Risk factors and epidemiology of Acinetobacter baumannii infections in a university hospital in Northern Italy: A case-control study

Background: Acinetobacter baumannii has emerged as a major cause of outbreaks of hospital-associated infections with increased morbidity and mortality among those affected.

Methods: We performed a 1:1 matched case-control study involving 68 cases in a teaching hospital in Northern Italy. Risk factors included general health conditions, comorbidities, diagnostic and therapeutic procedures, and antibiotic therapies. A multiple correspondence analysis (MCA) was performed to highlight possible association patterns among risk factors. After this, a conditional logistic regression model was applied.

Results: The combined results of the MCA and univariate regression models suggest that invasive procedures performed before intensive care unit admission, in particular bronchoscopy (odds ratio, 48.06) and oxygen therapy (odds ratio, 2.11), are associated with development of an infection. Malnutrition or obesity, lack of self-sufficiency, and severe liver diseases also proved to be significantly associated with infection. When analyzing antibiotic therapies, both the number of molecules administered and duration of therapy were significantly associated.

Conclusions: Early recognition of patients at high risk, environmental hygiene control measures, appropriate antibiotic prescriptions, especially regarding carbapenems, and high-quality training of health care workers in all hospital departments are all key aspects for prevention and control of Acinetobacter infection. Further studies are needed to investigate the role of antibiotics on microbial competition dynamics in relation to multidrug-resistant outbreaks.