Clinical, microbiological and genetic characteristics of heteroresistant vancomycin-intermediate Staphylococcus aureus bacteremia in a teaching Hospital

SABRINA DI GREGORIO, ; BEATRIZ PERAZZI.; ANDREA MARTINEZ; STELLA DE GREGORIO; MONICA FOCCOLI; MARÍA BEATRIZ LASALA; SUSANA GARCÍA; CARLOS VAY; ANGELA FAMIGLIETTI; MARTA MOLLERACH

MICROBIAL DRUG RESISTANCE-MECHANISMS EPIDEMIOLOGY AND DISEASE

MARY ANN LIEBERT INC

Lugar: New York; Año: 2015 vol. 21 p. 25 - 34

1076-6294

The emergence of vancomycin intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA)is of major concern worldwide. Our objective was to investigate the prevalence, phenotypic and molecularfeatures of hVISA strains isolated from bacteremic patients and to determine the clinical significance of thehVISA phenotype in patients with bacteremia. A total of 104 S. aureus blood isolates were collected from ateaching hospital of Argentina between August 2009 and November 2010. No VISA isolate was recovered, and3 out of 92 patients (3.3%) were infected with hVISA, 2 of them methicillin-resistant S. aureus (MRSA) (4.5%of MRSA). Macro Etest and prediffusion method detected 3/3 and 2/3 hVISA respectively. Considering the typeof bacteremia, the three cases were distributed as follows: two patients had suffered multiple episodes ofbacteremia (both hVISA strains recovered in the second episode), while only one patient had suffered asingle episode of bacteremia with hVISA infection. MRSA bloodstream isolates exhibiting the hVISA phenotypewere related to HA-MRSA Cordobes clone (ST5-SCCmec I-spa t149) and MRSA Argentinean pediatricclone (ST100-SCCmec IVNV-spa t002), but not to CA-MRSA-ST30-SCCmec IV-spa t019 clone that was one ofthe most frequent in our country. Although still relatively infrequent in our hospital, hVISA strains weresignificantly associated with multiple episodes of bacteremia ( p = 0.037) and genetically unrelated.