• 作者：C.C. Adjidé ; A. De Meyer ; M. Weyer ; O. Obin ; F. Lamory ; C. Lesueur ; L. Trouillet ; M. Biendo ; O. Ganry ; F. Eb
• 关键词：Stenotrophomonas maltophilia ; Selective isolation medium ; Sensitive isolation medium ; Specific isolation medium ; Predictive isolation medium ; Biocontamination ; Microbiologic risk assessment
• 刊名：Pathologie Biologie
• 出版年：2010
• 出版时间：February 2010
• 年：2010
• 卷：58
• 期：1
• 页码：11-17
• 全文大小：1003 K

Bacground

Stenotrophomonas maltophilia (Smalto) is a prominent nosocomial pathogen, commonly isolated in the hospital environment. Multiple Smalto nosocomial outbreaks have been linked to contaminated water sources. This study aimed to develop a medium able to ease healthcare environment Smalto isolation.

Methods

Financed, from March 2007 to June 2008, by a university hospital of Amiens’ clinical research program, this study allowed Stenotrophomonas maltophilia selective medium with coloured indicator (SM2i) development. SM2i is constituted of Mueller Hinton agar (MH), maltose, DL-methionine, bromothymol blue. The mixture sterilized is refreshed at 50 °C, its pH adjusted to 7.1, and render selective by addition of vancomycin, imipenem and amphotericin B. Then, SM2i agar is sunk into 90 cm diameter Petri dish dated and stored at 4 °C for 4 weeks. SM2i is developed using Pasteur Institute culture type collection (CIP) strains of Smalto, Burkholderia cepacia, Pseudomonas aeruginosa (Psa) and a Smalto strain of our hygiene laboratory collection. It was validate on Psa imipenem-resistant and Enterococcus faecium vancomycin-resistant strains, then, tested on cold water first jet and faucet cotton-swabs samples. SM2i tests were made in comparison with the MH agar, MH agar plus four paper disks loaded 10 μg of imipenem and Cetrimed agar. Its sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, accuracy, likehood-ratio (LR) and Youden index have been determined.

Results

SM2i agar is better in culturing Smalto test-strains. On SM2i, Smalto colonies are smooth, round, greeny, olive or lime green, have a green olive centre with a peripheral lighter or a dark green centre with an olive green suburb surrounded by a blue halo. SM2i is a selective, specific, predictive, accurate medium to search for Smalto in healthcare environment. In 122 pairs of cold water first jet and taps cotton-swabs samples, Smalto was isolated from 14.8 % of water samples, 10.7 % of cotton-swabs samples. It was isolated alone in 6.6 % of water samples and 2.5 % of swab samples. Thus, smalto has biocontaminated 17.2 % of cold water taps. Compared to MH agar, SM2i sensitivity, specificity, PPV, NPV, accuracy, LR were 100, 100, 100, 100, 100 % and ∞, and 87.5, 100, 100, 98.1, 98.4 % and ∞ for water and cotton-swabs samples respectively.

Conclusion

SM2i is a selective, specific, predictive medium which can allow easily isolating and identifying accurately Smalto in environmental samples. Its evaluation on clinical samples is on going.