Pathophysiological mechanisms in the development of anal fistula. Oral antibiotics after anal abscess drainage to diminish perianal Fistula Formation: a multicenter, randomized, observer-blind, placebo-controlled clinical trial.

INTERVENTION: Trade Name: Ciprofloxacin Product Name: Ciprofloxacin Pharmaceutical Form: Tablet INN or Proposed INN: ciprofloxacin CAS Number: 85721‐33‐1 Other descriptive name: CIPROFLOXACIN Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 500‐ Pharmaceutical form of the placebo: Capsule Route of administration of the placebo: Oral use Trade Name: Metronidazole Product Name: Metronidazole Pharmaceutical Form: Tablet INN or Proposed INN: METRONIDAZOLE CAS Number: 443‐48‐1 Other descriptive name: metronidazole Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 1000‐ Pharmaceutical form of the placebo: Capsule Route of administration of the placebo: Oral use CONDITION: Abscess and anal fistulas Therapeutic area: Body processes [G] ‐ Microbiological Phenomena [G06] PRIMARY OUTCOME: Main Objective: Demonstrate that oral antibiotic after perianal abscess debridement decreases the anal fistula incidence Primary end point(s): Fistula anal presence (Parks classification) Secondary Objective: Show the clinical benefit (quality of life included) of oral antibiotic after perianal abscess debridement in development of anal fistula; Describe the pacients under risk of anal fistulas aparition after anal abscess episode. Timepoint(s) of evaluation of this end point: 1st month; 3rd month; 6th month; 9th month SECONDARY OUTCOME: Secondary end point(s): Ultrasonography to fistula examination Timepoint(s) of evaluation of this end point: 6th months INCLUSION CRITERIA: 18 years or more Both genders Clinical diagnosis of anal abscess (acute inflammatory signs and presence of a purulent collection in the perianal area) seen or confirmed through punction aspiration of purulent material with needle. Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18‐64 years) yes F.1.2.1 Number of subjects for this age range 150 F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range 60