Optimizing Therapy for Vancomycin-Resistant Enterococci (VRE)

ABSTRACT

Enterococci are gram-positive, facultative bacteria with low intrinsic virulence but capable of causing a diverse variety of infections such as bacteremia with or without endocarditis, and intra-abdominal, wound, and genitourinary infection. During the past 2 decades the incidence of hospital-acquired enterococcal infection has significantly risen and is increasingly due to multidrug-resistant strains, primarily to the coacquisition of genetic determinants that encode for the stable expression of high-level β-lactam, aminoglycoside, and glycopeptide resistance.

Because enterococci constitute part of the normal colonizing flora, careful clinical interpretation of cultures that grow enterococci is paramount to avoid unnecessary and potentially deleterious antimicrobial therapy. Traditional antimicrobial treatment for ampicillin- and glycopeptide-susceptible enterococcal infection remains a penicillin-, ampicillin-, semisynthetic penicillin-based regimen, or vancomycin in a penicillin-intolerant individual. The need for a bactericidal combination with a cell-wall active agent combined with an aminoglycoside is most supported for native- or prosthetic valve endocarditis but is unproven for the majority of infections due to enterococci. The emergence of vancomycin-resistant enterococci prompted the clinical development of several novel and modified antimicrobial compounds approved for VRE infection (quinupristin-dalfopristin, linezolid) and several approved for non-VRE indications (daptomycin, tigecycline).

There is a paucity of comparative clinical trial data with these new agents, although linezolid, based upon its efficacy and tolerability, appears to be the cornerstone of current treatment approaches. Despite a relatively short period of clinical use, enterococcal resistance has now been described for quinupristin-dalfopristin and linezolid and more recently even for daptomycin and tigecycline. Moreover, the optimal treatment of endocarditis due to VRE strains is unknown because, with the exception of daptomycin, current treatment options only yield bacteriostasis. Nonantimicrobial measures to treat VRE infection, such as foreign body removal and percutaneous or surgical drainage of close-spaced infection, reduce both the need for and the duration of anti-enterococcal treatment and the emergence of resistance to the newer antimicrobials.

Enterococcus - vancomycin - linezolid - antimicrobial resistance - nosocomial infection

REFERENCES

• 1 Centers for Disease Control and Prevention . National Nosocomial Infection Surveillance (NNIS) system: report, data summary from January 1992 through June 2003, issued August 2003.  Am J Infect Control. 2003;  31 481-498
• 2 Wisplinghoff H, Bischoff T, Tallent S M, Seiferd H, Wenzel R P, Edmond M B. Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study.  Clin Infect Dis. 2004;  39 309-317
• 3 Moellering Jr R C. The Garrod Lecture. The Enterococcus: a classic example of the impact of antimicrobial resistance on therapeutic options.  J Antimicrob Chemother. 1991;  28 1-12
• 4 Murray B E. The life and times of the Enterococcus .  Clin Microbiol Rev. 1990;  3 46-65
• 5 Hodges T L, Zighelboim-Daum S, Eliopoulos G M, Wennersten C, Moellering Jr R C. Antimicrobial susceptibility changes in Enterococcus faecalis following various penicillin exposure regimens.  Antimicrob Agents Chemother. 1992;  36 121-125
