Approximately 7% of pneumonia cases acquired in the intensive care unit (ICU) can be classified as Staphylococcus aureus ICU pneumonia (SAIP), and patients colonized with S aureus at ICU admission have a 3.6-times higher daily risk of SAIP compared with patients without S aureus colonization, according to study results published in JAMA Network Open.

The study included a total of 1933 patients (mean age, 62 years) who were admitted to ICUs across 30 hospitals in 11 countries in Europe. Investigators from the ASPIRE-ICU (Advanced Understanding of Staphylococcus aureus and Pseudomonas aeruginosa Infections in Europe-ICU) cohort study ascertained S aureus colonization from the nose and lower respiratory tract of patients with an anticipated ICU length of stay of 48 hours or more who were also undergoing mechanical ventilation at the time of admission.

The objective of the study was to identify patients with SAIP, which was defined as the occurrence of any pneumonia during the ICU stay that developed 48 hours or more after admission in patients colonized with S aureus.

In this cohort, a total of 950 patients were carriers of S aureus at ICU admission, whereas 983 patients were not carriers of the gram-positive bacterium. Approximately 15.7% (n=304) of the overall study cohort developed ICU-acquired pneumonia, with 6.8% (n=131) of cases classified as SAIP. Weighted SAIP incidences for S aureus carriers and noncolonized patients were 11.7 and 2.9 events per 1000 patient-days, respectively. The overall incidence for the total population was 4.9 events per 1000 patient-days in the ICU.


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In a multivariable analysis, S aureus colonization status at ICU admission represented a significant independent factor associated with SAIP (cause-specific hazard ratio, 3.6; 95% CI, 2.2-6.0; P <.001).

Limitations of the study included the variation between countries in terms of SAIP diagnostic practices as well as the incomplete outcome data from some of the participating sites.

The researchers wrote that their “findings suggest that SAIP incidence may be higher than initially perceived, and future interventions to prevent SAIP should focus on patients colonized with S aureus to achieve a higher efficacy.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Paling FP, Hazard D, Bonten MJM, et al; for the ASPIRE-ICU Study Team. Association of Staphylococcus aureus colonization and pneumonia in the intensive care unit. Published online September 30, 2020. JAMA Netw Open. doi:10.1001/jamanetworkopen.2020.12741