Quote From "Antibiotics Simplified Second Edition"

[methylenewhite]

Don’t Forget! Surgical prophylaxis is the most common indication for first-generation cephalosporins in the hospital. Be sure to limit the duration of therapy for this use; administering more than one dose of antibiotics should be uncommon, and giving more than 24 hours of antibiotics is rarely justified. Such use does not lower infection rates, but it can select for more resistant organisms later in the hospital stay.

Am I getting it right that "does not lower infection rates" addressed prolonged use more then 24 hours? Because otherwise it looks little bit suspicious. Im not a native English speaker so help is highly appreciated.