High vancomycin minimum inhibitory concentration is a predictor of mortality in meticillin-resistant Staphylococcus aureus bacteraemia.
Failure of vancomycin in the treatment of meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia has been reported despite full susceptibility of the organism to vancomycin. A retrospective observational cohort study including 137 patients with MRSA bacteraemia was performed at two centres in South Korea during 2009-2010. A total of 137 patients with MRSA bacteraemia receiving vancomycin therapy were enrolled during the study period. Isolates from 13 (9.5%) of the 137 patients had minimum inhibitory concentrations (MICs) ≥1 μg/mL. The 30-day cumulative survival was 53.8% for patients infected with isolates having a MIC≥1 μg/mL and 79.8% for patients infected with isolates having a MIC<1 μg/mL (log-rank test, P=0.026). Vancomycin MIC≥1 μg/mL [hazard ratio (HR)=7.0, 95% confidence interval (CI) 2.2-22.1; P=0.001], nosocomial acquisition of bacteraemia (HR=5.4, 95% CI 1.4-20.1; P=0.013), rapidly fatal underlying diseases (HR=20.5, 95% CI 3.9-106.4; P<0.001), presentation with septic shock (HR=8.4, 95% CI 3.0-23.3; P<0.001), presence of complicated infections (HR=5.6, 95% CI 2.0-15.8; P=0.001) and persistent MRSA bacteraemia for ≥3 days (HR=4.2, 95% CI 1.4-12.7; P=0.012) were independent predictors of 30-day mortality in patients with MRSA bacteraemia. In patients with high Pitt bacteraemia scores (Pitt score ≥2), the delay in initiation of vancomycin therapy was significantly different between non-survivors and survivors (2.4 days vs. 1.1 days; P=0.012). Vancomycin MIC≥1 μg/mL had a significant impact on mortality of patients with MRSA bacteraemia. These findings support early consideration of alternative anti-MRSA agents in patients with MRSA bacteraemia who have high vancomycin MICs as well as prompt initiation of anti-MRSA treatment in patients with MRSA bacteraemia, especially those with high Pitt scores.
Division of Infectious Diseases, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Republic of Korea.
Yu Mi
YM
Wi
June Myung
JM
Kim
Eun-Jeong
EJ
Joo
Young Eun
YE
Ha
Cheol-In
CI
Kang
Kwan Soo
KS
Ko
Doo Ryeon
DR
Chung
Jae-Hoon
JH
Song
Kyong Ran
KR
Peck
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology; D016470:Bacteremia / Q000188:drug therapy / Q000382:microbiology / Q000401:mortality*; D016001:Confidence Intervals; D003428:Cross Infection / Q000188:drug therapy / Q000382:microbiology / Q000401:mortality; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000472:pathogenicity*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012772:Shock, Septic / Q000188:drug therapy / Q000382:microbiology / Q000401:mortality; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology / Q000401:mortality*; D016896:Treatment Outcome; D014640:Vancomycin / Q000008:administration & dosage* / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D014640:Vancomycin