Universidad del Desarrollo

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Dissecting the Mechanisms of Linezolid Resistance in a Drosophila melanogaster Infection Model of Staphylococcus aureus
(2013)
Lorena Diaz
;
Dimitrios P. Kontoyiannis
;
Diana Panesso
;
Nathaniel D. Albert
;
Kavindra V. Singh
Scopus© Citations 12 2
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Detection of heterogeneous vancomycin intermediate resistance in MRSA isolates from Latin America
(2020)
Betsy E Castro
;
Maritza Berrio
;
Monica L Vargas
;
Lina P Carvajal
;
Lina V Millan
<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Vancomycin is a common first-line option for MRSA infections. The heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) phenotype is associated with therapeutic failure. However, hVISA isolates are usually reported as vancomycin susceptible by routine susceptibility testing procedures.</jats:p></jats:sec><jats:sec><jats:title>Objectives</jats:title><jats:p>To detect and characterize the hVISA phenotype in MRSA isolates causing infections in nine Latin American countries.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We evaluated a total of 1189 vancomycin-susceptible MRSA isolates recovered during 2006–08 and 2011–14. After an initial screening of hVISA using glycopeptide-supplemented agar strategies, the detection of hVISA was performed by Etest (GRD) and Macro-method (MET). Isolates deemed to be hVISA were subjected to population analysis profile/AUC (PAP/AUC) and WGS for further characterization. Finally, we interrogated alterations in predicted proteins associated with the development of the VISA phenotype in both hVISA and vancomycin-susceptible S. aureus (VSSA) genomes.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>A total of 39 MRSA isolates (3.3%) were classified as hVISA (1.4% and 5.6% in MRSA recovered from 2006–08 and 2011–14, respectively). Most of the hVISA strains (95%) belonged to clonal complex (CC) 5. Only 6/39 hVISA isolates were categorized as hVISA by PAP/AUC, with 6 other isolates close (0.87–0.89) to the cut-off (0.9). The majority of the 39 hVISA isolates exhibited the Leu-14→Ile (90%) and VraT Glu-156→Gly (90%) amino acid substitutions in WalK. Additionally, we identified 10 substitutions present only in hVISA isolates, involving WalK, VraS, RpoB and RpoC proteins.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>The hVISA phenotype exhibits low frequency in Latin America. Amino acid substitutions in proteins involved in cell envelope homeostasis and RNA synthesis were commonly identified. Our results suggest that Etest-based methods are an important alternative for the detection of hVISA clinical isolates.</jats:p></jats:sec>
3 1Scopus© Citations 14
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Ceftaroline-Resistant, DaptomycinTolerant, and Heterogeneous Vancomycin-Intermediate MethicillinResistant Staphylococcus aureus Causing Infective Endocarditis
(2017)
Masayuki Nigo
;
Lorena Diaz
;
Lina P. Carvajal
;
Truc T. Tran
;
Rafael Rios
<jats:title>ABSTRACT</jats:title> <jats:p> We report a case of infective endocarditis (IE) caused by ceftaroline-resistant, daptomycin-tolerant, and heterogeneous vancomycin-intermediate methicillin-resistant <jats:named-content content-type="genus-species">S. aureus</jats:named-content> (MRSA). Resistance to ceftaroline emerged in the absence of drug exposure, and the E447K substitution in the active site of PBP2a previously associated with ceftaroline resistance was identified. Additionally, we present evidence of patient-to-patient transmission of the strain within the same unit. This case illustrates the difficulties in treating MRSA IE in the setting of a multidrug-resistant phenotype. </jats:p>
8 1Scopus© Citations 31
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A Prospective Cohort Multicenter Study of Molecular Epidemiology and Phylogenonnics of Staphylococcus aureus Bacterennia in Nine Latin American Countries
(2017)
Cesar A. Arias
;
Jinnethe Reyes
;
Lina Paola Carvajal
;
Sandra Rincon
;
Lorena Diaz
<jats:title>ABSTRACT</jats:title> <jats:p> <jats:named-content content-type="genus-species">Staphylococcus aureus</jats:named-content> is an important pathogen causing a spectrum of diseases ranging from mild skin and soft tissue infections to life-threatening conditions. Bloodstream infections are particularly important, and the treatment approach is complicated by the presence of methicillin-resistant <jats:named-content content-type="genus-species">S. aureus</jats:named-content> (MRSA) isolates. The emergence of new genetic lineages of MRSA has occurred in Latin America (LA) with the rise and dissemination of the community-associated USA300 Latin American variant (USA300-LV). Here, we prospectively characterized bloodstream MRSA recovered from selected hospitals in 9 Latin American countries. All isolates were typed by pulsed-field gel electrophoresis (PFGE) and subjected to antibiotic susceptibility testing. Whole-genome sequencing was performed on 96 MRSA representatives. MRSA represented 45% of all (1,185 <jats:named-content content-type="genus-species">S. aureus</jats:named-content> ) isolates. The majority of MRSA isolates belonged to clonal cluster (CC) 5. In Colombia and Ecuador, most isolates (≥72%) belonged to the USA300-LV lineage (CC8). Phylogenetic reconstructions indicated that MRSA isolates from participating hospitals belonged to three major clades. Clade A grouped isolates with sequence type 5 (ST5), ST105, and ST1011 (mostly staphylococcal chromosomal cassette <jats:italic>mec</jats:italic> [SCC <jats:italic>mec</jats:italic> ] I and II). Clade B included ST8, ST88, ST97, and ST72 strains (SCC <jats:italic>mec</jats:italic> IV, subtypes a, b, and c/E), and clade C grouped mostly Argentinian MRSA belonging to ST30. In summary, CC5 MRSA was prevalent in bloodstream infections in LA with the exception of Colombia and Ecuador, where USA300-LV is now the dominant lineage. Clonal replacement appears to be a common phenomenon, and continuous surveillance is crucial to identify changes in the molecular epidemiology of MRSA. </jats:p>
7 1Scopus© Citations 101

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