• 6 Hamilton-Miller J M, Purves D. Enterococci and antifolate antibiotics.  Eur J Clin Microbiol. 1986;  5 391-394
• 7 LeClercq R, Couvalin P. Bacterial resistance to macrolide, lincosamide and streptogramin antibiotics by target modification.  Antimicrob Agents Chemother. 1991;  35 1267-1272
• 8 Lefort A, Mainardi J L, Tod M, Lotholary O. Antienterococcal antibiotics.  Med Clin North Am. 2000;  84 1471-1495
• 9 Rybkine T, Mainardi J L, Sougakoff W, Collatz E, Gutmann L. Penicillin- binding protein 5 sequence alterations in clinical isolates of Enterococcus faecium with different levels of beta-lactam resistance.  J Infect Dis. 1998;  178 159-163
• 10 Grayson M L, Eliopoulos G M, Wennersten C B et al.. Increasing resistance to ß-lactam antibiotics amongst clinical isolates of Enterococcus faecium: a 22-year review at one institution.  Antimicrob Agents Chemother. 1991;  35 2180-2184
• 11 Horodniceanu T, Bougueleret L, El-Solh N, Bieth G, Delbos F. High level resistance to gentamicin in Streptococcus faecalis subsp. zymogenes .  Antimicrob Agents Chemother. 1979;  16 686-689
• 12 Mederski-Samoraj B D, Murray B E. High level resistance to gentamicin in clinical isolates of enterococci.  J Infect Dis. 1983;  147 751-757
• 13 Spiegel C A, Hucyke M. Endocarditis due to streptomycin-susceptible Enterococcus faecalis with high-level gentamicin resistance.  Arch Intern Med. 1989;  149 1873-1875
• 14 Eliopoulos G M. Aminoglycoside resistant enterococcal endocarditis.  Infect Dis Clin North Am. 1993;  7 117-133
• 15 Leclercq R, Dutka-Malen S, Brisson-Noel A et al.. Resistance of enterococci to aminoglycosides and glycopeptides.  Clin Infect Dis. 1992;  15 495-501
• 16 Leclercq R, Derlot E, Duval J, Courvalin P. Plasmid mediated resistance to vancomycin and teicoplanin in Enterococcus faecium .  N Engl J Med. 1988;  319 157-161
• 17 Centers for Disease Control and Prevention . Nosocomial enterococci resistant to vancomycin-United States 1989-1993.  MMWR Morb Mortal Wkly Rep.. 1993;  42 597-599
• 18 Biedenbach D J, Moet G J, Jones R N. Occurrence and antimicrobial resistance pattern comparisons among bloodstream infection isolates from the SENTRY Antimicrobial Surveillance Program (1997-2002).  Diagn Microbiol Infect Dis. 2004;  50 59-69
• 19 Lai K K, Fontecchio S A, Kelly A L, Baker S, Melvin Z S. The changing epidemiology of vancomycin-resistant enterococci.  Infect Control Hosp Epidemiol. 2003;  24 264-268
• 20 Courvalin P. Vancomycin resistance in gram-positive cocci.  Clin Infect Dis. 2006;  42 S25-S34
• 21 Handwerger S, Skoble J. Identification of chromosomal mobile element conferring high-level vancomycin resistance in Enterococcus faecium .  Antimicrob Agents Chemother. 1995;  39 2446-2453
• 22 Gold H S. Vancomycin resistant enterococci: mechanisms and clinical observations.  Clin Infect Dis. 2001;  33 210-219
• 23 Noble W C, Virani Z, Cree R G. Co-transfer of vancomycin and other resistance genes from Enterococcus faecalis NCTC 12201 to Staphylococcus aureus .  FEMS Microbiol Lett. 1992;  72 195-198
• 24 Chang S, Sievert D M, Hageman J C et al.. Infection with vancomycin- resistant Staphylococcus aureus containing the vanA resistance gene.  N Engl J Med. 2003;  348 1342-1347
• 25 Centers for Disease Control and Prevention (CDC) . Vancomycin-resistant Staphylococcus aureus-New York.  MMWR Morb Mortal Wkly Rep. 2005;  53 322-323
