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Imipenem resistance of enterobacter aerogenes mediated by outer membrane permeability
C Bornet1, A Davin-Regli, C Bosi
1Enveloppe Bactérienne, Antibiotiques et Colonisation, CJF 96-06 INSERM, Faculté de Médecine, Université de la Mediterrannée, 13385 Marseille Cedex 05, France.
Abstract:
Multidrug-resistant Enterobacter aerogenes strains are increasingly isolated in Europe and especially in France. Treatment leads to imipenem resistance, because of a lack of porin. We studied the evolution of resistance in 29 strains isolated from four patients during their clinical course. These strains belonged to the prevalent epidemiological type observed in France in previous studies (C. Bosi, et al., J. Clin. Microbiol. 37:2165-2169, 1999; A. Davin-Regli et al., J. Clin. Microbiol. 34:1474-1480, 1996). They also harbored a TEM-24 extended-spectrum beta-lactamase-coding gene. Thirteen strains were susceptible to gentamicin and resistant to imipenem and cefepime. All of the patients showed E. aerogenes strains with this resistance after an imipenem treatment. One patient showed resistance to imipenem after a treatment with cefpirome. Twelve of these 13 strains showed a lack of porin. Cessation of treatment with imipenem for three patients was followed by reversion of susceptibility to this antibiotic and the reappearance of porins, except in one case. For one patient, we observed three times in the same day the coexistence of resistant strains lacking porin and susceptible strains possessing porin. The emergence of multidrug-resistant E. aerogenes strains is very disquieting. In our study, infection by E. aerogenes increased the severity of the patients' illnesses, causing a 100% fatality rate.
Insights
Multidrug-resistant Enterobacter aerogenes strains develop imipenem resistance due to porin loss, particularly in France. Cessation of imipenem treatment can reverse resistance, but this pathogen causes severe illness with a high fatality rate.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Medicine
Background:
- Enterobacter aerogenes is a growing cause of multidrug resistance in Europe, especially France.
- The prevalent French E. aerogenes strains carry the TEM-24 extended-spectrum beta-lactamase gene.
- These strains are frequently associated with resistance to carbapenems like imipenem.
Observation:
- This study tracked resistance evolution in 29 E. aerogenes strains from four patients during clinical treatment.
- Resistance to imipenem and cefepime, alongside gentamicin susceptibility, was observed in 13 strains.
- A lack of porins correlated with imipenem resistance in 12 of these strains.
Findings:
- Imipenem treatment selected for E. aerogenes strains lacking porins and exhibiting resistance.
- Cessation of imipenem therapy led to the reversion of susceptibility and porin reappearance in most patients.
- Coexistence of susceptible and resistant strains was observed within the same patient on the same day.
Implications:
- The emergence of multidrug-resistant E. aerogenes poses a significant clinical threat.
- E. aerogenes infections are linked to increased patient illness severity and a 100% fatality rate in this study.
- Understanding resistance mechanisms, like porin loss, is crucial for effective antimicrobial stewardship.