Link: HighWire Press -- Medline Abstract.
Treatment of MRSA left-sided endocarditis in patients intolerant to vancomycin is challenging. The positive outcome in our patient is likely attributable to aggressive vancomycin dosing and extended duration of treatment prior to the initiation of daptomycin. The use of daptomycin in this case enabled successful management of left-sided endocarditis.
Link: HighWire Press -- Medline Abstract.
One hundred and twenty methicillin resistant Staphylococcus aureus (MRSA) strains were checked for minimum inhibitory concenteration (MIC) of vancomycin. The results showed that 98 strains (81.7 %) had MIC 32microg/mL) values points towards possible emergence of low level vancomycin resistance in the organisms and may explain the reasons of delayed therapeutic success of vancomycin in S.aureus bacteraemia in some situations.
Link: I Antimicrobial Agents and Chemotherapy.
This study compares beta-lactam vs. vancomycin among intravenous drug users (IVDUs) with methicillin-susceptible Staphylococcus aureus (MSSA) infective endocarditis (IE). Patients who received vancomycin had higher infection-related mortality even if they were switched to beta-lactam once culture results were available; this relationship persisted after logistic regression analysis controlled for clinical characteristics.
Results: All isolates were susceptible to vancomycin, linezolid and daptomycin and resistant to oxacillin. MICs increased for vancomycin, linezolid and oxacillin (P < 0.0001); however, daptomycin MICs decreased slightly (P = 0.0386). For vancomycin, linezolid and oxacillin, there were significant increases (P < 0.0001) in the percentage of isolates with MICs that were higher than the respective 2001 median MIC, but not for daptomycin (P = 0.1361). Oxacillin MICs were associated with MICs of linezolid (r = 0.364, P < 0.0001), vancomycin (r = 0.353, P < 0.0001) and daptomycin (r = 0.106, P = 0.0063). Conclusions: Oxacillin, vancomycin and linezolid MICs increased over time. For vancomycin and linezolid, these MIC increases were not reliably detected by percentage susceptibility as they occurred below the susceptibility breakpoint. Although the MICs of all agents appeared to be associated with increasing oxacillin MICs, the strongest associations were noted for vancomycin and linezolid.
Link: PharmaLive: New Drug Technology Being Developed by Wisconsin Start-Up Featured in Nature.
The study led by Centrose co-founder and UW-Madison Professor Jon Thorson was published last week in the Journal of the American Chemical Society. Nature reports that Centrose's technology allows for " ... an easier way to create vancomycin-like compounds that demonstrate more potency than their predecessor. The study highlights the simplicity of generating large libraries of such analogs [compounds modified using Centrose's unique technology] for optimizing antibiotics to target highly resistant pathogens." Centrose also plans to use its unique technology for methicillin-resistant Staphylococcus aureus, or MRSA, a bacterium responsible for more than 60% of hospital staph infections that can no longer be treated with methicillin, a penicillin-class antibiotic. A new national study released Monday by the Association for Professionals in Infection and Epidemiology (APIC) found that 46 out of every 1,000 hospital patients were either infected or colonized with MRSA. This rate is eight to 11 times greater than previous MRSA estimates
Link: Journal of Clinical Microbiology.
Staphylococcus aureus is one of the most commonly isolated organisms in nosocomial infections. While the prevalence of methicillin-resistant S. aureus (MRSA) continues to increase worldwide, there is concern about an increase in vancomycin MICs among S. aureus strains. The prevalence of MRSA and vancomycin MIC trends in S. aureus from patients in a university hospital were analyzed. Clinical Laboratory Standards Institute (CLSI, formerly NCCLS) reference broth microdilution MIC testing was performed on all clinically relevant S. aureus isolates from January 2000 through December 2004. A total of 6,003 S. aureus isolates were analyzed. No vancomycin-resistant S. aureus isolates were detected. One MRSA isolate had a vancomycin MIC of 8 �g/ml and was confirmed as vancomycin-intermediate S. aureus. Among the 6,002 remaining isolates, a shift in vancomycin MICs from ≤0.5 to 1.0 �g/ml was observed during the 5-year period. The percentage of S. aureus isolates with a vancomycin MIC of 1 �g/ml in 2004 was significantly higher than the percentage of isolates in 2000 (70.4% versus 19.9%; P < 0.01). This vancomycin MIC shift was more notable in methicillin-susceptible S. aureus. Our 5 years of routine testing of clinical isolates using the CLSI reference broth microdilution MIC method demonstrated a tendency toward decreasing susceptibility to vancomycin in S. aureus.