• 26 Miller D, Urdaneta V, Weltman A. Vancomycin-resistant Staphylococcus aureus-Pennsylvania 2002.  MMWR Morb Mortal Wkly Rep. 2002;  51 902
• 27 Sievert D M, Boulton M L, Stolzman G et al.. Staphylococcus aureus resistant to vancomycin-United States 2002.  MMWR Morb Mortal Wkly Rep. 2002;  51 565-567
• 28 Whitener C J, Park S Y, Browne F A et al.. Vancomycin-resistant Staphylococcus aureus in the absence of vancomycin exposure.  Clin Infect Dis. 2004;  38 1049-1055
• 29 Donskey C J. The role of the intestinal tract as a reservoir and source for transmission of nosocomial pathogens.  Clin Infect Dis. 2004;  39 219-226
• 30 Beezhold D W, Slaughter S, Hayden M K et al.. Skin colonization with vancomycin-resistant enterococci among hospitalized patients with bacteremia.  Clin Infect Dis. 1997;  24 704-706
• 31 D'Agata E M, Gautam S, Green W K, Tang Y W. High rate of false- negative results of the rectal swab culture method in detection of gastrointestinal colonization with vancomycin-resistant enterococci.  Clin Infect Dis. 2002;  34 167-172
• 32 Weinstein J W, Tallapragada S, Farrel P, Dembry L M. Comparison of rectal and peri-rectal swabs for detection of colonization with vancomycin-resistant enterococci.  J Clin Microbiol. 1996;  34 210-212
• 33 Montecalvo M A, Lencastre H, Carraher M et al.. Natural history of colonization with vancomycin-resistant Enterococcus faecium .  Infect Control Hosp Epidemiol. 1995;  16 680-685
• 34 Baden L R, Thiemke W, Skolnik A et al.. Prolonged colonization with vancomycin-resistant Enterococcus faecium in long-term care patients and the significance of “clearance”.  Clin Infect Dis. 2001;  33 1654-1660
• 35 Roghmann M C, Aquiyumi S, Schwalbe R, Morris Jr J G. Natural history of colonization with vancomycin-resistant Enterococcus faecium .  Infect Control Hosp Epidemiol. 1997;  18 679-680
• 36 Tornieporth N G, Roberts R B, Hafner J J, Riley L W. Risk factors associated with vancomycin-resistant Enterococcus faecium infection or colonization in 145 matched case and control patients.  Clin Infect Dis. 1996;  23 767-772
• 37 Bonten M J, Hayden M K, Nathan C et al.. Epidemiology of colonization of patients and environment with vancomycin-resistant enterococci.  Lancet. 1996;  348 1615-1619
• 38 Morris J G, Shay D K, Hebden J N et al.. Enterococci resistant to multiple antimicrobial agents including vancomycin, establishment of endemicity in a university medical center.  Ann Intern Med. 1995;  123 250-259
• 39 Warren D K, Kollef M H, Seiler S M, Fridkin S K, Fraser V J. The epidemiology of vancomycin-resistant Enterococcus in a medical intensive care unit.  Infect Control Hosp Epidemiol. 2003;  24 257-263
• 40 Donskey C J, Chowdhry T, Hecker M et al.. Effect of antibiotic therapy on the density of vancomycin-resistant enterococci in the stool of colonized patients.  N Engl J Med. 2000;  343 1925-1932
• 41 Bonten M J, Slaughter S, Ambergen A W et al.. The role of “colonization pressure” in the spread of vancomycin-resistant enterococci: an important infection control variable.  Arch Intern Med. 1998;  158 1127-1132
• 42 Linden P. Can enterococcal infections initiate sepsis syndrome?.  Curr Infect Dis Rep. 2003;  5 372-378
• 43 Kollef M H, Sherman G, Ward S, Fraser V J. Inadequate antimicrobial treatment of infections: a risk factor for hospital mortality among critically ill patients.  Chest. 1999;  115 462-472
