N-formimidoyl-thienamycin: in vitro activity in bacteria with resistance to beta-lactam antibiotics or gentamicin

The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of N-formimidoyl-thienamycin were determined for 25 strains each of Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens and Pseudomonas aeruginosa which were resistant to gentamicin and/or acylureido penicillins or cefotaxime, cefoperazone or moxalactam, and for 38 strains of the group D streptococci. The drug was very active against the most frequently encountered gram-negative resistant causative organisms of nosocomial infections. The MIC ranged from 0.25-1 mg/l for multiresistant Enterobacteriaceae, and from 0.5-4 mg/l for multiresistant P. aeruginosa. The group D streptococci (enterococci) showed a low MIC (median: 0.75 mg/l); the median of the MBC was greater than 64 mg/l, however.     

Contribution of beta-lactamase production to the resistance of mycobacteria to beta-lactam antibiotics

Changes in motor function were assessed in male rats after injecting graded doses (100, 200, 400, and 800 mg/kg, IP) of ammonium chloride and ammonium acetate. The effects were correlated with the concentrations of ammonia and glucose in the brain and blood. Spontaneous motor activity and motor coordination were inhibited after injecting 100 and 200 mg/kg, whereas with 400 and 800 mg/kg the animals exhibited convulsive movements. A dose-dependent increase was found in the concentrations of ammonia and glucose in both blood and brain. These were restored, 25 min after treatment, to control levels in the blood and not in the brain. A correlation was found between the time courses of inhibitory motor events and a rise in brain ammonia levels. Convulsant action of ammonium salts was accompanied by a marked elevation of ammonia and glucose concentration in the brain. The findings suggest that detoxication of diffused ammonia is a rate-limiting process in the brain and that ammonia, at toxic concentrations, decreases glucose utilization in the brain, resulting in an inhibition of motor function. A very high concentration of ammonia in the brain, although inhibiting glucose utilization, produces clonic convulsions probably by activating directly the motor neurons.     

Identification of beta-lactam antibiotics in tissue samples containing unknown microbial inhibitors

Differential display is a technique which relies on the polymerase chain reaction to identify messenger RNA differences between related tissue samples. We have employed an improved differential display technique, called fluorescent differential display (FDD), to identify the genes that are differentially expressed in normal and malignant mammary tissues. From FDD fingerprints, we identified changes in intensity of approximately 3% (185 bands) of a total of 5, 837 bands. Each of these 185 bands represented a differentially expressed gene, and we focused our attention on the expression of the gene for caltractin, a member of the calcium-binding EF-hand protein superfamily. Northern blot analysis revealed that the level of mRNA for caltractin was higher in breast carcinoma than in corresponding normal tissue in all cases tested (5/5). Moreover, high-level expression of the gene for caltractin was also recognized in other malignant tumors, such as hepatocellular carcinoma (HCC), gastric cancer and leiomyosarcoma. The results of in situ hybridization showed strong stainings for caltractin mRNA in tumor-infiltrating lymphocytes (TIL), but not in malignant tumor cells. Our data suggests that the caltractin gene might be associated with the function of TIL.     

The resistance to antibiotics and chemotherapeutics in bacteria (author''s transl)

The effect of conducted training begun at an early age on the femoral head tilt was studied in male adolescent competitive sportsmen and physical education students. The control group consisted of army recruits. The femoral head tilt proved to be smaller in both sportsmen and physical education students when compared with the control subjects. The results suggest that sports activities started at an early age would not contribute to epiphysiolysis and through that to later development of osteoarthritis in the hip joint.     

