Search PubMed⌕ Search

Biomedical subjects

C Thornsberry

Publications and source records attributed to C Thornsberry.

At least 253 records · Page 14Linked to original sources
PubMed1977

Isolation and characterization of a rough colony type of Neisseria gonorrhoeae.

A new colony type of Neisseria gonorrhoeae was detected in the primary cultures from 8 of 180 men with gonococcal urethritis. This colony type contrasts with those previously described by having a rough and irregular surface. In six of the eight cases, the rough form predominated. The distinctive morphology of the rough colony variant could be maintained indefinitely by selective subculture. By electron microscopy, organisms taken from rough colonies of each of the eight isolates were piliated. Antimicrobial susceptibilities of type 1 and rough clones derived from the same patients were identical for ampicillin, penicillin, tetracycline, and spectinomycin. After inoculation of rough colonies into subcutaneous chambers in mice and guinea pigs, type 1 colonies predominated in cultures of material obtained from the chambers. This new piliated colony type of N. gonorrhoeae may provide an opportunity to investigate factors other than pili that contribute to gonococcal virulence.

Animals↗
PubMed1977

Piperacillin (T-1220), a new semisynthetic penicillin: in vitro antimicrobial activity comparison with carbenicillin, ticarcillin, ampicillin, cephalothin, cefamandole and cefoxitin.

Piperacillin (T-1220) is a new semisynthetic penicillin with an unusually broad spectrum of antimicrobial activity. In vitro comparisons of this drug with 6 other beta-lactam antimicrobics (ticarcillin, carbenicillin, ampicillin, cephalothin, cefamandole and cefoxitin) were conducted. These included minimal inhibitory concentrations (MIC) against 394 bacterial isolates, the minimal lethal concentrations (MLC) against 79 of those, as well as the effect of inoculum size on the MIC and MLC of the drugs. Piperacillin had significantly greater activity than did the other penicillins against Pseudomonas species and Klebsiella pneumoniae. Against P. aeruginosa piperacillin was 8- and 16-fold more active than ticarcillin and carbenicillin, respectively. The MLC of piperacillin rarely differed from the MIC by more than one log2 dilutions except against P. aeruginosa in which the MLC was 4-fold greater or more than the MIC of 45% of isolates tested. Ticarcillin, carbenicillin and cefoxitin showed minimal inoculum size effects. Cefamandole results showed the greatest inoculum size variation with 55% and 37% of isolates showing an 8-fold increase in MIC and MLC respectively by increasing inoculum from 10(5) to 10(7) CFU/ml. Piperacillin was intermediately effected having 25% of strains greater than 8-fold increase in MIC.

Ampicillin↗
PubMed1977

BL-S786, a new parenteral cephalosporin. I. A collaborative in vitro susceptibility comparison to cephalothin against 5,762 clinical bacterial isolates.

The in vitro activity of Compound BL-S786 was compared with that of cephalothin against 5,762 clinical isolates by the microdilution broth method. BL-S786 demonstrated a broader spectrum and a significantly lower MIC against the Enterobacteriaceae. Although greater susceptibility to BL-S786 than to cephalothin was exhibited by Serratia marcescens, Proteus morganii and Proteus vulgaris, these three species were generally resistant to both drugs. By contrast, the staphylococci were significantly more susceptible to cephalothin than to BL-S786. Resistance to both drugs was demonstrated by Pseudomonas aeruginosa and other pseudomonads, enterococci and Bacteroides fragilis.

Anaerobiosis↗
PubMed1977

BL-S786, a new parenteral cephalosporin. II. In vitro antimicrobial activity comparison with six related cephalosporins.

