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Biomedical subjects

H D Isenberg

Publications and source records attributed to H D Isenberg.

At least 91 records · Page 5Linked to original sources
PubMed1978

Transport of antibiotics into the canine sinus. Experiments with penicillin G and erythromycin.

Complete and consistent occlusion of the nasofrontal duct of the canine sinus was achieved by introducing acrylic through a trephinated opening in the nasal dorsum. This surgical procedure resulted in the isolation of the frontal sinus, without impairing the integrity of the cavity. In this experimental canine model, potassium penicillin G and erythromycin lactobionate were absorbed into the blood equally well when placement was either in the intramuscular (IM) space or in frontal sinus cavity. When different concentrations of these antibiotics were injected into the IM space, peak blood levels occurred between one and two hours; however, peak sinus levels, following IM introduction, did not occur until four hours. The peak ratios show that between 4% and 20% of penicillin, and 1% and 12% of erythromycin in the blood is transferred across the normal sinus membrane.

Absorption↗
PubMed1978

Multi-laboratory evaluation of an automated microbial detection/identification system.

An automated and computerized system (Automicrobic System [AMS]) for the detection of frequently encountered bacteria in clinical urine specimens was tested in a collaborative study among six laboratories. The sensitivity, specificity, reliability, and reproducibility of the AMS were determined, and the system was compared with conventional detection and identification systems. In this study, pure cultures and mixtures of pure cultures were used to simulate clinical urine specimens. With pure cultures, the sensitivity of the AMS in identifying the nine groups of organisms most commonly found in urine averaged 92.8%. The specificity averaged 99.4%, and the reliability of a positive result averaged 92.1%. The latter value was strongly influenced by a relatively high occurrence of false positive Escherichia coli results. The AMS was capable of detecting growth of most organisms, including those which it was not designed to identify. However, it identified some of these incorrectly as common urinary tract flora. Reproducibility of results, both within laboratories and among different laboratories, was high. Fast-growing organisms, such as E. coli and Klebsiella/Enterobacter species, were detected often at cell populations well below the AMS enumeration threshold of 70,000/ml. In mixed culture studies, high levels of sensitivity and specificity were maintained but when Serratia species were present in mixtures with other organisms, there was often a false positive report of E. coli. The overall performance of the AMS was considered satisfactory under the test conditions used.

Bacteria↗
PubMed1977

Wound infection. Acute versus chronic cholecystitis.

Wound infection in 239 patients who underwent cholecystectomy were analyzed retrospectively. Seventeen per cent of the patients with acute cholecystitis had wound infection compared with 8.9 per cent of patients with chronic cholecystitis. Bacteriology of wound infections revealed Staphylococcus aureus in 76.4 per cent of the chronic cholecystitis group and in 12.5 per cent of the acute cholecystitis group. Wound infection in the acute cholecystitis group involved gram-negative rods predominantly. Organisms were isolated from bile culture in 71.4 per cent of acute cholecystitis patients compared with 59.6 per cent of chronic cholecystitis patients. Of patients with positive bile cultures 11.3 per cent had wound infections compared with 6.8 per cent of patients with negative bile cultures. The most common organisms isolated from bile cultures with resultant wound infections were S epidermis, S aureus, and Klebsiella sp. Wound infection after cholecystectomy for chronic cholecystitis arises from external sources and not contaminated bile. Antibiotic therapy should be directed accordingly.

Acute Disease↗
PubMed1977

Evaluation of the performance parameters of a prediluted, quantitative antibiotic susceptibility test device.

A multiwelled plastic strip containing prediluted antibiotics was tested. Antibiotics available at the time of testing included ampicillin, penicillin, methicillin, erythromycin, clindamycin, tetracycline, and minocycline. The effects of inoculum size, inoculum volume, temperature, and time of incubation were determined. A limited clinical evaluation using laboratory strains of selected bacteria proved this product to be a rapid, economical, and reliable method for the determination of the minimal inhibitory concentration of antibiotics.

Anti-Bacterial Agents↗
PubMed1977

In-use evaluation of a prediluted quantitative antibiotic susceptibility test device.

An antibiotic susceptibility test (AST) device is described. Minimum inhibitory concentration results on 1,294 clinical isolates with seven antibiotics were rapid, reliable, and reproducible. Agreement with the disk diffusion test was 90%. Interlaboratory agreement for the AST was 94%. The AST provides minimum inhibitory concentration capability without the necessity of prior weighing and dilution of antibiotics.

Anti-Bacterial Agents↗
PubMed1977

Clinical laboratory evaluation of a system approach to the recognition of nonfermentative or oxidase-producing gram-negative, rod-shaped bacteria.

The Oxi-ferm tube, an eight-compartment system suitable for the recognition of nonfermentative, gram-negative, rod-shaped bacteria, was evaluated in conjunction with the oxidase test in a clinical microbiology laboratory setting. A comparison between this system and the 17-test routine examination was performed with 265 cultures representing 21 species. The results obtained with the Roche systems were supplemented with simple additional tests in accordance with Computer Identification Data rovided by the manufacturer. The Oxi/ferm tube approach worked satisfactorily in establishing the identity of the bacteria isolated from clinical specimens augmented with some representatives from culture collections. Reactions within the Oxi/ferm system were reproducible and comparable to laboratory prepared and controlled substrates.

Bacteria↗
PubMed1977

Studies of the surgical scrub.

A study comparing the relative efficacy of a five versus a ten minute surgical scrub was carried out using random sampling of personnel scrubbing for routine scheduled hospital surgical procedures. Scrubbing for five minutes was found to be equally as effective as scrubbing for ten minutes. Betadine was compared to pHisoHex as a scrubbing agent and found to be statistically more effective in degerming the skin following a five minute scrub. As a result of this study, a routine preoperative surgical scrub of five minutes' duration, using Betadine as the scrubbing agent, is recommended.