Evaluation of delayed type hypersensitivity to beta-lactam antibiotics in mice

This study was designed to determine whether delayed type hypersensitivity could be evoked by protein-unconjugated beta-lactam antibiotics emulsified with Freund's complete adjuvant (FCA) in mice. The method providing the strongest sensitization was assessed by measuring footpad swelling induced by several biweekly intervals of subcutaneous injections of 0.8 mg/mouse cephalothin with FCA, followed by intradermal challenge with 1.0 mg/site cephalothin into the footpad in four different strains of female mice. A total of three and four injections, once every two weeks, in BDF1 and DBA/2 mice, respectively, produced the greatest potential for swelling. This swelling could be reinduced by the local passive transfer of cephalothin-primed splenocytes into the footpad of naive recipient mice. Moreover, the reaction was diminished by the addition of anti-Thy-1.2 monoclonal antibody with low-toxicity rabbit complement to cephalothin-primed splenocytes. Swelling in the footpad was therefore induced via the delayed type hypersensitivity reaction, indicating T-lymphocyte dependence. When the potential for beta-lactam antibiotics to elicit delayed type hypersensitivity was investigated in BDF1 mice, eight of the nine agents employed showed a 10-90% positive incidence. This result had a significant correlation (r = 0.76) with the data for skin reaction in guinea pigs, the method generally used for estimating allergenicity. These results suggest that this procedure may be a useful tool for evaluating delayed type hypersensitivity induction during the early development of novel antibiotics, since not only can sensitization be induced with protein-unconjugated antibiotic, but also because assessment can be made using a small amount of sample.     

Synergy and resistance to synergy between beta-lactam antibiotics and glycopeptides against glycopeptide-resistant strains of Enterococcus faecium

A synergistic effect between vancomycin or teicoplanin and different beta-lactam antibiotics was found for two strains of Enterococcus faecium, EFM4 and EFM11, expressing resistance to glycopeptides and belonging to the VANA class. The MICs of penicillin for these two strains were 16 and 128 micrograms/ml, respectively. By using a penicillin-binding protein (PBP) competition assay, it was shown that the affinities of PBPs for different beta-lactam antibiotics and the MICs of these antibiotics obtained in the presence of teicoplanin correlated with the substitution of two high-molecular-weight PBPs for the low-molecular-weight PBP5 as the essential target. Mutants of EFM4 and EFM11 which had lost the synergistic effect between beta-lactams and glycopeptides were selected on teicoplanin plus ceftriaxone at a frequency of 10(-5) and 10(-3), respectively. The mechanism of the loss of synergy was explored. For the mutants derived from EFM4, it was associated with a change in PBPs, while for the mutants derived from EFM11, it was related to some unknown change on the conjugative plasmid responsible for the glycopeptide resistance. These combined observations reflect the relationship which seems to exist between the new D-lactate peptidoglycan precursor, synthesized when the vancomycin resistance is expressed, and the affinity of the different PBPs for this precursor.     

Characterization of plasmids which mediate resistance to multiple antibiotics in gram-negative bacteria of nosocomial origin

BACKGROUND: The genetic and molecular mechanisms involved in antimicrobial resistance of 10 strains of gramnegative bacilli (1 Serratia marcescens; 2 Escherichia coli; 1 Proteus mirabilis; 4 Klebsiella pneumoniae; 1 Enterobacter cloacae y 1 Alcaligenes faecalis), isolated from adult patients with nosocomial pulmonary infection at the in-patient facilities of the University Hospital of Los Andes, Mérida, Venezuela, have been studied. METHODS: The antimicrobial susceptibility was determined by minimum inhibitory concentrations using the dilution method in agar. The study of extrachromosomal genes was carried out by conjugation, bacterial infection with the bacteriophage M13 and curing of plasmid by acridine orange. The plasmids were isolated by alkaline lysis and analysis of restriction endonuclease digestion was carried out separately using the enzymes EcoRI and HindIII. A DNA probe, derived from the region which encodes the TEM-1 beta-lactamase of the plasmid pBR322 was used for dot-blot hybridization tests. RESULTS: All of the gramnegative bacilli showed resistance to ampicillin, carbenicillin and cephalothin (> 128 micrograms/ml) and 3 strains also showed resistance to gentamicin (> 64 micrograms/ml). Genetic and molecular procedures showed the presence of conjugative plasmids of approximately 54 kb in all the 10 strains. The restriction patterns obtained by using EcoRI and HindIII indicated common DNA fragments in most of the plasmids studied. The dot-blot hybridization tests confirmed homology between the plasmids and the DNA probe used (TEM-1 beta-lactamase). CONCLUSIONS: In this study, the gramnegative bacteria of nosocomial origin harbored self-transferable plasmids of approximately 54 kb, which mediate resistance to gentamicin and encode a beta-lactamase of the TEM group.     

