Mendoza 1971.

Methods	Study design: double‐blind, randomized controlled study Study dates: not reported Setting: all participants hospitalized and examined daily Country: USA
Participants	Inclusion criteria: not reported Exclusion criteria: severe renal impairment, active severe cystitis, or known allergy to the active drug used Sample size: 2 trials of men were studied. In each trial, 30 participants were treated with an active drug and 30 with a placebo Age: not reported Sex: men
Interventions	Trial A Group 1 (n = 30): sulphamethoxypyridazine‐pyridazine, initial dose 1 g, and then 0.5 g, daily for 3 days Group 2 (n = 30): placebo Trial B Group 3 (n = 30): demeclocycline hydrochloride 150 mg 4 times a day for 4 days Group 4 (n = 30): placebo
Outcomes	Bacteriuria How measured: positive culture indicating presence of an organism usually considered pathogenic Time points measured: prior to cystoscopic examination and 1, 3, and 4 days after instrumentation each participant had a urine culture Time points reported: not reported Outcomes: in trial A, no statistically significant difference in any category between participants in terms of bacteriuria. In trial B, more cultures remained negative after demeclocycline hydrochloride than after placebo (20/22 vs 11/21). For participants who were initially totally asymptomatic, i.e. had no abnormal clinical symptoms or laboratory findings. In trial A, 6/8 participants in placebo group and 1/11 participants in treatment group had bacteriuria. In trial B, 4/9 participants in placebo group and 0 participants in treatment group had bacteriuria
Funding sources	No information about funding
Declarations of interest	No information about conflict and interest
Notes	No email address available for contacting the corresponding author for further information.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Active drugs and placebos were administered in capsule form, coded and assigned randomly to patients." Comment: method for generation of random sequence not given.
Allocation concealment (selection bias)	Unclear risk	Comment: no information regarding concealment of randomization.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Active drugs and placebos were administered in capsule form, coded and assigned randomly to participants, participants and personnel were likely to be blinded." Comment: blinding of participants and personnel performed adequately.
Blinding of outcome assessment (detection bias) Subjective outcomes	Unclear risk	Comment: subjective outcomes of systemic and localized symptoms after cystoscopy; adverse events not reported.
Blinding of outcome assessment (detection bias) Objective outcomes	Low risk	Comment: bacteriuria evaluated by urine culture was regarded as the primary outcome, the result was obtained from laboratory. Detection bias for this outcome was unlikely to be influenced by the unblinded design.
Incomplete outcome data (attrition bias) Systemic UTI	Unclear risk	Comment: outcome not reported.
Incomplete outcome data (attrition bias) Symptomatic UTI	Unclear risk	Comment: outcome not reported (bacteriuria was reported, but without differentiating whether participants had symptoms or not).
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	Unclear risk	Comment: outcome not reported.
Incomplete outcome data (attrition bias) Asymptomatic bacteriuria	Unclear risk	Comment: outcome not reported (bacteriuria was reported, but without differentiating whether participants had symptoms or not).
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.