Analysis of Gram-negative rod bacteremia in the surgical and medical ICU

Introduction

The aim was to analyze the Gram-negative bacteremia profile and the predisposing factors for length of stay in the surgical and medical ICU and outcome.

Methods

Retrospective data analysis of patients during 4 years treated in a surgical and medical ICU with positive blood culture for Gram-negative rod.

Results

Gram-negative rod monobacteremia (n = 160) cultures revealed: Escherichia coli (n = 52, 32.5%), Acinetobacter spp. (n = 47, 29.4%), Klebsiella spp. (n = 22, 13.7%), Enterobacter spp. (n = 20, 12.5%), Proteus spp. (n = 11, 6.9%), anaerobes (n = 3, 1.9%) and other Gram-negative rods, including Stenotrophomonas maltophilia, Haemophilus influenzae, Neisseria meningitidis, Achromobacter spp. and Actinobacillus limirensi (n = 5, 3.1%). Both E, coli and Acinetobacter spp. were responsible for the vast majority of Gram-negative rod monobacteremia (n = 99, 61.8%, P = 0.0128). Also most often (n = 50, 72.5%, P = 0.049) primary bacteremia was caused by E. coli and Acinetobacter spp. Separate group's multidrug resistance was found: E. coli in 12 (23.1%) cases, Acinetobacter spp. in 45 (95.7%, P = 0.02), Klebsiella spp. in nine (40.9%), Enterobacter spp. in 11 (55.0%), Proteus spp. in six (54.6%) cases. The vast majority of patients with multidrug-resistant bacteremia were aged over 65 years (n = 64, 77.1%, P = 0.042), stayed in the ICU less than 14 days (n = 70, 84.3%, P = 0.039), and had lethal outcome (n = 74, 89.2%, P = 0.03). Patients who stayed in the ICU less than 14 days presented with primary Gram-negative rod bacteremia (n = 67, 57.7%, P = 0.03), need for mechanical ventilation (n = 90, 77.6%, P = 0.043) and lethal outcome (n = 112, 96.6%, P = 0.01). Lethal outcome was confirmed in patients with primary Gram-negative rod bacteremia (n = 55, 79.7%, P = 0.03), MDR strain (n = 74, 89.2%, P = 0.03), presence of shock (n = 120, 75.0%, P < 0.001), mechanical ventilation (n = 133, 74.3%, P < 0.001), cancer chemotherapy (n = 18, 90.0%, P = 0.03), and chronic obstructive pulmonary disease (n = 13, 100%, P = 0.03).

Conclusion

E. coli and Acinetobacter spp. - the most often pathogens of Gram-negative rod bacteremia - were mostly multidrug resistant. Multidrug-resistant bacteremia was related to age, length of stay less than 14 days, and lethal outcome. Predisposing factors for shorter length of stay: primary bacteremia, mechanical ventilation, lethal outcome, and for lethal outcome: primary bacteremia, multidrug resistance, presence of shock, mechanical ventilation, cancer chemotherapy, chronic obstructive pulmonary disease.