• 44 Kumar A, Robert D, Wood K E et al.. Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock.  Crit Care Med. 2006;  34 1589-1596
• 45 Ibrahim E H, Sherman G, Ward S, Fraser V J, Kollef M H. The influence of inadequate antimicrobial treatment of bloodstream infections on patient outcomes in the ICU setting.  Chest. 2000;  118 146-155
• 46 Quale J, Landman D, Atwood E et al.. Experience with a hospital-wide outbreak of vancomycin-resistant enterococci.  Am J Infect Control. 1996;  24 372-379
• 47 Lai K K. Treatment of vancomycin resistant Enterococcus faecium infections.  Arch Intern Med. 1996;  156 2579-2584
• 48 Pankey G A, Sabath L D. Clinical relevance of bacteriostatic versus bactericidal mechanisms of action in the treatment of gram-positive bacterial infections.  Clin Infect Dis. 2004;  38 864-870
• 49 Finberg R W, Moellering R C, Tally F P et al.. The importance of bactericidal drugs, future directions in infectious diseases.  Clin Infect Dis. 2004;  39 1314-1320
• 50 Tsigrelis C, Singh K V, Coutinho T D, Murray B E, Baddour L M. Vancomycin-resistant Enterococcus faecalis endocarditis: linezolid failure and strain characterization of virulence factors.  J Clin Microbiol. 2007;  45 631-635
• 51 Mekonen E T, Noskin G A, Hacek D M, Peterson L R. Successful treatment of persistent bacteremia due to vancomycin resistant ampicillin resistant Enterococcus faecium .  Microb Drug Resist. 1995;  1 249-253
• 52 Dodge R A, Daly J S, Davaro R, Glew R H. High-dose ampicillin plus streptomycin for treatment of a patient with severe infection due to multi-drug resistant enterococci.  Clin Infect Dis. 1997;  25 1269-1270
• 53 Murray B E. Vancomycin-resistant enterococcal infections.  N Engl J Med. 2000;  342 710-721
• 54 Lautenbach E, Schuster M G, Biler W B et al.. The role of chloramphenicol in the treatment of bloodstream infection due to vancomycin-resistant Enterococcus .  Clin Infect Dis. 1998;  27 1259-1265
• 55 Gould C V, Fishman N O, Nakamkin N I, Lautenbach E. Chloramphenicol resistance in vancomycin resistant enterococcal bacteremia: impact of prior fluoroquinolone use.  Infect Control Hosp Epidemiol. 2004;  25 138-145
• 56 Howe R A, Robson M, Oakhill A et al.. Successful use of tetracycline as therapy of an immunocompromised patient with septicemia caused by a vancomycin-resistant Enterococcus .  J Antimicrob Chemother. 1997;  40 144-145
• 57 Linden P K, Pasculle A W, Manez R et al.. Utilization of novobiocin and ciprofloxacin for the treatment of serious infection due to vancomycin-resistant Enterococcus faecium. In: Program and Abstracts of the Thirty-Third Interscience Conference on Antimicrobial Agents and Chemotherapy, New Orleans, LA. Abstract 1027. Washington, DC; American Society for Microbiology 1993: 307
• 58 Montecalvo M A, Horowitz H, Wormser G P et al.. Effect of novobiocin containing antimicrobial regimens on infection and colonization with vancomycin resistant Enterococcus faecium. .  Antimicrob Agents Chemother. 1995;  39 794
• 59 Taylor S E, Paterson D L, Yu V L. Treatment options for chronic prostatitis due to vancomycin-resistant Enterococcus faecium .  Eur J Clin Microbiol Infect Dis. 1998;  17 798-800
• 60 Schmit J L. Efficacy of teicoplanin for enterococcal infections: 63 cases and review.  Clin Infect Dis. 1992;  15 302-306
• 61 Aslangul E, Baptista M, Fantin B et al.. Selection of glycopeptide-resistant mutants of VanB type Enterococcus faecalis BM4281 in vitro and in experimental endocarditis.  J Infect Dis. 1997;  175 598-605
