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At least 649 records · Page 36Linked to original sources
PubMed1984

Survey of the phenotypes of susceptibility to beta-lactams in Enterobacteriaceae at the Pitie-Salpetriere Hospital.

The phenotypes of susceptibility to ampicillin, carbenicillin, cephalothin, cefamandole, cefoxitin and cefotaxime were determined by the disc-diffusion method in 10,994 Enterobacteriaceae consecutively isolated from in-patients during 18 months. The susceptible phenotypes were much more frequent among Escherichia coli, Proteus mirabilis and Klebsiella (67.4 to 84.8%) than among Serratia, Enterobacter and Citrobacter (8.8 to 35.5%). In all species the most common resistance phenotypes were to ampicillin and carbenicillin: E. coli (28%), Pr. mirabilis (15.2%), Klebsiella (23.8%), indole-positive Proteus (33.3%), Serratia (74.4%), Enterobacter (61.4%) and Citrobacter (74.8%). Among E. coli 4.6% of the strains were resistant to ampicillin and cephalothin but susceptible to carbenicillin. Among E. coli, Pr. mirabilis and Klebsiella the strains susceptible only to cefotaxime represented 0.3 to 5% and no cefotaxime-resistant strain was isolated; whereas among Serratia, Enterobacter and Citrobacter the former represented 28.3 to 58.3% and the latter 7.5 to 18.5%. Some important differences in the distribution of the phenotypes according to the type of ward were observed.

Anti-Bacterial Agents↗
PubMed1985

beta-Lactamase susceptibility and comparative activity of Sch 34343 and other beta-lactams for non-fermenters, Neisseria spp. and beta-lactamase-positive Enterobacteriaceae.

By means of a micro-dilution technique (10(5) cfu/cup) 30 strains of Pseudomonas spp. were found resistant to Sch 34343. The susceptibility of Acinetobacter spp. (20 strains) was greatest for imipenem, followed by Sch 34343 (MIC approximately 0.7 mg/l), ceftazidime and ceftriaxone. Ten Moraxella strains were very susceptible to Sch 34343, imipenem and ceftazidime. For 35 strains of Neisseria gonorrhoeae (ten beta-lactamase-positive) and ten strains of N. meningitidis we noted no resistance to Sch 34343 (MIC 0.015-0.06 mg/l), or to any of the other drugs tested. Sixty-two strains of Enterobacteriaceae producing various beta-lactamases were tested for their sensitivity to Sch 34343 and seven other beta-lactams. To an even greater extent than imipenem and Sch 34343, latamoxef and ceftazidime proved very active against all these strains. A PSE-4-producing Escherichia coli strain was resistant to Sch 34343. The inoculum effect (10(6) vs 10(4) cfu/ml) on Sch 34343 activity was usually small (1-4). Tests for the beta-lactamase susceptibility of Sch 34343 showed that only one PSE-3, one PSE-4 and one chromosomal beta-lactamase from a strain of Enterobacter cloacae were slightly active.

Acinetobacter↗
PubMed1985

Sch 34343 activity against streptococci and beta-lactam-resistant Enterobacteriaceae.

The in-vitro activity of Sch 34343 was compared with that of cefotaxime, ceftazidime, latamoxef (moxalactam), aztreonam and ampicillin. Against pneumococci, Sch 34343 was as active as ampicillin, whereas against the other streptococci it was less active than ampicillin but significantly better than the other antibiotics against enterococci. With clinical isolates of Enterobacteriaceae resistant to cefotaxime, Sch 34343 had MICs generally less than 2 mg/l. After introduction of plasmid-mediated beta-lactamases into Escherichia coli Cla. there were no significant changes in the MICs of Sch 34343. Mutants of Enterobacter cloacae, Citrobacter freundii and Morganella morganii with derepressed cephalosporinases had susceptibilities equal to or less than 1 mg/l, which were generally lower than those of the other compounds tested. Comparison of parental strains and permeability mutants of E. coli, Ent. cloacae, and Serratia marcescens showed that the increase in MICs of Sch 34343 were lower than those found for the other antibiotics.

