Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0519030 (Klebsiella)
 21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Minimal inhibitory concentrations (MICs) of seven cephalosporins: cefotaxime (CTX), ceftriaxone (CRO), ceftazidime (CAZ), latamoxef (MOX), cefoxitin (FOX), cefotetan (CTT) and CM 40876 (CM), of aztreonam (ATM) and imipenem (IPM) were evaluated by agar dilution with and without 5 mg/l of clavulanic acid (AC) or sulbactam (SB) for 28 strains isolated in 1986 (15 K. pneumoniae, 3. K. oxytoca, 4 E. coli, 4 E. cloacae, 1 E. aerogenes and 1 C. freundii). Comparatively to MICs of sensitive strains and to those of cured variants, MICs of these strains were very increased for CTX, CRO, ATM (mode MIC: 1 mg/l), and CAZ (2); weakly increased for MOX and CTT (0.25), and identical for IMP (0.12-0.25), CM (0.06) and FOX (2-4), except for Enterobacter and Citrobacter (64). Association with AC or SB did not modify MICs of FOX, CM and IMP. For the other antibiotics, MICs were reduced by addition of AC: Klebsiella: 5 log2 for CTX and CRO, 4 for CAZ and ATM, 2 for MOX and CTT; E. coli: 4 log2 for CTX and ATM, 3 for CRO and CAZ, 1 for MOX and CTT; Enterobacter and Citrobacter 2 log2 for CTX, CRO, CAZ and ATM, 1 for MOX and CTT. With SB, decrease of MICs was two to for fold lesser than with AC. AC, and less efficiently SB, restored activity of CTX, CRO, CAZ and ATM on CTX-1 producing Enterobacteriaceae, particularly Klebsiella and E. coli. It was the same for MOX and CTT, weakly affected by this resistance. AC and SB had not effect on FOX, CM and IPM which remained active on these strains.
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PMID:[Activity of 9 beta-lactam antibiotics combined with clavulanic acid or sulbactam against the strains of broad-spectrum beta-lactamase (CTX-1) producing Enterobacteriaceae isolated at the Henri Mondor Hospital]. 304 38

A simple disk diffusion test was constructed for detection of IMP-1-type metallo-beta-lactamase-producing gram-negative bacteria. Two Kirby-Bauer disks containing ceftazidime (CAZ) and a filter disk containing a metallo-beta-lactamase inhibitor were used in this test. Several IMP-1 inhibitors such as thiol compounds including 2-mercaptopropionic acid, heavy metal salts, and EDTA were evaluated for this test. Two CAZ disks were placed on a Mueller-Hinton agar plate on which a bacterial suspension was spread according to the method recommended by the National Committee for Clinical Laboratory Standards. The distance between the disks was kept to about 4 to 5 cm, and a filter disk containing a metallo-beta-lactamase inhibitor was placed near one of the CAZ disks within a center-to-center distance of 1.0 to 2.5 cm. For IMP-1-producing strains, the growth-inhibitory zone between the two disks expanded, while no evident change in the shape of the growth-inhibitory zone was observed for CAZ-resistant strains producing serine beta-lactamases such as AmpC or SHV-12. As a result, 2 to 3 microliter of undiluted 2-mercaptopropionic acid or mercaptoacetic acid able to block IMP-1 activity gave the most reproducible and clearest results, and CAZ-resistant strains producing AmpC or extended-spectrum beta-lactamases were distinguishable from IMP-1 producers by this test. A similar observation was made with IMP-1-producing clinical isolates such as Serratia marcescens, Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas putida, Acinetobacter spp., and Alcaligenes xylosoxidans. The specificity and sensitivity of this test were comparable to those of PCR analysis using bla(IMP)-specific primers. Therefore, this convenient test would be valuable for daily use in clinical laboratories.
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PMID:Convenient test for screening metallo-beta-lactamase-producing gram-negative bacteria by using thiol compounds. 1061 60

