Sources of primary bloodstream infections in internal medicine patients - a cohort study

To describe the sources of bloodstream infections (BSIs) in internal-medicine patients, on admission and during hospitalization, and to determine the proportion of BSIs in which no secondary cause could be defined (i.e., primary-BSI).

We analyzed all BSIs at the internal-medicine wards of the two campuses of the Hadassah Hebrew-University Medical Center, during 2017-2018. We defined the BSI source of each event (secondary, Central-line associated BSI (CLABSI) or primary non-CLABSI) and compared BSIs present on admission (POA) to hospital acquired (HA).

There were 595 patient-unique BSI events, 316 (53.1%) POA-BSI and 279 (46.9%) HA-BSI. Overall, 309 (51.9%) were secondary, 194 (32.6%) primary non-CLABSI and 92 (15.5%) CLABSI. Primary non-CLABSI in the POA-BSI group was 20.6% vs. 46.2% in the HA-BSI group (p = 0.001). The length of hospital stay (LOS) of the HA-BSI group was longer than in the POA-BSI group (mean LOS, 19 days vs. 13.6 days, p = 0.01) and mortality rate was higher (48.7% vs. 19%, p = 0.001). Staphylococcus aureus was more common in primary non-CLABSI than in CLABSI and secondary BSI (29.5%, 12.8% and 16.2%, respectively).

The proportion of primary non-CLABSI among HA-BSI events is very high (46.2%). The absence of any plausible source for these BSIs, and the fact that in our hospital more than 90% of patients in medicine wards have peripheral lines, suggests that these may be a possible source for primary non-CLABSIs. Measures to prevent peripheral-line associated BSI (PLABSI), like those implemented successfully for the prevention of CLABSI, should be considered.