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PubMed2002

Reduction of perchlorate and nitrate by salt tolerant bacteria.

Spent regenerant brine from ion-exchange technology for the removal of perchlorate and nitrate produces a high salt waste stream, which requires remediation before disposal. Bioremediation is an attractive treatment option. In this study, we enriched for salt tolerant bacteria from sediments from Cargill salt evaporation facility (California, USA), the Salton Sea (California, USA), and a high density hydrocarbon oxidizing bacterial cocktail. The bacterial cocktail enrichment culture reduced ClO4- from 500 to 260 mg 1 in 4 weeks. Salt tolerant bacterial isolates from the enrichment cultures and two denitrifying salt tolerant bacteria, Haloferax denitrificans and Parococcus halodenitricans, substantially reduced perchlorate. The highest rate of perchlorate removal was recorded with the isolate, Citrobacter sp.: 32% reduction in 1 week. This bacterium substantially reduced perchlorate in 0-5% NaCl solutions and maximally at 30 degrees C and at an initial pH 7.5. In simulated brines containing 7.5% total solids, the Citrobacter sp. significantly reduced both perchlorate and nitrate with 34.9 and 15.6% reduction, respectively, in 1 week. Coculture of a potent perchlorate reducing, non-salt tolerant (non-saline) bacterium, perclace and the Citrobacter sp. proved most effective for perchlorate removal in the brine (46.4% in 1 week). This study demonstrates that both anions can be reduced in treatment of brines from ion exchange systems.

Biodegradation, Environmental↗
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↗
PubMed1978

Azlocillin and mezlocillin: new ureido penicillins.

The activity of azlocillin and mezlocillin, new semisynthetic ureido penicillins, was investigated and compared with that of other known beta-lactam antibiotics. At a concentration of 25 mug/ml, azlocillin inhibited 74% of Enterobacter, 97% of Proteus mirabilis, 64% of Citrobacter, 91% of Pseudomonas aeruginosa, and 82% of Bacteroides strains tested. Mezlocillin inhibited 86% of Shigella, 96% of Enterobacter, 80% of indole-positive Proteus, 88% of Bacteroides, and 63% of Pseudomonas strains tested. Azlocillin was more active against Pseudomonas than was ticarcillin, carbenicillin, or mezlocillin. Mezlocillin was more active than carbenicillin and ampicillin against Escherichia coli, Klebsiella, Enterobacter, Citrobacter, Acinetobacter, Serratia, and Bacteroides. Azlocillin and mezlocillin were less active than cefazolin against beta-lactamase-producing E. coli and Klebsiella strains but more active than cefazolin against Enterobacter, indole-positive Proteus, Acinetobacter, Citrobacter, and Serratia strains. Both compounds showed activity equivalent to that of cefoxitin against Bacteroides isolates. Both agents were destroyed by many of the beta-lactamases from gram-negative organisms.

Bacteria↗
PubMed2001

Identification and functional characterization of arylamine N-acetyltransferases in eubacteria: evidence for highly selective acetylation of 5-aminosalicylic acid.

Arylamine N-acetyltransferase activity has been described in various bacterial species. Bacterial N-acetyltransferases, including those from bacteria of the gut flora, may be involved in the metabolism of xenobiotics, thereby exerting physiopathological effects. We characterized these enzymes further by steady-state kinetics, time-dependent inhibition, and DNA hybridization in 40 species, mostly from the human intestinal microflora. We report for the first time N-acetyltransferase activity in 11 species of Proteobacteriaceae from seven genera: Citrobacter amalonaticus, Citrobacter farmeri, Citrobacter freundii, Klebsiella ozaenae, Klebsiella oxytoca, Klebsiella rhinoscleromatis, Morganella morganii, Serratia marcescens, Shigella flexneri, Plesiomonas shigelloides, and Vibrio cholerae. We estimated apparent kinetic parameters and found that 5-aminosalicylic acid, a compound efficient in the treatment of inflammatory bowel diseases, was acetylated with a catalytic efficiency 27 to 645 times higher than that for its isomer, 4-aminosalicylic acid. In contrast, para-aminobenzoic acid, a folate precursor in bacteria, was poorly acetylated. Of the wild-type strains studied, Pseudomonas aeruginosa was the best acetylator in terms of both substrate spectrum and catalytic efficiency. DNA hybridization with a Salmonella enterica serovar Typhimurium-derived probe suggested the presence of this enzyme in eight proteobacterial and four gram-positive species. Molecular aspects together with the kinetic data suggest distinct functional features for this class of microbial enzymes.

