Cam 2009.

Methods	Study design: parallel‐group, prospective randomized trial Study dates: not available Setting: 1 hospital Country: Turkey
Participants	Inclusion criteria: people undergoing diagnostic cystoscopy for check‐up of a superficial bladder tumour; people with subsequent incidental interventions, including punch biopsy and transurethral resection of a small bladder tumour; people with initial negative urine cultures Exclusion criteria: used antibiotics for any reason during last month. Moreover, people requiring antibiotic prophylaxis for infective endocarditis or those with positive urine cultures were excluded Sample size: 200 participants randomized Age (years): mean control group: 56.3 (SD 5.4); mean prophylaxis group: 58.9 (SD 5.2) Sex: control group: 59 men and 41 women; prophylaxis group: 62 men and 38 women
Interventions	Group 1 (n = 100): antibiotic prophylaxis, intravenous, single dose 1 g, at the time of induction of anaesthesia Group 2 (n = 100): no antibiotic prophylaxis
Outcomes	Systemic UTI How measured: participants had a follow‐up visit at the first month after cystoscopy; clinical parameters including fever, dysuria, and frequency evaluated Time points measured: within 30 days after cystoscopy Time points reported: within 30 days after cystoscopy Outcomes: no fever or any other severe symptom was detected in any participant Localized UTI How measured: participants with positive urine cultures had complaints of dysuria and frequency Time points measured: urine culture tested 1 day after cystoscopy Time points reported: not available Outcomes: placebo group: 1/100 had localized symptom and positive urine culture 1 day after cystoscopy; treatment group: 1/100 had localized symptom and positive urine culture 1 day after cystoscopy Asymptomatic bacteriuria How measured: participants with positive urine culture and no symptoms Time points measured: urine culture tested 1 day after cystoscopy Time points reported: not reported Outcomes: control group: 1/100 had asymptomatic bacteriuria; treatment group: 0/100 had asymptomatic bacteriuria
Funding sources	No information about funding
Declarations of interest	No information about conflict and interest
Notes	Used rigid cystoscopes. 2 participants, 1 from each group, had dysuria without associated positive culture results. We tried to contact corresponding author about allocation concealment, but we received no response.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was performed using tables of random numbers and using a block randomization." Comment: random sequence generation performed adequately.
Allocation concealment (selection bias)	Unclear risk	Comment: no information regarding concealment of randomization.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "The first group received no antibiotic prophylaxis, the second group had a single dose of intravenous cefoperazone (1 g)." Comment: participants in control group were not administered antibiotic prophylaxis, while the treatment group received intravenously antibiotic prophylaxis. Unlikely that participants and personnel were blinded to the intervention.
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	Quote: "The first group received no antibiotic prophylaxis, the second group had a single dose of intravenous cefoperazone (1 g)." Comment: participants were not blinded to their treatment. Risk of detection bias for systemic UTI, localized UTI and asymptomatic bacteriuria was high.
Blinding of outcome assessment (detection bias) Objective outcomes	Unclear risk	Comment: not applicable, since the objective outcome of drug resistance was not reported.
Incomplete outcome data (attrition bias) Systemic UTI	Low risk	Quote: "No statistical difference was detected regarding age and gender between the groups, two groups were similar with regard to the distribution of cystoscopy indications." Comment: 200/200 randomized participants (100 participants in each arm) were included for analysis of this outcome.
Incomplete outcome data (attrition bias) Symptomatic UTI	Low risk	Quote: "No statistical difference was detected regarding age and gender between the groups, two groups were similar with regard to the distribution of cystoscopy indications." Comment: 200/200 randomized participants (100 participants in each arm) were included for analysis of this outcome.
Incomplete outcome data (attrition bias) Serious adverse events	Unclear risk	Comment: outcome not reported.
Incomplete outcome data (attrition bias) Minor adverse events	Unclear risk	Comment: outcome not reported.
Incomplete outcome data (attrition bias) Localized UTI	Low risk	Quote: "No statistical difference was detected regarding age and gender between the groups, two groups were similar with regard to the distribution of cystoscopy indications." Comment: 200/200 randomized participants (100 participants in each arm) were included for analysis of this outcome.
Incomplete outcome data (attrition bias) Asymptomatic bacteriuria	Low risk	Quote: "No statistical difference was detected regarding age and gender between the groups, two groups were similar with regard to the distribution of cystoscopy indications." Comment: 200/200 randomized participants (100 participants in each arm) were included for analysis of this outcome.
Incomplete outcome data (attrition bias) Bacterial resistance	Unclear risk	Comment: outcome not reported.
Selective reporting (reporting bias)	Unclear risk	Comment: data reported on all outcomes specified in methods section, but there was no access to trial protocol/registration to further assess selective reporting.
Other bias	Low risk	Comment: no other bias detected.