Penicillin resistance in Enterococcus faecalis: Molecular determinants and epidemiology

Polish Journal of Microbiology

Volumn 61, Issue 3, 2012, Pages 153-160

  Gawryszewska, Iwona ^a   Hryniewicz, Waleria ^a   Sadowy, Ewa ^a  

^a NATIONAL MEDICINES INSTITUTE   (Poland)

Author keywords

Enterococcus faecalis; HiRECC; PBP; Penicillin; Resistance; Lactamase

Indexed keywords

EID: 84868095492     PISSN: 17331331     EISSN: None     Source Type: Journal    
DOI: 10.33073/pjm-2012-020     Document Type: Review

References (91)

1. Al-Obeid S., L. Gutmann and R. Williamson. 1990. Modification of penicillin-binding proteins of penicillin-resistant mutants of different species of enterococci. J. Antimicrob. Chemother. 26:613-618.
2. Arias C. A. and B. E. Murray. 2008. Emergence and management of drug-resistant enterococcal infections. Expert Rev. Anti. Infect. Ther. 6:637-655
3. Bonafede M. E., L. L. Carias and L. B. Rice. 1997. Enterococcal transposon Tn5384: evolution of a composite transposon through cointegration of enterococcal and staphylococcal plasmids. Antimicrob. Agents Chemother. 41:1854-1858. (Pubitemid 27383216)
4. Butcu M., S. S. Akcay, A. S. Inan, S. Aksaray, D. O. Engin and G. Calisici. 2011. In vitro susceptibility of enterococci strains isolated from urine samples to fosfomycin and other antibiotics. J. Infect. Chemother. 17:575-578.
5. Calderón-Jaimes E., J. L. Arredondo-García, F. Aguilar-Ituarte, P. García-Roca. 2003. In vitro antimicrobial susceptibility in clinical isolates of Enterococcus species. Salud Pública Méx 45:96-101. (Pubitemid 36565129)
6. Canepari P., M. M. Lleò, G. Cornaglia, R. Fontana and G. Satta. 1986. In Streptococcus faecium penicillin-binding protein 5 alone is sufficient for growth at sub-maximal but not at maximal rate. J. Gen. Microbiol. 132:625-631. (Pubitemid 16064044)
7. Canepari P., M. M. Lleò, R. Fontana and G. Satta. 1987. Streptococcus faecium mutants that are temperature sensitive for cell growth and show alterations in penicillin-binding proteins. J. Bacteriol. 169:2432-2439. (Pubitemid 17104297)
8. Causse M., F. Franco-Alvarez De Luna, A. D. García-Mayorgas, F. C. Rodríguez and M. Casal. 2006. Antimicrobial susceptibility of Enterococcus faecalis isolated from patients in Córdoba (Spain). Rev. Esp. Quimioter. 19:140-143. (Pubitemid 44186631)
9. Cercenado E., M. F. Vicente, M. D. Díaz, C. Sánchez- Carrillo and M. Sánchez-Rubiales. 1996. Characterization of clinical isolates of beta-lactamase-negative, highly ampicillin-resistant Enterococcus faecalis. Antimicrob. Agents Chemother. 40:2420-2422. (Pubitemid 26328058)
10. Chow J. W., M. B. Perri, L. A. Thal and M. J. Zervos. 1993. Mobilization of the penicillinase gene in Enterococcus faecalis. Antimicrob. Agents Chemother. 37:1187-1189. (Pubitemid 23141346)
11. Clinical and Laboratory Standards Institute. 2011. Performance Standards for Antimicrobial Susceptibility Testing; Twenty-First Informational Supplement. M100-S21. Vol. 31 no. 1.
12. Conceição N., C. Oliveira Cda, P. R. Silva, B. G. Avila and A. G. Oliveira. 2011. Trends in antimicrobial resistance among clinical isolates of enterococci in a Brazilian tertiary hospital: a 4-year study. Rev. Soc. Bras. Med. Trop. 44:177-181.
13. Coudron P. E., S. M. Markowitz and E. S. Wong. 1992. Isolation of a beta-lactamase-producing, aminoglycoside-resistant strain of Enterococcus faecium. Antimicrob. Agents Chemother. 36:1125-1126.