Acetylation↗
PubMed1969

Taxonomic investigations on expressed and cryptic phospho-beta-glucosidases in Enterobacteriaceae.

In the Enterobacteriaceae, beta-glucosides are catabolized by a complex system formed of three permeases, with partly overlapping substrate specificities, and two hydrolytic enzymes, phospho-beta-glucosidase A and B, which hydrolyze only phosphorylated beta-glucosides. Some Enterobacteriaceae such as Klebsiella-Aerobacter (Enterobacter) possess the complete system; others possess only parts of it or may have a cryptic phospho-beta-glucosidase activity without permease activity. A screening test applied to strains belonging to several genera of Enterobacteriaceae showed that strains of Citrobacter, Hafnia, and Serratia exhibit a degree of similarity in phospho-beta-glucosidase activity and inducibility which could be useful in their taxonomic characterization; others, such as Aerobacter aerogenes, Erwinia, and Proteus vulgaris, are more heterologous. Owing to the presence of inducible phospho-beta-glucosidases A and B in Citrobacter, the fermentation of beta-methyl glucoside and the fermentation of arbutin in mixture with cellobiose could be of diagnostic value in the differentiation of Citrobacter from Salmonella. Wild-type strains of Escherichia coli, Shigella, and Salmonella are phenotypically similar in their inability to catabolize beta-glucosides, the presence of constitutive P-beta-glucosidase A, and the lack of beta-glucoside permeases I and II. Their beta-glucoside-fermenting mutants show, however, a phospho-beta-glucosidase and beta-glucoside permease activity which is characteristic for mutants from each genus. The differences in the phenotype of the mutants reflect probable differences in the presence of cryptic genes in the wild-type strains and could be of evolutionary significance.

Bacteriological Techniques↗
PubMed1980

Screening of bacterial isolates for mannose-specific lectin activity by agglutination of yeasts.

A total of 393 clinical bacterial isolates were tested for their ability to agglutinate yeast cells of either Saccharomyces cerevisiae or Candida albicans. A positive agglutination of yeasts that could be prevented by methyl alpha-D-mannoside was taken as an indication for the possible presence of a mannose-specific lectin (carbohydrate-binding protein) on the surface of the tested bacteria. Agglutination tests on glass slides showed that 38% of all the isolates tested were positive in their capacity to agglutinate yeasts. Among the various strains tested, all isolates of Serratia marcescens, Proteus morganii, and Citrobacter diversus, as well as 94% of Klebsiella pneumoniae, were positive. On the other hand, only 46% of the Escherichia coli, 48% of the salmonellae, 44% of the Citrobacter freundii, and 71% of the Aeromonas hydrophila isolates were positive. A quantitative determination of the lectin activity done by observing the agglutination of yeasts in microtiter plates showed that S. marcescens isolates were the most avid binders to the yeast, whereas Klebsiella and Citrobacter isolates were the weakest.

Agglutination↗
PubMed2000

[The structure and antibiotic sensitivity of the causative agents of community-acquired infectious diseases of bacterial origin in children].