A multidrug-resistant plasmid encoding TEM-1, SHV-12, and a variant of IMP-2 metallo-beta-lactamase, designated IMP-8, was identified from a clinical isolate of Klebsiella pneumoniae. There are four nucleotide differences between bla(IMP-2) and bla(IMP-8), resulting in two amino acid differences. bla(IMP-8) was also found to be carried by an integron-borne gene cassette similar to the bla(IMP-2) cassette.
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PMID:Identification of a plasmid encoding SHV-12, TEM-1, and a variant of IMP-2 metallo-beta-lactamase, IMP-8, from a clinical isolate of Klebsiella pneumoniae. 1145 99

Klebsiella pneumoniae strains with the transferable carbapenem-hydrolyzing metallo-beta-lactamases, which include IMP- and VIM-type enzymes, remain extremely rare. To investigate whether IMP- or VIM-producing K. pneumoniae isolates had spread at a university medical center in Taiwan, a total of 3,458 clinical isolates of K. pneumoniae consecutively collected in 1999 and 2000 were tested by the agar diffusion method, colony hybridization, PCR, and nucleotide sequencing. A total of 40 isolates (1.2%), or 17 nonrepetitive isolates, from 16 patients were found to carry bla(IMP-8), a metallo-beta-lactamase gene recently identified from a K. pneumoniae strain in Taiwan. Carriage of bla(VIM) or other bla(IMP) genes was detected in none of the remaining isolates. Of the 17 nonrepetitive bla(IMP-8)-positive isolates, 15 isolates (88.2%) appeared susceptible to imipenem (MICs, <or=4 microg/ml) and meropenem (MICs, <or=1 microg/ml), indicating the difficulty in detecting bla(IMP-8) in K. pneumoniae by routine susceptibility tests; 14 isolates (82.4%) produced SHV-12 as well; and 14 isolates (82.4%) were also resistant to fluoroquinolones. The organisms caused wound infections in eight patients and bloodstream infections in three patients. They were not directly associated with the death of nine patients. Before the recovery of the bla(IMP-8)-positive isolates, all 16 patients had undergone various surgical procedures, and 15 patients had been admitted to the surgical intensive care unit, suggesting a nosocomial outbreak. Two major patterns were observed by pulsed-field gel electrophoresis for 14 of the 17 nonrepetitive isolates, indicating that the clonal spread was mainly responsible for the outbreak.
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PMID:Outbreak of infection with multidrug-resistant Klebsiella pneumoniae carrying bla(IMP-8) in a university medical center in Taiwan. 1172 57

Carbapenemases may be defined as beta-lactamases that significantly hydrolyze at least imipenem or/and meropenem. Carbapenemases involved in acquired resistance are of Ambler molecular classes A, B, and D. Class A, clavulanic acid-inhibited carbapenemases are rare. They are either chromosomally encoded (NMC-A, Sme-1 to Sme-3, IMI-1) in Enterobacter cloacae and Serratia marcescens, or plasmid encoded, such as KPC-1 in Klebsiella pneumoniae and GES-2 in Pseudomonas aeruginosa, the latter being a point-mutant of the clavulanic acid-inhibited extended-spectrum beta-lactamase GES-1. The class B enzymes are the most clinically significant carbapenemases. They are metalloenzymes of the IMP or VIM series. They have been reported worldwide but mostly from South East Asia and Europe. Metalloenzymes, whose genes are plasmid and integron located, hydrolyze virtually all beta-lactams except aztreonam. Finally, the class D carbapenemases are increasingly reported in Acinetobacter baumannii but compromise imipenem and meropenem susceptibility only marginally. The sources of the acquired carbapenemase genes remain unknown, as does the relative importance of the spread of epidemic strains as opposed to the spread of plasmid- or integron-borne genes. Because most of these carbapenemases confer only reduced susceptibility to carbapenems in Enterobacteriaceae, they may remain underestimated as a consequence of the lack of their detection.
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PMID:Emerging carbapenemases in Gram-negative aerobes. 1208 99