14. Coudron P. E., C. G. Mayhall, R. R. Facklam, A. C. Spadora, V. A. Lamb, M. R. Lybrand and H. P. Dalton. 1984. Streptococcus faecium outbreak in a neonatal intensive care unit. J. Clin. Microbiol. 20:1044-1048. (Pubitemid 15219301)
15. Duez C, W. Zorzi, F. Sapunaric, A. Amoroso, I. Thamm and J. Coyette. 2001. The penicillin resistance of Enterococcus faecalis JH2-2r results from an overproduction of the low-affinity penicillinbinding protein PBP4 and does not involve a psr-like gene. Microbiology 147:2561-2569. (Pubitemid 32899252)
16. Dunny G. M. 1990. Genetic functions and cell-cell interactions in the pheromone-inducible plasmid transfer system of Enterococcus faecalis. Mol. Microbiol. 4:689-696.
17. Edwards D. D. 2000. Enterococci attract attention of concerned microbiologists. ASM News 66:540-545.
18. European Centre for Disease Prevention and Control. 2010. Antimicrobial resistance surveillance in Europe 2009. Annual Report of the European Antimicrobial Resistance Surveillance Network (EARS-Net). Stockholm. ECDC.
19. European Committee on Antimicrobial Susceptibility Testing. 2011. Breakpoint tables for interpretation of MICs and zone diameters. Version 1.3.
20. Fontana R., M. Aldegheri, M. Ligozzi, H. Lopez, A. Sucari and G. Satta. 1994. Overproduction of a low-affinity penicillin-binding protein and high level ampicillin resistance in Enterococcus faecium. Antimicrob. Agents Chemother. 38:1980-1983. (Pubitemid 24278788)
21. Fontana R, R. Cerini, P. Longoni, A. Grossato and P. Canepari. 1983. Identification of a streptococcal penicillin-binding protein that reacts very slowly with penicillin. J. Bacteriol. 155:1343-1350. (Pubitemid 14231717)
22. Fontana R., A. Grossato, L. Rossi, Y. R. Cheng and Satta G. 1985. Transition from resistance to hypersusceptibility to beta-lactam antibiotics associated with loss of a low-affinity penicillin-binding protein in a Streptococcus faecium mutant highly resistant to penicillin. Antimicrob. Agents Chemother. 28:678-683. (Pubitemid 16215536)
23. Fontana R, M. Ligozzi, F. Pittaluga, and G. Satta. 1996. Intrinsic penicillin resistance in enterococci. Microb. Drug Resist. 2:209-213. (Pubitemid 26249927)
24. Gales A. C., H. S. Sader, J. Ribeiro, C. Zoccoli, A. Barth and A. C. Pignatari. 2009. Antimicrobial susceptibility of gram-positive bacteria isolated in Brazilian hospitals participating in the SENTRY Program (2005-2008). Braz. J. Infect. Dis. 13:90-98.
25. Galli D and R. Wirth. 1991. Comparative analysis of Enterococcus faecalis sex pheromone plasmids identifies a single homologous DNA region which codes for aggregation substance. J. Bacteriol. 173:3029-3033.
26. Galloway-Peña J. R., S. R. Nallapareddy, C. A. Arias, G. M. Eliopoulos and B. E. Murray. 2009. Analysis of clonality and antibiotic resistance among early clinical isolates of Enterococcus faecium in the United States. J. Infect. Dis. 200:1566-1573.
27. Ghuysen J. M., P. Charlier, J. Coyette, C. Duez, E. Fonzé, C. Fraipont, C. Goffin, B. Joris and M. Nguyen-Distèche. 1996. Penicillin and beyond: evolution, protein fold, multimodular polypeptides, and multiprotein complexes. Microb. Drug Resist. 2:163-175. (Pubitemid 26249921)
28. Grayson M. L., G. M. Eliopoulos, C. B. Wennersten, K. L. Ruoff, P. C. De Girolami, M. J. Ferraro and R. C. Moellering Jr. 1991. Increasing resistance to beta-lactam antibiotics among clinical isolates of Enterococcus faecium: a 22-year review at one institution. Antimicrob. Agents Chemother. 35:2180-2184.
29. Guardabassi L., J. Larsen, R. Skov and H. C. Schønheyder. 2010. Gentamicin-resistant Enterococcus faecalis sequence type 6 with reduced penicillin susceptibility: diagnostic and therapeutic implications. J. Clin. Microbiol. 48:3820-3821.
30. Hardie J. M. and R. A. Whiley. 1997. Classification and overview of the genera Streptococcus and Enterococcus. Soc. Appl. Bacteriol. Symp. Ser. 26:1S-11S.
