Vancomycin enterococcal

Therapy for Native-Valve or Prosthetic-Valve Enterococcal Endocarditis Caused by Strains Susceptible to Penicillin, Gentamicin, and Vancomycin... 

Montecalvo MA Ramoplanin A novel antimicrobial agent with the potential to prevent vancomycin-resistant enterococcal infection in high-risk patients. J Antimicrob Chemother 2003 51(suppl 3) 31—35. 

Murray BE. Vancomycin-resistant enterococcal infections. N Engl J Med 2000 342 710-721. 

Resistance to vancomycin in enterococci is due to modification of the D-Ala-D-Ala binding site of the peptidoglycan building block in which the terminal D-Ala is replaced by D-lactate. This results in the loss of a critical hydrogen bond that facilitates high-affinity binding of vancomycin to its target and loss of activity. This mechanism is also present in vancomycin-resistant S aureus strains (MIC s32. ug/mL), which have acquired the enterococcal resistance determinants. The mechanism for reduced vancomycin susceptibility of vancomycin-intermediate strains (MICs = 8-16 g/mL) is not known. 

Scheme 2-5. Molecular basis of enterococcal vanA/B- and vanC-glycopeptide resistance. Interaction of vancomycin with D-Ala-D-Lac. The lactate ester bond leads to a lowered ligand binding affinity by loss of one hydrogen bond and electronic repulsion (solid arrow).

Because of its potential toxicity, vancomycin is reserved for serious infections in which less toxic antibiotics are ineffective or not tolerated. Generally, vancomycin is administered intravenously because of poor intestinal absorption. It is the drug of choice for treating infections caused by methicillin-resistant staphylococci and penicillin-resistant Streptococcus pneumoniae. Vancomycin has been used to treat enterococcal infections because of their resistance to the P-lactam antibiotics, but most enterococci are now also resistant to vancomycin. Oral administration of rancomycin is important for treatment of some gastrointestinal infections such as pseudomembranous colitis caused by C. difficile. 

A morbidly obese 17-year-old Hispanic girl, who had a cadaveric renal transplantation 5 years before, took ciclosporin and prednisone for stabilization. She was treated with chloramphenicol 875 mg qds and ceftazidime 2 g tds for vancomycin-resistant enterococcal sinusitis. There was a substantial and sustained increase in ciclosporin concentrations after chloramphenicol was added. Normalization was achieved after withdrawal of chloramphenicol. 

Raad I, Hachem R, Hanna H, Girgawy E, Rolston K, Whimbey E, Husni R, Bodey G. Treatment of vancomycin-resistant enterococcal infections in the immunocompromised host quinupristin-dalfopristin in combination with minocycline. Antimicrob Agents Chemother 2001 45(ll) 3202-4. 

Kuehnert MJ, Jernigan JA, Pullen AL, Rimland D, Jarvis WR. Association between mucositis severity and vancomycin-resistant enterococcal bloodstream infection in hospitalized cancer patients. Infect Control Hosp Epidemiol 1999 20(10) 660-3. 

Raymond et al. reported on a rotation study in a surgical intensive care unit with a different twist.Patients were stratified as either having sepsis/peritonitis or pneumonia, and empiric therapy was cycled every 3 months by syndrome. Fourteen hundred fifty-six admissions and 540 infections were treated over a 2-year period. With similar severity of illness during the before and after periods (mean APACHE II = 19), the authors demonstrated a reduction of length of stay from a mean of 62 days to 39 days, a reduction of vancomycin-resistant enterococcal and methicillin-resistant staphylococcal infection from 14 per 100 admissions to 8 per 100 admissions and death due to any cause dropped from 25 in the before period to 18 in the rotation period. Antimicrobial susceptibility and several other key parameters needed to evaluate the effectiveness of this program were not reported. 

After culture and sensitivity results are obtained, antibiotic therapy should be adjusted appropriately (Fig. 45-5). If the patient does not show signs of clinical improvement within 72 hours after antibiotic treatment is initiated, the culture should be repeated and the patient re-evaluated. For streptococcal or enterococcal peritonitis, IP ampicillin (125 mg/L in each exchange) is the preferred treatment. For Enterococcus, the addition of an aminoglycoside, depending on sensitivities, may be warranted for synergy. In addition, if the Enterococcus is resistant to both ampicillin and vancomycin, linezolid or quinupristin/dalfopristin are recommended. However, quinupristin/ dalfopristin is not effective against E.faecalis. 

Antibiotic resistance behaviour of 308 enterococci isolated from Bryndza cheese is shown in Fig. 5. All enterococcal isolates from Bryndza cheese were susceptible to ampicillin, streptomycin, gentamicin, vancomycin, and teicoplanin. For these same isolates, resistance rates to rifampicin, erythromycin, ciprofloxacin, and... 

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