Transferable beta-lactamase. A new mechanism for in vitro penicillin resistance in Streptococcus faecalis.

Abstract

A B S T R A C T Although enterococci are relatively resistant to penicillin, the mechanism of resistance is largely unknown and enzymatic inactivation does not play a role. In this study, an isolate of Streptococcus faecalis was found to have beta lactamase activity resulting in complete inactivation of penicillin. With a high inoculum, this strain was resistant to >1,000 ,ug/ ml of penicillin. Penicillin resistance and beta lactamase activity were transferred by conjugation at a high frequency to an enterococcal laboratory recipient strain together with two plasmids of molecular size 34 X 106 and 56 X 106, thus demonstrating the emergence of plasmid-mediated penicillin resistance in the genus Streptococcus.

Genetic modifications to temperate Enterococcus faecalis phage ϕEf11 that abolish the establishment of lysogeny and sensitivity to repressor, and increase host range and productivity of lytic infection

“…In terms of oral disease, E. faecalis is the most commonly isolated species from infected root canals of teeth that fail to heal following root canal therapy (Sundqvist et al, 1998;Peciuliene et al, 2000;Pinheiro et al, 2003 Complicating management of these infections is the development of resistance among many enterococcal strains against many of the available, previously effective antibiotics, including vancomycin (Havard et al, 1959;Murray & Mederski-Samaroj, 1983;Uttley et al, 1988;Grayson et al, 1991;Bonten et al, 2001;Tenover & McDonald, 2005). Although a modest number of new antibiotics, such as linezolid and daptomycin, have been developed to provide treatment alternatives in cases of infection by organisms that are resistant to all previously available antibiotics, there have been numerous reports of resistance by E. faecalis and E. faecium strains to these antibiotics as well (Eliopoulos et al, 1998;Prystowsky et al, 2001;Gonzales et al, 2001;Herrero et al, 2002;Johnson et al, 2004;Munoz-Price et al, 2005;Kanafani et al, 2007;Hidron et al, 2008;Marshall et al, 2009;Kelesidis et al, 2011;Ross et al, 2011;Ntokou et al, 2012).…”

Chromosomally mediated beta-lactamase production and gentamicin resistance in Enterococcus faecalis

“…In marked contrast, P-lactamase-mediated penicillin resistance in enterococci did not appear until more than 40 years after the clinical introduction of penicillin and is still a distinctly rare finding despite intensive and widespread screening by certain groups (16,17,19). Although the gene responsible for enterococcal ,-lactamase production is homologous with that found in Staphylococcus aureus, its phenotypic expression differs in that enterococcal P-lactamase is produced constitutively, is not excreted into the medium, and has only a minimal effect on the penicillin MIC at standard inoculum sizes (16).…”

Genetic Analysis of Faropenem-resistant Enterococcus faecalis in Urinary Isolates

“…Beta-lactamase production was first reported in 1983 [15], and there have been several subsequent reports of beta-lactamase-producing penicillin resistance in E. faecalis [16ϳ19]; nevertheless, betalactamase production is a very rare mechanism in enterococci [3,4,34]. E. faecalis strains carrying blaR1 and bla1, staphylococcal beta-lactamase regulatory genes, produced small amounts of class A beta-lactamases [17,35]; these enzymes do not hydrolyze either carbapenems or penems [2,4,5].…”

“…We tested the supernatant for beta-lactamase activity with nitrocefin (Oxoid, Ltd., United Kingdom). We used Escherichia coli ATCC 35218 which was a positive control strain for beta-lactamase activity [15].…”