31. Hidron A. I., J. R. Edwards, J. Patel, T. C. Horan, D. M. Sievert, D. A. Pollock, S. K. Fridkin, National Healthcare Safety Network Team; Participating National Healthcare Safety Network Facilities. 2008. NHSN annual update: antimicrobial-resistant pathogens associated with healthcare-associated infections: annual summary of data reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention, 2006-2007. Infect Control Hosp Epidemiol 29:996-1011.
32. Erratum in: Infect. Control. Hosp. Epidemiol. 2009. 30:107.
33. Hiraga N, T. Muratani, S. Naito and T. Matsumoto. 2008. Genetic analysis of faropenem-resistant Enterococcus faecalis in urinary isolates. J. Antibiot. 61:213-221.
34. Hodges T. L., S. Zighelboim-Daum, G. M. Eliopoulos, C. Wennersten and R. C. Moellering Jr. 1992. Antimicrobial susceptibility changes in Enterococcus faecalis following various penicillin exposure regimens. Antimicrob. Agents Chemother. 36:121-125.
35. Jabalameli F., M. Emaneini, S. Shahsavan, H. Sedaghat, Z. Abdolmaliki and M. Aligholi. 2009. Evaluation of antimicrobial susceptibility patterns of enterococci isolated from patients in Tehran University of Medical Sciences Teaching Hospitals. Acta Med. Iran. 47:325-328.
36. Jett B. D., M. M. Huycke and M. S. Gilmore. 1994. Virulence of enterococci. Clin. Microbiol. Rev. 7:462-478.
37. Jones M. E., D. C. Draghi, C. Thornsberry, J. A. Karlowsky, D. F. Sahm and R. P. Wenzel. 2004. Emerging resistance among bacterial pathogens in the intensive care unit a European and North American Surveillance study (2000-2002). Ann. Clin. Microbiol. Antimicrob. 3:14.
38. Kaçmaz B. and A. Aksoy. 2005. Antimicrobial resistance of enterococci in Turkey. Int. J. Antimicrob. Agents 25:535-538. (Pubitemid 40732609)
39. Leavis H. L., M. J. Bonten and R. J. Willems. 2006. Identification of high-risk enterococcal clonal complexes: global dispersion and antibiotic resistance. Curr. Opin. Microbiol. 9:454-460. (Pubitemid 44397629)
40. Lester C. H., D. Sandvang, S. S. Olsen, H. C. Schønheyder, J. O. Jarløv, J. Bangsborg, D. S. Hansen, T. G. Jensen, N. Frimodt- Møller, A. M. Hammerum, DANRES Study Group. 2008. Emergence of ampicillin-resistant Enterococcus faecium in Danish hospitals. J. Antimicrob. Chemother. 62:1203-1206.
41. Ligozzi, M., F. Pittaluga and R. Fontana. 1993. Identification of a genetic element (psr) which negatively controls expression of Enterococcus hirae penicillin-binding protein 5. J. Bacteriol. 175:2046-2051. (Pubitemid 23097513)
42. Ligozzi, M., F. Pittaluga and R. Fontana. 1996. Modification of penicillin binding protein 5 associated with high-level ampicillin resistance in Enterococcus faecium. Antimicrob. Agents Chemother. 40:354-357. (Pubitemid 26049346)
43. Lleó M. M., P. Canepari, G. Cornaglia, R. Fontana and G. Satta. 1987. Bacteriostatic and bactericidal activities of beta-lactams against Streptococcus (Enterococcus) faecium are associated with saturation of different penicillin-binding proteins. Antimicrob. Agents Chemother. 31:1618-1626. (Pubitemid 17140824)
44. Markowitz S. M., V. D. Wells, D. S. Williams, C. G. Stuart, P. E. Coudron and E. S. Wong. 1991. Antimicrobial susceptibility and molecular epidemiology of beta-lactamase-producing, aminoglycoside-resistant isolates of Enterococcus faecalis. Antimicrob. Agents Chemother. 35:1075-1080.
45. Marothi Y. A., H. Agnihotri and D. Dubey. 2005. Enterococcal resistance - an overview. Indian J. Med. Microbiol. 23:214-219. (Pubitemid 41769360)
46. Mazzulli T., S. M. King and S. E. Richardson. 1992. Bacteremia due to beta-lactamase-producing Enterococcus faecalis with highlevel resistance to gentamicin in a child with Wiskott-Aldrich syndrome. Clin. Infect. Dis. 14:780-781.
