Prevalence and Clinical Impact of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Isolated From Hospitalized Patients

BACKGROUND: We estimated the prevalence and clinical impact of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA). The concordance between macromethod and glycopeptide resistance detection (GRD) E tests was determined. In addition, predictors of clinical outcomes in hospitalized patients with S. aureus bacteremia (SAB) or pneumonia (SAP) were evaluated. METHODS: We obtained 229 consecutive S. aureus isolates from all hospitalized patients at two university hospitals located in Busan and Yangsan, Korea. Standard, macromethod, and GRD E tests were performed. Additionally, we reviewed the medical records of all patients. Among the 229 patients, predictors of clinical outcomes were analyzed for 107 patients with SAB and 39 with SAP. RESULTS: Among the 229 isolates, 34.5% of S. aureus isolates and 50.7% of methicillin-resistant S. aureus isolates exhibited the hVISA phenotype based on the macromethod E test. hVISA was nearly associated with treatment failure in patients with SAB (P=0.054) and was significantly associated with treatment failure in patients with SAP (P=0.014). However, hVISA was not associated with 30-day mortality in patients with SAB or SAP. The concordance between the macromethod and GRD E tests was 84.2%. CONCLUSIONS: hVISA is quite common in the southeastern part of Korea. hVISA is associated with treatment failure in patients with SAP.

Epidemiology of heterogeneous vancomycin-intermediate Staphylococcus aureus from sterile body fluid specimens / 国际检验医学杂志

Objective To investigate the prevalence and molecular characteristic of heterogeneous‐ vancomycin intermediate Staphylococcus aureus(hVISA) among methicillin‐resistant Staphylococcus aureus (MRSA)strains isolated from sterile body fluid specimens from 2009 to 2013 in Huangzhou District People′s Hospital in Huanggang City .Methods The minimum inhibitory con‐centrations (MIC) of antibiotics was determined by agar dilution method .The hVISA strains were detected by population analysis profile/area under the curve method (PAP/AUC) .The staphylococcal cassette chromosome mec (SCCmec) ,multilocus‐sequence typing (MLST) ,accessory gene regulator (agr) and Staphylococcus aureus protein A(spa) typing of hVISA strains were detected using PCR method .Results 32 hVISA strains were detected among 285 MRSA strains ,the prevalence rate of hVISA was 11 .2% , and the detection rates of hVISA from 2009 to 2013 were 0 .0% ,6 .4% ,9 .0% ,14 .3% and 18 .8% ,respectively ,showed an increas‐ing trend .The main hVISA epidemic clone was ST239‐SCCmecIII‐ t030‐agrI type(28strains ,accounting for 87 .5% ) .Conclusion The detection rate of hVISA showed an increasing trend in the past 5 years ,should be paid attention to strictly control the utiliza‐tion of glycopeptide drugs .

The incidence and risk factors for heterogeneous vancomycin intermediate Staphylococcus aureus / 中华内科杂志

Objectives To investigate the prevalence of heterogeneous vancomycin intermediate Staphylococcus aureus(hVISA) and the sensitivity of hVISA to novel antibiotics,and to explore the risk factors and infection attributable mortality associated with hVISA infection.Methods A total of 456 methicillin resistant Staphylococcus aureus (MRSA) isolates were isolated in Zhongshan Hospital from January,2008 to November,2010.All MRSA isolates were investigated for hVISA by two agar screening methods BHIA5T (brain-heart infusion containing teicoplanin 5 mg/L)or BHIA6V (brain-heart infusion containing vancomycin 6 mg/L),as well as macroEtest method(MET).Possible hVISA isolates were tested by modified population analysis profile-area under the curve (PAP-AUC).The minimal inhibitory concentrations(MICs) of vancomycin,teicoplanin and linezolid were determined by microbroth dilution as recommended by Clinical Laboratory Standards Institute(CLSI).The contribution difference between hVISA and vancomycin susceptible Staphylococcus aureus (VSSA) in different MIC range was compared.A retrospective case-control study of the patients with hVISA infection or VSSA infection was carried out and statistical analysis was performed using t test,Mann-Whitney test,x2 test and Fisher exact test.Results A total of 105 isolates of hVISA were screened by BHIA5T and BHIA6V (23.0％) with other 23 isolates by MET(5.0％) and 21 by PAP-AUC(4.6％).All isolates were 100％ sensitive to vancomycin,teicoplanin and linezolid.The vancomycin MIC [(1.76 ±-0.16) mg/L] in hVISA group was significantly higher than that in VSSA group[(1.09 ± 0.07)mg/L,P ＜ 0.01],which was a potential risk factor for hVISA infection.The retrospective study showed chronic obstructive pulmonary disease (COPD) was also a risk factor for hVISA infection of the lower respiratory tract.No significant difference in infection attributable mortality was showed between the hVISA group and the VSSA group.Conclusions The overall prevalence of hVISA in Zhongshan Hospital is estimated as 4.6％,while the prevalence of hVISA isolated from blood is as high as 12.5％.All isolates are 100％ sensitive to vancomycin and linezolid.COPD is a risk factor for hVISA infection of the lower respiratory tract.

Be alert to the alterations in the biological characteristics in heterogeneous vancomycin-intermediate Staphylococcus aureus.

The development of reduced vancomycin susceptibility in Staphylococcus aureus in many cases appears to be associated with characteristic changes. These changes may have pitfall of identifying S. aureus by automated testing methods like Vitek 32. In this study, we retested 24 heterogeneous vancomycin-intermediate Staphylococcus haemolyticus (h-VISH) collected in 2008-2010 at the Department of Clinical Microbiology by conventional biochemical tests and polymerase chain reaction (PCR). The heterogeneous vancomycin-intermediate S. aureus (hVISA) reversion test and electron microscopic examination were also used. Six isolates of 24 h-VISH possessed nuc, coa, and 16S rRNA genes, and could be reversed into S. aureus. It suggested that biochemical and morphological changes in hVISA and vancomycin-intermediate S. aureus (VISA) should be considered, and the detection of S. aureus, especially reduced vancomycin susceptibility isolates, requires more attention and different techniques.