Duration from start of antibiotic exposure to onset of infection for different antibiotics in a non-outbreak setting.

Background: Antibiotic treatment is a well-known risk factor for infection (CDI). The time from start of antibiotic exposure to onset of CDI for different antibiotics is sparsely studied. CDI with onset in the community is often treatable without in-hospital care while CDI patients treated in hospital need isolation, resulting in higher costs and infection control measures.

Objectives: To determine the time from start of antibiotic exposure to onset of healthcare facility-associated CDI for different antibiotics.

Methods: Time between antibiotic exposure and disease onset was evaluated retrospectively with chart reading in a two-centre Swedish setting. A case was attributed to an antibiotic group if this represented more than 2/3 of total antibiotic exposure 30 days before onset of CDI.

Results: Cephalosporins caused CDI faster (mean 7.6 days), and more often during ongoing antibiotic therapy (81% of the cases) than any other antibiotic group. All other common agents had between 2-3 times longer period between start of exposure to onset of CDI (quinolones more than 3 times).

Conclusions: The time gap between antibiotic exposure and onset of CDI is markedly different between different antibiotics. Decreased cephalosporin use could delay onset of healthcare facility-associated CDI and limit infections with onset within the hospital. This might decrease costs for inpatient care, need of infection control measures and shortage of beds in the hospital.