Resistance to beta-lactam antibiotics and aminoglycosides in gram negative bacteria. 1. Molecular and genetic characterization of R-factors (author's transl)

With frequent use of aminoglycoside antimicrobials and beta-lactam antibiotics in hospitals in the last few years, the number of bacterial strains resistant to these chemotherapeutics increased. Lately, strains of E. coli, Klebsiella, Enterobacter, Serratia, Proteus and Pseudomonas resistant to many antimicrobials (ampicillin, carbenicillin, cephalothin, chloramphenicol, gentamycin, tobramycin, sisomycin, neomycin, paromomycin, kanamycin, streptomycin, spectinomycin, tetracycline, sulphonamides) were isolated from patients of the university hospital in Zuerich. The resistant phenotype of two representative strains (Klebsiella pneumoniae 1 and Serratia marcescens 2) could be transferred by mixed cultivation to E. coli K-12. Multiple resistance of strain 1, and addition, could be transferred to Salmonella typhimurium, Serratia marcescens, Providencia, Proteus mirabilis and Klebsiella pneumoniae in varying frequencies. Transfer to Pseudomonas aeruginosa, however, could not be achieved. Spontaneous instability of resistance was observed in 0.15% of the cells of an overnight brothe culture and in 90% of the cells of a three months old culture. Conjugation, instability and the response to the sex phages MS-2 and If-1 suggested that resistance was mediated by a monomolecular R-factor, belonging to the fi+-type. This suggestion was confirmed by molecular characterization of the resistance plasmids. After transfer of the R-factors of K. pneumoniae 1 (R-FK 1) and Serratia marcescens 2 (R-FK2) into E. coli K-12, plasmid DNA was labelled with (methyl-3H) thymidine, and isolated by isopycnic centrifugation in cesiumchlorid-ethidium-bromide. Analysis of plasmid DNA then was carried out by sedimentation in a 5-20% neutral sucrose gradient together with reference plasmids of known molecular weights and sedimentation constants. The analysis revealed that R-FK1 had a molecular weight of 54 X 10(6) and R-FK2 of 50 X 10(6) daltons. The values were confirmed by contour length measurements of open circular forms with an electron microscope. A comparison of the sedimentation profile of labelled plasmid DNA from strain 1 and 14C-labelled DNA of E. coli K-12 (R-FK1) showed that the wild-type strain contained, besides the large resistance plasmid, at least two smaller "cryptic" plasmids. These smaller plasmid molecules were also found in antibiotic susceptible variants of strain 1, which did not contain the 54 X 10(6) dalton plasmid molecule, responsible for the resistant phenotype. The number of copies of R-FK1 in E. coli K-12 was determined to be 2, indicating stringent control of replication. It is discussed that the growing number of isolations of strains of Escherichia, Klebsiella, Serratia, Proteus, Providencia and Pseudomonas, exhibiting the same resistance phenotype, results from the spread of the R-factor described above among the hospital bacterial flora.     

Type of punishment as a determinant of resistance to deviation.