BL-S786 was compared by in vitro studies with 6 other parenteral cephalosporins (cefamandole, cefazolin, cefoxitin, cephaloridine, cephalothin and cephradine). The following parameters were assessed: Comparative MICs against a wide variety of bacterial isolates, MIC/MBC comparisons and the effect of inoculum size on the MIC. BL-S786 showed the greatest antimicrobial activity against K. pneumoniae, C. diversus and Salmonella species; was equal to cefamandole against E. coli, E. agglomerans and P. mirabilis; and was second to cefamandole against Shigella, E. tarda, C. freundii, E. cloacae, E. aerogenes and the pathogenic Neisseriae. Essentially no activity against Serratia and Pseudomonas species was observed. Compared to the other cephalosporins tested BL-S786 showed poor activity against staphylococci and streptococci. For most species tested, the MBC of the various cephalosporins was the same or within one dilution of their respective MICs. However, for Enterobacter and indole-positive Proteus species, the MBC of BL-S786 and cefamandole was usually larger than or equal to 8-fold higher than the MICs. Cefoxitin, on the other hand, showed little MIC/MBC variations against indole-positive Proteus species. Inoculum size had only a small effect on the MICs against most gram-negative species--in some instances greater than 64-fold increases in MIC resulted by increasing inoculum size from 10(5) to 10(7) organisms per ml.

Bacteria↗
PubMed1977

Penicillin resistance in Neisseria gonorrhoeae due to beta-lactamase production.

Two isolates of Neisseria gonorrhoeae from two patients who did not respond to repeated treatment with penicillin were found to contain an active beta-lactamase. This enzyme has not been previously found in other gonococci isolated in the United States. Compared to other gonococci, these isolates had higher penicillin minimal inhibitory concentrations, and gave very small or no zones of inhibition in the disc agar diffusion test. The enzyme was demonstrated with three different rapid tests for beta-lactamase, by disc diffusion assay methods, and by gas-liquid chromatography-mass spectrometry determination of penicilloic acid--the enzymatic end product from penicillin.

Anti-Bacterial Agents↗
PubMed1977

Hemophilus endocarditis: new cases, literature review and recommendations for management.

Rarely is endocarditis attributed to the species of Hemophilus. Most frequently implicated are H aphrophilus and H parainfluenzae, but H influenzae also is seen. We report six cases of endocarditis due to H aphrophilus or H parainfluenzae and review the literature. Emboli to skin, lungs, kidneys, spleen, brain, and other organs are common complications, and acute glomerulonephritis and meningitis often occur. Ampicillin is the mainstay of antimicrobial therapy for patients whose isolates are sensitive to it, but the duration of antimicrobial therapy necessary for eradication of the infection is not clear. Studies of antimicrobial synergism are warranted in instances of endocarditis caused by ampicilin- or penicillin-resistant strains of Hemophilus, or when patients are allergic to penicillin; in these instances, combination antimicrobial therapy must be given when bactericidal synergism can be demonstrated. Intensive management of complications caused by embolization is crucial to patient survival.

Adult↗
PubMed1976

National gonorrhea therapy monitoring study: treatment results.

To monitor the efficacy of the 1972 United States Public Health Service recommended treatment regimens for uncomplicated gonorrhea, we studied 9008 patients who were randomly assigned either to aqueous procaine penicillin G, 4.8 million units intramuscularly plus 1 g of oral probenecid, or to one of the three other recommended regimens. Among the 3871 patients re-examined within three to seven days after therapy, the penicillin-probenecid regimen was successful in 96.8 per cent, whereas the cure rates of the ampicillin-probenecid, tetracycline, and spectinomycin regimens were 92.8, 96.2, and 94.8 per cent, respectively. In clinics comparing the regimens, penicillin G-probenecid was as effective as tetracycline, but more effective than ampicillin-probenecid (P less than 0.05) and spectinomycin (P less than 0.01). However, in patients re-examined three to 14 days after treatment, only the ampicillin-probenecid regimen was significantly less effective than penicillin probenecid (P less than 0.01). Despite these differences in results, all four regimens recommended by the Public Health Service provided effective therapy for uncomplicated gonorrhea.

Administration, Oral↗
PubMed1976

National gonorrhea therapy monitoring study: in vitro antibiotic susceptibility and its correlation with treatment results.

