We found that HAIs contributed to approximately one-third of unexpected in-hospital deaths. The most common HAIs were central line—associated bloodstream infection, surgical site infection, pneumonia, and gastrointestinal infection. The most common pathogens recovered were Enterobacteriaceae, S. aureus, P. aeruginosa, and C. difficile. Overall, 45% of bacterial isolates were multidrug resistant.
The CDC has estimated that pneumonia, central line—associated bloodstream infection, urinary tract infection, and surgical site infection were the most common infections associated with death.2
In contrast, we found fewer cases of pneumonia and urinary tract infections and more gastrointestinal infections (primarily C. difficile
More recently, using the same data-collection system, the CDC's NHSN has reported on the frequency of different infectious pathogens identified in common HAIs.7
The most common organisms identified were coagulase-negative Staphylococcus
(15% of isolates), S. aureus
(15% of isolates), Enterococcus
species (12% of isolates), and Candida
species (11% of isolates), followed by various gram-negative bacilli. Notably present in the CDC report was the large proportion of infections caused by coagulase-negative Staphylococcus,
which mostly caused central line—associated bloodstream infection or surgical site infection.7
In our study, coagulase-negative staphylococcal infections were rare, and gastrointestinal infections due C. difficile
were relatively common. C. difficile
infection would not have been reported to the NHSN, because data on gastrointestinal infections are not routinely collected. Approximately 16% of the pathogenic isolates reported to the NHSN were multidrug resistant,7
whereas in our study, 45% of bacterial isolates were multidrug resistant. This is likely because multidrug-resistant infections are more common among critically ill patients.
Our study was a single-center study within a Department of Veterans Affairs hospital, which limits its generalizability. Categorizing deaths as expected or unexpected is imprecise, and many severely ill patients who die are still included in the calculation of unexpected deaths because they are reasonably expected to live for more than 6 months. However, by excluding patients who were expected to die within 6 months, we were able to focus our study on a smaller group of patients who are probably more likely to benefit from infection prevention efforts.3,6
HAIs are an important factor in approximately 1 in 3 unexpected in-hospital deaths. Multidrug-resistant and antibiotic-associated bacteria are common causes of HAIs, especially multidrug-resistant gram-negative bacteria, methicillin resistant S. aureus, and C. difficile. To reduce mortality due to HAIs, infection prevention efforts need to focus on measures that impact multiple types of infections and multidrug-resistant organisms.