Compared the effectiveness of an aversive stimulus, withholding of resources, withdrawal of love, and reasoning, when used alone and when combined with praise, in a standard laboratory punishment paradigm using 120 1st- and 2nd-grade boys and girls as Ss. Resistance to deviation and stability of resistance to deviation were used as the measures of punishment effectiveness. Sex of child, use of praise, and type of punisher were combined in a 2 * 2 * 5 factorial design, with a female as the punitive agent. An aversive stimulus appeared to produce more suppression of deviant behavior, but the effect was not significant for all response measures. The stability of the deviant response pattern varied for each punisher, but the most stable response pattern resulted from the use of an aversive stimulus. Neither use of praise nor sex of child significantly influenced punisher effectiveness. Results are discussed within the framework of anxiety arousal and information content of the punishers, and the practice of grouping various punishers under the categories of sensitization and induction measures is considered. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amino acid variation in the GyrA subunit of bacteria potentially associated with natural resistance to fluoroquinolone antibiotics

In studies of genetic diversity in natural microbial populations, we have analyzed nucleotide sequences in the quinolone resistance-determining region of the bacterial gyrA gene in ciprofloxacin-resistant and nonselected soil bacteria obtained from the environment. It is apparent that this sequence is highly variable, and resistance to fluoroquinolone antibiotics occurring in environmental populations of bacteria is due at least in part to natural sequence variation in this domain. We suggest that the development of new antimicrobial agents, including completely synthetic antimicrobials such as the fluoroquinolones, should incorporate the analysis of resistance mechanisms among microbes in natural environments; these studies could predict potential mechanisms of resistance to be encountered in subsequent clinical use of the agents and would guide chemical modification designed to evade resistance development.     

Semisynthetic beta-lactam antibiotics. 8 Structure-activity relationships of alpha-sulfocephalosporins

Synthesis and in vitro activity of a number of cephalosporins having alpha-sulfoacyl- or other acyl groups, e.g., alpha-carboxyacyl- and alpha-sulfoaminoacyl- at the 7-position and bearing a variety of heterocyclic thioether or pyridinium moieties at the 3-position are described.     

Resistance of respiratory and enteral bacteria to antibiotics

The relationship of the serum antibody titer and avidity to the putative periodontal pathogens Actinobacillus actinomycetemcomitans (Aa) strains Y4 and 29523 and Porphyromonas gingivalis (Pg) strain 381 were examined in relation to clinical parameters in 26 gingivitis and 28 periodontitis patients. The relationship of antibody titer and avidity to infection with the homologous organism was also examined in a subset of 30 patients. Antibody titer was determined by an enzyme-linked immunosorbent assay, and antibody avidity was assessed using a dissociation assay. Considering all patients, there was a significant negative correlation between mean probing depth and antibody titer (r=-0.28) and avidity (r=-0.28) to Aa Y4. There was a significant positive correlation of probing depth and antibody titer (r=0.46) and avidity (r=0.46) to Pg. The correlation of antibody titer and avidity to Aa and infection with Aa Y4 (r=-0.32, r=-0.21) and Aa 29523 (r=-0.35, r=-0.39) was negative, while the correlations of titer and avidity to Pg and presence of the organisms was strongly positive (r=0.40, r=0.35). These data indicate that the relationship of serum antibody titer and avidity to clinical parameters of periodontal disease severity and the level of infection with the homologous organism appears to be different for Aa and Pg. The development of an antibody response to Aa appears to protect the individual from infection with the organism. In contrast, the development of an antibody response to Pg was not able to eliminate the infection. These results should be considered when developing a diagnostic strategy for periodontal disease utilizing the humoral immune response.     

Joint tolerance to beta-lactam and fluoroquinolone antibiotics in Escherichia coli results from overexpression of hipA

The basis of joint tolerance to beta-lactam and fluoroquinolone antibiotics in Escherichia coli mediated by hipA was examined. An antibiotic tolerance phenotype was produced by overexpression of hipA under conditions that did not affect the growth rate of the organism. Overexpressing hipA probably decreases the period in which bacteria are susceptible to the antibiotics by temporarily affecting some aspect of chromosome replication or cell division.     

