Showing papers on "Penicillin published in 1975"
TL;DR: Evidence is presented that penicillin bulge formation is due to the inhibition of proteins 2 and 3 in the absence of inhibition of protein 1.
Abstract: The varied effects of beta-lactam antibiotics on cell division, cell elongation, and cell shape in E. coli are shown to be due to the presence of three essential penicillin binding proteins with distinct roles in these three processes. (A) Cell shape: beta-Lactams that specifically result in the production of ovoid cells bind to penicillin binding protein 2 (molecular weight 66,000). A mutant has been isolated that fails to bind beta-lactams to protein 2, and that grows as round cells. (B) Cell division: beta-Lactams that specifically inhibit cell division bind preferentially to penicillin binding protein 3 (molecular weight 60,000). A temperature-sensitive cell division mutant has been shown to have a thermolabile protein 3. (C) Cell elongation: One beta-lactam that preferentially inhibits cell elongation and causes cell lysis binds preferentially to binding protein 1 (molecular weight 91,000). Evidence is presented that penicillin bulge formation is due to the inhibition of proteins 2 and 3 in the absence of inhibition of protein 1.
973 citations
01 Jan 1975
TL;DR: The modern antibiotic era can be said to have opened on February 12, 1941, with the first clinical trial of penicillin, shortly followed by the introduction of one after another of the major antibiotic substances which remain the mainstay of clinical therapy of infectuous diseases to this date.
Abstract: The modern antibiotic era can be said to have opened on February 12, 1941, with the first clinical trial of penicillin. Within a couple of years man had at last, after eons of adventitious searching, a truly effective and safe agent for the treatment of many systemic bacterial infections. This was shortly followed by the introduction of one after another of the major antibiotic substances which remain the mainstay of clinical therapy of infectuous diseases to this date. Intensive screening of fermentation liquors derived from various microbes, principally fungi and streptomycetes, has resulted in literature descriptions of more than 2,000 Individual antibiotics to date, and It has been estimated that more than 20,000 analogs of 6-amino- penicillante acid alone have been made by chemists working tn close collaboration with biochemists and microbiologists. Several of these substances are currently on the market.
284 citations
TL;DR: It is suggested that inhibition of cell wall synthesis by any means triggers bacterial autolytic enzymes by destabilizing the endogenous complex of an autolysin inhibitor (lipoteichoic acid) and Autolytic enzyme.
Abstract: During penicillin treatment of an autolysin defective mutant pneumococcus we have observed three novel phenomena: (i) Growth of the mutant cultures is inhibited by the same concentrations of penicillin that induce lysis in the wild type. (ii) Mutant bacteria treated with the minimum growth inhibitory concentration of penicillin will lyse upon the addition of wild-type autolysin to the growth medium. Chloramphenicol and other inhibitors of protein synthesis protect the cells against lysis by exogenous enzyme. Sensitivity of the cells to exogenous autolysin requires treatment with penicillin or other inhibitors of cell wall synthesis (e.g., D-cycloserine or fosfonomycin) since exogenous autolysin alone has no effect on bacterial growth. (iii) Treatment with penicillin (or other inhibitors of cell wall synthesis) causes the escape into the medium of a choline-containing macromolecule that has properties suggesting that it contains pneumococcal lipoteichoic acid (Forssman antigen). Each one of these three phenomena (growth inhibition, sensitization to exogenous autolysin, and leakage of lipoteichoic acid) shows the same dose response as that of the penicillin-induced lysis of wild-type pneumococci. On the basis of these findings we propose a new hypothesis for the mechanism of penicillin-induced lysis of bacteria. It is suggested that inhibition of cell wall synthesis by any means triggers bacterial autolytic enzymes by destabilizing the endogenous complex of an autolysin inhibitor (lipoteichoic acid) and autolytic enzyme. Escape of lipoteichoic acid-like material to the growth medium is a consequence of this labilization. Chloramphenicol protects bacteria against penicillin-induced lysis by interfering with the activity of the autolytic enzyme, rather than by depleting the concentration of the enzyme at the cell surface.