To monitor temporal trends and regional differences in antibiotic susceptibility, we measured the minimum inhibitory concentrations for penicillin G, ampicillin, tetracycline, and spectinomycin of 4405 pre-treatment gonococcal isolates from patients with uncomplicated gonorrhea. As compared to isolates studied in 1970-1971, recent United States isolates appeared equally sensitive to penicillin G and more sensitive to tetracycline. Relatively resistant strains were found throughout the country. We also studied 1974 patients, treated for uncomplicated gonorrhea according to the 1972 regimens recommended by the United States Public Health Service, to determine the relation between pretreatment minimum inhibitory concentrations and treatment results. For patients receiving the procaine penicillin-probenecid and ampicillin-probenecid regimens, minimum inhibitory concentrations to the treatment drugs were significantly higher in patients not cured than in those cured (P less than 0.01 fr penicillin and P less than 0.05 for ampicillin). In contrast, spectinomycin-treatment results appeared to be independent of the isolate's susceptibility to spectinomycin and other antibiotics.

Ampicillin↗
PubMed1976

Inter- and intralaboratory variability in antibiotic susceptibility tests with Pseudomonas aeruginosa and Enterobacteriaceae.

A two-phase collaboratice study was designed for definition of the extent to which results of disk diffusion tests can be reproduced. Two currently recommended techniques, the Kirby-Bauer method and the agar overlay method, were used. Of special concern were tests of Pseudomonas aeruginosa with moderate susceptibility to carbenicillin; gentamicin, tobramycin, polymyxin B, and colistin were also tested with P. aeruginosa as well as with Klebsiella pneumoniae, Escherichia coli, and Proteus species. The agar overlay method tended to give zones that were somewhat smaller than those given by the Kirby-Bauer method. Both disk methods demonstrated an excellent degree of reproducibility, being at least as reproducible as the standard agar dilution technique for measurement of minimal inhibitory concentrations. Slight changes in carbenicillin disk potency affected the zones of inhibition around P. aeruginosa more than those around susceptible E. coli. This fact suggests that a standard strain of P. aeruginosa would be advantageous for quality control of carbenicillin disk tests.

Carbenicillin↗
PubMed1976

Susceptibility of ampicillin-resistant Haemophilus influenzae to seven penicillins.

Sixty-seven clinical isolates of Haemophilus influenzae from various sections of the United States, England, and Germany were tested for susceptibility to penicillin, ampicillin, amoxicillin, epicillin, carbenicillin, ticarcillin, and methicillin. Fifty-three of the strains had previously been judged to be ampicillin resistant and 14 had been determined to be ampicillin susceptible. Fifty-two of the 53 resistant strains produced beta-lactamase, but none of the susceptible strains produced it. On the basis of minimal inhibitory concentrations, the most active compounds were ticarcillin and carbenicillin. Whether this greater activity is useful clinically has not been established.

Ampicillin↗
PubMed1976

Halophilic Vibrio species isolated from blood cultures.

The Special Bacteriology Section of the Center for Disease Control has received 38 cultures of a halophilic bacterium which apparently unnamed. On the basis of the minimal characteristics of Vibrio species proposed by Hugh and Sakazaki, this bacterium belongs to the genus Vibrio. The unnamed species can be differentiated from Vibro parahaemolyticus by a lower tolerance for sodium chloride (NaC1) and the fermentation of lactose. The failure to ferment sucrose is an additional characteristic which differentiates these organisms from V. alginolyticus. Of 33 unnamed species strains tested, all were sensitive to penicillin, ampicillin, carbenicillin, cephalothin, chlorapmphenicol, gentamicin, tetracycline, rifampin, nitrofurantoin, and sulfisoxazole by agar diffusion and agar dilution tests. The sources of isolation of the cultures of the unnamed species suggest that it is a clinically important organism. Twenty strains were isolated remaining cultures were isolated from localized infections of the extremities. In contrast, only 2 of 60 cultures of V. parahaemolyticus and V. alginolyticus received in our laboratory as human isolates from extra-intestinal sources were isolated from blood.