Four hundred and forty pediatric patients at the age of 7 days to 15 years with various infections admitted to the Hospital within a month were examined. The biological material was inoculated to blood agar on the first days of the patient admittance to the Hospital and after the growth the organisms were isolated and identified. Antibiotic susceptibility of the isolates was assayed with the disk diffusion method. 479 strains in all were tested. The most frequent cases requiring hospitalization and antibiotic therapy were those of respiratory tract infections (54.09 per cent), urinary tract infections (26.36 per cent), cutaneous and subcutaneous fat diseases, gastrointestinal diseases and others (about 25 per cent of the cases in all). The main pathogens were Streptococcus viridans, S.aureus and S.epidermidis, as well as Enterobacteriaceae (chiefly E.coli) whose frequencies were practically equal (in 25-35 per cent of the cases). The Pneumococcus isolates amounted to 6.3 per cent. Nonfermenting bacteria (Pseudomonas aeruginosa and Acinetobacter) and some representatives of Enterobacteriaceae (Citrobacter, Serratia, Morganella) were isolated from 7 per cent of the patients. The frequency of Klebsiella and Enterobacter was about 11 per cent. The main pathogens were tested for their susceptibility to amoxycillin/clavulanic acid, ampicillin, oxacillin and gentamicin. The least active antibiotic was ampicillin. 88.8 per cent of the E.coli isolates and 100 per cent of the Klebsiella, P.mirabilis, Morganella, Citrobacter, Enterobacter and Serratia isolates were resistant to it. 53.2 per cent of the Streptococcus isolates including 64.5 per cent of the Pneumococcus isolates were as well resistant to ampicillin. 59.5 per cent of the Streptococcus isolates (mainly S.viridans and Enterococcus) was susceptible to oxacillin, 22.2 per cent of them being moderately susceptible. 62.5 per cent of the Pneumococcus isolates and 78.1 per cent of the Staphylococcus isolates were also susceptible to oxacillin. The highest susceptibility of the isolates was that to amoxycillin/clavulanic acid, i.e. 90.1 per cent of the strains, 79.9 per cent of them being highly susceptible. All the isolates of Citrobacter, Serratia and Morganella and some isolates of P.aeruginosa, Acinetobacter, Enterobacter, Klebsiella and E.coli were resistant to amoxycillin/clavulanic acid. As for the latter 5 organisms their susceptibility to amoxycillin/clavulanic acid was comparable with that to gentamicin. The susceptibility of the Streptococcus and Staphylococcus isolates to amoxycillin/clavulanic acid was significantly much higher than that to oxacillin, gentamicin and ampicillin: 93 per cent of the Streptococcus isolates (62.7 per cent of the Pneumococcus isolates) and 90.7 per cent of the Staphylococcus isolates.

Adolescent↗
PubMed2002

[Species composition and microbial contamination of atmospheric humidity condensate and potable water from the Mir water supply systems during Mir main missions 4 through 27].

Analyzed were quantitative and qualitative characteristics, and processes of formation and transformation of microflora in the atmospheric humidity condensate (AHC) and potable water (PW) regenerated from the condensate by the long-operating system (SRV-K) aboard space station Mir. The paper presents data on species composition of microflora of AHC, and PW regenerated by SRV-K in the period from 1989 through to 1999. The following microbial species were identified in AHC: Alcaligenes (14.8%), Bacillus (3.7%), Citrobacter (7.4%), Clostridium (11.1%), Enterobacter (7.4%), Proteus (7.4%), Pseudomonas (18.5%), and Staphylococcus (100%). There were two PW cocks in SRV-K--"hot" and "cold". "Hot" PW microflora included Alcaligenes (15%), Bacillus (5%), Citrobacter (20%), Clostridium (5%), Enterobacter (15%), Proteus (10%), Pseudomonas (15%), and Staphylococcus (75%). "Cold" PW microflora included Aeromonas (14.3%), Alcaligenes (21.4%), Bacillus (7.1%), Citrobacter (7.1%), Clostridium (7.1%), Enterobacter (7.1%), Moraxella (7.1%), Pseudomonas (7.1%), and Staphylococcus (78.5%). Microbial content averaged 8.9 x 10(2) +/- 1.3 (0.01-4) x 10(3) CFU/ml in condensate and 1.5 +/- 0.1 (0-3.0) CFU/ml in regenerated potable water.

Atmosphere↗
PubMed1992

The current and future impact of antimicrobial resistance among nosocomial bacterial pathogens.