215 citations
TL;DR: Low-level resistance to tetracycline or chloramphenicol was due to similar additive effects between mutations at the nonspecific ery and penB loci and a locus specific for resistance to each drug (tet and chl, respectively).
Abstract: The genetics of low-level resistance to penicillin and other antibiotics in a clinical isolate and a multistep laboratory mutant of Neisseria gonorrhoea was studied by transformation. Mutations at three loci affected sensitivity to penicillin. Mutation at penA resulted in an eightfold increase in resistance to penicillin without affecting response to other antimicrobial agents. Mutation at ery resulted in a two- to fourfold increase in resistance to penicillin and similar increases in resistance to many other antibiotics, dyes, and detergents. Mutation at penB resulted in a fourfold increase in resistance to penicillin and tetracycline, the phenotypic expression of which was dependent on the presence of mutation at ery. The cumulative effect of mutations at penA, ery, and penB was an approximate 128-fold increase in penicillin resistance, to a minimum inhibitory concentration of 1.0 mug/ml. Low-level resistance to tetracycline or chloramphenicol was due to similar additive effects between mutations at the nonspecific ery and penB loci and a locus specific for resistance to each drug (tet and chl, respectively). No evidence was found for penicillinases or other drug-inactivating enzymes.
167 citations
TL;DR: This model appears to offer an effective method for evaluation of antimicrobial treatment of staphylococcal endocarditis and therapy with rifampin led to the emergence of resistant organisms.
Abstract: The rate at which various antimicrobial agents eradicated Staphylococcus aureus from cardiac vegetations in a rabbit model of endocarditis was studied. The rate at which various drugs and combinations killed high titers of bacteria in broth correlated with the relative effectiveness of the agents in vivo. Gentamicin plus penicillin proved to be synergistic in vitro and more effective in eradicating bacteria from cardiac vegetations in vivo than was penicillin alone. Vancomycin killed bacteria at a rate similar to that for the combination of penicillin and gentamicin, and the rate for cefazolin was similar to that for penicillin alone. Clindamycin was less effective in vivo and in vitro than penicillin. Therapy with rifampin led to the emergence of resistant organisms, and, when penicillin, this drug was less effective in vitro and in vivo than was penicillin alone. This model appears to offer an effective method for evaluation of antimicrobial treatment of staphylococcal endocarditis.
152 citations
TL;DR: A sensitive iodometric test will enable the hospital laboratory to obtain presumptive evidence of ampicillin resistance on the same day that H. influenzae is isolated.
Abstract: Strains of Haemophilus influenzae type b sporadically isolated from clinical specimens are ampicillin resistant due to production of a beta-lactamase. This enzyme which inactivates ampicillin and penicillin G is not produced by ampicillin-susceptible strains. Various characteristics of beta-lactamase production and ampicillin resistance of three H. influenzae type b isolates were investigated. A sensitive iodometric test was employed to detect beta-lactamase; positive results were obtained in 5 min with 10(9) bacteria taken from cultures on a nutritionally adequate agar medium. This simple chemical test will enable the hospital laboratory to obtain presumptive evidence of ampicillin resistance on the same day that H. influenzae is isolated.
118 citations
TL;DR: In this paper, semi-synthetic derivatives of penicillin and cephalosporin have been developed in which the conventional phenyl or heteroaromatic group has been replaced by a ferrocene moiety, and the metal atom is in close proximity to the β-lactam ring of the antibiotic.
118 citations
TL;DR: It is suggested that the hepatitis found in these 17 cases of early syphilis was produced by treponemes.
108 citations
TL;DR: It is indicated that penicillin G is the preferred agent for pulmonary infections involving anaerobic bacteria and clindamycin is a suitable alternative for patients in whom penicillus G is contraindicated.
