JAC Advance Access published online on July 17, 2008
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkn289
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Original research |
Prediction models to identify hospitalized patients at risk of being colonized or infected with multidrug-resistant Acinetobacter baumannii calcoaceticus complex
1 Department of Infectious Diseases, Università Cattolica Sacro Cuore, 00168 Rome, Italy 2 Department of Microbiology, Università Cattolica Sacro Cuore, 00168 Rome, Italy 3 Hospital Head Unit, Policlinico Agostino Gemelli, 00168 Rome, Italy 4 Anaesthesiology and Intensive Care Medicine, Università Cattolica Sacro Cuore, 00168 Rome, Italy
Received 6 March 2008; returned 8 April 2008; revised 18 June 2008; accepted 20 June 2008
* Corresponding author. Tel: +39-06-30155527; Fax: +39-06-3054519; E-mail: etacconelli{at}rm.unicatt.it
Background: The multidrug-resistant (MDR) Acinetobacter baumannii calcoaceticus complex (Abc) has emerged as an important cause of nosocomial infections. The aims of the study were to evaluate risk factors for MDR-Abc in intensive care units (ICUs) as well as in medical and surgical wards, to define the likelihood ratios (LRs) of risk factors and to determine if risk factors differ depending on whether colonization or infections are considered.
Methods: Two prospective matched case–control studies were performed. MDR-Abc was defined as a strain resistant to four or more classes of antibiotics. The two case groups included patients with MDR-Abc infections or colonization. Controls were selected among patients not harbouring Abc. Matching criteria were the number of days from admission to MDR-Abc isolation among cases and the duration of hospitalization among controls.
Results: Overall, 514 patients were included in the study. One hundred and thirty-seven patients were infected and 120 colonized. A Charlson score >3 and previous methicillin-resistant Staphylococcus aureus isolation and β-lactam use were independent risk factors for colonization and infection. Bedridden status and previous ICU admission were associated with colonization, while the presence of a central venous catheter and surgery were related to infection. The analysis of LRs showed an association between the presence of more than two risk factors and colonization or infection. The highest predicting value was observed for the presence of more than two risk factors and colonization in patients with no history of ICU admission.
Conclusions: This study provides novel information that can be used to identify interventions for different stages of the spread of MDR-Abc.
Key Words: nosocomial infections , antibiotic resistance , likelihood ratio