A total of 9082 clinical isolates of Enterobacteriaceae other than Klebsiella spp. collected in 1999 and 2000 at a university hospital in Taiwan were investigated for the production of metallo- beta-lactamases (MBLs). Thirty-six (2.9%) of the 1261 Enterobacter cloacae isolates and one (0.3%) of the 340 Citrobacter freundii isolates were found to carry bla(IMP-8) and bla(VIM-2), respectively, by colony hybridization, PCR and sequence analysis. The IMP-8 producers were recovered from 20 patients and four of them had recently transferred from other hospitals, implying spread of IMP-8-producing E. cloacae among different healthcare settings. Of the 20 non-repetitive IMP-8 producers, 17 (85%) isolates also harboured bla(SHV-12), which was on the same transferable plasmids with bla(IMP-8). The bla(VIM-2)-positive isolate and all non-repetitive bla(IMP-8)-positive isolates appeared susceptible to imipenem (MICs < 8 mg/L) and meropenem (MICs < 4 mg/L), indicating the difficulty in detection of MBLs in Enterobacteriaceae by routine susceptibility testing. Ribotyping of the IMP-8-producing E. cloacae isolates indicated that the dissemination of bla(IMP-8) was due largely to the spread of an epidemic clone, but horizontal transfer among unrelated strains also occurred.
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PMID:Metallo-beta-lactamase-producing Enterobacteriaceae isolates in a university hospital in Taiwan: prevalence of IMP-8 in Enterobacter cloacae and first identification of VIM-2 in Citrobacter freundii. 1235 94

The combined effects of (-)-epigallocatechin gallate (EGCg) and beta-lactams were investigated against various beta-lactamase-producing clinical isolates, including 21 Staphylococcus aureus, 6 Escherichia coli, 3 Klebsiella pneumoniae and 8 Serratia marcescens strains. Penicillin in combination with EGCg at 12.5 microg mL(-1) showed the most potent synergy against 100% penicillinase-producing S. aureus. However, cefotaxime or imipenem in combination with higher concentration of EGCg (100 microg mL(-1)) only showed slight synergy against 2 of 17 Gram-negative rods. Similar to the effect on the penicillinase from S. aureus, however, EGCg also directly inhibited the extracted beta-lactamases from the Gram-negative rods, thereby protecting beta-lactams from inactivation. The different effects of the combinations on different beta-lactamase-producing species were confirmed to be related to the cellular locations of beta-lactamases. In contrast to a 32.7% extracellular fraction of total beta-lactamase activity in a penicillinase-producing S. aureus, the fractions were 0.6%, 0.6% and 1.2% in a TEM-derived extended-spectrum beta-lactamase-producing E. coli, an inhibitor-resistant beta-lactamase-producing K. pneumoniae and an IMP-producing S. marcescens, respectively. In conclusion, the combination of penicillin with EGCg showed potent synergy against penicillinase-producing S. aureus in-vitro. The combinations of beta-lactams and EGCg against beta-lactamase-producing Gram-negative rods do indicate a limitation owing to the cellular location of beta-lactamases.
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PMID:Restoration of antibacterial activity of beta-lactams by epigallocatechin gallate against beta-lactamase-producing species depending on location of beta-lactamase. 1284 32

Doripenem (S-4661), a new parenteral carbapenem, was tested against over 250 clinical isolates, mutants, and transconjugants of Enterobacteriaceae and Acinetobacter spp., selected or derived for their beta-lactamase expression characteristics. Imipenem, meropenem, and ertapenem were tested as comparators, along with cephalosporins and piperacillin-tazobactam, by using National Committee for Clinical Laboratory Standards agar dilution methodology. Doripenem MICs were from 0.03 to 0.25 microg/ml for Klebsiella isolates, irrespective of the presence of extended-spectrum beta-lactamases (ESBLs) or plasmid-mediated AmpC or hyperproduced K1 beta-lactamase. Similarly, MICs of doripenem for both AmpC-inducible and -derepressed Enterobacter isolates were 0.06 to 0.5 microg/ml. ESBL production did not raise the MICs of doripenem for Escherichia coli transconjugants, and studies with known expression mutants confirmed that neither inducible nor depressed AmpC beta-lactamase expression was protective in Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, or Morganella morganii. In all of these respects, doripenem resembled meropenem and imipenem, whereas the MICs of ertapenem were raised (but still < or =1 microg/ml) for many ESBL-producing klebsiellas and AmpC-derepressed E. cloacae and C. freundii strains. Resistance to all carbapenems, including doripenem (MICs of mostly 16 to 64 microg/ml, compared with 0.25 to 1 microg/ml for typical strains), was seen in Acinetobacter isolates with metallo-beta-lactamases or OXA-carbapenemases. Isolates of Klebsiella and Serratia spp. with IMP, KPC, and SME beta-lactamases also were resistant to doripenem (MICs, 8 to >64 microg/ml) and to other carbapenems, although the continued apparent susceptibility (MICs, < or =0.5 microg/ml) of E. coli derivatives with cloned IMP-1 and NMC-A beta-lactamases suggested that carbapenem resistance might require other factors besides the enzymes.
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PMID:Comparative activities of doripenem versus isolates, mutants, and transconjugants of Enterobacteriaceae and Acinetobacter spp. with characterized beta-lactamases. 1504 35

