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Biomedical subjects

S Shelton

Publications and source records attributed to S Shelton.

At least 37 records · Page 2Linked to original sources
PubMed1993

Dilemmas in diagnosis and management of cephalosporin-resistant Streptococcus pneumoniae meningitis.

We recently managed an infant with meningitis caused by Streptococcus pneumoniae in whom ceftriaxone failed to sterilize the cerebrospinal fluid after 6 days of therapy. This strain, which had a penicillin minimal inhibitory concentration (MIC) of 2 micrograms/ml, appeared susceptible to ceftriaxone (MIC < 0.5 micrograms/ml) when evaluated by a commercial MIC panel (Microtech Medical Systems, Inc., Aurora, CO) but was found to have a ceftriaxone MIC of 4 micrograms/ml when evaluated by conventional microtiter broth dilution technique. Furthermore ceftriaxone therapy of meningitis induced with this strain in a rabbit model was ineffective. Thirteen of 112 pneumococcal strains (11.6%) isolated recently at Children's Medical Center of Dallas were penicillin-resistant, and 3 of these were highly penicillin-resistant (MIC > or = 2 micrograms/ml). The incidence of pneumococcal strains with cefotaxime MICs > or = 1.0 micrograms/ml has increased from 0 of 258 from 1981 to 1983 to 5 of 112 (4.5%) from 1991 to 1992. The definition of cephalosporin resistance for pneumococci requires modification and further studies of the antibiotic management of meningitis caused by such strains are needed because resistance to cephalosporins is increasing and the extended spectrum cephalosporins may be ineffective as sole therapy.

Animals↗
PubMed1993

Screening for cephalosporin-resistant Streptococcus pneumoniae with the Kirby-Bauer disk susceptibility test.

Kirby-Bauer disk susceptibility tests with five standard cephalosporin disks were performed on 23 penicillin-resistant Streptococcus pneumoniae isolates for which ceftriaxone MICs were 0.125 to 4 micrograms/ml. Cefuroxime disk inhibition zone diameters distinguished clearly isolates for which ceftriaxone MICs were > or = 2 micrograms/ml from more susceptible strains, whereas cephalothin, ceftizoxime, cefotaxime, and ceftriaxone disks distinguished these isolates less clearly than the cefuroxime disk did.

Ceftriaxone↗
PubMed1992

Visualization of dopamine nerve terminals by positron tomography using [18F]fluoro-beta-fluoromethylene-m-tyrosine.

[18F]-6-Fluoro-beta-fluoromethylene-m-tyrosine ([18F]FFMMT) was evaluated as a potential imaging agent for dopamine nerve terminals using positron emission tomography (PET). Biodistribution and time course of this tracer in mice after i.p. injection was consistent with the distribution of dopamine. PET imaging studies involving rhesus macaques showed specific uptake in the dopamine-rich caudate-putamen region. This specific localization was blocked by inhibiting the enzyme L-aromatic amino acid decarboxylase and the transport of the tracer into brain was shown to be stereospecific. These results show the promise of L-[18F]FFMMT as a PET tracer in monitoring degeneration of the CNS dopamine system.

Animals↗
PubMed1991

Comparative evaluation of loracarbef and amoxicillin-clavulanate for acute otitis media.

One hundred five infants and children with acute otitis media were randomized to therapy with loracarbef, an experimental carbacephem antibiotic, or amoxicillin-clavulanate (Augmentin), an approved drug for this disease. Ninety-two were evaluable (46 in each group). Middle ear fluid samples obtained for culture before therapy grew Haemophilus spp. in 30% of cases, pneumococci in 29% of cases, and Moraxella catarrhalis in 15% of cases. beta-Lactamase-producing bacteria were found in 37% of patients. Clinical failure occurred in four loracarbef-treated patients and one amoxicillin-clavulanate-treated patient (P = 0.361). Recurrence of acute otitis media was more common in the 2 to 3 weeks after loracarbef treatment (eight patients) than it was after amoxicillin-clavulanate therapy (three patients), but not significantly so (P = 0.197). Thus, combined failure and recurrence occurred in 12 loracarbef-treated patients and four amoxicillin-clavulanate-treated patients (P = 0.052). Gastrointestinal side effects occurred in 13 loracarbef-treated and 21 amoxicillin-clavulanate-treated patients (P = 0.13). Diaper rash was more common with amoxicillin-clavulanate (22 patients) than with loracarbef (10 patients; P = 0.016). Satisfactory results were achieved with both antibiotics, and adverse effects, although common, were minor.

Acute Disease↗
PubMed1990

Loracarbef concentrations in middle ear fluid.

Loracarbef concentrations in plasma and middle ear fluid (MEF) were measured in specimens obtained approximately 2 h after doses of 7.5 or 15 mg/kg. The mean +/- standard deviation concentrations in MEF were 2.0 +/- 2.6 mg/liter (48% of the concentration in plasma) after the smaller dose and 3.9 +/- 2.6 mg/liter (42% of the concentration in plasma) after the larger dose. With the larger dose, the concentrations in MEF were greater than the MIC for 90% of strains of the usual pathogens of acute otitis media tested in 16 of 17 specimens.

Body Fluids↗
PubMed1990

Pharmacokinetics of cefprozil in infants and children.