Abstract: Aspiration pneumonitis and lung abscess generally involve anaerobic bacteria, which normally colonize the upper respiratory passages. The therapeutic response of these infections to parenteral penicillin G (49 patients) and parenteral clindamycin (35 patients) was compared to determine relative efficacy. No difference was discerned between these two agents in terms of time required for defervescence, roentgenographic clearing, and ultimate outcome. Seven patients with infections includingBacteroides fragiliswere treated with penicillin G, and all responded well. These data indicate that penicillin G is the preferred agent for pulmonary infections involving anaerobic bacteria. Clindamycin is a suitable alternative for patients in whom penicillin G is contraindicated. (JAMA234:935-937, 1975)
103 citations
TL;DR: Bacampicillin is a new orally well-absorbed penicillin, highly active in vivo due to rapid transformation into ampicillin, which is stable in vitro at gastric pH and hydrolyzed slowly to amicillin at neutral pH but very rapidly in the presence of biological fluids, e.g., tissue homogenates or serum.
Abstract: Bacampicillin (proposed international nonproprietary name), 1′-ethoxycarbonyloxyethyl 6-(d-α-aminophenylacetamido)penicillanate, is a new orally well-absorbed penicillin, highly active in vivo due to rapid transformation into ampicillin. The compound is stable in vitro at gastric pH and hydrolyzed slowly to ampicillin at neutral pH but very rapidly in the presence of biological fluids, e.g., tissue homogenates or serum. In vivo the transformation into ampicillin is so rapid that no unchanged compound could be detected in the blood after oral administration of bacampicillin to rats, dogs, and humans. On oral administration to mice, rats, and dogs, bacampicillin was found to be better absorbed than ampicillin, giving higher and earlier peak blood levels of ampicillin. The bioavailability of bacampicillin in rats and dogs was three to four times higher than that of an equimolar amount of ampicillin. On oral administration to rats, bacampicillin was found to give higher levels of ampicillin in organs such as the kidney, liver, and spleen than ampicillin itself. In “tissue cages” in rats, higher transudate levels of antibiotic were found after oral administration of bacampicillin than after ampicillin. On oral treatment of experimentally infected mice, bacampicillin was found to be more active than ampicillin.
101 citations
TL;DR: Bactericidal concentrations of cefoxitin and cephalothin were determined for 51 selected strains by the broth dilution technique, and the activities of these drugs were compared with those of two other drugs known to be very active against anaerobes.
Abstract: The agar dilution technique was used for determination of the bacteriostatic activity of carbenicillin, penicillin G, cefazolin, cephaloridine, cefoxitin, and cephalothin against a variety of anaerobic bacteria. Carbenicillin showed a high level of activity at a concentration of 100 /zg/ml. Cefoxitin, a/3-lactamase-resistant drug, was highly active against B. fragilis and most other anaerobes at a concentration of < 32 /g/ml; the exceptions were one strain of Bacteroides species and 13 of 28 strains of Clostridium species. The other cephalosporins were less active against B. fragilis but exhibited good activity against most of the other strains tested. Bactericidal concentrations of cefoxitin and cephalothin were determined for 51 selected strains by the broth dilution technique, and the activities of these drugs were compared with those of two other drugs (clindamycin and metronidazole) known to be very active against anaerobes. Metronidazole was the most consistently bactericidal of the four drugs tested for this activity.
TL;DR: Erythromycin uniformly failed to protect animals from bacterial endocarditis but showed greater prophylactic efficacy when a low inoculum of streptococci was used.
Abstract: The ability of antibiotics to prevent Streptococcus sanguis endocarditis was tested in rabbits. Only vancomycin or a combination of penicillin G plus streptomycin always prevented infection when administered as a single dose. A loading dose of 30 mg/kg of phenoxymethyl penicillin (penicillin V) followed by additional 7.5 mg/kg doses for 48 h proved to be the only successful prophylactic program that could be given orally to man. Cefazolin alone or with streptomycin in multiple doses was also an effective alternative to penicillin or penicillin derivatives. Erythromycin uniformly failed to protect animals from bacterial endocarditis but showed greater prophylactic efficacy when a low inoculum of streptococci was used.
