Background: Prosthetic joint infection (PJI) caused by Acinetobacter baumannii (Ab) has become a growing concern due to its overwhelming ability to express resistance to antibiotics and produce biofilm.

Aim: This study aimed to identify independent risk factors (RFs) associated with Ab-associated PJI and their role in the treatment outcome.

Methods: This was a single-centre, retrospective cohort study of PJI patients diagnosed between January 2014 and July 2018. A PJI diagnosis was made based upon the MSIS 2018 criteria. To estimate RFs associated with Ab-associated PJI, multivariate analyses with a level of significance of p < 0.05 were performed. To evaluate treatment failure, Kaplan-Meier analysis and log-rank test were performed.

Results: Overall, 98 PJI cases were assessed, including 33 with Ab-associated PJI and 65 with PJI involving other microorganisms (non-Ab-associated PJI). Independent RFs associated with Ab-associated PJI were revision arthroplasty [odds ratio (OR) = 3.01; 95% confidence interval (CI) = 1.15-7.90; p = 0.025] and nonelective arthroplasty (OR = 2.65; 95% CI = 1.01-7.01; p = 0.049). Ab-associated PJI was also more likely than non-Ab-associated PJI to be classified as a chronic late infection (OR = 5.81; 95% CI = 2.1-16.07; p = 0.001). Ab-associated PJI was not associated with treatment failure (p = 0.557).

Conclusions: Late chronic infections, surgical revision and nonelective arthroplasty are well-known predictors of PJI but were also independently associated with Ab-associated PJI. Infections caused by Ab and surgical treatment with debridement, antibiotics and implant retention were not associated with PJI treatment failure.

Trial registration: Study data supporting our results were registered with the Brazilian Registry of Clinical Trials ( https://www.ensaiosclinicos.gov.br/rg/RBR-6ft5yb/ ), an open-access virtual platform for the registration of studies on humans performed in Brazil. Registration no. RBR-6ft5yb .

The authors declare no conflict of interest.

Rodrigo Otavio Dias de Araújo: Specialist doctor in Orthopedics, Traumatology and Sports Medicine. Master’s in health education. Technical Director and Principal Investigator of Fundação Hospitalar São Francisco de Assis - Santa Lúcia Unit. Head of Orthopedics. University Professor at the José do Rosário Vellano University (UNIFENAS). Professor of the Medicine course and coordinator of the Post-Graduation in Health Education at the Faculty of Medical Sciences of Minas Gerais (FCM / FELUMA-MG).

Mauro Costa Salles: Graduated in Medicine at Federal University of Pará (State of Pará) (1983–1988), Specialization in Internal Medicine at” Santa Casa de Misericórdia de São Paulo “(1989-1991) and Medical Residency in Infectious Diseases at the “Instituto de Infectologia Emílio Ribas” (1993–1995).Attended the Master of Science (MSc) in Applied Molecular Biology of Infectious Diseases by the London School of Hygiene & amp; Tropical Medicine (LSHTM), University of London-UK (1998). Doctorate obtained in 2008 by the Faculty of Medical Sciences of Santa Casa de São Paulo. He is currently an Adjunct Professor of the Discipline of Infectious Diseases at the Faculty of Medical Sciences of Santa Casa de São Paulo (FCMSCSP) and Coordinator of the Infectious Diseases Clinic at the “Irmandade da Santa Casa de Misericórdia de São Paulo” (FCMSCSP). Member of the Board of the Postgraduate Program in Health Sciences at FCMSCSP since 2017.Since 2018 he has also been Adjunct Professor A1 of the Discipline of Infectious and Parasitic Diseases at the Federal University of São Paulo (UNIFESP)