Ventilator-associated lower respiratory tract infections and bacteremia in medical and surgical critical care patients colonized by multidrug-resistant bacteria

We investigated the risk of bloodstream infections (BSI) and ventilator-associated lower respiratory tract (LRT) infections, including pneumonia (VAP) and tracheobronchitis (VAT), due to multidrug-resistant bacteria (MDRB) in colonized critical care patients attended in the medical intensive care unit (MICU) and surgical critical care unit (SCCU). Observational, unicentric study including 573 consecutive adult patients (median age of 66 years; range, 18–85 years) and comprising a total of 585 admissions. Universal MDRB screening cultures (from nasal, pharyngeal, rectal, and axillary sites) were regularly performed. Blood cultures and (semi)quantitative cultures of endotracheal or bronchoscopic specimens were performed and interpreted following consensus guidelines. Colonization by MDRB was documented in 201 out of 585 admissions (34.4%), in which 261 MDRB were isolated, most frequently extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales (n = 102) followed by MDR-S. maltophilia (n = 45), carbapenemase-producing Enterobacterales (n = 40), MDR-Gram-positive bacteria (n = 35), and MDR-P. aeruginosa (n = 28). There were 21 MDRB BSI, mostly caused by Gram-negative bacteria (95.8%). Colonization by MDRB was independently associated with subsequent MDRB BSI (HR14.1; 95% CI, 3.29–60.65 P < 0.001). MDRB were recovered in 157/430 admissions requiring invasive mechanical ventilation (36.5%) and there were 25 episodes of ventilator-associated LRT infections due to MDRB, mostly MDR-Gram-negative bacteria. Colonization by MDRB was independently associated with subsequent MDRB LRT infections (HR, 6.59; 95% CI, 2.67–16.26; P < 0.001). MDRB colonization is a significant risk factor for the occurrence of MRDB-matched invasive infections in a mixed cohort of MICU and SCCU patients. MDRB screening cultures using a multi-site sampling approach may be useful for tailoring empirical antimicrobial treatments on an individual basis.