Stenotrophomonas maltophilia bacteraemia in Turkish children

Background: Stenotrophomonas maltophilia is an important cause of life-threatening nosocomial infection. Aim: To evaluate the clinical features, antibiotic treatment and prognosis of S. maltophilia bacteraemia. Methods: Patients with blood cultures positive for S. maltophilia at the Children's Hospital, Ankara University Medical School between 1995 and 2005 were evaluated retrospectively. The results were compared with those of a case-control group of patients with Pseudomonas aeruginosa bacteraemia (n=33). Antibiotic susceptibilities of S. maltophilia strains were determined by disc diffusion. Susceptibility to ciprofloxacin was also determined by broth dilution. Results: Thirty-six (2.2%) blood cultures were positive for S. maltophilia. Neutropenia was more common in the P. aeruginosa group (p=0.001). Breakthrough bacteraemia developed more commonly during carbapenem treatment in the S. maltophilia group (p=0.02). Ciprofloxacin and trimethoprim-sulfamethoxazole in combination with/without an aminoglycoside were the antibiotics most commonly selected to treat S. maltophilia bacteraemia. Mortality was more common in the P. aeruginosa (13/33) than in the S. maltophilia (2/33) group (p=0.001). According to susceptibility, determination by the disk diffusion method, beta-lactam antibiotics, aminoglycosides and chloramphenicol had little or no effect, whereas trimethoprim-sulfamethoxazole, doxycycline and fluoroquinolones were more active against S. maltophilia strains. However, ciprofloxacin susceptibility results were quite different when determined by disk diffusion (97% isolates susceptible) and broth dilution (49% isolates susceptible). Conclusions: Although S. maltophilia bacteraemia is rare in children, antibiotic resistance to these strains is an important problem. Tetracyclines, trimethoprim-sulfamethoxazole and fluoroquinolones are the most active agents against S. maltophilia strains.