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Biomedical subjects

J K Todd

Publications and source records attributed to J K Todd.

At least 91 records · Page 5Linked to original sources
PubMed1975

Rapid detection of bacteremia by an early subculture technic.

Routine blood cultures in a pediatric hospital were subcultured after 4 to 14 hours of incubation (average 8 hours). Eighty-five per cent of all significant, positive blood cultures were detected within 24 hours of initial incubation. Contaminant organisms rarely grew on early subculture plates. Compared with the traditional 24-hour or 48-hour stain and subculture technics, the 4--14-hour (early) subculture method allows more rapid detection, identification, and sensitivity testing of most bacteria isolated from clinically significant positive blood cultures.

Bacteriological Techniques↗
PubMed1975

Effect of carbon cup aging on plasma zinc determination by flameless atomic adosorption spectrometry.

Determination of zinc in blood plasma by flameless atomic absorption spectrometry is discussed, with particular reference to the protocol required for the successful use of the Varian-Techtron Carbon Rod Atomizer. Cup aging is shown to be an important factor in limiting the precision of this analytical technique and ways of minimizing the problem are described. Matrix problems have also been encountered, which precluded the use of aqueous standard curves and the method of standard additions. We propose the use of plasma in preparing standard curves, the values for which are corrected for inherent plasma zinc, as a possible solution to the problem.

Carbon↗
PubMed1975

Gastric outlet obstruction due to X-linked chronic granulomatous disease.

Children with chronic granulomatous disease (CGD) may develop a peculiar form of gastric outlet obstruction due to involvement of the stomach wall with granulomatous tissue. An illustrative case is presented (which occurred despite adequate control of infection with antibiotherapy), including details of surgical management, distinctive radiographic and pathologic findings, and a review of other reported cases.

Anti-Bacterial Agents↗
PubMed1968

Characteristics of bacteriophages attacking psychrophilic and mesophilic pseudomonads.

Ten Pseudomonas phage were isolated by sewage enrichment. Five psychrophilic and five mesophilic phage were selected for a description of some of their biological properties. In addition to growth on psychrophilic hosts, the psychrophilic phage studied were also able to grow on a mesophilic host within its growth temperature range. Latent periods for psychrophilic phage at 3.5 C were 6 to 12 hr and at 25 C were 30 to 60 min. Mesophilic phage had a latent period of 85 to 190 min at 25 C and 35 to 85 min at 37 C. Psychrophilic phage were significantly more heat-sensitive than the mesophilic phage. Of all the parameters studied, only thermal sensitivity correlated with growth at 3.5 C. Phage used in this study had a deoxyribonucleic acid base composition ranging from 39.6 to 68.2% guanine plus cytosine, deduced from melting temperature measurements.

Bacteriophages↗
PubMedDate not supplied

Alteration of proteins reacting with antibody to toxic shock syndrome toxin 1 by endogenous proteases of Staphylococcus aureus.

Many cases of toxic shock syndrome (TSS) have been associated with Staphylococcus aureus strains that produce in vitro a 22,000-dalton protein called toxic shock syndrome toxin 1 (TSST-1). TSST-1 has been shown to be linked phenotypically to the production of the type II (thiol) staphylococcal protease; however, some strains clearly associated with TSS do not produce TSST-1. With the use of a variety of antibodies to TSST-1, representatives of both TSST-1-positive and TSST-1-negative TSS-associated strains were shown to produce proteins of 32,000, 53,000, and 76,000 daltons that cross-reacted with TSST-1 but that did not appear to be TSST-1 aggregates or to be protein A. TSST-1-negative strains were significantly (P less than .05) more likely than TSST-1-producing strains to produce the type I protease and less likely to produce the type II protease. In vitro the type I (serine) protease digests purified TSST-1. When combinations of type II and type III protease chemical inhibitors were used, the production of the high-molecular-weight cross-reacting proteins during in vitro growth could be selectively enhanced. Since the infected foci (e.g., abscess, vagina) associated with TSS may contain natural protease inhibitors, it is possible that such TSST-1 cross-reacting proteins may be expressed in vivo or that levels of TSST-1 may be increased by an inhibitor of the serine protease.