TL;DR: All group B streptococci were sensitive in vitro to comparable levels of penicillin G, ampicillin, and cephalothin and were highly resistant to kanamycin.
Abstract: Eighty-six percent of 707 p-hemolytic streptococci isolated in a general hospital and excluded by presumptive tests from groups A and D were identified serologically as group B. More than 70% of the group B isolates were from urine cultures, the female genital tract, or newborn infants. Types III and II were the most common group B serotypes from most sources. However, types Ia, Ib, and Ic were more commonly isolated from the respiratory tract than from other sites, and type III was responsible for most serious neonatal infections. All group B streptococci were sensitive in vitro to comparable levels of penicillin G, ampicillin, and cephalothin and were highly resistant to kanamycin. Seventy-two percent were resistant to tetracycline but only 1%-2% to erythromycin, clindamycin, and chloramphenicol. Despite consistent sensitivity to penicillin G, the minimal inhibitory concentrations were significantly higher for group B than for group A streptococci.
TL;DR: Subinhibitory concentrations of penicillin do not kill staphylococci; they seem to inhibit lysis of cross walls, preventing the separation of otherwise divided cells.
Abstract: A strain of Staphylococcus aureus was planted on filter membranes placed on Trypticase soy agar (BBL). After incubation, the membranes with growing staphylococci were transferred to Trypticase soy agar containing a subinhibitory concentration of penicillin (one-third minimal inhibitory concentration) and again incubated. The membranes were then returned to drug-free agar and incubated once more. Counts of the colony-forming units and electron microscopy were carried out at several time intervals. When grown on agar containing penicillin, the staphylococci formed what appeared to be abnormally large cells with multiple and unusually thick septa. Examination of a number of sections showed that these large cells were in reality clusters of staphylococci that had divided but failed to separate. When these large cells were subsequently grown on drug-free agar, smaller cells and normal staphylococci emerged. Subinhibitory concentrations of penicillin do not kill staphylococci; they seem to inhibit lysis of cross walls, preventing the separation of otherwise divided cells. Images
TL;DR: The relative rate of in vitro bacterial killing by various antibiotics and combinations was predictive of the efficacy of these drugs in eradicating enterococci from cardiac vegetation in experimental endocarditis.
Abstract: The successful therapy of enterococcal endocarditis requires prolonged administration of synergistic antibiotic combinations. Controversy has arisen regarding optimal therapy (i) when the organism possesses high-level streptomycin resistance, and (ii) when the patient is allergic to penicillin. This study examines these questions in vitro and in a rabbit model of enterococcal endocarditis. The combination of penicillin with either streptomycin or gentamicin increased the rate of bacterial killing in vitro and in vivo when compared with penicillin alone ( P P 150,000 μg/ml). The combination of vancomycin and streptomycin was more rapidly bactericidal than vancomycin alone in vitro and in the animal model against the streptomycin-susceptible strain ( P
TL;DR: A 60-year-old man with symptomatic neurosyphilis was treated with penicillin G procaine in the dosages recommended by the Public Health Service, and a less than spirocheticidal level of penicillus G was found in the cerebrospinal fluid.
Abstract: A 60-year-old man with symptomatic neurosyphilis was treated with penicillin G procaine in the dosages recommended by the Public Health Service, and a less than spirocheticidal level of penicillin G was found in the cerebrospinal fluid. (JAMA232:270-271, 1975)
TL;DR: These studies showed a unique, time-related bactericidal action of metronidazole as compared with the other three antimicrobial agents.
