Kellum 1992.

Study characteristics
Methods	Open‐label, RCT, multicentre
Participants	77 patients randomised, 30 vs. 21 participants Inclusion: Abdominal tenderness and signs of infection: fever/leucocytosis (white blood cells = 9.5 cells/mm3 or more), radiological (CT: colonic wall thickening/increased density of pericolic fat or contrast enema with intramural/extramural tracking/abscess), surgical (3 participants) or pathologic (1 participant) evidence, 2 participants with clinical diagnosis Exclusion: Requirement of immediate emergency surgery, admission creatinine of 3 mg/dL or more, need of additional antibiotics not permitted by the study protocol
Interventions	Intervention: IV Cefoxitin: 1‐2 g/6h Control: IV gentamicin/clindamycin (1.7 mg/kg followed by 1‐1.4 mg/kg/8h maintenance dose)/(2.4‐2.7 mg/d) Duration of treatment was determined by attending physician based on clinical assessment.
Outcomes	Cured: Resolved clinical findings and discharged with no recurrence for at least 6 weeks or alternatively a candidate for elective surgery with primary anastomosis and no septic complications (wound infection, intra‐abdominal abscess or anastomotic leak)  Failure: At least 48 h of AB with subsequent need of emergency surgery or switch of AB. Alternatively, the participants had undergone elective surgery with septic complications following a successful AB
Notes	This study was supported in part by the grant from Merck Sharp and Dohme, West Point, Pennsylvania.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised to receive either cefoxitin (CFX) or a combination of gentamicin and clindamycin (G/C)
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	High risk	Open‐label study
Incomplete outcome data (attrition bias) All outcomes	High risk	26 were deemed non‐evaluable (CFX: 10 vs. G/C: 16). Seven received additional antibiotics not permitted by study protocol. Interpretation: 34% of randomised participants were excluded from analysis. The exclusion was described in numbers and reasons adequately for 19 participants. The reason for the exclusion of the last 7 participants was not reported. Lost to follow‐up during the six weeks described in the methods section was not addressed in the results section. The questionable exclusion of participants, the big exclusion rate, the missing reporting on lost to follow‐up, and the overall small sample size of the study all contributed to high risk attrition bias. Frequency and time points for white blood cell count measurements was not described. This suggests that the stated significant conclusion, that leucocytosis resolved more rapidly in the single‐compound group than in the combination group, questionable. All of the above factors resulted in a high risk of reporting bias.
Selective reporting (reporting bias)	Unclear risk	A protocol was mentioned once in the results section. Specification of outcomes was provided in the methods section but they were never described as predefined. The recurrence outcome was never addressed in the results section although mentioned in the methods section.