ANTIBIOTIC RESISTANCE PATTERNS OF BLOOD CULTURE ISOLATES IN INTENSIVE CARE UNIT (ICU) PATIENTS: A DESCRIPTIVE CROSS-SECTIONAL STUDY

Abstract

Background: Bloodstream infections remain a major cause of clinical deterioration and death in intensive care units, where invasive procedures, critical illness, prolonged hospitalization, and extensive antimicrobial exposure increase infection risk. Gram-negative organisms are especially concerning because they frequently acquire resistance to multiple antimicrobial classes, including carbapenems. Local surveillance of causative organisms and susceptibility patterns is therefore essential for selecting appropriate empirical therapy, strengthening infection-prevention practices, and supporting antimicrobial stewardship in critically ill patients overall in practice.

Objective: To determine the blood culture positivity rate, bacteriological profile, antimicrobial resistance patterns, and clinical outcomes among patients admitted to an intensive care unit.

Methods: A retrospective descriptive cross-sectional study analysed 350 eligible ICU patient records with blood cultures obtained for suspected bloodstream infection or sepsis. Demographic, clinical, microbiological, susceptibility, and outcome data were extracted using a structured form. Multidrug resistance, carbapenem resistance, septic shock, mechanical ventilation, ICU stay, and mortality were assessed. Chi-square or Fisher’s exact test, Welch’s t-test, and Mann–Whitney U test were applied, with p<0.05 considered significant.

Results: Blood cultures were positive in 70/350 patients (20.0%), and all isolates were Gram-negative. Acinetobacter species accounted for 24/70 isolates (34.3%), Klebsiella species for 22/70 (31.4%), and Pseudomonas species for 15/70 (21.4%). Multidrug resistance and carbapenem resistance were each present in 58/70 isolates (82.9%). Resistance was 100.0% to ampicillin and ceftriaxone, 96.8% to amoxicillin–clavulanate, 87.5% to ciprofloxacin, 84.6% to cefepime, 82.9% to carbapenems, and 77.6% to piperacillin–tazobactam. Tigecycline susceptibility was 92.6%. Mortality was higher in culture-positive than culture-negative patients (80.0% vs 57.9%; p=0.001). Culture positivity was associated with older age, longer ICU stay, septic shock, and mechanical ventilation (all p≤0.001), but not with sex (p=0.500).

Conclusion: Gram-negative bloodstream infections showed a high burden of multidrug and carbapenem resistance and were associated with adverse ICU outcomes. Unit-specific antibiograms, prompt culture-guided treatment, antimicrobial stewardship, and strengthened infection-control practices are therefore essential.

Keywords: Bacteremia; Blood Culture; Drug Resistance, Multiple, Bacterial; Gram-Negative Bacterial Infections; Intensive Care Units; Microbial Sensitivity Tests; Mortality