Risk factors and outcomes for multidrug-resistant Gram-negative bacteremia in the NICU

Abstract

Objectives: To assess the risk factors antibiotic therapy and outcomes of multidrug-resistant (MDR) Gram-negative bacilli (GNB) bacteremia in NICU patients.

Methods: Episodes of MDR GNB bacteremia were compared with a non-MDR GNB bacteremia group in an 8-year cohort study.

Results: Of 1106 bacteremias, 393 (35.5%) were caused by GNB. Seventy (18.6%) were caused by an MDR strain. The most frequent mechanism of resistance was extended-spectrum β-lactamase production (67.1%), mainly by Klebsiella pneumoniae (59.6%). Previous antibiotic exposure to third-generation cephalosporin (odds ratio [OR]: 5.97; 95% confidence interval [CI]: 2.37-15.08; P < .001) and carbapenem (OR: 3.60; 95% CI: 1.26-10.29; P = .017) and underlying renal disease (OR: 7.08; 95% CI: 1.74-28.83; P = .006) were identified as independent risk factors for MDR GNB acquisition. Patients with MDR GNB bacteremia more likely received inadequate initial antibiotic therapy (72.9% vs 7.8%; P < .001) had higher rates of infectious complication (21.4% vs 10.5%; P = .011) and overall case fatality +rate (28.6% vs 10.5%; P < .001). Independent risk factors for overall mortality were presence of infectious complications after bacteremia (OR: 3.16; 95% CI: 1.41-7.08; P = .005) and underlying secondary pulmonary hypertension with or without cor pulmonale (OR: 6.19; 95% CI: 1.88-20.31; P = .003).

Conclusions: MDR GNB accounted for 18.6% of all neonatal GNB bacteremia in the NICU, especially in those with previous broad-spectrum antibiotic therapy and underlying renal disease. The most frequent mechanism of resistance was extended-spectrum β-lactamase (ESBL) production. Neonates with MDR GNB were more likely to develop infectious complications, which were independently associated with a higher overall case-fatality rate.

Keywords: Gram-negative bacilli; bacteremia; extended-spectrum β-lactamase–producing bacteria; mortality; nosocomial infection.