Hand↗
PubMed1976

Rat polyvinyl sponge model for the study of infections: initial investigations.

Polyvinyl sponges were implanted subcutaneously on both sides of young female rats. One sponge was infected with 10(8) of either Escherichia coli K-12 F-, Staphylococcus aureus ATCC 25923, or Pseudomonas aeruginosa CDC 7725. P. aeruginosa remained at the inoculum level and S. aureus declined by 1 log, whereas E. coli was reduced 1,000-fold. Only P. aeruginosa was recovered from the blood in 36% of the animals in 24 h and in 20% of the rats in 48 h. The nutrient potential of rat inflammatory fluid was compared to nutrient broth by growth of each bacterium in untreated and heat-inactivated sponge fluids and Trypticase soy broth.

Animals↗
PubMed1976

Rat polyvinyl sponge model for the study of infections: host factors and microbial proliferation.

Female rats were treated with several administration regimens of methylprednisolone, cobra venom anti-complementary factor, and cyclophosphamide in conjunction with polyvinyl sponge implantations. The effect of these drugs on host factors active against bacteria was evaluated with Staphylococcus aureus ATCC 25933, Escherichia coli K-12, and Pseudomonas aeruginosa CDC 7725. One of two implants in each animal was infected with 10(8) of one of the three bacteria, and bacterial and granulocyte content was determined in the infected and control sponges after 48 h. The single large dose of methylprednisolone decreased staphylococcal and E. coli clearance while promoting dissemination of P. aeruginosa. A low chronic dose of the steroid inhibited E. coli chemotaxis only. A higher dose of the steroid administered chronically interfered markedly with S. aureus and E. coli curtailment by the host while leading to enhanced dissemination of P. aeruginosa, accompanied by a precipitous decline in granulocytes. Results with cobra factor resembled the higher chronic dose of steroid enhancing, especially the dissemination of the pseudomonad and its anti-granulocytic propensity. Cyclophosphamide depression of granulocytes revealed the rat's ability to curtail the proliferation of particular S. aureus and E.coli strains even in the absence of leukocytes. This treatment resulted in the rapid spread of P. aeruginosa, leading to the death of some experimental animals. These experiments underline the versatility of this animal model in the study of host and microbial factors influential in infectious disease.

Animals↗
PubMed1976

Fibroblast DNA synthesis activation in sponge induced granulation tissue. The effect of antineutrophil serum and cyclophosphamide.

DNA synthesis in rat and rabbit polyvinyl sponge induced granulation tissue has been studied using thymidine (methyl-3H). Synthesis was determined by measurement of thymidine incorporation into cold trichloroacetic acid insoluble material and by autoradiography. Granulation tissue was removed and immediately incubated in vitro in the presence of thymidine (methyl-3H) for three hours. The label was incorporated into the nuclei of fibroblasts and, to a lesser extent, of endothelial cells. The labeled material was 93% lysable by DNase and its synthesis was inhibited by hydroxyurea and bleomycin. In this system synthesis was linear for two hours and then ceased. A marked increase in DNA synthesis occurred in tissue harvested at 44 hours after sponge implantation. This rise was confirmed by autoradiographic studies which showed an increase in nuclear labeling at two days after implantation. Neutropenia produced by injections of antineutrophil serum or cyclophosphamide failed to inhibit activation of DNA synthesis in fibroblasts or endothelial cells. Amonocytosis also had no effect on this process. Rates of thymidine incorporation into DNA and thymidine phosphates in vivo were similar to those found during in vitro incubations of granulation tissue.

Animals↗
PubMed1976

Acute hematogenous osteomyelitis: an experimental model.

The injection of barium sulphate (micropaque) contaminated with Staphylococcus aureus into the nutrient artery of the canine tibia produced typical inflammatory bone changes. This alteration, similar to those observed in human hematogenous osteomyelitis, consisted of medullary destruction, spontaneous fractures, and intense periosteal new bone formation. This system seems to mimic the characteristics of some clinical bone infections and may provide a model for therapeutic trials.

Acute Disease↗
PubMed1976

Clinical laboratory evaluation of the fifty-milliliter vacutainer blood culture tube.

The efficacy of the 50-ml vacutainer culture tube (Becton-Dickinson) for recovery of microorganisms from blood cultures was compared with laboratory-prepared blood culture media. The isolation of Bacteroides sp. was significantly higher in the 50-ml vacutainer culture tube whereas that of nonfermenting gram-negative rods and yeasts was higher in the in-house media. There was no significant difference in the recovery of all other organisms.

Bacteria↗
PubMed1976

Wound infection: a prospective study of 7519 operations.

Wound infection was prospectively studied in 7,519 consecutive operations after preoperative classification as clean, clean-contaminated, and infected. The overall infection rate was 3.9 per cent. Clean, 3.2 per cent; clean-contaminated, 4.4 per cent; contaminated, 12.4 per cent; infected, 16.2 per cent. Wound infection was not seasonally related or dependent on changes in house staff. In clean cases, the predominant role of Staphylococcus aureus (37%) has been superceded by enterococci (44%). In clean-contaminated cases, enterococci (43.5%) were the most common, followed by Escherichia coli (40.0%). In contaminated wounds, E. coli was most common (40.0%). The infected case category grew mixed flora (E. coli, 82 per cent; enterococci, 54 per cent, and Pseudomonas aeruginosa, 43 per cent). Nosocomial organisms were important only in the contaminated (14%) and infected (43%) categories. Antibiotic therapy before cultures are available should include agents with activity against enterococci as well as S aureus, and E. coli in clean cases.

Bacteria↗