47. McBride S. M., V. A. Fischetti, D. J. Leblanc, R. C. Moellering Jr and M. S. Gilmore. 2007. Genetic diversity among Enterococcus faecalis. PLoS ONE 2:e582.
48. Metzidie E., E. N. Manolis, S. Pournaras, D. Sofianou and A. Tsakris. 2006. Spread of an unusual penicillin-and imipenemresistant but ampicillin-susceptible phenotype among Enterococcus faecalis clinical isolates. J. Antimicrob. Chemother. 57:158-160. (Pubitemid 43057080)
49. Moellering R. C. Jr and A. N. Weinberg. 1971. Studies on antibiotic synergism against enterococci. II. Effect of various antibiotics on the uptake of 14 C-labeled streptomycin by enterococci. J. Clin. Invest. 50:2580-2584.
50. Mollerach M. E., P. Partoune, J. Coyette and J. M. Ghuysen. 1996. Importance of the E-46-D-160 polypeptide segment of the nonpenicillin-binding module for the folding of the low-affinity multimodular class B penicillin-binding protein 5 of Enterococus hirae. J. Bacteriol. 178:1774-1775.
51. Murdoch D. R., S. Mirrett, L. J. Harrell, J. S. Monahan and L. B. Reller. 2002. Sequential emergence of antibiotic resistance in enterococcal bloodstream isolates over 25 years. Antimicrob. Agents Chemother. 46:3676-3678. (Pubitemid 35192951)
52. Murray B. E. 1998. Diversity among multidrug-resistant enterococci. Emerging Infect. Dis. 4:37-47. (Pubitemid 28347414)
53. Murray B. E. and B. Mederski-Samaraj. 1983. Transferable betalactamase. A new mechanism for in vitro penicillin resistance in Streptococcus faecalis. J. Clin. Invest. 72:1168-1171. (Pubitemid 14212635)
54. Murray B. E., F. Y. An and D. B. Clewell. 1988. Plasmids and pheromone response of the beta-lactamase producer Streptococcus (Enterococcus) faecalis HH22. Antimicrob. Agents Chemother. 32:547-551. (Pubitemid 18089363)
55. Murray B. E., D. A. Church, A. Wanger, K. Zscheck, M. E. Levison, M. J. Ingerman, E. Abrutyn and B. Mederski-Samoraj. 1986a. Comparison of two beta-lactamase-producing strains of Streptococcus faecalis. Antimicrob. Agents Chemother. 30:861-864. (Pubitemid 17209138)
56. Murray B. E., B. Mederski-Samoraj, S. K. Foster, J. L. Brunton and P. Harford. 1986b. In vitro studies of plasmid mediated penicillinase from Streptococcus faecalis suggest a staphylococcal origin. J. Clin. Invest. 77:289-293. (Pubitemid 16101231)
57. Murray B. E., H. A. Lopardo, E. A. Rubeglio, M. Frosolono and K. V, Singh. 1992. Intrahospital spread of a single gentamicinresistant, beta-lactamase-producing strain of Enterococcus faecalis in Argentina. Antimicrob. Agents Chemother. 36:230-232.
58. Murray B. E., K. V. Singh, S. M. Markowitz, H. A. Lopardo, J. E. Patterson, M. J. Zervos E. Rubeglio, G. M. Eliopoulos, L. B. Rice, F. W. Goldstein and others. 1991. Evidence for clonal spread of a single strain of beta-lactamase-producing Enterococcus (Streptococcus) faecalis to six hospitals in five states. J. Infect. Dis. 163:780-785.
59. Nallapareddy S. R., H. Wenxiang, G. M. Weinstock and B. E. Murray. 2005. Molecular characterization of a widespread, pathogenic, and antibiotic resistance-receptive Enterococcus faecalis lineage and dissemination of its putative pathogenicity island. J. Bacteriol. 187:5709-5718. (Pubitemid 41134307)
60. Okamoto R, T. Okubo and M. Inoue. 1996. Detection of genes regulating beta-lactamase production in Enterococcus faecalis and Staphylococcus aureus. Antimicrob. Agents Chemother. 40:2550-2554. (Pubitemid 26367641)
61. Oncu S., M. Punar and H. Eraksoy. 2004. Susceptibility patterns of enterococci causing infections. Tohoku J. Exp. Med. 202:23-29. (Pubitemid 38128815)
62. Ono S., T. Muratani and T. Matsumoto. 2005. Mechanisms of resistance to imipenem and ampicillin in Enterococcus faecalis. Antimicrob. Agents Chemother. 49:2954-2958. (Pubitemid 40917616)
63. Palmer K. L., V. N, Kos and M. S. Gilmore. 2010. Horizontal gene transfer and the genomics of enterococcal antibiotic resistance. Curr. Opin. Microbiol. 13:632-639.
