rate of no-growth cultures emphasizes the need to improve sample collection and consider advanced diagnostics. Regular surveillance of microbial patterns is essential to guide effective treatment strategies.

1. Limited Diagnostic Tools: The study relied solely on conventional culture methods. Fastidious organisms or those requiring specialized media might have been missed, contributing to the high rate of no-growth cultures.
2. Prior Antibiotic Use: A potential confounding factor is that some patients may have received antibiotics before sample collection, which can suppress microbial growth and result in false-negative cultures.
3. Short Study Duration and Single-Center Study: Conducted over only six months at a single tertiary care hospital, the findings may not be generalizable to other settings or across seasons, potentially limiting epidemiological validity.
4. Lack of Molecular Diagnostics: No use of PCR or other molecular techniques that could have detected pathogens not captured by culture, especially in cases with negative culture results.
5. No Antibiotic Sensitivity Profile Included: While the study mentions the presence of multidrug-resistant organisms, it does not provide a detailed antibiogram, which is crucial for treatment guidance.
6. No Correlation with Clinical Outcomes: The study does not link microbial findings with patient outcomes such as duration of hospital stay, organ dysfunction, or mortality, limiting its clinical impact assessment.

Declaration of Interests: There are no conflicts of interest.

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