Abstract: The comparative bactericidal activity of penicillin G, carbenicillin, clindamycin, and metronidazole against eight susceptible strains of Bacteroides fragilis and four strains of Clostridium perfringens was determined by performing colony counts anaerobically of cultures incubated in brucella broth. With the B. fragilis strains, there was a lag phase of growth of approximately 8 h, during which time metronidazole did not reduce the colony counts. However, within 4 h of the onset of exponential growth, metronidazole caused an abrupt decrease in counts to less than 100 colonies per ml in all strains tested. Moreover, in two strains in which the bactericidal rate was followed hourly, a 3- to 6-log decrease occurred over 1 h or less. In contrast, penicillin G and carbenicillin caused a gradual decline in colony counts from the start of approximately 1 log for each 8-h interval and were bactericidal for all strains tested. Clindamycin demonstrated the slowest bactericidal activity and for 25% of the strains was only bacteriostatic. With the C. perfringens strains, after a lag phase of 4 h, an abrupt decrease in colony counts also occurred with metronidazole, whereas penicillin and clindamycin again demonstrated more gradual killing effects. These studies showed a unique, time-related bactericidal action of metronidazole as compared with the other three antimicrobial agents.
Journal Article•
TL;DR: Until the importance of these resistant strains can be ascertained, hospital laboratories are urged to test clinical isolates of H. influenzae type b for susceptibility to ampicillin, and physicians must reconsider the treatment of patients with severe disease due to this organism.
Abstract: Strains of Hemophilus influenzae type b highly resistant in vitro to ampicillin have been reported from several widely separated locations in the United States since December 1973.1-4 These strains were isolated from children with meningitis and the clinical course corroborated the in vitro susceptibility results. Until the importance of these resistant strains can be ascertained, hospital laboratories are urged to test clinical isolates of H. influenzae type b for susceptibility to ampicillin, and physicians must reconsider the treatment of patients with severe disease due to this organism. Ampicillin disk sensitivity tests of H. influenzae isolates are satisfactory for screening purposes but strains that are of equivocal sensitivity or are resistant should also be tested by a quantitative method, such as the tube dilution or agar diffusion techniques. The appropriate methods for antibiotic susceptibility tests were reviewed recently in a weekly report of the Center for Disease control.5 If facilities for these tests are unavailable or if confirmation of test results is desired, the bacterial strains may be forwarded, via the State Public Health Laboratory, to the Center for Disease Control. In areas where resistant strains have been recognized, initial therapy of children with documented or suspected severe infection due to H. infiuenzae type b, such as sepsis, meningitis, epiglottitis, arthritis, or cellulitis, should include an antimicrobial agent of known efficacy. Initial administration of penicillin G or ampicillin and chloramphenicol would seem appropriate at this time. The antimicrobial regimen should be reevaluated when the results of the bacterial isolation studies and antimicrobial sensitivity tests are available.
TL;DR: D-Alanine carboxypeptidase from Bacillus stearothermophilus is a membrane-bound enzyme which is inhibited by covalent interaction with penicillin G and is identified as phenylacetylglycine by chromatographic techniques, infrared spectroscopy, and mass spectrometry.
Abstract: D-Alanine carboxypeptidase from Bacillus stearothermophilus is a membrane-bound enzyme which is inhibited by covalent interaction with penicillin G. The penicilloyl enzyme spontaneously reactivates and simultaneously releases a penicillin G degradation product; 0.2 mumol of the latter was isolated after incubation of 4.2 mumol of [8-14C]penicillin G with 10 g of membrane protein. It was identified as phenylacetylglycine by chromatographic techniques, infrared spectroscopy, and mass spectrometry. A mechanism for the degradation is proposed in which the remaining part of penicillin G would be released as 5,5-dimethyl-delta2-thiazoline-4-carboxylic acid. The implications of this finding are discussed.
TL;DR: The synthesis of peptidoglycan by an autolysin-deficient beta-lactamase-negative mutant of Bacillus licheniformis was studied in vivo in the absence of protein synthesis to reveal the presence of excess of alanine resulting from the continued inhibition of D-alanine carboxypeptidase.
