Transrectal prostate biopsy (TRPB) has been associated with increased risk of infection between 3.6-5% and sepsis rates of 0.3-3.1% mainly due to fluoroquinolone resistance (FQR). At present, FQ antibiotic prophylaxis is utilised commonly across North America and Europe but due to the prevalence of FQR, 20% of urologists in America are using combination therapy. Antibiotic prophylaxis guided by rectal cultures has been shown to reduce risk of post-TRBP infections. The aim of this study was to assess the natural progression of FQR rectal colonisation and its correlation with TRPB infection and the potential benefits of routine preoperative rectal cultures. This study is an international, multi-institutional collaborative study involving six institutions. Patients had documentation of chosen antibiotics; all patients had pre-TRPB rectal cultures and follow-up was carried out with direct interview or review of charts. Infection was determined by fever, urinary tract infection, additional antibiotic therapy, and emergency assessment or hospital admission for infection. Two thousand, six hundred and seventy-three men underwent rectal cultures pre-TRPB between January 2007 and September 2013. Ninety-three percent were given FQ pre-biopsy and 24% were given a further dose post-biopsy. FQR was found in 20.5%, with overall infection rate of 2.6% and hospital admission rate due to infection of 1.6%. Patients negative for FQR had post-biopsy infection rate of 1.6% versus 6.6% in those positive for FQR. FQR positive patients who only received FQ prophylaxis had 8.2% infection risk in comparison to 1.8% in those who were FQR negative. In FQR positive patients who received combination therapy, the infection rate reduced from 8.2-6.3%, however, this reduction was not statistically significant. Hospital admission rate was increased by having FQR bacteria – 4.4% in comparison to 0.9% in those with negative cultures. Gentamicin, amikacin, trimethoprim / sulfamethoxate and ceftriaxone are the most commonly used antibiotics in combination with FQ prophylaxis. However, resistance to these antibiotics has been found in FQR bacteria and the lowest co-resistance rates are found with meropenam, imipenem and amikacin. This study shows a role for rectal culture pre-TRPB to identify those who may require different antibiotics.