• 62 Hayden M K, Trenholme G M, Schultz J E et al.. In vivo development of teicoplanin resistance in a VanB Enterococcus faecalis .  J Infect Dis. 1993;  167 1224-1227
• 63 Zhanel G G, Hoban D J, Karlowsky J A. Nitrofurantoin is active against vancomycin-resistant enterococci.  Antimicrob Agents Chemother. 2001;  45 324-326
• 64 Linden P, Coley K, Kusne S. Bacteriologic efficacy of nitrofurantoin for the treatment of urinary tract infection due to vancomycin-resistant Enterococcus faecium .  Clin Infect Dis. 1999;  29 999
• 65 Cocito C, DiGiambattista M, Nyssen E, Vannuffel P. Inhibition of protein synthesis by streptogramins and related antibiotics.  J Antimicrob Chemother. 2007;  39(Suppl A) 7-13
• 66 Hershberger E, Donabedian S, Konstantinou K, Zervos M J. Quinupristin-dalfopristin resistance in gram-positive bacteria: mechanism of resistance and epidemiology.  Clin Infect Dis. 2004;  38 92-98
• 67 Moellering R C, Linden P K, Reinhardt J et al.. The efficacy and safety of quinupristin/dalfopristin for the treatment of vancomycin-resistant Enterococcus faecium .  J Antimicrob Chemother. 1999;  44 251-271
• 68 Linden P K, Moellering R C, Wood C A et al.. Treatment of vancomycin-resistant Enterococcus faecium infections with quinupristin/dalfopristin.  Clin Infect Dis. 2001;  33 1816-1823
• 69 Brown J, Freeman B B. Combining quinupristin/dalfopristin with other agents for resistant infections.  Ann Pharmacother. 2004;  38 677-685
• 70 Bethea J A, Walko C M, Targos P A. Treatment of vancomycin-resistant Enterococcus with quinupristin/dalfopristin and high dose-ampicillin.  Ann Pharmacother. 2004;  38 989-91
• 71 Thompson R L, Lavin B, Talbot G H. Endocarditis due to vancomycin-resistant Enterococcus faecium in an immunocompromised patient: cure by administering combination therapy with quinupristin/dalfopristin and high-dose ampicillin.  South Med J. 2003;  96 818-820
• 72 Raad I, Hachem R, Hanna H et al.. Treatment of vancomycin-resistant enterococcal infections in the immunocompromised host: quinupristin-dalfopristin in combination with minocycline.  Antimicrob Agents Chemother. 2001;  45 3202-3204
• 73 Olsen K M, Rebuck J A, Rupp M E. Arthralgias and myalgias related to quinupristin-dalfopristin administration.  Clin Infect Dis. 2001;  32 e83-e86
• 74 Werner G, Klare I, Spencker F B, Witte W. Intra-hospital dissemination of quinupristin-dalfopristin- and vancomycin-resistant Enterococcus faecium in a paediatric ward of a German hospital.  J Antimicrob Chemother. 2003;  52 113-115
• 75 Donabedian S M, Perri M B, Vager D et al.. Quinupristin-dalfopristin resistance in Enterococcus faecium isolates from humans, farm animals, and grocery store meat in the United States.  J Clin Microbiol. 2006;  44 3361-3365
• 76 Moellering R C. Linezolid: the first oxazolidinone antimicrobial.  Ann Intern Med. 2003;  138 135-142
• 77 Pharmacia and Upjohn .Linezolid for the Treatment of Vancomycin Resistant Enterococcal Infections: A Double-Blind Trial Comparing 600 mg Linezolid Every 12 Hours with 200 mg Linezolid Every 12 Hours (study report M/1260/0054A). Peapack, NJ; Pharmacia Upjohn 1999
• 78 Birmingham M C, Raynes C R, Meagher A K, Flavin S M, Batts D H, Schentag J J. Linezolid for the treatment of multidrug-resistant gram-positive infections: experience from a compassionate use program.  Clin Infect Dis. 2003;  36 159-168
