Methods: This retrospective cohort study assessed adult patients admitted with HCAP from 2010- 2015 to 177 US hospitals participating in Premier and providing administrative and microbacteriological data. HCAP was defined as having prior hospitalization within 90 d, hemodialysis, admission from skilled nursing facility, or immune suppression. Patients with identical gram negative organisms in blood and urine were excluded. Cultures were obtained in the first 5 hospital days.
Results: Of 48,440 patients hospitalized with HCAP, 36.0% were admitted to ICU. Mean age was 69± 15 (range 18 - 89) and 49% were male. Almost all patients (98%) had at least one culture, including blood (96%) and respiratory (64%) specimens. Of the respiratory cultures, 6554 (22%) were positive, whereas only 3,688 (8%) of blood cultures were positive. Gram-negative bacteria accounted for 55% of respiratory and 36% of blood pathogens. The most common respiratory pathogens were S. aureus (37.5%), P. aeruginosa (20.6%), E. coli (6.2%) and S. pneumoniae (5.9%). The most common blood pathogens were S. aureus (25.8%), S. pneumoniae (18.4%), E.coli (13.7%) and P. aeruginosa (5.3%). Positive cultures were more common in ICU than non-ICU patients (12.0% v. 5.6% for blood, 30.4% v. 15.1% for respiratory), but the relative frequency of pathogens was similar in both settings. Respiratory pathogens had lower mortality than blood pathogens for S. aureus (18.4% v. 26.5%; p<0.002) and P. aeruginosa (13.9% v. 30.4%; p<0.002) but not for S. pneumoniae (13.8% v. 11.4%, p=0.21) and E. coli (20.6% v. 19.2%, p=0.56). Patients with positive blood cultures had the highest mortality, followed by positive respiratory cultures and no growth (16.9% v. 14.8 v. 9.0, p<0.0001).
Conclusion: In a large US inpatient sample, microbial etiology of HCAP pathogens differed by specimen type. S. aureus was the most common respiratory and blood pathogen, P.aeruginosa was more common in respiratory cultures and S. pneumoniae in blood. Lower mortality for some respiratory cultures may indicate colonization rather than infection.
K. Brizendine, None
P. Lindenauer, None
P. C. Yu, None
M. D. Zilberberg, The Medicines Company: Grant Investigator and Investigator , Grant recipient , Research grant and Research support
Tetraphase: Grant Investigator and Investigator , Grant recipient , Research grant and Research support
Merck, Inc.: Consultant , Grant Investigator and Investigator , Grant recipient , Research grant and Research support
P. Bakaki, None
T. Higgins, None
M. Rothberg, None
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