The selection of drug-resistant microorganisms has generally been associated with the widespread use of antimicrobial agents. The emergence of these antimicrobial resistance has an undesirable impact that often severely limits the use of these drugs that could have otherwise been identified as "drugs of first choice." Among the most serious drug-resistance problems, the chromosomally mediated type -I beta-lactamase mechanism has become more common among the infecting Gram-negative bacteria. Type-I beta-lactamases are routinely identified in Enterobacter spp., Citrobacter freundii, Proteus vulgaris, Pseudomonas spp., Providencia spp., Morganella spp., Serratia spp., and various nonfermenters, including Acinetobacter spp., and can be induced to high production when exposed to certain beta-lactam antibiotics (for example, ceftazidime or cefoxitin). These organisms can also undergo spontaneous mutations to become high-level constitutive beta-lactamase producers, thus remaining resistant to most beta-lactam antibiotics. This has been the most common event at our medical center since 1986. Plasmid-mediated beta-lactamases and bacterial cell membrane protein alterations also confer resistance, resulting in clinically important challenges. At the University of Iowa Hospitals and Clinics, beta-lactam-resistant Pseudomonas, Citrobacter, and Enterobacter were observed over a 2-year period, an event that correlated with the introduction of the "third-generation" cephalosporin ceftazidime to the formulary. As ceftazidime use increased from 1986 to 1988, the minimal inhibitory concentrations (MICs) for not only ceftazidime but also some other "third-generation" cephems increased for Pseudomonas aeruginosa. Similarly, susceptibility of Citrobacter spp. and Enterobacter spp. declined during this period for ceftazidime and, to a lesser extent, the unrelated broad-spectrum penicillin, piperacillin.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMed1990

In vitro activity against clinically important gram-positive and gram-negative bacteria of sulbactam, alone and in combination with ampicillin, cefotaxime, mezlocillin, and piperacillin.

The in vitro effects of the single agents, and the synergistic/antagonistic action of three different combinations of ampicillin (AMP, CAS 69-53-4), cefotaxime (CTX, CAS 63527-52-6), mezlocillin (MEZ, CAS 51481-65-3), and piperacillin (PIP, CAS 61477-96-1) with the beta-lactamase inhibitor sulbactam (SUL, CAS 68373-14-8) were determined against 675 gram-positive and gram-negative, both aerobic and anaerobic bacteria. All the combinations of sulbactam and the antibiotics (1: 1, 1:2 and 1:4) exhibited very similar synergistic action. The percentage of the total strains tested for which synergistic activity was found was 51% with SUL + AMP (1:1), 24% with SUL + CTX (1:1), 31% with SUL + MEZ (1:1), and 28% with SUL + PIP (1:1). A fourfold or greater reduction of MIC's in the comparison with the antibiotics alone was found with 23% of the total strains tested for the SUL + AMP, with 9% of the strains tested with SUL + CTX, with 11% of the strains tested with SUL + MEZ, and with 15% of the strains tested with the SUL + PIP-combination. In the presence of sulbactam, 18% of the strains tested showed a significant reduction in the number of resistant strains with ampicillin, 7% with cefotaxime, 16% with mezlocillin, 14% with piperacillin, and in parallel there was an increase in the number of fully susceptible strains (shift from resistant or moderately sensitive to sensitive) by about 14%. In comparison with the antibiotic alone, the most marked reductions in the number of resistant strains on combination with sulbactam were as follows (the percentage of reduction is shown in brackets): for SUL + AMP and Acine-tobacter spp. (39% fewer resistant strains). Citrobacter spp. (-60%), Enterobacter aerogenes (-48%), Klebsiella oxytoca (-49%), Klebsiella pneumoniae (-63%), Morganella morganii (-74%), and Proteus vulgaris (-55%); for SUL + CTX and Acinetobacter spp. (-38%), Enterobacter cloacae (-6%), Klebsiella pneumoniae (-16%), Serratia marcescens (-9%), and Bacteroides fragilis (-31%); for SUL + MEZ and Acinetobacter spp. (-68%), Citrobacter spp. (-27%), Enterobacter spp. (-23%), Klebsiella pneumoniae (-32%), and Serratia marcescens (-19%); for SUL + PIP and Acinetobacter spp. (-41%), Citrobacter spp. (-30%), Klebsiella spp. (-30%), and Serratia marcescens (-33%).

Ampicillin↗
PubMed1989

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from urinary tract infections (1986). III. Secular changes in susceptibility].