Anti-Bacterial Agents↗
PubMed1976

Epidemiologic characteristics of infections caused by ampicillin-resistant Hemophilus influenzae.

Hrom February 1974 through May 1975, 58 isolates of ampicillin-resistant Hemophilus influenzae from patients were submitted to the Center for Disease Control from 23 states and the District of Columbia. The epidemiologic characteristics of these widely scattered cases were strikingly similar to those of cases previously reported from individual communities or institutions. Because of the nationwide distribution of resistant isolates and the adverse consequences of ineffective therapy, the use of chloramphenicol is recommended for the initial management of systemic illness definitely or probably due to H. influenzae type b.

Ampicillin↗
PubMed1975

Broth-dilution method for determining the antibiotic susceptibility of anaerobic bacteria.

A broth-dilution method for performing antimicrobial susceptibility tests on anaerobic bacteria has been proposed. The medium used in the test was Schaedler broth, with incubation in a glove box with an atmosphere of 5% CO(2), 10% H(2), and 85% N(2), or in the GasPak system. Minimal inhibitory concentrations for selected antibiotics were determined, under these conditions, by using a conventional twofold dilution scheme for the antibiotics and a "categorization three-tube method" in which two or three clinically significant concentrations of each antibiotic were used. Minimal inhibitory concentrations obtained by both methods were very similar. The categorization method could be used routinely to test the antimicrobial susceptibility of anaerobic bacteria.

Anaerobiosis↗
PubMed1975

Laboratory evaluation of a rapid, automatic susceptibility testing system: report of a collaborative study.

Seven laboratories participated in a collaborative study to evaluate the Autobac 1 system. Results obtained with this assay system were compared to those obtained by the standardized Bauer-Kirby disk diffusion test, and each of these two methods was compared to the agar dilution technique. Comparison of the Autobac 1 and the disk diffusion results from the seven laboratories showed an overall average of 91.5% interpretive agreement with the 17 antimicrobial agents tested. The distribution in the levels of Autobac 1/disk diffusion agreement was such that with 13 antimicrobial drugs agreement was 90% or higher; with three, between 85 and 90%; and with one, 77% (nitrofurantoin). Comparison of the Autobac 1 and disk diffusion tests with the International Collaborative Study agar dilution test showed that both methods gave levels of agreement with the International Collaborative Study agar dilution technique that were generally high and equivalent. The average overall agreement between the agar dilution test and each of the other two methods was approximately 90%. Disagreements that did occur tended to involve organisms that were drug susceptible by the Autobac 1 system but intermediate or resistant by the other two methods. This was in part due to the narrow intermediate interpretive zone of the Autobac 1 test. In reproducibility studies with the Autobac 1 and disk diffusion methods, no significant differences were observed between the interpretive reproducibility of the two methods.

Anti-Bacterial Agents↗
PubMed1975

Effect of calcium and magnesium ions on the susceptibility of Pseudomonas species to tetracycline, gentamicin polymyxin B, and carbenicillin.

The effect of calcium and magnesium on the susceptibility of 13 species of Pseudomonas to tetracycline, gentamicin, polymyxin B, and carbenicillin was measured. The majority of the minimum inhibitory concentrations (MICs) of these antibiotics was increased if these cations were added to the test media. The increases in MICs caused by calcium or magnesium were similar, but the combination of both ions generally caused a greater change than either alone. Although the MIC of polymyxin B was most affected by calcium and magnesium, its interpretive susceptibilities (i.e., whether susceptible or resistant) were least changed. Susceptibility tests on Pseudomonas species probably should be done with Muller-Hinton broth supplemented with physiological concentrations of calcium and magnesium to better approximate the in vivo activity of these antibiotics. When the susceptibility tests were performed with Mueller-Hinton agar, the MICs were slightly less than those obtained with Mueller-Hinton broth supplemented with both cations but greater than those obtained with Mueller-Hinton broth supplemented with individual cations.

Calcium↗