Abstract: The synthesis of peptidoglycan by an autolysin-deficient beta-lactamase-negative mutant of Bacillus licheniformis was studied in vivo in the absence of protein synthesis. Benzylpenicillin and cephaloridine inhibited the formation of cross-bridges between newly synthesized peptidoglycan and the pre-existing cell wall. This inhibition, detected by measurement of the incorporation of N-acetyl[14C]glucosamine into the glycan fraction of the cell wall, was reversed by treatment with beta-lactamase and washing. Inhibition of D-alanine carboxypeptidase by benzylpenicillin was not reversed under similar conditions. Cells in which the initial penicillin inhibition of transpeptidation had been reversed showed an increased sensitivity to a subsequent addition of the antibiotic. Chemical analysis of peptidoglycan synthesized after reversal of penicillin inhibition revealed the presence of excess of alanine resulting from the continued inhibition of D-alanine carboxypeptidase. When the cell walls were digested to yield muropeptides so that the degree of cross-linking could be measured, the product after reversal of penicillin inhibition contained fewer cross-links than did the control preparation. Cultures treated with benzylpenicillin and cephaloridine continued to synthesize uncross-linked soluble peptidoglycan, which accumulated in the medium. This soluble material was all newly synthesized peptidoglycan and did not result from autolysis of the bacteria. The average chain lengths of the glycan synthesized in vivo and released as soluble peptidoglycan in the presence of both benzylpenicillin and cephaloridine were similar to those found previously in this organism.
TL;DR: Results indicate that B. fragilis can protect F. necrophorum from penicillin in vivo and in vitro, and suggest that the extent of protection afforded by a strain of B. Fragilis was related to its level of resistance toPenicillin.
Abstract: A mixed infection of Bacteroides fragilis and Fusobacterium necrophorum was resistant to treatment with penicillin even though a pure F. necrophorum infection could be successfully treated with penicillin. Since B. fragilis alone did not produce infection, these results indicate that B. fragilis can protect F. necrophorum from penicillin in vivo. The extent of protection afforded by a strain of B. fragilis was related to its level of resistance to penicillin. Only a few cells of B. fragilis were required in the initial bacterial injection. Moreover, protection was demonstrated when B. fragilis cells were injected as late as 24 h after the F. necrophorum cells. Protection of F. necrophorum from penicillin by B. fragilis was also demonstrated in vitro.
TL;DR: Application of this method to patients with various degrees of renal impairment by either constant-rate infusion or intermittent infusion gave serum penicillin G concentrations within the desired range in all but 1 of 15 instances, and practical guidelines for "comparably massive" peniillin G therapy are suggested.
Abstract: Impairment of penicillin G excretion in renal failure may result in life-threatening, dose-related toxicity. We report a method for achieving a desired mean serum penicillin G concentration in patients with renal failure, with minimal risk of both undertreatment and drug toxicity. The method is based on the linear relation between the total plasma clearance of penicillin G (Cpen) and the endogenous creatinine clearance. The daily maintenance dose of penicillin G (units) is defined by the product, Cpen (ml/min) times desired mean serum penicillin G concentration (mug/ml) times 2300. Application of this method to patients with various degrees of renal impairment by either constant-rate infusion or intermittent infusion gave serum penicillin G concentrations within the desired range in all but 1 of 15 instances. On the basis of these observations, practical guidelines for "comparably massive" penicillin G therapy are suggested.
TL;DR: The combination of penicillin with either an aminoglycoside antibotic or erythromycin is more effective than a single drug in the therapy of infection caused by the Smith strain of S. aureus.