Resistance to beta-lactam antibiotics continues to increase, mostly due to the presence of various beta-lakta mases. As a result of the ability of the plasmids to acquire additional resistance determinants, many of the beta-lactamase producing pathogens became multidrug resistant. The most important beta-lactamases which compomise the use of beta-lactams nowdays are extended-spectrum beta-lactamases, inhibitor-resistant TEM and SHV beta-lactamases and carbapenemases. Carbapenemases are beta-lactamases which hydrolyse carbapenems. They belong to molecular classes A, B, and D. Class A comprises carbapenemases sensitive to inhibition by clavulanic acid. Most of them are chromosomaly encoded, but some of them are plasmid-mediated such as KPC-1 in Klebsiella pneumoniae and GES-2 in Pseudomonas aeruginosa. The class B carbapenemases are metallo-beta-lactamases of the IMP or VIM group. The class D carbapenemases are the most frequent in Acinetobacter baumannii but confer resistance to carbapenems only if other resistance mechanisms such as porin alterations, are present. Inhibitor resistant beta-lactamases are one of the most important causes of resistance to beta-lactam-inhibitor combinations. The resistance to these formulations can be also due to hyperproduction of TEM-1 beta-lactamase, modifications of the outer membrane proteins or production of OXA-type enzymes. IRT enzymes are derived from parenthal TEM-1 or TEM-2 beta-lactamases by point mutations in the beta-lactamase gene. The frequent use of beta-lactamase inhibitors in hospitals and general practice pose a selection pressure which favours spread of such strains in hospitals and community.
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PMID:[Beta-lactamases and their role in resistance. PART 2: beta-lactamases in 21st century]. 1614 68

The aim of this study was to search for plasmid-encoded quinolone resistance determinants QnrA and QnrS in fluoroquinolone-resistant and extended-spectrum beta-lactamase (ESBL)-producing enterobacterial isolates recovered in Sydney, Australia, in 2002. Twenty-three fluoroquinolone-resistant, of which 16 were also ESBL-positive, enterobacterial and nonrelated isolates were studied. PCR with primers specific for qnrA and qnrS genes and primers specific for a series of ESBL genes were used. A qnrA gene was identified in two ESBL-positive isolates, whereas no qnrS-positive strain was found. The QnrA1 determinant was identified in an Enterobacter cloacae isolate and in a carbapenem-resistant Klebsiella pneumoniae isolate, both of which expressed the same ESBL SHV- 12. Whereas no plasmid was identified in the E. cloacae isolate, K. pneumoniae K149 possessed two conjugative plasmids, one that harbored the qnrA and bla (SHV)-12 genes whereas the other expressed the carbapenemase gene bla (IMP-4). The qnrA gene, was located in both cases downstream of the orf513 recombinase gene and upstream of the qnrA1 gene, a structure identical to that found in sul1-type integron In36 and qnrA-positive strains from Shanghai, China. However, the gene cassettes of the sul1-type integrons were different. This study identified the first plasmid-mediated quinolone resistance determinant in Enterobacteriaceae in Australia.
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PMID:Plasmid-mediated quinolone resistance in Australia. 1692 24


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