title: Is linezolid a risk factor for Gram-negative bacillus infections in intensive care unit patients? A comparative study with vancomycin.
abstract: BACKGROUND
  Linezolid is frequently used in critically ill patients with ventilator-associated pneumonia. Its potent activity against Gram-positive microorganisms and its high tissue penetration may favour Gram-negative colonization and infection. The aim of our study was to evaluate the risk for Gram-negative infections in critically ill patients treated with linezolid or vancomycin.
  
  
  METHODS
  The cases of all patients admitted over an 18-month period to a hepatic intensive care unit for ≥ 1 week, and treated with linezolid or vancomycin, were retrospectively reviewed. The main clinical characteristics and infections due to Gram-negative bacteria in the month after starting linezolid or vancomycin were obtained.
  
  
  RESULTS
  Seventy-one patients treated with linezolid and 68 treated with vancomycin fulfilled the inclusion criteria. Co-morbidities were similar in both groups. Patients on linezolid treatment had a longer stay in the ICU (mean ± standard deviation 41 ± 38 days vs 18.4 ± 13 days), received this treatment later (14.3 ± 15.1 days vs 6.3 ± 6.5 days), had a higher mean serum creatinine concentration (1.71 ± 1.18 mg/dl vs 1.04 ± 1.04 mg/dl), more often required haemodiafiltration (29.6% vs 13.2%), and 30 day-mortality was higher (42.3% vs 20.6%) than in patients receiving vancomycin. More than 95% in both groups received a broad-spectrum beta-lactam in addition to linezolid or vancomycin. The rate of Gram-negative infection during the following month was 28.2% in the linezolid group and 26.5% in the vancomycin group (p > 0.5).
  
  
  CONCLUSIONS
  Linezolid was more frequently used in critically ill patients with longer ICU stay and renal failure. The rate of infection due to Gram-negative microorganisms was similar in patients who received linezolid or vancomycin.
authors.affiliation: Department of Internal Medicine, Hospital Universitario Insular de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: Holger
authors.initials: H
authors.lastname: Sterzik
authors.forename: Alejandro
authors.initials: A
authors.lastname: Soriano
authors.forename: Al-Montaser
authors.initials: AM
authors.lastname: Mohamad
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Martínez
authors.forename: Javier
authors.initials: J
authors.lastname: Fernandez
authors.forename: Nazaret
authors.initials: N
authors.lastname: Cobos
authors.forename: Laura
authors.initials: L
authors.lastname: Morata
authors.forename: Josep
authors.initials: J
authors.lastname: Mensa
mesh_terms: D000081:Acetamides / Q000009:adverse effects* / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000627:therapeutic use; D015897:Comorbidity; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006090:Gram-Negative Bacteria / Q000254:growth & development; D016905:Gram-Negative Bacterial Infections / Q000139:chemically induced* / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D007902:Length of Stay / Q000706:statistics & numerical data; D000069349:Linezolid; D008297:Male; D008875:Middle Aged; D023303:Oxazolidinones / Q000009:adverse effects* / Q000627:therapeutic use; D051437:Renal Insufficiency; D012189:Retrospective Studies; D012307:Risk Factors; D014640:Vancomycin / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; D014640:Vancomycin; D000069349:Linezolid