Molecular epidemiology of TEM-3 (CTX-1) beta-lactamase

Abstract

A total of 33 clinical isolates encoding TEM-3 (CTX-1) from four French hospitals were studied. The strains belonged to seven species, Klebsiella pneumoniae (n = 24), Escherichia coli (n = 3), Serratia marcescens (n = 2), Citrobacterfreundii (n = 1), Enterobacter aerogenes (n = 1), Enterobacter cloacae (n = 1), and Klebsiella oxytoca (n = 1). All the strains harbored an Inc7 or M self-transferable plasmid with a size of approximately 85 kilobases. The plasmids had closely related EcoRI, HincH, HindIll, and PvuH restriction endonucleasegenerated patterns and conferred resistance to all P-lactams, except cephamycins and imipenem; to tetracycline, because of the presence of the genes blatem3 and tetC, respectively, as determined by hybridization with specific probes; and to sulfonamide. Depending on the presence or absence and level of expression of the genes aacA4, aadA, and dfrl and of insertion element IS15, four types of plasmids could be distinguished.Plasmid pCFF04, the prototype plasmid encoding TEM-3, was widespread and appeared, by Southern hybridization, as the progenitor of the other types of replicons. The plasmid epidemic responsible for dissemination of TEM-3 in clinical isolates of members of the family Enterobacteriaceae may have originated in S. marcescens since pCFF04 was first detected in this species.In 1983, Knothe et al. (9) described the first transferable resistance to broad-spectrum cephalosporins in clinical isolates of Klebsiella pneumoniae and Serratia marcescens. This new resistance phenotype was due to production of a broad-spectrum P-lactamase, SHV-2, which evolved from the chromosomal SHV-l enzyme (8). Since 1984, strains of K. pneumoniae that produce a novel, transferable, broadspectrum P-lactamase have been isolated in Clermont-Ferrand hospitals (21). The enzyme was designated CTX-1 because of its high hydrolytic activity against cefotaxime. It was later shown to be derived from the TEM-2 enzyme (23) and was therefore redesignated TEM-3. In an earlier study (22), we screened 490 members of the family Enterobacteriaceae isolated between 1984 and 1987 that exhibited an antibiotic resistance phenotype similar to that of the first TEM-3-producing strains (21). We concluded that P-lactam resistance via synthesis of TEM-3 spread into seven different bacterial genera and was due to dissemination of a single 85-kilobase (kb) Inc7 or M plasmid, pCFF04. Here we report the molecular characterization of the plasmids isolated in 33 clinical isolates representative of the TEM-3-producing strains obtained from Clermont-Ferrand hospitals and three other geographically distant French hospitals. MATERIALS AND METHODSBacterial strains and plasmids. Twenty-eight strains of members of the family Enterobacteriaceae (22) were selected to represent all species of bacteria involved, different times of isolation over a 3-year period, different wards in which infection with TEM-3-producing bacteria occurred, and different biotypes (API 50 CH; API System S.A., Montalieu-Vercieu, France) of the most important ...

Evolution of multi-resistance plasmids in Australian clinical isolates of Escherichia coli

“…Furthermore, the phylogenetic relationships between the plasmids (based on multiple gene sequences) differed from those of the host cells, implying a high rate of plasmid transfer even between the major ECOR groups. Other authors have also highlighted the importance of recombination in the evolution of plasmids from various members of the Enterobacteriaceae (Blazquez et al, 1996;Boerlin, 1999;Petit et al, 1990;Preston et al, 2003). However, some authors have found that transposons and integron cassette systems are major mediators of resistance plasmid evolution in the Enterobacteriaceae, rather than recombination (Brown et al, 2000;Carattoli et al, 2002;Guessouss et al, 1996;Radstrom et al, 1991;Tosini et al, 1998).…”

“…However, a range of other mechanisms, including recombination and the acquisition of integron cassettes, have also been observed (Boerlin, 1999;Boyd et al, 1996;Brown et al, 2000;Lindler et al, 1998;Prentice et al, 2001;Radstrom et al, 1991;Venkatesan et al, 2001). While several individual plasmids have been the subject of intensive study, there is limited information available regarding plasmid populations (Blazquez et al, 1996;Boyd et al, 1996;Brown et al, 2000;Carattoli, 2003;Carattoli et al, 2001 Carattoli et al, , 2002Groves, 1979;Ling et al, 1993;Petit et al, 1990;Preston et al, 2003;Radstrom et al, 1991;Saksena & Truffaut, 1992;Tosini et al, 1998). To date we know of no study that has attempted to infer the processes underlying plasmid evolution through an investigation of the genetic relationships within a large collection of singleand multiple-resistance plasmids.…”

Structure-function relationships among wild-type variants of Staphylococcus aureus beta-lactamase: importance of amino acids 128 and 216

“…Broad-spectrum TEM and SHV variant ␤-lactamases capable of hydrolyzing ceftazidime, cefotaxime, and/or other newer cephalosporins have become problematic in many medical centers in recent years, especially among isolates of Klebsiella pneumoniae and E. coli (14,17,31). As with the S. aureus enzymes, the altered kinetic profile of the broad-spectrum TEM-type ␤-lactamases is based on modest changes in primary structure, generally one to three amino acid substitutions at sites close to the active site (32). In addition, single mutations that result in TEM and SHV variant ␤-lactamases exhibiting resistance to commercially available ␤-lactamase inhibitors such as clavulanic acid have been described (7,15).…”

Long-term investigation of the clonal dissemination of Klebsiella pneumoniae isolates producing extended-spectrum -lactamases in a university hospital

“…They have been responsible for outbreaks, particularly in intensive care units and in chronic care facilities, but have occasionally spread also to medical and surgical wards [7-131. Hospital colonisation by ESBL-producing bacteria can reflect dissemination of a few clones, or the spread of plasmids and resistance genes [13][14][15][16][17][18][19][20][21], facilitated by antibiotic pressure and inadequate infection-control practice [9-10, [22][23][24]. Several outbreaks of nosocomial infections caused by ESBL-producing K. pneumoniae occurred in our hospital between 1988 and 199 1.…”