Pneumonia Caused by Methicillin-Resistant Staphylococcus aureus: Does Vancomycin Heteroresistance Matter?

Claeys, Kimberly C; Lagnf, Abdalhamid M; Hallesy, Jessica A.; Compton, Matthew; Gravelin, Alison L.; Davis, Susan L.; Rybak, Michael J.

doi:10.1128/aac.02388-15

Cited by 30 publications

(20 citation statements)

References 49 publications

(60 reference statements)

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“…For other antimicrobials, such as colistin or vancomycin, a reduced efficacy of these antimicrobials in infections with the presence of heteroresistant subpopulations has been observed [20,21]. In vitro studies have shown lower fitness in fosfomycinresistant mutants; however, these results have not been evaluated in vivo, or for longer periods where compensatory mutations may occur re-establishing the biological cost of these mutations [22].…”

Section: Discussionmentioning

confidence: 99%

Role of inoculum and mutant frequency on fosfomycin MIC discrepancies by agar dilution and broth microdilution methods in Enterobacteriaceae

Ballestero-Téllez

Docobo-Pérez

Rodríguez-Martínez

et al. 2017

Clinical Microbiology and Infection

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Section: Discussionmentioning

confidence: 99%

Role of inoculum and mutant frequency on fosfomycin MIC discrepancies by agar dilution and broth microdilution methods in Enterobacteriaceae

Ballestero-Téllez

Docobo-Pérez

Rodríguez-Martínez

et al. 2017

Clinical Microbiology and Infection

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“…Hetero-resistance is characterized by the occurrence within a bacterial population of a subset being resistant and the rest being susceptible to an antibiotic, based on the breakpoints of in vitro susceptibility [29]. Although its clinical significance is still a matter of debate [27,29,30], some studies have reported significant impact of S. aureus hetero-resistance on clinical outcomes [31,32]. Negative impacts have been described among dialysis patients and patients presenting bacteremia or endocarditis for whom therapeutic failures might have been related to that hetero-resistant phenotype [30,33,34].…”

Section: Discussionmentioning

confidence: 99%

Frequent occurrence of trimethoprim-sulfamethoxazole hetero-resistant Staphylococcus aureus isolates in different African countries

Coelho

Lencastre

Aires-de-Sousa

2017

Eur J Clin Microbiol Infect Dis

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High rates of trimethoprim/sulfamethoxazole (SXT) resistance, a combination of two antifolate antibiotics trimethoprim (TMP) and sulfamethoxazole (SMZ), have been reported among Staphylococcus aureus isolates in Portuguese-speaking African countries. Our study aimed to evaluate the occurrence of TMP resistance markers in major SXT methicillin-resistant S. aureus (MRSA) clones from these countries. We accessed also different fitness traits that could explain the success of these isolates over the Brazilian MRSA (the most successful SXT MRSA clone worldwide but never identified in these countries). Minimum inhibitory concentrations for SXT, TMP and SMZ were determined, and genes encoding TMP resistance (dfrG, dfrA, dfrK and dfrB) were searched. Representatives of the Brazilian clone and of the major MRSA African clones were evaluated for their fitness by individual growth curves, competition assays, survival under desiccation, autolytic activity, resistance to oxidative stress, and also growth at high osmolarity and in acid and alkaline environments. Although all African isolates showed high-level resistance to TMP, the majority presented hetero-resistance to SXT. TMP resistance was linked to the presence of dfrG (78%), dfrA (19%) or both (3%) genes. Compared to the Brazilian clone, the African isolates showed higher growth rates and autolytic activity, and better survival to desiccation and alkaline conditions. Since isolates exhibiting SXT hetero-resistance are frequent in Africa, the implementation of standardized guidelines to detect this phenomenon is of major interest. The predominant MRSA clones in Portuguese-speaking African countries likely possess significant advantages over other clones, such as the Brazilian MRSA, that may explain their epidemiological success.

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“…However, two recent studies have found a link between hVISA and higher mortality rate. Claeys et al reported that patients with hVISA pneumonia experienced signiicantly higher inpatient mortality than those with VSSA pneumonia [42]. Hu et al demonstrated that patients with hVISA bacteremia had a signiicantly higher in-hospital mortality than those with VSSA bacteremia [43].…”

Section: Clinical Signiicance Of Hvisa/visa and Vrsamentioning

confidence: 99%

Glycopeptide Resistance in S. aureus

Mirza¹

2017

The Rise of Virulence and Antibiotic Resistance in ≪i>Staphylococcus Aureus

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The glycopeptides (particularly vancomycin) have been the recommended therapy for serious methicillin-resistant Staphylococcus aureus (MRSA) infections. The increased incidence of MRSA has led to the frequent use of vancomycin. Unfortunately, with the increased use of vancomycin, isolates of S. aureus have been discovered with reduced susceptibility to vancomycin. Several studies suggest that reduced vancomycin susceptibility is associated with vancomycin treatment failure. Various forms of glycopeptide resistance have appeared in MRSA strains, including high-level resistance, homogeneous and heterogeneous intermediate resistance. While vancomycin-resistant S. aureus (VRSA) strains are limited to a handful of reported cases and vancomycinintermediate S. aureus (VISA) strains remain rare; heterogeneous VISA (hVISA) strains are more common. This article summarizes the current knowledge regarding the history, deinition, mechanisms, detection methods, epidemiology and clinical signiicance of 'glycopeptide resistance in S. aureus' and discusses therapeutic optıons for the treatment of hVISA/VISA infections.

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Pneumonia Caused by Methicillin-Resistant Staphylococcus aureus: Does Vancomycin Heteroresistance Matter?

Cited by 30 publications

References 49 publications

Role of inoculum and mutant frequency on fosfomycin MIC discrepancies by agar dilution and broth microdilution methods in Enterobacteriaceae

Role of inoculum and mutant frequency on fosfomycin MIC discrepancies by agar dilution and broth microdilution methods in Enterobacteriaceae

Frequent occurrence of trimethoprim-sulfamethoxazole hetero-resistant Staphylococcus aureus isolates in different African countries

Glycopeptide Resistance in S. aureus

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