Table 2.
Summary of Studies Examining Vancomycin Minimum Inhibitory Concentration “Creep”
| Study [Reference] | Study Features | MIC “Creep” | Comments |
|---|---|---|---|
| Wang et al, 2006 [58] | Single US center, 6003 isolates from 2000 to 2004 | Yes—proportion of isolates with BMD >1 μg/mL | Proportion increased from 20% to 70% |
| No typing performed | |||
| Robert et al, 2006 [59] | Single French center, 1445 isolates from 1983 to 2001 | Yes—Etest geometric mean | 1.54-fold increase in mean MIC |
| No typing performed | |||
| Jones et al, 2006 [20] | Multicenter worldwide study (SENTRY data), 35 485 isolates from 1998 to 2003 | No—proportion of isolates with BMD >2 μg/mL | No typing performed |
| Steinkraus et al, 2007 [60] | Single US center, 662 isolates from 2001 to 2005 | Yes—Etest geometric mean | 1.5-fold increase in mean MIC |
| No typing performed | |||
| Alos et al, 2008 [61] | Single Spanish center, 3141 isolates from 2002 to 2006 | No—proportion of isolates with BMD >2 μg/mL | No typing performed |
| Holmes et al, 2008 [62] | Single US center, 240 isolates from 1999 to 2006 | No—BMD MIC90 | No typing performed |
| Rybak et al, 2008 [63] | Single US center, 1499 isolates from 1986 to 2007 | Yes—proportion of isolates with BMD >1 μg/mL | Proportion increased from 81% to 93% |
| No typing performed | |||
| Sader et al, 2009 [64] | Multicenter US study, 1800 isolates from 2002 to 2006 | No—BMD modal MIC | 3 sites showed low-level geometric mean creep |
| No typing performed | |||
| Musta et al, 2009 [17] | Single-center US study, 489 isolates from 1996 to 2006 | No—proportion of isolates with Etest >1, 1.5, or 2 μg/mL | No typing performed |
| Ho et al, 2010 [65] | Multicenter Hong Kong study, 247 isolates from 1997 to 2008 | Yes—proportion of isolates with Etest >1 μg/mL | Proportion increased from 11% to 38% |
| Typing suggestive of clonal MIC “creep” | |||
| Adam et al, 2010 [66] | Multicenter Canadian study, 6397 isolates from 1995 to 2006 | No—BMD modal or proportion of isolates >2 μg/mL | No typing performed |
| Pitz et al, 2011 [67] | Single-center US study, 167 isolates from 2000 to 2008 | No—proportion of isolates with Etest >1 μg/mL | No typing performed |
| Gasch et al, 2011 [50] | Single-center Spanish study, 524 isolates from 1990 to 2008 | No—decline in geometric mean MIC by Etest | Typing confirmed clonal replacement with ST125 and ST228 |
| van Hal et al, 2011 [25] | Single-center Australian study, 417 isolates from 1997 to 2008 | No—creep dependent on MIC methodology and measurement used for analysis | Typing performed |
| Edwards et al, 2012 [49] | Multicenter Scottish study, 208 isolates from 2006 to 2010 | No—significant effect on MIC of storage most pronounced for Etest | Typing performed |
| Yeh et al, 2012 [15] | Single-center Taiwanese study, 140 isolates during 2001, 2005, & 2009 | Yes—Etest geometric mean | No typing performed |
Abbreviations: BMD, broth microdilution; MIC, minimum inhibitory concentration.