title: Fecal colonization and infection with Pseudomonas aeruginosa in recipients of allogeneic hematopoietic stem cell transplantation.
abstract: BACKGROUND
  Pseudomonas aeruginosa, especially multidrug-resistant (MDR) isolates, is an important pathogen in allogeneic hematopoietic stem cell transplant (HCT) recipients. The ability to identify patients at risk for these infections and administer appropriate empiric therapy, particularly during episodes of neutropenia, may improve outcomes and also direct infection control and antimicrobial stewardship efforts. Many transplant centers obtain routine surveillance stool cultures (SSCs) from HCT recipients to test for colonization with vancomycin-resistant enterococci, and extended-spectrum beta lactamase-producing Enterobacteriaceae. Our center initiated the performance of SSCs for P. aeruginosa, because of a perceived increase in the frequency of infection with MDR strains. The aim of this study was to determine the utility of this practice.
  
  
  METHODS
  We conducted a 2-year (2010-2011) retrospective review of the medical records of all patients who underwent allogeneic HCT at our cancer center to (a) determine the frequency of fecal colonization with P. aeruginosa, including MDR strains; (b) to determine the overall frequency of subsequent P. aeruginosa infection, as well as the frequency of infection with MDR strains; (c) to ascertain the proportion of subsequent infections likely arising from the intestinal tract; and (d) to determine risk factors for progression from colonization to infection.
  
  
  RESULTS
  Of 794 study patients, 58 (7.3%) had at least 1 positive SSC for P. aeruginosa; 19/58 (32.8%) developed a subsequent pseudomonal infection (11 with matching antimicrobial resistance patterns). On the other hand, 37/736 (5%) of the patients who were not colonized, developed a pseudomonal infection. The type of infection observed was pneumonia in 26 (46%) patients, bloodstream infection in 20 (36%), urinary tract infection in 8 (14%), and infections at other sites in 2 (4%). The incidence of MDR P. aeruginosa in the entire cohort was 2.2% (18 of 794): 12 had positive SSCs and 7 of these patients later developed MDR P. aeruginosa infections. Patients with acute myelogenous leukemia were more likely to be colonized and to develop subsequent infection. No infection-related deaths were observed during the first 30 days after infection.
  
  
  CONCLUSIONS
  The incidence of P. aeruginosa colonization and subsequent infection was low. Patients who were not colonized had a low chance of developing P. aeruginosa infection. Most patients who developed infection did not have fecal colonization, suggesting a different source of infection. SSCs for P. aeruginosa provide incomplete information regarding the source of infection.
authors.affiliation: Department of Infectious Diseases, Infection Control and Employee Health, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
authors.forename: L
authors.initials: L
authors.lastname: Nesher
authors.forename: K V I
authors.initials: KV
authors.lastname: Rolston
authors.forename: D P
authors.initials: DP
authors.lastname: Shah
authors.forename: J T
authors.initials: JT
authors.lastname: Tarrand
authors.forename: V
authors.initials: V
authors.lastname: Mulanovich
authors.forename: E J
authors.initials: EJ
authors.lastname: Ariza-Heredia
authors.forename: R F
authors.initials: RF
authors.lastname: Chemaly
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D005243:Feces / Q000382:microbiology; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects*; D006801:Humans; D017053:Infection Control; D008297:Male; D008875:Middle Aged; D011552:Pseudomonas Infections / Q000453:epidemiology* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification*; D012189:Retrospective Studies; D018571:Sentinel Surveillance; D013781:Texas / Q000453:epidemiology; D014184:Transplantation, Homologous; D055815:Young Adult
keywords: Pseudomonas aeruginosa; multidrug-resistant; stem cell transplantation; stool culture; surveillance