Animals↗
PubMedDate not supplied

Criteria for the discontinuation of antibiotic therapy during presumptive treatment of suspected neonatal infection.

Unstable newborns are often subjected to multiple diagnostic tests and then treated presumptively for bacterial infection. Inconclusive test results may perpetuate unnecessary therapy. One hundred twenty-three neonates were prospectively evaluated for infection. Complete physical examinations and chest radiographs were performed. Of ten screening tests only the white blood cell count, absolute band count, absolute band/neutrophil ratio and C-reactive protein showed statistical differences (P less than 0.05) among 32 patients with positive "nonpermissive" (blood, cerebrospinal fluid, suprapubic or catheter urine, needle aspirate, tracheal aspirate) cultures and 50 with negative cultures who had antibiotic therapy discontinued within 72 hours. Forty-one additional patients were continued on therapy despite negative cultures. Incomplete bacteriologic evaluation resulted in unconfirmed "pneumonia" in 16 of these children. No statistical differences between the culture negative groups existed regardless of treatment status, suggesting that patients in the latter group may not have required continued treatment. A definitive, bacteriologic evaluation emphasizing "nonpermissive" cultures should be completed in newborns suspected of infection which, when negative, should allow discontinuation of antibiotics. In equivocal cases, a negative C-reactive protein best supports cessation of therapy. This approach can reduce the total duration of newborn exposure to antibiotics in a high risk nursery by 20%. A prospective, definitive, diagnostic evaluation (emphasizing non-permissive cultures) avoids uninterpretable but frequently used tests and reduces cost while adding confidence in the termination of therapy.

Anti-Bacterial Agents↗
PubMedDate not supplied

Antimicrobial susceptibility testing in the office laboratory.

The performance, quality control and interpretation of antimicrobial susceptibility tests are a complex affair. Fortunately empiric oral antimicrobial therapy usually suffices for most nonsystemic pediatric bacterial infections which would ordinarily be treated on an outpatient basis (e.g. otitis media, streptococcal pharyngitis, pyoderma, UTI). Common pediatric pathogens such as H. influenzae and S. pneumoniae require uncommon expertise and complex systems for appropriate susceptibility testing. Direct susceptibility testing of urine specimens is the only current antimicrobial test that can be practically and reliable performed in most office laboratories. Access to a reliable reference laboratory with appropriate quality control systems is essential for other antimicrobial susceptibility testing needs.

Bacterial Infections↗
PubMedDate not supplied

Bacteriology and treatment of purulent nasopharyngitis: a double blind, placebo-controlled evaluation.

One hundred forty-two children with purulent nasopharyngitis were randomized to four treatment groups with an antibiotic (cephalexin) alone or combined with a decongestant/antihistamine (pseudoephedrine/triprolidine) or their corresponding placebo equivalents. Follow-up evaluations by parents and physicians and bacteriologic evaluations were performed after 5 to 6 days of therapy. Groups were comparable with regard to age, sex, race, number of patients withdrawn from the study, fever greater than 38.0 degrees C, appearance of nasal discharge, nasal crusting and number of days until follow-up. Initial cultures from patients grew: Streptococcus pneumoniae, 46%; Haemophilus influenzae type b, 21%; and Streptococcus pyogenes, 8%. Nasal crusting was significantly associated with the growth of S. pneumoniae or H. influenzae type b. There were no significant differences between active drug and placebo treatment groups for change in nasal discharge, complications or apparent drug benefit. Cephalexin therapy did not result in a decrease in cultivation of pathogenic organisms from the nasopharynx. Significantly more side effects were attributed to pseudoephedrine/triprolidine treatment than to placebo. Routine culture or treatment of purulent nasopharyngitis should not be considered unless future controlled clinical trials demonstrate some therapeutic benefit.

Bacterial Infections↗