• 79 Stevens M P, Edmond M B. Endocarditis due to vancomycin-resistant enterococci: case report and review of the literature.  Clin Infect Dis. 2005;  41 1134-1142
• 80 Archuleta S, Murphy B, Keller M J. Successful treatment of vancomycin-resistant Enterococcus faecium endocarditis with linezolid in a renal transplant recipient with human immunodeficiency virus infection.  Transpl Infect Dis. 2004;  6 117-119
• 81 Babcock H M, Ritchie D J, Christiansen E, Starlin R, Little R, Stanley S. Successful treatment of vancomycin-resistant Enterococcus endocarditis with oral linezolid.  Clin Infect Dis. 2001;  32 1373-1375
• 82 Zimmer S M, Caliendo A M, Thigpen M C, Somani J. Failure of linezolid treatment for enterococcal endocarditis.  Clin Infect Dis. 2003;  37 e29-e30
• 83 Tsigrelis C, Singh K V, Coutinho T D, Murray B E, Baddour L M. Vancomycin-resistant Enterococcus faecalis endocarditis: linezolid failure and strain characterization of virulence factors.  J Clin Microbiol. 2007;  45 631-635
• 84 Gonzales R D, Schreckenberger P C, Graham M B et al.. Infections due to vancomycin-resistant Enterococcus faecium resistant to linezolid.  Lancet. 2001;  357 1179
• 85 Seedat J, Zick G, Klare I et al.. Rapid emergence of resistance to linezolid during linezolid therapy of an Enterococcus faecium infection.  Antimicrob Agents Chemother. 2006;  50 4217-4219
• 86 Marra A R, Major Y, Edmond M D. Central venous catheter colonization by linezolid-resistant, vancomycin-susceptible Enterococcus faecalis .  J Clin Microbiol. 2006;  44 1915-1916
• 87 Rahim S, Pillai S K, Gold H S, Venkataraman L, Inglima K, Press R A. Linezolid-resistant, vancomycin-resistant Enterococcus faecium infection in patients without prior exposure to linezolid.  Clin Infect Dis. 2003;  36 E146-148
• 88 Swaney S M, Shinabarger D L, Schaadt R D, Bock J H, Slightom J L, Zurenko G E. Oxazolidinone resistance is associated with a mutation in the peptidyl transferase region of 23S rRNA [abstract C-104]. In: Program and Abstracts of the 38th Interscience Conference on Antimicrobial Agents and Chemotherapy; San Diego. Washington, DC; American Society for Microbiology 1998: 98-99
• 89 Herrero I A, Issa N C, Patel R. Nosocomial spread of linezolid-resistant vancomycin-resistant Enterococcus faecium .  N Engl J Med. 2002;  346 867-869
• 90 Marshall S H, Donskey C J, Hutton-Thomas R, Salata R A, Rice L B. Gene dosage and linezolid resistance in Enterococcus faecium and Enterococcus faecalis .  Antimicrob Agents Chemother. 2002;  46 3334-3336
• 91 Pai M P, Rodvold K A, Schreckenbefger P C, Gonezales R D, Petrolatti J M, Quinn J P. Risk factors associated with the development of infection with linezolid- and vancomycin-resistant Enterococcus faecium .  Clin Infect Dis. 2002;  35 1269-1272
• 92 Green S L, Maddox J C, Huttenbach E D. Linezolid and reversible myelosuppression.  JAMA. 2001;  285 1291
• 93 Halpern M. Linezolid-induced pancytopenia.  Clin Infect Dis. 2002;  35 347-348
• 94 Wigen C L, Goetz M B. Serotonin syndrome and linezolid.  Clin Infect Dis. 2002;  34 1651-1652
• 95 Saijo T, Hayashi K, Yamada H, Wakakura M. Linezolid-induced optic neuropathy.  Am J Ophthalmol. 2005;  139 1114-1116
• 96 Bressler A M, Zimmer S M, Gilmore J L, Somani J. Peripheral neuropathy associated with prolonged use of linezolid.  Lancet Infect Dis. 2004;  4 528-531
• 97 Apodaca A A, Rakita R M. Linezolid-induced lactic acidosis.  N Engl J Med. 2003;  348 86-87
