Tahir Naeem, Muhammad Absar, Ali M Somily


Background: Stenotrophomonas maltophilia has emerged as a significant pathogen in compromised
patients, causing infections which are difficult to treat. This study was carried out to comprehend the
recent trend of antimicrobial resistance among clinical isolates of S. maltophilia and suggest
management guidance for patients in general and in our region in particular. Methods: A total of 222
clinical isolates were tested between Jan 2003 to Jun 2009 at King Khalid University Hospital,
College of Medicine, King Saud University, Riyadh Saudi Arabia. The organisms were identified as
per standard guidelines. Final identification and minimum inhibitory concentration (MIC) was
determined by using Microscan®. Results: S. maltophilia showed absolute resistance to Imipenem.
In vitro, least resistance was observed against Cotrimoxazole (9.45%) followed by Ceftazidime
(57.21%), Piperacillin/Tazobactam (60.82%), Ciprofloxacin (77.03%), Aztreonam (86.03%).
Gentamicin showed overall highest resistance (87.39%). The crude mortality rate was 47%.
Conclusion: Cotrimoxazole is still the most effective agent against S. maltophilia but, keeping in
view the increasing resistance to first and second line drugs, there is an urgent need for an effective
surveillance system. To discourage development of resistance and devise an effective empirical
therapy, large scale study should be considered.
Keywords: Stenotrophomonas maltophilia, antibiotic resistance, mortality rate, minimum inhibitory

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