Anti-Bacterial Agents↗
PubMed1985

Multiple antibiotic resistance plasmids in Enterobacteriaceae isolated from diarrhoeal specimens of hospitalized children in Indonesia.

We studied the plasmid and antibiotic resistance characteristics of 35 strains of Enterobacteriaceae recovered from faecal specimens of children with diarrhoea in Central General Hospital, Bandung, Indonesia. Twenty three Escherichia coli, three Providencia, three Proteus, three Klebsiella, two Enterobacter and one Citrobacter were examined. All strains were multiply resistant, many carrying six to nine antibiotic resistances. Most of these resistances were transferable to a laboratory E. coli strain and were carried on large-sized plasmids. All recently-described tetracycline resistance determinants (Classes A----D) were represented; the most common was the Class B, or TN10 type. The TEM-1 beta-lactamase was detected in 17 out of 21 ampicillin-resistant strains examined. The OXA-1, PSE-1, and SHV-1 enzymes were also found. Of 23 plasmids tested, all could be classified into one of eight different incompatibility groups: IncFII, IncN, IncB, IncF1, IncI1, IncI2, IncH2 and IncT. These studies demonstrate the existence of large multiresistant transferable plasmids representing common incompatibility groups and bearing common tetracycline and ampicillin resistance determinants in enteric strains isolated from children hospitalized in Indonesia.

Child↗
PubMed1985

Interaction of gentamicin, dibekacin, netilmicin and amikacin with various penicillins, cephalosporins, minocycline and new fluoro-quinolones against Enterobacteriaceae and Pseudomonas aeruginosa.

Thirty strains of Enterobacteriaceae and ten strains of Pseudomonas aeruginosa were selected to study the in-vitro activity of various combinations containing aminoglycosides, by the checkerboard method. The following aminoglycosides: gentamicin, dibekacin, netilmicin and amikacin were used in combination with each of the following: ampicillin, ticarcillin, piperacillin, cefazolin, cefuroxime, ceftazidime, norfloxacin, enoxacin and minocycline. Synergy was not a constant feature of beta-lactam+aminoglycoside combinations. Discrepancies occurred with the same strain submitted to combinations containing different aminoglycosides. The combinations containing new quinolones+aminoglycosides were usually additive, although occasionally synergy occurred. The combination minocycline+aminoglycoside was usually additive but partial antagonism (FIC or FBC index: 1 X 5- less than 2) occurred in 10 to 40% of the strains depending on the aminoglycoside. The combinations of beta-lactams with dibekacin or netilmicin most frequently produced partial or full synergy against strains of Ps. aeruginosa susceptible to all four aminoglycosides tested.

Amikacin↗
PubMed1986

Plasmid trimethoprim resistance in Vibrio cholerae: migration of the type I dihydrofolate reductase gene out of the Enterobacteriaceae.

Two strains of Vibrio cholerae biotype el tor were isolated in Tanzania. Each possessed a single resistance plasmid of 113 kbases belonging to the C incompatibility group. Both plasmids conferred resistance to sulphamethoxazole, ampicillin, streptomycin, chloramphenicol, tetracycline and trimethoprim. They are the first plasmids derived from V. cholerae strains, isolated in Southern Africa, to confer trimethoprim resistance. The trimethoprim resistance resulted from the plasmid-mediated production of a trimethoprim resistant dihydrofolate reductase which was very similar to the type I plasmid enzyme. This is the first example of movement of the gene encoding the type I dihydrofolate reductase into genera of other families besides the Enterobacteriaceae.

Drug Resistance, Microbial↗
PubMed1986

Comparative activities of the beta-lactamase inhibitors YTR 830, clavulanate and sulbactam combined with extended-spectrum penicillins against ticarcillin-resistant Enterobacteriaceae and pseudomonads.

