The first thing is that common office toilet is less likely a cause for urinary infection
Its common in female. Even more if sexually active. Even more if maintaining poor hygiene.
Urine infection depends on grade of antibiotic therapy and its effectiveness.
Best way is to drink plenty of water (likely 3-4 litres/day) and take precautions for its flare ups.
Infection can be of multiple types and therapy worries accordingly.
Best way to go for urine examination at the end of therapy.