Hemodialysis catheter-related bacteremia caused by Stenotrophomonas maltophilia

Sir,

Catheter-related bloodstream infections cause significant morbidity and mortality in hemodialysis patients. Other than the commonly isolated organisms such as coagulase negative Staphylococcus aureus and other skin commensals, Gram-negative organisms including Pseudomonas are identified especially in those with frequent exposures with health care environment.[1] We encountered catheter-related bacteremia by Stenotrophomonas maltophilia in three hemodialysis patients that were successfully treated with dialysis catheter removal and antibiotic therapy. The patients presented with acute onset of fever without any localizing symptom [Table 1]. All patients had tunneled internal jugular catheters for dialysis access, with benign exit sites and no evidence of tunnel infection. Blood cultures from the tunneled catheters grew S. maltophilia in all within 24–72 h of incubation. The strains were sensitive to ampicillin-sulbactam, levofloxacin and trimethoprim-sulfamethoxazole (TMP-SMX). The bacteremia persisted despite treatment with dual antibiotic therapy for 4–5 days, necessitating catheter removal. Subsequently, the patients recovered and repeat blood cultures were sterile. New tunneled catheters were inserted for further dialysis in all patients. Each patient received either oral levofloxacin or ampicillin-sulbactam along with TMP-SMX for 3 weeks.

Table 1.

Demographic features and clinical course of the patients

Bacteremia in hemodialysis patients commonly originates from the dialysis catheter itself. S. maltophilia is a ubiquitous Gram-negative bacillus and is closely related to the Pseudomonas species.[2] Risk factors for infection with S. maltophilia include hospitalization, HIV infection, malignancy, neutropenia, mechanical ventilation and presence of central venous catheters. S. maltophilia can form biofilm on the catheters and other in situ-devices.[3] Strains are frequently resistant to a number of antibiotics including aminoglycosides and carbapenems.

Historically, S. maltophilia bacteremia was described with the use of contaminated O-rings inside the dialyzers and contaminated water for reprocessing dialyzers.[4] Routine surveillance cultures of the dialysate water did not show any microbial growth in our dialysis unit. Treatment of S. maltophilia bacteremia in hemodialysis patients commonly necessitates dialysis catheter removal along with dual antibiotic coverage for at least 3 weeks. The rational for dual antibiotic therapy for bacteremia caused by S. maltophilia is based on the reported in vitro synergy of combined antibiotics including TMP-SMX plus ceftazidime, TMP-SMX plus ticarcillin-clavulanic acid, and ticarcillin-clavulanic acid plus ciprofloxacin.[5]