64. Patterson J. E., S. M. Colodny and M. J. Zervos. 1988a. Serious infection due to beta-lactamase-producing Streptococcus faecalis with high-level resistance to gentamicin. J. Infect. Dis. 158:1144-1145.
65. Patterson J. E., B. L. Masecar, C. A. Kauffman, D. R. Schaberg, W. J. Hierholzer Jr and M. J. Zervos. 1988b. Gentamicin resistance plasmids of enterococci from diverse geographic areas are heterogeneous. J. Infect. Dis. 158:212-216.
66. Patterson J. E., K. V. Singh and B. E. Murray. 1991. Epidemiology of an endemic strain of beta-lactamase-producing Enterococcus faecalis. J. Clin. Microbiol. 29:2513-2516.
67. Patterson, J. E., A. Wanger, K. K. Zscheck, M. J. Zervos and B. E. Murray. 1990. Molecular epidemiology of β-lactamase producing enterococci. Antimicrob. Agents Chemother. 34:302-305. (Pubitemid 20046885)
68. Paulsen I. T., L. Banerjei, G. S. Myers, K. E. Nelson, R. Seshadri, T. D. Read, D. E. Fouts, J. A. Eisen, S. R. Gill, J. F. Heidelberg and others. 2003. Role of mobile DNA in the evolution of vancomycin resistant Enterococcus faecalis. Science 299:2071-2074. (Pubitemid 36383734)
69. Reinert R. R., D. E. Low, F. Rossi, X. Zhang, C. Wattal and M. J. Dowzicky. 2007. Antimicrobial susceptibility among organisms from the Asia/Pacific Rim, Europe and Latin and North America collected as part of TEST and the in vitro activity of tigecycline. J. Antimicrob. Chemother. 60:1018-1029. (Pubitemid 47617749)
70. Rhinehart E., N. E. Smith, C. Wennersten, E. Gorss, J. Freeman, G. M. Eliopoulos, R. C. Moellering Jr. and D. A. Goldmann. 1990. Rapid dissemination of β-lactamase-producing, aminoglycosideresistant Enterococcus faecalis among patients and staff on an infanttoddler surgical ward. N. Engl. J. Med. 323:1814-1818.
71. Rice L. B. and L. L. Carias. 1998. Transfer of Tn5385, a composite, multiresistance chromosomal element from Enterococcus faecalis. J. Bacteriol. 180:714-721. (Pubitemid 28100558)
72. Rice, L. B., L. L. Carias, and S. H. Marshall. 1995. Tn5384, a composite enterococcal mobile element conferring resistance to erythromycin and gentamicin whose ends are directly repeated copies of IS256. Antimicrob. Agents Chemother. 39:1147-1153.
73. Rice L. B., L. L. Carias, S. H. Marshall and M. E. Bonafede. 1996. Sequences found on staphylococcal beta-lactamase plasmids integrated into the chromosome of Enterococcus faecalis CH116. Plasmid 35:81-90. (Pubitemid 26117225)
74. Rice L. B., G. M. Eliopoulos, C. Wennersten, D. Goldmann, G. A. Jacoby and R. C. Moellering Jr. 1991. Chromosomally mediated beta-lactamase production and gentamicin resistance in Enterococcus faecalis. Antimicrob. Agents Chemother. 35:272-276.
75. Rice, L. B., S. H. Marshall, and L. L. Carias. 1992. Tn5381, a conjugative transposon identifiable as a circular form in Enterococcus faecalis. J. Bacteriol. 174:7308-7315.
