Stenotrophomonas maltophilia多重抗藥性的研究
Investigation of multidrug resistance in Stenotrophomonas maltophilia
Date Issued
2005
Date
2005
Author(s)
Lee, Yu-Liang
DOI
zh-TW
Abstract
Stenotrophomonas maltophilia is an aerobic, nonfermentative gram-negative bacterium. The organism has increasingly emerged as an important nosocomial pathogen, particularly for immunocompromised patients. It is characterized by its hegh-level resistance to a variety of structurally unrelated antimicrobials, including quinolones, aminoglycosides and β-lactams. SmeDEF and SmeABC multidrug efflux pumps have been described in S. maltophilia.SmeDEF has been shown to play a role in the drug resistance of clinical strains. The SmeABC multidrug system is regulated by a two-component regulatory system encoded by the smeSR genes.Related studies about SmeDEF and SmeABC are still deficient. Integrons have the ability tocapture and mobilize gene cassettes via a site-specific recombinase that blongs to the integrase family.Besides, some structural change in the proteins or lipopolsaccharide correlate well with drug susceptibility. Mutants lacking spgM gene, which is responsible for the production of a phosphoglucomutase (PGM) associated with LPS and alginate biosynthesis in S. maltophilia, displayed a modest increase in susceptibility to several antimicrobial agents. It has been observed that the resistance of biofilms to antibiotics is increased compared with what is normally seen with planktonic cells, and cells become 10-1000 times more resistant to the effects of antibiotics when existing in a biofilm. When strains of S. maltophilia exist at a specific growth stage, they synthesize the melanins, which protect bacteria against stresses unfavorable for growth.
In the present study, 40 clinical multidrug resistance strains (resistant to more than 7 drugs tested) and 30 susceptible strains (less than 5 drug) were collected to investigate the multidrug resistance in S. maltophilia. They were investigated the presence of integrons by PCR and found an obvious difference between the multidrug resistance strains and the susceptible strains in the rate of carrying class 1 integrons (82.5% and 30%, respectively), with an increasing tendency towards the multidrug resistance in carrying class 1 integrons.RT-PCR was then performed to assess and semi-quantify the expression of the Sme efflux pumps and PGM of S. maltophilia.It was found that the rate of multidrug resistance strains was higher than that of susceptible strains in hyperexpresion of smeABC (57.5% and 20%, respectively), smeDEF(45% and 10%) and spgM(75% and 60%), with an respective increasing tendency towards the multidrug resistance in hyperexpresion of these genes.Further, I found multidrug-resistant strains exhibit higher expression of SmeDEF (86%) than SmeABC (66%). This implies SmeDEF plays a more important role in multidrug resistance in S. maltophilia. Besides, the ability to form melanins and biofilms of the multidrug-resistant strains is also greater than that of the susceptible strains, and the difference is significant in statistics. We found the more above-mentioned mechanisms that strains possess, the more possibilities for strains to express multidrug resistance.
Subjects
多重抗藥性
Stenotrophomonas maltophilia
multidrug resistance
Type
other
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