Changes in the susceptibility of various infectious microorganisms to antimicrobial agents from 1982 to 1986 were evaluated. The microorganisms investigated were Escherichia coli, Klebsiella spp., Citrobacter spp., Enterobacter spp., Proteus spp., Serratia marcescens and Pseudomonas aeruginosa isolated from patients with urinary tract infections. We compared susceptibilities of microorganisms obtained from simple urinary tract infections with those from complicated infections with or without indwelling catheter. Among penicillins, mecillinam (MPC) showed the strongest activity against E. coli obtained from the patients: 3.13 to 6.25 micrograms/ml of MPC inhibited the growth of over 90% of the isolates. Among the second and the third generation cephalosporins, cefotiam and cefmenoxime (CMX) showed the strongest activity and the growth of isolates was inhibited at concentrations of 0.39 to 0.78 microgram/ml and below 0.10 to 0.20 microgram/ml, respectively. The activities of penicillins against Klebsiella spp. were weak. CMX showed strong activity against Klebsiella spp; 91.7% of the isolates from patients with simple infections were inhibited at 0.39 microgram/ml of the agent; 90.7% and 91.6% of isolates from patients with complicated infections with or without indwelling catheter were inhibited at 0.78 microgram/ml and 1.56 microgram/ml of the agent, respectively. Gentamicin (GM) also showed strong activity against isolates from patients with simple infections and weaker activity against isolates from patients with complicated infections with the catheter; 0.78 microgram/ml of ofloxacin (OFLX) inhibited the growths of 90% of the isolates from these patients. Penicillins showed weak activity against Citrobacter spp. obtained from the patients. Among the second and the third generation cephalosporins, CMX and latamoxef (LMOX) showed strong activities against the Citrobacter isolates; about 50% of the isolates were inhibited at 0.20 microgram/ml of either agent. 1.56 microgram/ml of minocycline inhibited the growth of 75 to 90% of the isolates and 1.56 microgram/ml of OFLX inhibited the growth of 93 to 100% of the isolates. Against isolates of Proteus spp. penicillins also showed weak activities. Among them, however, piperacillin (PIPC) inhibited the growth of over 90% of the isolates at concentrations ranging from 0.78 to 1.56 micrograms/ml. Among the second and third generation cephalosporins, CMX and LMOX showed strong activities; 0.20 microgram/ml of CMX inhibited the growth of 94.4%, 90.4%, and 83.1% of isolates from the 3 types of the patients, respectively. 0.20 microgram/ml of LMOX inhibited the growth of 94.4%, 91.8%, and 88.3% of the isolates, respectively. Enterobacter spp. showed resistance to the beta-lactam antibiotics.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Bacterial Agents↗
PubMed1987

[In vitro chemo-antibiotic sensitivity of gram-negative bacteria from various biological materials. Comparison between aztreonam and other agents].

527 Gram negative bacterial strains isolated from different biological substances were studied by chemo-antibiotic sensitivity. The examination was carried out by the agar diffusion test (Kirby-Bauer). A very good sensitivity to aztreonam (E. coli, Serratia spp., Klebsiella spp., Proteus spp.), to amikacin (Pseudomonas spp., Enterobacter spp., Citrobacter spp.) and to norfloxacin (Citrobacter spp.) was found. Even when it was not the best, aztreonam was the second (Citrobacter spp.) or the third choice (Pseudomonas spp.), always near to the drug of first choice.

Amikacin↗
PubMed1996

[Fluoroquinolone and aminoglycoside resistance in chromosomal cephalosporinase-overproducing gram-negative bacilli strains with inducible beta-lactamase].