Abstract: A penicillin-sensitive strain of Staphylococcus aureus was used to evaluate the efficacy of six antibiotic combinations in the therapy of an experimental infection in mice. One hour after intraperitoneal infection, animals were treated with penicillin G, erythromycin, clindamycin, gentamicin, or tobramycin singly or in various combinations of two of these drugs. Penicillin in combination with tobramycin, gentamicin, or erythromycin significantly reduced mortality as compared with therapy with a single drug. Survival of animals treated with the combinations of penicillin and clindamycin, clindamycin and gentamicin, and erythromycin and gentamicin was not different from that seen with single-drug therapy. Penicillin plus either gentamicin or erythromycin significantly reduced the number of culturable organisms from livers and spleens of infected animals when compared with penicillin, gentamicin, or erythromycin alone. In vitro studies correlated with some aspects of in vivo results but conflicted with others. Thus the combination of penicillin with either an aminoglycoside antibiotic or erythromycin is more effective than a single drug in the therapy of infection caused by the Smith strain of S. aureus.
TL;DR: 3H was incorporated into solvent-soluble penicillin from isopenicillin N and 6-aminopenicillanic acid 3H-labelled in the 2beta-methyl group when the labelled compounds were incubated with a crude extract of Penicillum chrysogenum.
Abstract: 1. 3H was incorporated into solvent-soluble penicillin from isopenicillin N and 6-aminopenicillanic acid 3H-labelled in the 2beta-methyl group when the labelled compounds were incubated with a crude extract of Penicillum chrysogenum. 2. With a soluble protein fraction of the extract incorporation from isopenicillin N occurred on addition of phenyl-acetyl-CoA. 3. Labelled benzylpenicillin was isolated after incubation of the crude extract with phenylacetyl-CoA and isopenicillin and the addition of unlabelled benzylpenicillin as a carrier. 4. No incorporation of 3H into solvent-soluble penicillin was detected on incubation of these extracts with penicillin N.
TL;DR: It is shown that most practise prophlaxis of bacterial endocarditis, but that few follow currently recommended regimens, and practices are contrasted with current medical recommendations and discussed with reference to fresh experimental evidence on prevention of bacterialendocarditis.
Abstract: A survey of Oxfordshire dentists showed that most practise prophlaxis of bacterial endocarditis, but that few follow currently recommended regimens. for example, prophylactic antibiotics are started one or more days before the procedure by 72 per cent of dentists, and two or more days before by 25 per cent. Eight-seven per cent administer antibiotics for a total of four or more days. Penicillin is most often given, but tetracyline remains the commonest second choice. Only 12 per cent use intramuscular drugs as first choice, and procaine penicillin is seldom used. These practices are contrasted with current medical recommendations and discussed with reference to fresh experimental evidence on prevention of bacterial endocarditis.
TL;DR: When penicillin was applied to the neuromuscular junctions of the superficial flexor muscles of crayfish, the excitatory junctional potential (EJP) amplitudes were increased, suggesting that augmentation of EJPs may have been due to alterations at the presynaptic nerve terminals.
TL;DR: Cefamandole, a new cephalosporin derivative, was found to have a broad spectrum of activity against a cross-section of both gram-positive and gram-negative bacteria isolated from clinical material, and Gram-positive cocci, except for Streptococcus faecalis, were very susceptible.
Abstract: Cefamandole, a new cephalosporin derivative, was found to have a broad spectrum of activity against a cross-section of both gram-positive and gram-negative bacteria isolated from clinical material. Gram-positive cocci, except for Streptococcus faecalis, were very susceptible. Penicillin G-resistant Staphylococcus aureus also was susceptible to cefamandole. Minimal bactericidal concentrations for gram-positive cocci approximated the minimal inhibitory concentrations. Strains of Haemophilus influenzae were very susceptible to the drug. Most strains of Escherichia coli, Klebsiella sp., and Proteus sp. were inhibited by low concentrations. Increasing resistance occurred with larger inocula. Strains of Pseudomonas sp. were resistant to cefamandole.
TL;DR: Two experiments were performed to investigate the effect of feed additive antibiotics on Clostridium perfringens and Enterobacteriaceae in the ceca of chickens infected with Eimeria tenella and dietary administration of antibiotics did not reduce gross cecal lesions.