Risk factors for colistin-resistant, extensively drug-resistant (XDR) and pandrug-resistant (PDR) <i>Acinetobacter baumannii</i> infections: a review

<i>Acinetobacter baumannii</i> clinical isolates commonly have high antimicrobial resistance levels. We evaluated the risk factors associated with colistin-resistant, extensively drug-resistant (XDR), and pan-drug-resistant (PDR) <i>Acinetobacter baumannii</i>. A literature review was done using three electronic resources, encompassing 18 observational studies with 2,462 participants. Our study examined the association between risk factors and infections caused by colistin-resistant (6 studies, 847 participants), XDR (10 studies, 1413 participants), and PDR <i>Acinetobacter baumannii</i> (3 studies, 202 participants). The most common independent risk factor identified for all three resistance phenotypes was prior use of antibiotics, with adjusted odds ratios (aORs) ranging from 1.3 to 155.9. Additional contributing factors included mechanical ventilation, prolonged stays in the intensive care unit (ICU), and use of invasive devices, such as urinary catheters, central line catheters, and hemodialysis catheters. The severity of illness was also linked to these infections, as indicated by high scores on the APACHE II, SOFA, or SAPS II scales. Certain risk factors, particularly prior use of antibiotics, have been consistently associated with the development of three resistant phenotypes. Future research should focus on multicenter studies with well-defined criteria for resistance, identifying risk factors, and guiding intervention strategies more effectively.