The in-vitro synergistic activity of YTR 830, a new beta-lactamase inhibitor, combined with four extended-spectrum penicillins (ticarcillin, piperacillin, mezlocillin and apalcillin) against ticarcillin-resistant clinical isolates of Gram-negative enteric bacilli was compared with that of clavulanate and sulbactam. Synergy testing was performed with fixed concentrations of beta-lactamase inhibitors (8 mg/l) combined with doubling dilutions of beta-lactams in microdilution trays. Synergy was defined as a four-fold or greater decrease of beta-lactam MIC in the combination compared with the beta-lactam alone. For 79 ticarcillin-resistant Enterobacteriaceae, ticarcillin-YTR 830 and ticarcillin-clavulanate were synergistic against 90% of strains; for ticarcillin-sulbactam, 70% showed synergy. The synergistic activity of all three inhibitors was similar against strains resistant only to ticarcillin; for strains resistant to all four extended-spectrum penicillins, the activity of ticarcillin with YTR 830 and clavulanate was similar (synergy against 79% of strains) and superior to ticarcillin-sulbactam (synergy against 39% of strains). YTR 830 was more active than clavulanate against Serratia, Citrobacter, Proteus and Providencia spp. Piperacillin, mezlocillin and apalcillin susceptible strains, with MICs of 8-16 mg/l, showed synergy with inhibitors against 37-87% of strains. Amongst pseudomonads, no synergy was demonstrated against Pseudomonas aeruginosa; ticarcillin produced synergy with the inhibitors against Ps. maltophilia, while piperacillin-YTR 830 and apalcillin-YTR 830 were synergistic against Ps. cepacia. YTR 830 appears to have comparable in-vitro activity to that of clavulanate, and further development of this compound is warranted.

Ampicillin↗
PubMed1986

Selective growth of resistant variants during incubation of Enterobacteriaceae with four aminoglycosides.

The selective growth of resistant variants, present at low frequencies, varied with different strains of Enterobacteriaceae and different aminoglycosides. This phenomenon was more pronounced during incubation with amikacin than with gentamicin, netilmicin and tobramycin. Selective growth of the resistant variants resulted in an inoculum effect and an increase in MIC with longer incubation. In-vitro evaluation of this phenomenon may be justified when choosing an aminoglycoside for therapy.

Adenosine Triphosphate↗
PubMed1986

Comparison of a slow-release trimethoprim with co-trimoxazole: efficacy and selection of resistance in the Enterobacteriaceae.

One hundred and fifty one patients with symptoms of urinary tract infection were treated randomly in a double blind study with a slow release form of trimethoprim or with co-trimoxazole. Similar cure rates were seen. There was no difference between the proportions of patients in the two groups who acquired trimethoprim-resistant Enterobacteriaceae. Further clinical trials with slow release trimethoprim should be performed.

Adult↗
PubMed1986

Elimination of plasmids from Enterobacteriaceae by 4-quinolone derivatives.

Twelve 4-quinolones (cinoxacin, ciprofloxacin, enoxacin, flumequin, nalidixic acid, norfloxacin, oxolinic acid, pefloxacin, pipemidic acid, rosoxacin, and piromidic and beta-hydroxypiromidic acids) and novobiocin, were used at subinhibitory concentrations to eliminate from Escherichia coli 11 antibiotic resistance plasmids belonging to different incompatibility groups. The 12 4-quinolones were also tested for their ability to cure virulence plasmids from five species of Enterobacteriaceae. All quinolones eliminated three antibiotic resistance plasmids (R446b, R386, S-a) and one virulence plasmid (pWR105), but at a low rate. Optimal curing of antibiotic resistance plasmids was obtained in human urine. Two virulence plasmids (pWR24 and pWR110) were eliminated only by flumequin and pefloxacin. Novobiocin eliminated three antibiotic resistance plasmids (R446b, R386, pIP24). The variable and low level of plasmid loss may be explained by the induction of the recA system. In addition, the inability to eliminate certain plasmids could be due to their presence in high numbers per cell.

Culture Media↗
PubMed1987

The effect of imipenem on strains of Enterobacteriaceae expressing Richmond & Sykes class I beta-lactamases.

Fourteen strains of Enterobacteriaceae producing Richmond & Sykes Class I beta-lactamase were studied. The ability of cefoxitin and imipenem to induce beta-lactamase production (reversible derepression) and to select stably derepressed mutants in these strains was assessed. beta-Lactamase induction by cefoxitin and imipenem was demonstrated by the disc diffusion technique in all strains. Cefoxitin selected stably derepressed mutants for all strains in broth cultures, but in an identical experiment imipenem did not. The susceptibility of each strain and its stably derepressed mutant (selected with cefoxitin) to a range of beta-lactam antibiotics was then ascertained. The stably derepressed mutants exhibited decreased susceptibility to all antibiotics tested except imipenem. The decrease in susceptibility varied between strains and between antibiotics but reached a maximum of a 256-fold decrease. The beta-lactamase activity of selected stably derepressed mutant strains showed at least a 600-fold increase in activity. Imipenem would therefore seem an appropriate choice for therapy of infections caused by this group of organisms, as it is active against derepressed mutants and unlikely to select any such strains during therapy.

Anti-Bacterial Agents↗
PubMed1989

In-vitro activity of FCE 22101 and other beta-lactam antibiotics against Enterobacteriaceae resistant to third generation cephalosporins.

The in-vitro activity of FCE 22101 was compared with those of imipenem, aztreonam, cefotaxime, ceftriaxone and latamoxef against 225 Enterobacteriaceae (209 clinical isolates and 16 derivatives of Escherichia coli K12) chosen for their resistance (MIC greater than or equal to 8 mg/l) to third-generation cephalosporins. The beta-lactamases produced by the strains of Enterobacter cloacae, Klebsiella pneumoniae and Esch. coli were identified. The mean MICs of FCE 22101 were 2-8 mg/l for Ent. cloacae, Citrobacter freundii and Morganella morganii. For Ent. cloacae, the MICs were slightly higher for the cephalosporinase non overproducing (5.5-8 mg/l) than for the cephalosporinase overproducing (4.5 mg/l) strains. The mean MIC was 9 mg/l for Serratia spp. but for half of the strains the MICs were greater than or equal to 16 mg/l. The MICs of FCE 22101 were 0.5-1 mg/l for the resistant clinical isolates or isogenic derivatives of K. pneumoniae and Esch. coli producing extended broad-spectrum beta-lactamases (SHV-2, SHV-3 or CTX-1), whether measured in the presence of clavulanate or not, and against the sensitive controls. This showed that the compound was not affected by these new beta-lactamases. The MICs of imipenem, on the average four to five times lower than those of FCE 22101, were found to be very similar for resistant and sensitive strains. The MICs of aztreonam were high (32-128 mg/l) for C. freundii, K. oxytoca and cephalosporinase overproducing strains of Ent. cloacae. There was cross-resistance between the third-generation cephalosporins, but the MICs of latamoxef remained low (1 mg/l) against M. morganii, Klebsiella spp. and Esch. coli.

Carbapenems↗
PubMed1990

A comparison of the mechanisms of decreased susceptibility of aztreonam-resistant and ceftazidime-resistant Enterobacteriaceae.

Twenty five strains of Enterobacteriaceae (five each of Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, Morganella morganii and Providencia stuartii) were exposed to aztreonam and ceftazidime at 1/2 and 1 x MIC in liquid medium for 22 h, and also to 3, 5 and 10 x MIC and 16 mg/l of each agent in agar. Any putative mutant with an increase in the MIC of greater than or equal to 4 fold was examined for beta-lactamase expression and outer membrane protein profile. Mutants were selected on agar at approximately 10(7); however in liquid medium not all strains yielded mutants. Mutants lacking an outer membrane protein (OMP) with a molecular weight of 40,000 (+/- 5000) were selected with both agents, as were mutants expressing constitutive Richmond and Sykes Class 1 beta-lactamase. For the Ent. cloacae mutants increased beta-lactamase gave rise to MICs above the breakpoint of both agents, whereas with the other species ceftazidime susceptibility was more affected. Strains that were OMP- rarely had MICs above the breakpoint, unless there was also increased beta-lactamase expression, as in species such as M. morganii. Hence the major mechanism of resistance in these strains would appear to be beta-lactamase mediated rather than due to altered expression of outer membrane proteins.

Aztreonam↗
PubMed1991

Characterization of FCE 22101-resistant Enterobacteriaceae and the effect of FCE 22101 upon the activity of anti-pseudomonal beta-lactams for Pseudomonas aeruginosa.

Twenty-five strains of Enterobacteriaceae (five each of Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, Morganella morganii, and Providencia stuartii) were exposed to FCE 22101 in agar containing 3, 5, or 10 x the MIC. Any putative mutant with a greater than or equal to four-fold increase in the MIC was examined for beta-lactamase expression and outer membrane protein (OMP) profile. Mutant colonies were selected at a frequency of 10(-7)-10(-11) with decreased susceptibility to FCE 22101 and other beta-lactams, but after one subculture on antibiotic-free agar the mutants from 13 of the 25 strains reverted to wild-type. Only 19 stable mutants were selected from the other 12 wild-type strains, of which 15 lacked an OMP of similar molecular size to OmpF, and/or a low size OMP of approximately 18 kDa. None of the mutants had a significant alteration in expression of Richmond & Sykes class I beta-lactamase. In a separate section of the study in which 50 strains of Pseudomonas aeruginosa were examined, it was found that FCE 22101, at a concentration of 4 mg/L, induced beta-lactamase expression such that, after 24 h exposure, 24 of the 50 strains had a greater than or equal to four-fold rise in the MIC of several anti-pseudomonal beta-lactams.

Anti-Bacterial Agents↗
PubMed1993

Activity of the beta-lactamase inhibitor BRL 42715 against cephalosporinases produced by Enterobacteriaceae.

BRL 42715, a novel beta-lactamase inhibitor, was evaluated for its capacity to inhibit cephalosporinases. BRL 42715 was effective in potentiating the activity of antibiotics against clinical isolates of Enterobacteriaceae that produced high levels of cephalosporinases. This correlated well with the very low 50% inhibition values (< 0.004 mg/L) of BRL 42715 for cephalosporinases extracted from different species. When compared in vitro to clavulanic acid, sulbactam, and tazobactam, BRL 42715 was the most efficient inhibitor of cephalosporinase.

Anti-Bacterial Agents↗
PubMed1993

Characterization of ceftriaxone-resistant Enterobacteriaceae: a multicentre study in 26 French hospitals. Vigil'Roc Study Group.

During a multicentre study performed in 26 French hospitals, 287 (3.2%) of 9038 Enterobacteriaceae isolated, mainly Enterobacter spp., Serratia spp., Citrobacter spp. and Klebsiella spp. were classified as ceftriaxone resistant on the basis of an MIC > 4 mg/L or the presence of an extended-spectrum beta-lactamase. Extended-spectrum beta-lactamase was present mainly in Klebsiella pneumoniae (65 strains, 10.2%) and very rarely in Escherichia coli, Proteus mirabilis, Klebsiella oxytoca, Citrobacter spp. and Enterobacter spp. The extended-spectrum beta-lactamases conferred low-level resistance to ceftriaxone in nearly 60% of the strains harbouring them, emphasizing the need for routine testing for the presence of these enzymes. Among transconjugants three types of extended-spectrum beta-lactamase were identified. Those resembling TEM-3 were the most common, but TEM-21, and SHV-4 were also found. Clavulanate and to a lesser extent sulbactam inhibited all the extended-spectrum beta-lactamases encountered in this study.

Ceftriaxone↗
PubMed1994

In-vitro activity of five beta-lactam/beta-lactamase inhibitor combinations against consecutive isolates of the Enterobacteriaceae and Pseudomonas aeruginosa.

Susceptibility tests were performed on 2402 of consecutive isolates of Enterobacteriaceae and 254 strains of Pseudomonas aeruginosa in five separate medical centres. Five beta-lactams were evaluated with and without a beta-lactamase inhibitor. The effect of different inhibitors was species specific and the rank order of decreasing efficacy against all enteric bacilli was: cefoperazone-sulbactam > piperacillin-tazobactam > cefoperazone > ticarcillin-clavulanic acid > piperacillin > co-amoxiclav > ampicillin-sulbactam > ticarcillin > ampicillin > amoxycillin.

Anti-Bacterial Agents↗