Clinical outcomes and molecular typing of heterogenous vancomycin-intermediate Staphylococcus aureus bacteremia in patients in intensive care units.
BACKGROUND
Staphylococcus aureus is one of most common pathogens in humans. Methicillin-resistant S. aureus (MRSA) accounts for 64 % of S. aureus bacteremia isolated in intensive care units (ICUs), and heteroresistant vancomycin-intermediates S. aureus (hVISA) is a phenotype of MRSA. However, studies focusing on the hVISA impact on critically ill patients are scarce.


METHODS
This was a retrospective study conducted in a tertiary medical center from January 2009 to December 2010. All adult patients in ICUs with MRSA bloodstream infection were eligible. A modified population analysis profile and area under the curve method was applied to all isolates to confirm hVISA phenotype. Multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) and the accessory gene regulator (agr) typing were performed individually. Clinical outcomes including in-hospital mortality, length of stay in intensive care unit and hospital after MRSA bacteremia of the patients were also analyzed.


RESULTS
A total of 48 patients were enrolled and 14 patients were confirmed to have the hVISA phenotype. The prevalence of hVISA was 29.2 %. There was no difference in the age, sex, comorbidity, Charlson's comorbidity score and previous vancomycin therapy between the hVISA and VSSA groups. The hVISA group had a significantly higher in-hospital mortality than the VSSA group (13/14 versus 22/34; p = 0.046). All of the 14 hVISA patients had an MIC = 2 mg/L by E-test and this represented a significant association between high MIC and the development of hVISA (p < 0.001). MLST analysis showed all the isolates in the hVISA group were ST239, while ST239 (14/34; 41.2 %) and ST5 (12/34; 35.3 %) were predominant in the VSSA group (p = 0.007). A comparison of the survivor and non-survivor group showed that the hVISA phenotype (OR 11.8; 95 % CI 1.1-126.99; p = 0.042) and sequential organ failure assessment (SOFA) score (OR 1.39; 95 % CI 1.07-1.81; p = 0.014) were independent factors significantly associated with in-hospital mortality.


CONCLUSIONS
Patients in ICUs with MRSA bacteremia may have a higher in-hospital mortality if they have the hVISA phenotype. SOFA score is also predictor of mortality.
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. h3226@cloud.cgmh.org.tw.|Department of Respiratory Therapy, Chang Gung University, College of Medicine, Taoyuan, Taiwan. h3226@cloud.cgmh.org.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. h3226@cloud.cgmh.org.tw.
Han-Chung
HC
Hu
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. kck0502@cloud.cgmh.org.tw.|Department of Respiratory Therapy, Chang Gung University, College of Medicine, Taoyuan, Taiwan. kck0502@cloud.cgmh.org.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. kck0502@cloud.cgmh.org.tw.
Kuo-Chin
KC
Kao
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. cremaster54@yahoo.com.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. cremaster54@yahoo.com.tw.
Li-Chung
LC
Chiu
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. ma7384@cloud.cgmh.org.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. ma7384@cloud.cgmh.org.tw.
Chih-Hao
CH
Chang
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. sima7372@gmail.com.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. sima7372@gmail.com.
Chen-Yiu
CY
Hung
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. lfp3434@cloud.cgmh.org.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. lfp3434@cloud.cgmh.org.tw.
Li-Fu
LF
Li
Department of Laboratory Medicine, Chang Gung Memorial Hospital at LinKou, 5, Fu-Shin St., Kwei-Shan, Taoyuan, 333, Taiwan. blue1010@cloud.cgmh.org.tw.
Tsui-Ping
TP
Liu
Department of Laboratory Medicine, Chang Gung Memorial Hospital at LinKou, 5, Fu-Shin St., Kwei-Shan, Taoyuan, 333, Taiwan. leollc@gmail.com.
Lee-Chung
LC
Lin
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. nhchen@cloud.cgmh.org.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. nhchen@cloud.cgmh.org.tw.
Ning-Hung
NH
Chen
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. cch4848@cloud.cgmh.org.tw.|Department of Respiratory Therapy, Chang Gung University, College of Medicine, Taoyuan, Taiwan. cch4848@cloud.cgmh.org.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. cch4848@cloud.cgmh.org.tw.
Chung-Chi
CC
Huang
Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan. yang1946@cloud.cgmh.org.tw.|Department of Respiratory Therapy, Chang Gung University, College of Medicine, Taoyuan, Taiwan. yang1946@cloud.cgmh.org.tw.|Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. yang1946@cloud.cgmh.org.tw.
Cheng-Ta
CT
Yang
Department of Laboratory Medicine, Chang Gung Memorial Hospital at LinKou, 5, Fu-Shin St., Kwei-Shan, Taoyuan, 333, Taiwan. janglu45@gmail.com.|Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan. janglu45@gmail.com.
Jang-Jih
JJ
Lu
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D016470:Bacteremia / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology; D001426:Bacterial Proteins / Q000235:genetics; D005260:Female; D005838:Genotype; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D016015:Logistic Models; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D016017:Odds Ratio; D010641:Phenotype; D015995:Prevalence; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology / Q000627:therapeutic use; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D014640:Vancomycin