Should the Patient Discontinue Keflex After Negative UA and Culture?
No, the patient should discontinue Keflex immediately since the urine analysis and culture are negative—there is no urinary tract infection to treat. 1, 2
Rationale for Discontinuation
Antimicrobial stewardship principles explicitly state that prescribing antibiotics in the absence of a proven or strongly suspected bacterial infection increases the risk of drug-resistant bacteria and is unlikely to provide benefit to the patient. 3
The IDSA guidelines specifically recommend against treating catheter-associated asymptomatic bacteriuria in pregnant women when cultures are negative, and this principle extends to all suspected UTIs with negative confirmatory testing. 1
Continuing unnecessary antibiotics during pregnancy exposes both mother and fetus to potential adverse effects without any therapeutic benefit. 3
Important Exception: Group B Streptococcus
If the culture specifically identified Group B Streptococcus (GBS) at any concentration, treatment should be completed and the patient should receive intrapartum prophylaxis during labor, regardless of symptom resolution. 2
GBS bacteriuria during pregnancy is a marker for heavy genital tract colonization and requires both immediate treatment and intrapartum prophylaxis. 2
Clinical Context for Pregnancy and UTI
While pregnancy is the one clinical scenario where asymptomatic bacteriuria must always be treated (due to 20-30 fold increased pyelonephritis risk), this recommendation applies only when bacteriuria is actually present on culture. 2
A negative culture definitively rules out bacteriuria, making continued antibiotic therapy both unnecessary and potentially harmful. 1, 2
The FDA drug label for cephalexin explicitly warns that the medication should only be used to treat bacterial infections, and that skipping doses or not completing therapy applies when treating an actual infection—not when no infection exists. 3
Avoiding Common Pitfalls
Do not continue antibiotics "just to be safe" or to complete an arbitrary course when cultures are negative. This practice promotes antimicrobial resistance without clinical benefit. 1, 3
Do not perform repeat surveillance urine testing or treat asymptomatic bacteriuria repeatedly after initial negative cultures, as this fosters antimicrobial resistance. 2
If the patient had symptoms that prompted the initial prescription, consider alternative diagnoses for those symptoms rather than continuing empiric antibiotic therapy. 4