INTRODUCTION: The increasing prevalence of stable derepressed mutants over-producers of type I chromosomal cephalosporinase in inducible Enterobacteriaceae and Pseudomonas aeruginosa challenges the adequacy of third generation cephalosporins in the empirical treatment of certain nosocomial infections. We sought to determine the frequency of stable over-producers of type I enzyme and their associated resistance to fluoroquinolones and aminoglycosides. METHODS: Disc-diffusion and MIC determinations to extended-spectrum beta-lactams, imipenem, ciprofloxacin and gentamicin were performed in all cell isolates of inducible enteric bacteria (Enterobacter spp., Citrobacter spp., Serratia spp., Morganella morganii, Providencia spp.) and P. aeruginosa collected during the period of study (1992-1993). RESULTS: A total of 1,426 isolates of inducible enteric bacteria and P. aeruginosa were studied. Each one represented a single patient. Among the 511 isolates of enteric bacteria 15.1% of strains were found to be stable derepressed mutants (Serratia 2.2%; Morganella spp., 3%; Providencia and Proteus 3%; Citrobacter spp., 10%; Enterobacter spp., 23.6%); among the 916 P. aeruginosa isolates studied, 9.2% were stable over-producers. Among Citrobacter, Providencia and Proteus spp., 53.1% of stable over-producers were resistant to ciprofloxacin versus 20.2% of non-over-producers (p < 0.01); in P. aeruginosa, 35.3% of over-producers were resistant to gentamicin versus 25.0% in non-over-producers (p < 0.01). CONCLUSION: The prevalence of stable derepressed mutants is high among enteric bacteria and P. aeruginosa with type I inducible beta-lactamase. These strains frequently exhibit resistance to fluoroquinolones and aminoglycosides, reducing considerably the available therapeutic options.

Aminoglycosides↗
PubMed1999

Synthesis and evaluation of 2 beta-oxyimino and alkenylpenicillanic acid sulfone derivatives as beta-lactamase inhibitors.

The synthesis and in vitro synergies of 2 beta-alkenyl and oxyiminopenam sulfone derivatives are described. Most of the compounds synthesized exhibited good inhibitory activities and synergistic antibacterial activities with piperacillin and ceftriaxone, respectively, against several beta-lactamase producing strains. Particularly the 2 beta-alkenylpenam sulfone derivatives. 1e and 1g, showed good synergistic activity with ceftriaxone against Citrobacter freundi NIH 10018-68 and Proteus vulgaris 20. Also the compounds 2a, 2c, and 2f, 2 beta-oxyiminopenam sulfone derivatives, exhibited improved synergistic activity with piperacillin against Citrobacter freundi NIH 10018-68.

Ceftriaxone↗
PubMed1979

In vitro investigations with fosfomycin on Mueller-Hinton agar with and without glucose-6-phosphate.

Determination of the minimal inhibitory concentration of fosfomycin in the agar dilution test on Mueller-Hinton agar showed that the addition of glucose-6-phosphate to the nutrient medium potentiates the action of fosfomycin against Escherichia coli, Klebsiella, Enterobacter, Citrobacter and Staphylococcus aureus, sometimes by as much as 256-fold. Such a potentiation of action was not detectable with Serratia marcescens, the individual Proteus species, Pseudomonas aeruginosa or enterococci. Fosfomycin is very effective against most medically important bacterial species on Mueller-Hinton agar containing 25 micrograms/ml glucose-6-phosphate. Over 90% of the cultures of E. coli, Citrobacter, Enterobacter, S. marcescens,Proteus mirabilis, Proteus vulgaris, Proteus rettgeri, P. aeruginosa, S. aureus and enterococci examined were inhibited by less than or equal to 64 micrograms/ml fosfomycin.

Agar↗
PubMed1998

Comparative activities of novel beta-lactamase inhibitors, 6-exomethylene penamsulfones (CH1240, CH2140) in experimental mouse infection model.

The antibacterial activity of novel beta-lactamase inhibitors, 6-exomethylene penamsulfones (CH1240, CH2140), has been compared in vivo with that of sulbactam and clavulanic acid against beta-lactamase producing strains. In vivo microbiological assessment was used as experimental mouse infection model by gram negative strains. Against Pseudomonas aeruginosa F0013, cefoperazone/CH1240 was slightly less active than sulbactam. Ampicillin/CH1240 was more active than sulbactam against Citrobacter diversus species. That of ampicillin/CH2140 was less effective than sulbactam against Escheriachia coli 3457. Especially against Citrobacter diversus 2046E, amoxicillin/CH2140 was the most potent and amoxicillin/CH1240 was slightly more active than clavulanic acid. Consequently the difference in efficacy between the drug combinations appears to be related to the degree of protection afforded the animals by the beta-lactamase inhibitors. CH1240 and CH2140 are promising new agents and should undergo further investigations.

Animals↗
PubMed2005

Prevalence and antimicrobial susceptibility data for extended-spectrum beta-lactamase- and AmpC-producing Enterobacteriaceae from the MYSTIC Program in Europe and the United States (1997-2004).

This article presents prevalence and susceptibility data from the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program in Europe (1997-2004) and the United States (1999-2004) for Enterobacteriaceae producing extended-spectrum beta-lactamase (ESBL) and/or AmpC beta-lactamases. For ESBL-producing isolates, the prevalence of Escherichia coli and Klebsiella spp. in Europe and Enterobacter spp. in the United States increased over time. For AmpC-producing isolates, the prevalence of Enterobacter spp. and Citrobacter spp. decreased over time in Europe and the United States, respectively. Compared with other antimicrobial agents, meropenem and imipenem had greatest activity against ESBL-producing E. coli and Klebsiella spp. in both Europe (96.9-100.0%) and the United States (100.0%). Such activity was also found for AmpC-producing Enterobacteriaceae in Europe (50.0-100.0%), and Enterobacter spp. and Citrobacter spp. from the United States (100.0% for both). The continued efficacy of carbapenems such as meropenem confirms that these remain first-line agents for treatment of nosocomial infections caused by Enterobacteriaceae-producing ESBL or AmpC beta-lactamases.

Anti-Bacterial Agents↗
PubMed2001

Oral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci in irradiated, dentate, xerostomic individuals.

This study aimed at investigating the oral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci in head- and neck-irradiated, dentate, xerostomic individuals. Subjects were recruited from a nasopharyngeal carcinoma clinic and were segregated into group A: <60 years (n=25, 48+/-6 years, 5+/-5 years post-irradiation) and group B: >or=60 years (n=8, 67+/-4 years, 2+/-2 years post-irradiation) and were compared with age- and sex-matched normal individuals, group C: <60 years (n=20, 44+/-12 years) and group D: >or=60 years (n=10, 70+/-3 years). Selective culture of the oral rinse samples was carried out to isolate, quantify and speciate (using API 20E kit) aerobic and facultatively anaerobic gram-negative rods and cocci recovery. All test subjects were put under comprehensive oral and preventive care for 3 months, and 12 group A and 5 group B subjects were recalled for reassessment of aerobic and facultatively anaerobic gram-negative rods and cocci colonization. All identical isolates, pre- and post-hygienic care, were phenotypically (Vitek, Hazelwood, MA and antibiogram profile) and genotypically (pulsed-field gel electrophoresis) evaluated. The aerobic and facultatively anaerobic gram-negative rods and cocci isolated from the first round oral rinse samples included: Acinetobacter, Neisseria, Chryseomonas, Flavimonas, Pseudomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, Flavobacterium and Weeksella species. The aerobic and facultatively anaerobic gram-negative rods and cocci isolation rate was high for irradiated individuals, and they were 64/25% and 100/80% for groups A/C and B/D, respectively. Recovery of aerobic and facultatively anaerobic gram-negative rods and cocci and Klebsiella pneumoniae subsp. pneumoniae in oral rinse samples were found to be significantly more prevalent in the irradiated subjects (groups A and B). Enterobacteriaceae were more frequently isolated from oral rinse samples of aged irradiated subjects (group B vs D, P<0.05), where the quantity of Citrobacter freundii (colony-forming units/ml oral rinse) was also significantly elevated. The isolation rate of aerobic and facultatively anaerobic gram-negative rods and cocci after hygienic care remained unchanged; 3 of 12 and 3 of 5 of the recalled subjects from groups A and B, respectively, harbored same aerobic and facultatively anaerobic gram-negative rods and cocci species. However, only two pairs of K. pneumoniae subsp. pneumoniae, sequentially isolated from same patients in group B, were found to be identical by pulsed-field gel electrophoresis. This may be due to reinfection of the microbes from the same source or permanent colonization. In conclusion, irradiation-induced xerostomia seems to favor frequent, repeated, transient intraoral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci.

Acinetobacter↗