• 98 Carpenter C F, Chambers H F. Daptomycin: another novel agent for treating infections due to drug-resistant gram-positive pathogens.  Clin Infect Dis. 2004;  38 994-1000
• 99 Pfaller M A, Sader H S, Jones R N. Evaluation of the in vitro activity of daptomycin against 19615 clinical isolates of gram positive cocci collected in North American hospitals (2002-2005).  Diagn Microbiol Infect Dis  2007;  57 459-465
• 100 Jorgensen J H, Crawford S A, Kelly C C, Patterson J E. In vitro activity of daptomycin against vancomycin-resistant enterococci of various Van types and comparison of susceptibility testing methods.  Antimicrob Agents Chemother. 2003;  47 3760-3763
• 101 Anastasiou D M, Thorne G M, Luperchio S A, Alder J D. In vitro activity of daptomycin against clinical isolates with reduced susceptibility to linezolid and quinupristin/dalfopristin.  Int J Antimicrob Agents. 2006;  28 385-388
• 102 Poutsiaka D D, Skiffingeron S, Miller K B, Hadley S, Snydman D R. Daptomycin in the treatment of vancomycin-resistant Enterococcus faecium bacteremia in neutropenic patients.  J Infect. 2007;  54 567-571
• 103 Segreti J A, Crank C W, Finney M S. Daptomycin for the treatment of gram-positive bacteremia and infective endocarditis: a retrospective case series of 31 patients.  Pharmacotherapy. 2006;  26 347-352
• 104 Long J K, Choueiri T K, Hall G S, Avery R K, Sekeres M A. Daptomycin-resistant Enterococcus faecium in a patient with acute myeloid leukemia.  Mayop Clin Proc. 2005;  80 1215-1216
• 105 Munoz-Price L S, Lolans K, Quinn J P. Emergence of resistance to daptomycin during treatment of vancomycin-resistant Enterococcus faecalis infection.  Clin Infect Dis. 2005;  41 565-566
• 106 Lewis II J S, Owens A, Cadena J et al.. Emergence of daptomycin resistance in Enterococcus faecium during daptomycin therapy.  Antimicrob Agents Chemother. 2005;  49 1664-1665
• 107 Green M R, Anasetti C, Sandin R L, Rolfe N E, Greene J N. Development of daptomycin resistance in a bone marrow transplant patient with vancomycin-resistant Enterococcus durans .  J Oncol Pharm Pract. 2006;  12 179-181
• 108 Stein G E, Craig W A. Tigecycline: a critical analysis.  Clin Infect Dis. 2006;  43 518-524
• 109 Sader H S, Jones R N, Stilwell M G, Dowzicky M J, Fritsche T R. Tigecycline activity tested against 26,474 bloodstream infection isolates: a collection from 6 continents.  Diagn Microbiol Infect Dis. 2005;  52 181-186
• 110 Streit J M, Sader H S, Fritsche T R, Jones R N. Dalbabancin activity against selected populations of antimicrobial resistant gram-positive pathogens.  Diagn Microbiol Infect Dis. 2005;  53 307-310
• 111 Barrett J F. Recent developments in glycopeptide antibacterials.  Curr Opin Investig Drugs. 2005;  6 781-790
• 112 Baltch A L, Smith R P, Ritz W J, Bopp L H. Comparison of inhibitory and bactericidal activities and postantibiotic effects of LY-333328 and ampicillin used singly and in combination against Enterococcus faecium .  Antimicrob Agents Chemother. 1998;  42 2564-2568
• 113 Stryjewski M E, Chu V H, O'Riordan W D et al.. Telavancin versus standard therapy for treatment of complicated skin and skin structure infections caused by gram-positive bacteria: FAST 2 Study.  Antimicrob Agents Chemother. 2006;  50 862-867
• 114 Poulakou G, Giamarellou H. Investigational treatments for postoperative surgical site infections.  Expert Opin Investig Drugs. 2007;  16 137-155