Rapid increase of pneumococcal resistance to beta-lactam and other antibiotics in isolates from the respiratory tract (Nagasaki, Japan: 1975-1994)

The susceptibility of 101 pneumococcal isolates from the respiratory tract during 1991-1994 was examined and compared with the susceptibility of isolates over the period of 1975-1990. A rapid increase of resistance was seen not only to penicillin but also other antimicrobial agents. During 1991-1994, 38% of all the isolates were resistant to penicillin. The rates of resistance during this period were 16-23% for three newer cephalosporins, 18% for imipenem, 69% for tetracycline, 31% for erythromycin, 20% for chloramphenicol and 9% for clindamycin. The use of antibiotics within one month prior to pneumococcal isolation was correlated with penicillin resistance (P < 0.05). Serotyping of the isolates by antiserum revealed differences in predominant types between penicillin-resistant (19F, 23F,4) and -susceptible isolates (15, 4, 11A). Our data suggests that anti-pneumococcal antibiotics should be carefully chosen on the basis of susceptibility tests.     

The secretory intestinal transport of some beta-lactam antibiotics and anionic compounds: a mechanism contributing to poor oral absorption

PURPOSE: To measure the effect of silicon diode detectors used for in vivo dosimetry on beam characteristics and determine whether this effect is clinically significant. METHODS AND MATERIALS: Commercially available photon and electron diodes were placed on the central axis of photon and electron beams. The beam characteristics were measured for 6- and 10-MV photon and 6-20-MeV electron energies from a Varian Clinac 1800 medical linear accelerator. Water was used for the medium, and measurements were made for various clinically common field sizes and depths. RESULTS: Beam attenuations along the central axis were 10 and 7.5% for 6- and 10-MV photons, respectively. Electron beam dose reductions were between 13 and 25% for 20-6-MeV electrons. Photon beam flatness varied up to 7% at different depths, but the symmetry was not affected much. Electron beam flatness and symmetry were significantly changed to as much as 18 and 6%, respectively. CONCLUSION: Use of diode detectors on central axis of photon and electron beams for in vivo dosimetry causes significant attenuation and alteration of the beam characteristics. The percentage of the volume affected is significant (e.g., 23% of the volume in a 4 x 4 field gets 10% less dose for a 6-MV photon beam), especially if these diodes are used for in vivo dosimetry on the central axis every day for every treatment, as is done in some clinics. Other beam parameters such as penumbra and skin dose are also affected. It is therefore recommended that the diodes be used only as needed.     

Identification of the Par2 (Pulmonary adenoma resistance) locus on mouse chromosome 18, a major genetic determinant for lung carcinogen resistance in BALB/cByJ mice

The A/J mouse strain is 14 times more susceptible to urethane-induction of lung carcinogenesis than the BALB/cByJ strain (BALB). The relative resistance of BALB is dominant over the high sensitivity of A/J, since (BALBxA/J)F1 mice are phenotypically similar to the parental BALB mice. BALB mice must thus possess modifier genes suppressing phenotypic expression of the Pas (Pulmonary adenoma susceptibility) genes, which are known to be dominant genetic determinants for lung carcinogenesis in A/J mice. In order to genetically dissect the dominant resistance of the BALB mouse, we performed a linkage analysis to chromosomally map modifier genes by using 130 (A/JxBALB)F1xA/J backcross mice. Each backcross mouse was injected i.p. with urethane (1 mg/g bw) at 6 weeks of age and lung tumors were enumerated after 120 days. When the backcross mice were genotyped at multiple simple sequence repeat marker loci distributed on all the chromosomes, a significant linkage between the presence of a BALB allele and resistance to lung tumor induction was found on distal chromosome 18 (maximum LOD = 12.2). Thus, distal chromosome 18 of the BALB mouse contains a modifier gene for lung carcinogenesis: The locus, designated Par2 (Pulmonary adenoma resistance), accounted for 38% of the phenotypic variance in the backcross population, indicating a major role in protection against lung tumor development.