title: Do Polymicrobial Intra-Abdominal Infections Have Worse Outcomes than Monomicrobial Intra-Abdominal Infections?
abstract: BACKGROUND
  Numerous studies have demonstrated microorganism interaction through signaling molecules, some of which are recognized by other bacterial species. This interspecies synergy can prove detrimental to the human host in polymicrobial infections. We hypothesized that polymicrobial intra-abdominal infections (IAI) have worse outcomes than monomicrobial infections.
  
  
  METHODS
  Data from the Study to Optimize Peritoneal Infection Therapy (STOP-IT), a prospective, multicenter, randomized controlled trial, were reviewed for all occurrences of IAI having culture results available. Patients in STOP-IT had been randomized to receive four days of antibiotics vs. antibiotics until two days after clinical symptom resolution. Patients with polymicrobial and monomicrobial infections were compared by univariable analysis using the Wilcoxon rank sum, χ(2), and Fisher exact tests.
  
  
  RESULTS
  Culture results were available for 336 of 518 patients (65%). The durations of antibiotic therapy in polymicrobial (n = 225) and monomicrobial IAI (n = 111) were equal (p = 0.78). Univariable analysis demonstrated similar demographics in the two populations. The 37 patients (11%) with inflammatory bowel disease were more likely to have polymicrobial IAI (p = 0.05). Polymicrobial infections were not associated with a higher risk of surgical site infection, recurrent IAI, or death.
  
  
  CONCLUSIONS
  Contrary to our hypothesis, polymicrobial IAI do not have worse outcomes than monomicrobial infections. These results suggest polymicrobial IAI can be treated the same as monomicrobial IAI.
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Puja M
authors.initials: PM
authors.lastname: Shah
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Brandy L
authors.initials: BL
authors.lastname: Edwards
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Zachary C
authors.initials: ZC
authors.lastname: Dietch
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Guidry
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Davies
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Sara A
authors.initials: SA
authors.lastname: Hennessy
authors.affiliation: 2 Department of Surgery, John Peter Smith Health Network , Fort Worth, Texas.
authors.forename: Therese M
authors.initials: TM
authors.lastname: Duane
authors.affiliation: 3 Department of Surgery, Maricopa Integrated Health System , Phoenix, Arizona.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: O'Neill
authors.affiliation: 4 Department of Surgery, University of California San Diego , San Diego, California.
authors.forename: Raul
authors.initials: R
authors.lastname: Coimbra
authors.affiliation: 5 Department of Surgery, Beth Israel Deaconess Medical Center , Boston, Massachusetts.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Cook
authors.affiliation: 6 Department of Surgery, Brigham and Women's Hospital , Boston, Massachusetts.
authors.forename: Reza
authors.initials: R
authors.lastname: Askari
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Popovsky
authors.affiliation: 1 Department of Surgery, University of Virginia , Charlottesville, Virginia.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Sawyer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001424:Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology; D060085:Coinfection / Q000188:drug therapy* / Q000382:microbiology; D005260:Female; D006801:Humans; D059413:Intraabdominal Infections / Q000188:drug therapy* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D013530:Surgical Wound Infection / Q000453:epidemiology; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents