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Biomedical subjects

A Philippon

Publications and source records attributed to A Philippon.

At least 73 records · Page 4Linked to original sources
PubMed1991

Construction by polymerase chain reaction and use of intragenic DNA probes for three main types of transferable beta-lactamases (TEM, SHV, CARB) [corrected].

Intragenic DNA probes were synthesized by polymerase chain reaction using fragments of the genes of three major types of beta-lactamases (TEM, SHV, CARB) as templates. The TEM probe hybridized with the genes encoding TEM-1, TEM-2 and six extended-spectrum related enzymes (TEM-3 to TEM-7, TEM-2O) in colony hybridizations and Southern-blot analysis. The SHV probe hybridized with the genes for SHV-1, OHIO-1 and four derived extended-spectrum beta-lactamases (SHV-2, SHV-3, SHV-4 and SHV-5). The CARB probe hybridized with the genes for PSE-1 (CARB-2), PSE-4 (CARB-1), CARB-3 and CARB-4. None of the probes hybridized with genes for any of eight oxacillin-hydrolysing enzymes, PSE-2, OXA-1 to OXA-7, ROB-1 and chromosomal beta-lactamases of various Enterobacteriaceae (except Klebsiella pneumoniae) and Pseudomonas aeruginosa. Investigations of Escherichia coli clinical isolates using these probes indicate the presence of a novel type of extended-spectrum, transferable beta-lactamase.

Base Sequence↗
PubMed1991

Novel transferable extended-spectrum beta-lactamase (SHV-6) from Klebsiella pneumoniae conferring selective resistance to ceftazidime.

A clinical isolate of Klebsiella pneumoniae sensu lato isolated from throat and a blood culture taken from a neutropenic patient treated for 2 weeks with ceftazidime and vancomycin was resistant to ceftazidime (MIC: 32 micrograms/ml) and moderately susceptible to aztreonam (MIC: 4 micrograms/ml). The isolate contained a plasmid of 180 kb which, when transferred to Escherichia coli by conjugation, conferred resistance to ceftazidime and tetracycline. The transconjugant had decreased susceptibility to ceftazidime (128-fold) and aztreonam (8-fold). Clavulanic acid and sulbactam each inhibited the resistance and clavulanic acid showed a synergistic effect when associated with ceftazidime and aztreonam. An extended-spectrum beta-lactamase with an isoelectric point of 7.6 was detected in the clinical isolates from blood and its transconjugant. This beta-lactamase showed similar substrate and inhibition profiles to SHV-1. In particular it did not hydrolyse ceftazidime. Hybridization with an intragenic probe for SHV-3 indicates that this beta-lactamase is an SHV-type enzyme. We propose that this novel CAZ-type extended-spectrum beta-lactamase be named SHV-6.

Ceftazidime↗
PubMed1991

Nosocomial outbreak of acute gastroenteritis in a neonatal intensive care unit in Tunisia caused by multiply drug resistant Salmonella wien producing SHV-2 beta-lactamase.

In a Tunisian hospital 27 babies, including 12 who were premature, in a single intensive care unit suffered acute gastroenteritis in the period from January to May 1988. The mean age at the onset of gastroenteritis was 8.4 days; nine babies died. Salmonella wien was isolated from stools (all babies) and blood (4 babies). It was also isolated from the stools of one nurse and from a mattress. Twelve of the babies had received cefotaxime, which was successfully replaced by oral colimycin. The outbreak was stopped by the implementation of infection control measures. All isolates of Salmonella wien were of the same biotype, and had the same antibiotic resistance pattern (third generation cephalosporins, monobactams, aminoglycosides, chloramphenicol, trimethoprim and sulphonamides) and plasmid DNA restriction pattern. The isolates were all susceptible to a combination of cefotaxime and clavulanic acid (a beta-lactamase inhibitor), which displayed synergy, suggesting the presence of a beta-lactamase (geometric mean MICs 11.24 micrograms/ml for cefotaxime alone and 0.24 micrograms/ml in combination with 0.1 micrograms/ml potassium clavulanate). All isolates produced TEM-1 and SHV-2 beta-lactamase which was not transferable to Escherichia coli by conjugation. The presence of the SHV-2 enzyme in Salmonella wien may allow it to adapt to newer beta-lactams which is a cause for concern in this hospital.

Acute Disease↗
PubMed1991

[Detection of extended broad-spectrum beta-lactamases with the ATB MIC system].

The Enterobacteriaceae producing extended broad-spectrum beta-lactamases (ESB) must be detected even when their MIC to oxyiminocephalosporins are low. We tested 164 isolates (133 ESB, 31 non ESB) on two experimental ATB MIC plates containing cefotaxime or ceftazidime (0.06-128 mg/l) alone or associated with sulbactam (4 mg/l). Fifty four per cent of the ESB isolates are sensitive to cefotaxime, and 30% to ceftazidime. Respectively 95% and 94% of these bacteria have a synergism index (MIC CIII alone/MIC CIIII + sulbactam) greater than or equal to 4 with cefotaxime and ceftazidime. The isolates that do not produce ESB have all a rate less than 4. The ATB system can detect the extended broad spectrum beta-lactamases when low concentrations of cephalosporins are used, alone and in association with an inhibitor of beta-lactamases.

Cefotaxime↗
PubMed1990

[Prospective, randomized, controlled study of imipenem-cilastatin versus cefotaxime-amikacin in the treatment of lower respiratory tract infection and septicemia at intensive care units].

In a multicentre, prospective, controlled trial 211 patients with suspected septicaemia or pneumonia were allocated at random to either imipenem-cilastatin 500 mg 8-hourly or cefotaxime 1 g 6-hourly combined with amikacin 5 mg/kg 8-hourly. The treatments were administered for at least 5 days. Seventy patients on imipenem and 70 patients on cefotaxime-amikacin were assessable for comparison. There were no statistically significant differences between the two groups in underlying pathology and in the clinical results obtained: septicaemia 20/26 patients of the imipenem group and 20/25 patients of the cefotaxime-amikacin group were cured; pneumonia 38/44 patients of the imipenem group and 34/45 patients of the cefotaxime-amikacin group were cured. There were also no differences in the initial organisms and in the bacteriological cure rate, except for Pseudomonas aeruginosa. At the moment, imipenem administered alone is as effective as the cefotaxime-amikacin combination in the treatment of septicaemia or pneumonia in intensive care patients, with the exception of P. aeruginosa pneumonia in patients under assisted ventilation.

Adult↗
PubMed1990

Two novel transferable extended-spectrum beta-lactamases from Klebsiella pneumoniae in Tunisia.

Two novel beta-lactamases conferring multiresistance to antibiotics including oxyimino beta-lactams have been identified in two nosocomial K. pneumoniae strains isolated in Tunis in 1986 and 1988. Both enzymes were encoded by ca. 150-kilobase plasmids. Donor and transconjugant strains producing these enzymes exhibited highly similar pattern of resistance (CTX phenotype) to beta-lactams including penicillins and oxyimino beta-lactams e.g. cefotaxime, ceftriaxone, ceftazidime, and aztreonam. High and variable synergy (16 to 1066-fold) was obtained when combined to 0.1 microgram/ml of clavulanate (beta-lactamase inhibitor). The isoelectric points of these two enzymes were 5.4 and 6.4. These beta-lactamases differed from TEM types by hydrolysis for cefotaxime or ceftriaxone but were inhibited by clavulanate and cloxacillin. DNA hybridization studies suggested that that the genes of these enzymes may be derived from genes encoding TEM-type enzymes.

DNA, Bacterial↗
PubMed1990

Outbreak of nosocomial infections due to Klebsiella pneumoniae producing SHV-4 beta-lactamase.

One hundred and fifty-four clinical isolates of Klebsiella pneumoniae resistant to broad-spectrum cephalosporins, aztreonam and amikacin were responsible for an outbreak of nosocomial infections lasting eight months in a university hospital in Paris. This outbreak occurred in the intensive care unit (39 patients), haematology units (8 patients) and surgical and medical units (11 patients). Antibiotic resistant strains were isolated from the urinary tract (48%), wound and drainage fluids (21%), respiratory tract (14%), blood (12%) and stools (5%). High resistance to oxyimino-beta-lactams was mediated by a plasmid-encoded beta-lactamase with an isoelectric point of 7.8 (SHV-4). This CAZ-type enzyme conferred a higher level of resistance to ceftazidime and aztreonam (geometric mean MIC 135 mg/l) than to cefotaxime (geometric mean MIC 14 mg/l). All isolates were of the same biotype (weakly urease positive and no sucrose fermentation). Eight Klebsiella pneumoniae strains isolated in different units and at different times of the outbreak were of the same serotype, had common plasmid patterns and harboured a large self-transferable plasmid of about 180 kilobases encoding resistance to penicillins, oxyimino-beta-lactams, aminoglycosides, tetracycline and trimethoprim. These eight large plasmids had indistinguishable EcoRI restriction patterns. These results suggest that a single strain of Klebsiella pneumoniae was responsible for this outbreak.

Anti-Bacterial Agents↗
PubMed1990

In vitro susceptibility of Corynebacterium group D2 and Corynebacterium jeikeium to twelve antibiotics.

The in vitro susceptibility of 83 Corynebacterium group D2 strains and 44 Corynebacterium jeikeium strains to 12 antimicrobial agents was determined by an agar dilution technique using Mueller-Hinton agar supplemented with Tween 80 (0.025%). All strains of Corynebacterium group D2 were highly sensitive to fusidic acid, pristinamycin, teicoplanin and vancomycin (geometric mean MICs 0.047, 0.048, 0.338 and 0.396 mg/l respectively). Most of the strains were resistant to other antibiotics tested (ciprofloxacin, erythromycin, gentamicin, lincomycin, rifampin and tetracycline). However, a few strains were highly sensitive (MICs less than or equal to 0.2 mg/l). The overall pattern of susceptibility of 44 strains of Corynebacterium jeikeium was similar; the geometric mean MICs of fusidic acid, pristinamycin, vancomycin and teicoplanin were 0.234, 0.235, 0.557 and 0.652 mg/l respectively.

Anti-Bacterial Agents↗
PubMed1990

Susceptibility of Alcaligenes denitrificans subspecies xylosoxydans to beta-lactam antibiotics.

The susceptibility of 56 clinical isolates and two reference strains of Alcaligenes denitrificans subsp. xylosoxydans to beta-lactam agents was tested and related to beta-lactamase activity of the strains. The MICs of 12 beta-lactams determined by an agar dilution method showed that all the strains were sensitive to imipenem and moxalactam. Forty-one cloxacillin-sensitive beta-lactamase producing strains were highly susceptible to azlocillin, piperacillin and ticarcillin, and less susceptible to several cephalosporins (cefamandole, cefoperazone, ceftazidime). The 17 remaining beta-lactamase-producing strains, which were sensitive to clavulanic acid and to a lesser extent cloxacillin, had variable resistance to the penicillins tested and synergy was obtained when these penicillins were combined with clavulanic acid or tazobactam. The choice of agents for treatment of infections with this organism must take into account the susceptibility phenotype of clinical isolates.

Alcaligenes↗
PubMed1990

Importance of organisms producing broad-spectrum SHV-group beta-lactamases into the United Kingdom.

We report the isolation of three strains of Klebsiella pneumoniae sensu lato, brought into the United Kingdom by patients from Greece and Egypt, that showed plasmid-determined resistance to ceftazidime. All three produced beta-lactamases shown by DNA hybridisation studies to belong to the SHV group. One produced an enzyme that appeared to be related to, but distinguishable from, SHV-1; another SHV-2 and the third SHV-5.

Blotting, Southern↗
PubMed1990

Prevalence of a transferable SHV-5 type beta-lactamase in clinical isolates of Klebsiella pneumoniae and Escherichia coli in Greece.

Analysis with a double-disc synergy test (DDST) of clinical isolates of Klebsiella pneumoniae and Escherichia coli during the period October 1988-September 1989 revealed that 24% of the former and 4% of the latter, mainly isolated from urine, possessed an extended-spectrum beta-lactamase. During this period no DDST was positive for isolates of other enterobacterial species. Transfer of ceftazidime resistance was demonstrated from six K. pneumoniae and two E. coli isolates resistant to third generation cephalosporins and aztreonam. Apart from one strain of K. pneumoniae, these strains harboured self-transferable multiresistance plasmids (c. 91 kb) with closely related EcoRI, HindIII, AvaII and PstI restriction patterns. These plasmids encoded an extended-spectrum beta-lactamase that conferred an unusually high level of resistance to ceftazidime and aztreonam (MIC greater than or equal to 64 mg/l). This enzyme had a pI of 8.2 and a substrate profile similar to that of the SHV-5 enzyme isolated initially in Chile, and later in France (CAZ-4). The remaining K. pneumoniae isolate harboured a transmissible multiresistance plasmid (c. 182 kb) that encoded the widely distributed SHV-2 enzyme. The resistance to cefoxitin that was observed in some of these strains was associated with outer membrane protein alterations.

Bacteria↗
PubMed1990

Characterization of beta-lactamases from non-Bacteroides fragilis group Bacteroides spp. belonging to seven species and their role in beta-lactam resistance.

Twelve beta-lactamase-positive non-Bacteroides fragilis group Bacteroides spp. belonging to seven different species were examined by MIC determination and enzyme characterization. MICs of most beta-lactams except cefoxitin, cefotetan, imipenem, and meropenem were relatively high or very high. All enzymes hydrolyzed cephaloridine (Vmax, 100%; Km, 12 to 70 microM), cephalothin (Vmax, 25 to 826%; Km, 8 to 143 microM), cefamandole (Vmax, 13 to 158%; Km, 17 to 170 microM), and cefuroxime (hydrolysis rate, 19 to 98%), and 11 of 12 hydrolyzed cefotaxime (Vmax, 26 to 145%; Km, 13 to 127 microM); no hydrolysis of cefoxitin or moxalactam was observed. Penicillins were hydrolyzed at lower rates, with Vmax values less than or equal to 20% of that obtained with cephaloridine. Addition of clavulanate, sulbactam, or tazobactam led to a 4- to 2,048-fold lowering of MICs of penicillins as well as cephalosporins. All enzymes were inhibited by clavulanate (50% inhibitory concentration [IC50], 0.01 to 1.8 microM), sulbactam (IC50, 0.02 to 1.9 microM), tazobactam (IC50, 0.001 to 0.9 microM), cefoxitin (IC50, 0.002 to 0.35 microM), and moxalactam (IC50, 0.03 to 6.6 microM). No enzymes were inhibited by 100 microM EDTA or p-chloromercuribenzoic acid; an enzyme of one strain of B. loescheii was inhibited by 100 microM cloxacillin (IC50, 2.35 microM). Ten enzymes had optimal activity at pH 5.0 to 6.0, and two had optimal activity at pH 8.0. Isoelectric focusing revealed pIs between 4.2 and 5.6. These enzymes seem to belong to a previously unclassified group of beta-lactamases, related (but not identical) to beta-lactamases of the B. fragilis group.

Anti-Bacterial Agents↗
PubMed1990

Activity of sulbactam in combination with ceftriaxone in vitro and in experimental endocarditis caused by Escherichia coli producing SHV-2-like beta-lactamase.

We studied the efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ceftriaxone in vitro and in experimental endocarditis due to an Escherichia coli strain producing an extended-spectrum beta-lactamase most similar to SHV-2, a new mechanism of resistance to broad-spectrum cephalosporins among members of the family Enterobacteriaceae. In vitro, ceftriaxone demonstrated an important inoculum effect (MICs were 2 and 256 micrograms/ml with 5 X 10(5) and 5 X 10(7) CFU of inoculum per ml, respectively). Sulbactam inhibited the beta-lactamase degradation of ceftriaxone and enhanced the killing by ceftriaxone with both inocula tested. In vivo, sulbactam (100 mg/kg every 8 h) or ceftriaxone (15 or 30 mg/kg every 24 h) alone were ineffective after a 4-day therapy. The addition of sulbactam to ceftriaxone (15 mg/kg) or to the ceftriaxone (15 mg/kg)-netilmicin (6 mg/kg every 24 h) combination produced a reduction of 2 log10 CFU/g of vegetation greater than that produced by therapy without sulbactam. The sulbactam-ceftriaxone (30 mg/kg) combination produced a reduction of almost 5 log10 CFU/g of vegetation greater than that produced by single-drug therapy (P less than 0.01), sterilized five of eight vegetations (versus none of seven for ceftriaxone [30 mg/kg] alone; P less than 0.05), and was as effective as the ceftriaxone (15 mg/kg)-sulbactam-netilmicin combination. We concluded that (i) SHV-2 production was responsible for ceftriaxone failure in vivo, probably because of the high inoculum present in vegetations; (ii) sulbactam used in a regimen which provided levels in serum constantly above 4 micrograms/ml and a vegetation/serum peak ratio of approximately 1:3 enhanced the activity of a broad-spectrum cephalosporin in a severe experimental infection; and (iii) the highest dose of ceftriaxone in combination with sulbactam was as effective as the lowest dose of ceftriaxone plus sulbactam plus an aminoglycoside.

Animals↗
PubMed1990

[Enzymatic resistance to cefotaxime in 56 strains of Klebsiella spp., Escherichia coli and Salmonella spp. at a Tunisian hospital (1984-1988)].

The enzymatic and plasmid-encoded resistance towards oxyimino-beta-lactams has been recently reported as related to the production of an extended-spectrum beta-lactamase (e.g. SHV-2, CTX-1 or TEM-3), in particular in our hospital since 1984. The prevalence of that resistance has been examined from January 1984 to December 1988 in function of specimen, unit and type of enzyme among 8,421 isolates of Klebsiella spp., E. coli, Salmonella spp. Each isolate showing a diameter of inhibition zone size inferior or equal to 25 mm for cefotaxime, the double disk synergy test was performed between a disk of amoxicillin and a clavulanic acid disk of cefotaxime, ceftriaxone, ceftazidime and aztreonam. In case of synergy, sonicated extracts have been prepared and examined by isoelectrofocusing with the detection of beta-lactamase activity by ceftriaxone and nitrocefin. 56 isolates (K. pneumoniae, K. oxytoca, E. coli, S. wien, S. typhimurium scored positive including 27 in pediatrics, 18 in surgery, and 8 in medicine. 41% of isolates have been obtained from blood cultures and 26.8% from urines. A majority of isolates (49/56) produced the SHV-2 type, but other types mediating the resistance phenotype CTX have been individualized initially by their isoelectric points e.g. 5.4 (TEM-20 in K. pneumoniae in July 1986), 6.4 (TEM-21 in E. coli, 1 K. pneumoniae in July 1988). The prevalence of resistance to cefotaxime from 1984 to 1988 has increased (from 0.3 to 1.4%), the highest rate being observed in pediatrics (5.6% in 1984 and 22.1% in 1988).

Cefotaxime↗
PubMed1989

[Antibacterial effect of cefixime in the presence of the type of beta-lactamases produced by Enterobacteriaceae].

The susceptibility of isolates or Enterobacteriaceae to orally absorbed beta-lactams (amoxicillin, cephalexin, cefaclor, cefuroxime, and cefixime), was maximum for the iminomethoxy-aminothiazolyl-cephalosporin but variable according to bacterial species. For E. coli, P. mirabilis, Salmonella, Shigella, K. pneumoniae, K. oxytoca (group 1) MIC50 were congruent to 0.06 mg/l, and MIC90 congruent to 0.12 mg/l. Finally for C. freundii, E. aerogenes, E. cloacae, S. marcescens, M. morganii, MIC50 were higher, congruent to 1, and MIC90 16 mg/l. The slight increase reported between MIC50 ans MIC90 of cefixime against isolates belonging to group 1 was related to stability towards beta-lactamases (TEM, SHV) unlike groups 2 and 3, where the drug was less stable to chromosomal type 1 enzyme. The discovery of extended-spectrum beta-lactamases (ESB) (e.g. SHV-2, CTX-1 or TEM-3), mainly in K. pneumoniae, led to further investigations of the behavior of cefixime. The in vitro activity of cefixime (CFM), amoxicillin (AMX) combined or not with clavulanate (AMC, 2 mg/l), ticarcillin (TIC), cephalothin (CF), cefotaxime (CTX), ceftazidime (CAZ) and aztreonam (AZM) was determined by the agar dilution method (inoculum 10(5) cfu/ml) against clinical isolates: E. coli (26), K. pneumoniae (42), K. oxytoca (9), Salmonella (3) producing several types of beta-lactamases, chromosomal (cephalosoporinase, broad-spectrum) or plasmid-encoded (TEM-1, TEM-2, CTX-1, SHV-2, SHV-3, SHV-4). The geometric mean MIC values of AMX, AMC, TIC, CF, CTX, CAZ, AZM and CFM were as follows: greater than 480, 21.6, greater than 285, 45.6, 0.53, 1.12, 0.51, and 0.77 respectively. An MIC increase of oxyimino beta-lactams (CTX, CAZ, AZM, CFM) was observed against over-producing isolates of K. oxytoca and isolates producing ESB (CTX-1, SHV-2, SHV-3, SHV-4). The comparative behavior of cefixime was determined after transfer by conjugation to E. coli K-12. Sixty-one derivatives were constructed producing TEM-1, TEM-2, SHV-1, CTX-1, TEM-4, CAZ-2, SHV-2, SHV-3, SHV-4, the MICs of cefixime were stable against derivatives producing a penicillinase (TEM-1, TEM-2, SHV-1), but not against those producing an ESB. The MIC increases of undigestible beta-lactams ranged from 1 to 135 fold (CFM), 40 to 200 fold (CTX) 12 to 232 fold (CAZ), and 4 to 240 fold (AZM).

Anti-Bacterial Agents↗
PubMed1989

Detection of extended broad-spectrum beta-lactamases in Enterobacteriaceae in four French hospitals.

In 210 strains of Enterobacteriaceae which were isolated in four hospitals and which showed reduced susceptibility to cefotaxime, high synergy was demonstrated between amoxicillin (20 micrograms) + clavulanate (10 micrograms) and cefotaxime (30 micrograms) using a simple double-disk test. Isoelectric focusing on gel and specific iodometric detection using ceftriaxone identified four extended broad-spectrum beta-lactamases (isoelectric points 7.6, 6.3, 7.0 and 5.9) produced by the strains.

Amoxicillin↗