Link: Aggressive Vancomycin Dosing Unlikely to Boost Survival in MRSA Pneumonia.
For patients with methicillin-resistant Staphylococcus aureus (MRSA) pneumonia acquired in the healthcare setting, aggressive dosing strategies for vancomycin may not offer any advantage over traditional dose targets, study findings suggest. Specifically, trough levels of vancomycin greater than 15 g/mL are unlikely to increase survival compared with dosing aimed at trough concentrations in the range of 5 to 15 g/mL, clinicians from St. Louis, Missouri report in the October issue of CHEST. Among 102 patients with MRSA healthcare-associated pneumonia identified at Barnes-Jewish Hospital, St. Louis, over a 6.5 year period, 32 (31.4%) died while in the hospital, Dr. Marin H. Kollef of Washington University, St. Louis and colleagues report. According to the investigators, the average vancomycin trough concentrations and AUC values did not differ between those that survived and those that died. Trough levels were 13.6 and 13.9 g/mL and AUC values were 351 and 354 g/h/mL, respectively. While time to apyrexia was shorter in patients with AUC values greater than 400, there was "no evidence that greater vancomycin trough concentrations or AUC values correlated with hospital outcome," the team notes in the report. "The main issue," Dr. Kollef told Reuters Health, "is that MRSA healthcare-associated pneumonia is becoming an increasingly important infection in terms of incidence and costs to society."
Link: HighWire Press -- Medline Abstract.
CONCLUSIONS: Surgery within the previous 6 months and intensive care unit admission were identified as significant risk factors for patients with MRSA bacteremia with a vancomycin MIC 2 microg/mL undergoing hemodialysis. These patients experienced a longer mean hospital length of stay and increased hospital costs compared with patients with MRSA bacteremia with a vancomycin MIC < or =0.5 microg/mL and uninfected controls.
Link: Journal of Clinical Microbiology.
Staphylococcus aureus is one of the most commonly isolated organisms in nosocomial infections. While the prevalence of methicillin-resistant S. aureus (MRSA) continues to increase worldwide, there is concern about an increase in vancomycin minimal inhibitory concentrations (MICs) among S. aureus. The prevalence of MRSA and vancomycin MICs trends in S. aureus from patients in a university hospital was analyzed. Clinical Laboratory Standards Institute (CLSI) reference broth microdilution MIC testing was performed on all clinically relevant S. aureus isolated from January 2000 through December 2004. A total of 6,003 S. aureus were analyzed. No vancomycin-resistant S. aureus was detected. One MRSA isolate had a vancomycin MIC of 8 �g/ml and was confirmed as a vancomycin-intermediate S. aureus. Of the 6,002 remaining isolates, a shift in vancomycin MICs from ≤ 0.5 to 1.0 �g/ml was observed during the five year period. The percentage of S. aureus isolates with a vancomycin MIC of 1 �g/ml in 2004 was significantly higher than the percentage of isolates in 2000 (70.4% vs. 19.9%, P < 0.01). This vancomycin MIC shift was more notable in methicillin-susceptible S. aureus . Our five years of routine testing of clinical isolates using the CLSI reference broth microdilution MIC method demonstrated a tendency of decreasing susceptibility to vancomycin in S. aureus.
Link: ICAAC 2006:
Vancomycin may be overused for the treatment of hospital-acquired pneumonia, perhaps because of physicians' perceptions that patients are at high risk for methicillin-resistant Staphylococcus aureus (MRSA), according to a study by Robert H. Eng, MD, and colleagues at the Veterans Affairs New Jersey Health Care System in East Orange, NJ. The study was presented at the 45th ICAAC meeting in Washington, DC.
The researchers sought to determine whether vancomycin was used appropriately or inappropriately for the treatment of pneumonia at their institution, in accordance with guidelines developed by the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS). To do so, they developed an electronic form at the point of antibiotic order to capture vancomycin prescribers' decisions and thoughts.
More at the link above
A short introduction from Dave Roberts
This 12 minute introduction will help you grasp the key facts and the key issues surrounding drug resistant staph aureus (mersa, mursa)
