Epidemiological features of nosocomial Stenotrophomonas maltophiliapseudobacteraemia

Abstract number: 1134_04_173

Xanthaki A., Toutouza M., Vourli S., Vatopoulos A.C., Tsiringa A., Kontou-Castellanou C.

Objectives:  

Stenotrophomonas maltophilia is an important nosocomial pathogen responsible for serious infections. It is associated with high morbidity and mortality especially in immunocompromised patients. It can also be a contaminant or member of the endogenous flora of hospitalized patients. In our hospital, S.maltophilia was recovered from the blood cultures of 7 patients hospitalized in the same Internal Medicine Ward, during a period of 40 days. We present here the clinical, microbiological and epidemiological characteristics of this outbreak.

Methods:  

Identification of the microorganisms was performed by the VITEK II system (Biomerieux-France). Susceptibility to antibiotics was assessed by both the disk diffusion method and MIC breakpoints determination by the VITEK II system. Molecular typing was done by the ERIC-II PCR method. The epidemiological investigation included the review of the medical records of the respective patients, as well as of the medical and nursing practices in the ward. Surveillance cultures from surfaces and also from hospital personnel (hand and throat swabs) working in the specific ward were also performed.

Results:  

All strains were multiresistant and shared the same phenotype being sensitive to quinolones, ticarcillin-clavulanate and piperacillin-tazobactam and resistant to all other groups of antibiotics tested. Molecular analysis showed that all S.maltophilia strains had identical patterns. None of the 7 patients had fever or other signs of infection during the respective period. Moreover clearance of bacteraemia occured spontaneously and without any specific treatment in all cases. All surveillance cultures were negative. The epidemiological investigation revealed that a particular povidone-iodine solution was used on all infected patients used during the process of blood culturing. Although the solution was not available for culturing, it was concluded that all data are indicative not of a real outbreak but of a pseudo outbreak, due to the contamination of blood cultures from the solution.

Conclusions:  

Pseudo outbreaks due to contaminated antiseptic solutions should be suspected in the event of clustering of positive cultures without the respective clinical signs of infection.