Abstract

MORALES-AGUIRRE, José Juan  and  ANDRADE-VELASQUEZ, Joyce Katherine. Risk factors associated with mortality and antibiotic susceptibility patterns in Pseudomonas aeruginosa bacteremia. Bol. Med. Hosp. Infant. Mex. [online]. 2006, vol.63, n.5, pp.291-300. ISSN 1665-1146.

Introduction. Pseudomonas aeruginosa is a common opportunistic pathogen of human and a frequent cause of nosocomial infections, generally with high lethality. Among the principal risk factors for fatal outcome are: severe sepsis, pneumonia and delay in the initiation of effective antimicrobial therapy. Material and methods. A retrospective case-study at Hospital Infantil de Mexico Federico Gomez including from 1 month to 18 years of age whose diagnosis included bacteremia due to P. aeruginosa between January 2003 and December 2005. The objective of the study was to identify factors associated with mortality and the antimicrobial susceptibility pattern of the P. aeruginosa isolates. The predisposing risk factors included: previous antibiotic therapy, hospitalization in the pediatric intensive care unit (PICU), surgery, mechanical ventilation, immunosuppressive therapy, and intravenous catheter placement within the 30 days prior to developing bacteremia. In oncologic patients, the type and staging of the malignancy and the absolute neutrophil count were additional risk factor. Results. During the study period, we identified 108 bacteremic events in 103 patients. There were 63 (58%) females, and in 65 (60%) the events were deemed to be nosocomial. The overall mortality was 21/ 108 (19%), and was higher (21%), in nosocomial events. The mortality in children with < 200 absolute neutrophil count was 22% (7/31) and 18% in those with > 200 neutrophil (P =0.60). Factors associated with the highest mortality due to P. aeruginosa included septic shock (P < 0.0001), lactate > 1.5 and 2 (P =0.0007 vs P =0.0001, respectively), as well as inappropriate antibiotic therapy at the time bacteremia was diagnosed (P =0.03). Antibiotic resistance to carbapenems was documented in 35-40% of the P. aeruginosa nosocomial and community isolates, respectively. There was a 90-100% susceptibility to third and fourth generation antipseudomonal cephalosporins. Conclusions. Bacteremias due to P. aeruginosa were associated with a high mortality rate and were principally found in immunocompromised patients. Among the main predisposing factors associated with mortality were: neutropenia with an absolute neutrophil count < 200 cells/mL, the presence of septic shock, serum lactate > 2 mmol/L and having received previous antibiotic therapy.

Keywords : Pseudomonas aeruginosa; Pseudomonas bacteremia; septic shock; risk factors for mortality; nosocomial infections.