44 Gram stain and intraabdominal infection: narrative revision

Abstract Aim Our aim is to determine whether Gram staining can confirm the presence of pathogens in an intra-abdominal infection (IAI), identify filamentous forms or provide information for the initiation of antibiotic treatment and/or drainage of a collection. It also intended to assess whether the Gram stain result may support the diagnosis of primary or secondary peritonitis. Methods A narrative literature review was conducted. Articles published in English or Spanish since 1990 were included. Experimental studies, peritoneal dialysis and liver cirrhosis were excluded. SINTAXIS: ‘Intraabdominal Infections’ (diverticulitis, colonic; Appendicitis; cholecystitis, acute; Peptic Ulcer Perforation; Intestinal Perforation; secondary peritonitis; Abdominal Abscess; Postoperative complications) AND (‘Gentian Violet’ OR ‘Gram's stain). Results Forty papers were found and eight were selected for review (7 retrospective and 1 prospective observational studies). The usefulness of Gram staining was discussed in acute cholecystitis, liver abscess, secondary peritonitis, blood stream infections and soft tissue infections, but no uniform criteria were found in the patients included. According to studies, we cannot conclude that Gram stain is useful in IAI. It does not seem to predict the outcome of cultures or influence the duration and selection of antimicrobial therapy, whereas it may be slightly more useful for fungi due to its higher negative predictive value. Gram stain positivity seems to mean an increased risk of SSI in certain pathologies and closer outpatient monitoring could be applied in these cases. Microbiological characterization of the Gram stain in certain pathologies (soft tissue infection, blood stream infection) may point to an intra-abdominal origin of the primary infection. Conclusions Considering the heterogeneity of the studies reviewed, no clear conclusions can be drawn about the usefulness of Gram staining in IAI.