76. Ruiz-Garbajosa P., M. J. Bonten, D. A. Robinson, J. Top, S. R. Nallapareddy, C. Torres, C. M. Coque, R. Cantón, F. Baquero, B. E. Murray and others. 2006. Multilocus sequence typing scheme for Enterococcus faecalis reveals hospital-adapted genetic complexes in a background of high rates of recombination. J. Clin. Microbiol. 44:2220-2228. (Pubitemid 43902179)
77. Rybkine T, J. L. Mainardi, W. Sougakoff, E. Collatz and Gutmann. 1998. Penicillin-binding protein 5 sequence alterations in clinical isolates of Enterococcus faecium with different levels of beta-lactam resistance. J. Infect. Dis. 178:159-163. (Pubitemid 28328088)
78. Seetulsingh P. S., J. F. Tomayko, P. E. Coudron, S. M. Markowitz, C. Skinner, K. V. Singh and B. E. Murray. 1996. Chromosomal DNA restriction endonuclease digestion patterns of beta-lactamase-producing Enterococcus faecalis isolates collected from a single hospital over a 7-year period. J. Clin. Microbiol. 34:1892-1896. (Pubitemid 26239218)
79. Sherman J. M. 1937. The streptococci. Bacteriol Rev 1:3-97.
80. Signoretto, C, and P. Canepari. 2000. Paradoxical effect of inserting, in Enterococcus faecalis penicillin-binding protein 5, an amino acid box responsible for low affinity for penicillin in Enterococcus faecium. Arch. Microbiol. 173:213-219. (Pubitemid 30143580)
81. Signoretto C, M. Boaretti and P. Canepari. 1994. Cloning, sequencing and expression in Escherichia coli of the low-affinity penicillin binding protein of Enterococcus faecalis. FEMS Microbiol. Lett. 123:99-106. (Pubitemid 24312570)
82. Sydnor E. R. and T. M. Perl. 2011. Hospital epidemiology and infection control in acute-care settings. Clin. Microbiol. Rev. 24:141-173.
83. Titze-de-Almeida R, M. R. Filho, C. A. Nogueira, I. P. Rodrigues, J. E. Filho, R. S. Do Nascimento, R. F. Ferreira, L. M. P. Moraes, H. Boelens, A. Van Belkum and others. 2004. Molecular epidemiology and antimicrobial susceptibility of Enterococci recovered from Brazilian intensive care units. Braz. J. Infect. Dis. 8:197-205.
84. Tomayko J. F., K. K. Zscheck, K. V. Singh, B. E. Murray. 1996. Comparison of the beta-lactamase gene cluster in clonally distinct strains of Enterococcus faecalis. Antimicrob. Agents Chemother. 40:1170-1174. (Pubitemid 26136029)
85. Top J., R. Willems, H. Blok, M. De Regt, K. Jalink, A. Troelstra, B. Goorhuis and M. Bonten. 2007. Ecological replacement of Enterococcus faecalis by multiresistant clonal complex 17 Enterococcus faecium. Clin. Microbiol. Infect. 13:316-319. (Pubitemid 46603364)
86. Wells V. D., E. S. Wong, B. E. Murray, P. E. Coudron, D. S. Williams and S. M. Markowitz. 1992. Infections due to beta-lactamase-producing, high-level gentamicin-resistant Enterococcus faecalis. Ann. Intern. Med. 116:285-292.
87. Williamson R., S. B. Calderwood, R. C. Moellering Jr. and A. Tomasz. 1983. Studies on the mechanism of intrinsic resistance to beta-lac tam antibiotics in group D streptococci. J. Gen. Microbiol. 129:813-822. (Pubitemid 13146949)
88. Zapun, A., C. Contreras-Martel and T. Vernet. 2008. Penicillinbinding proteins and beta-lactam resistance. FEMS Microbiol. Rev. 32:361-385.
89. Zorzi W, X. Y. Zhou, O. Dardenne, J. Lamotte, D. Raze, J. Pierre, L. Gutmann and J. Coyette. 1996. Structure of the low-affinity penicillin-binding protein 5 PBP5fm in wild-type and highly penicillinresistant strains of Enterococcus faecium. J. Bacteriol. 178:4948-4957. (Pubitemid 26321297)
90. Zscheck K. K. and B. E. Murray. 1991. Nucleotide sequence of the beta-lactamase gene from Enterococcus faecalis HH22 and its similarity to staphylococcal beta-lactamase genes. Antimicrob. Agents Chemother. 35(9):1736-40.
91. Zscheck K. K. and B. E. Murray. 1993. Genes involved in the regulation of beta-lactamase production in enterococci and staphylococci. Antimicrob. Agents Chemother. 37:1966-1970. (Pubitemid 23265561)