Twenty pediatric patients (ages, between 8 months and 8 years) received a single oral dose of cefprozil at levels of 15 and 30 mg/kg of body weight. Cefprozil consists of cis (BMY-28100) and trans (BMY-28167) isomers in an approximately 90:10 ratio. Six plasma samples were collected from each pediatric patient and assayed for drug concentrations. As measured by a microbiological assay, peak concentrations of 11.16 and 15.93 micrograms of cefprozil per ml occurred at 1 h for patients who received the 15- and 30-mg/kg doses, respectively. The respective mean half-lives of cefprozil were 1.77 and 2.14 h, and the respective mean areas under the curve were 28.05 and 45.28 micrograms.h/ml for patients who received the 15- and 30-mg/kg doses. When measured by a high-pressure liquid chromatography method, peak concentrations of 12.09 and 18.04 micrograms of the cis isomer per ml were obtained at 1 h, with mean half-lives of 1.63 and 2.06 h and mean areas under the curve of 30.48 and 49.34 micrograms.h/ml in patients who received the 15- and 30-mg/kg doses, respectively. For the trans isomer, peak concentrations of 1.16 and 1.63 micrograms/ml occurred at 1 h, respectively, with mean half-lives of 1.61 and 1.65 h and mean areas under the curve of 2.89 and 4.34 micrograms.h/ml in patients who received the 15- and 30-mg/kg doses, respectively.

Administration, Oral↗
PubMed1989

Simultaneous detection of Escherichia coli heat-stable and heat-labile enterotoxin genes with a single RNA probe.

A single RNA probe was synthesized and used to detect simultaneously the methanol-soluble heat-stable enterotoxin and heat-labile enterotoxin genes in Escherichia coli strains. The results with the biotinylated or radioactive probe correlated 100% with the biological assay results for both toxins. The RNA probe detected the three known heat-stable enterotoxin A alleles.

Alleles↗
PubMed1988

Five vs. ten days of therapy for acute otitis media.

In a double blind study 175 patients with acute otitis media were randomized into 2 treatment groups: 10 days of therapy with cefaclor or 5 days of therapy followed by 5 days of placebo. The dosage of cefaclor was 40 mg/kg/day administered orally in equally divided doses at 12-hour intervals. Tympanocentesis before treatment yielded specimens that contained Streptococcus pneumoniae or Haemophilus influenzae or both in 55% of specimens. Branhamella catarrhalis was isolated from 21% of specimens. Culture of material from the ear canal of patients with spontaneous perforation of the tympanic membrane of less than 24 hours duration yielded pneumococci or H. influenzae or both in 38% of specimens and staphylococci in 31%. Patients were scheduled for follow-up examinations at 5 or 6, 10, 30, 60 and 90 days. Of the 175 children 151 were evaluable at 10 days. There were 123 patients with both tympanic membranes intact at the time of diagnosis. There were 6 (10%) treatment failures of therapy in the 59 patients assigned to 5 days of therapy and 4 (6%) failures and 1 (2%) early relapse in the 64 assigned to 10 days of therapy (difference not significant). There were 28 evaluable patients with spontaneous perforation. There were 8 (53%) failures in the 15 children assigned to 5 days of therapy and only 1 (8%) failure in the 13 children assigned to receive 10 days of therapy (P = 0.016, Fisher exact test). Rates of reinfection and persistent middle ear effusion at 10, 30, 60 and 90 days follow-up were not significant different in patients assigned to 5 to 10 days of therapy. In patients with acute otitis media with intact tympanic membranes we have not been able to show any advantage of the standard duration of 10 days of therapy over a shortened course of 5 days. A 5-day course of antibiotic therapy does not appear to be sufficient for children with acute otitis media and spontaneous purulent drainage.

Acute Disease↗
PubMed1988

Pharmacokinetics of LY163892 in infants and children.

Two dosages (7.5 and 15 mg/kg of body weight) of LY163892 were given to infants and children, and five plasma specimens were collected for antibiotic assay during the ensuing 4 h. Peak concentrations of 12.6 and 18.7 micrograms/ml occurred at 45 min. The mean half-lives were 0.85 and 0.78 h, and the mean areas under the curve were 24.4 and 38.0 micrograms.h/ml.

Adolescent↗
PubMed1988

In vitro susceptibilities of common pediatric pathogens to LY163892.

LY163892 is a carbacephem antibiotic for oral administration with an antibacterial spectrum similar to that of cefaclor and amoxicillin-clavulanic acid. It has greater stability than cefaclor and greater activity against beta-lactamase-producing Haemophilus influenzae and Escherichia coli. LY163892 is less active than amoxicillin against streptococci and less active than amoxicillin-clavulanic acid against Branhamella catarrhalis but comparable against other pathogens.

Anti-Bacterial Agents↗
PubMed1987

Imipenem and cilastatin in acute osteomyelitis and suppurative arthritis. Therapy in infants and children.

Twenty-five infants and children with acute osteomyelitis (n = 7), suppurative arthritis (n = 11), or both (n = 7) were treated with imipenem and cilastatin sodium. Patients ranged in age from 5 months to 11.3 years. Needle aspiration of infected sites was performed in all patients, and 11 (44%) required further surgical drainage. Imipenem and cilastatin sodium in a dosage of 100 mg/kg/d was used for children 3 years of age or younger, while older ones received 60 mg/kg/d intravenously, divided in four equal doses. Bacterial pathogens were identified in 15 patients (60%): Staphylococcus aureus in five, Haemophilus influenzae b in four, Pseudomonas aeruginosa in two, Streptococcus pneumoniae in one, group A Streptococcus in one, Kingella kingae in one, and Citrobacter amalonaticus in one. All isolates were susceptible to imipenem in vitro. Imipenem and cilastatin therapy was continued for a median of six days followed by treatment with appropriate orally administered antibiotics. Median peak serum bactericidal titers after imipenem and cilastatin infusions were 1:512 for S aureus, 1:32 for H influenzae b, 1:512 for streptococci, and 1:16 for gram-negative rods. All but one patient with P aeruginosa osteomyelitis responded favorably to imipenem and cilastatin. The median duration until resolution of symptoms was six days. Imipenem and cilastatin infusions were well tolerated, and side effects included maculopapular rash in one patient, watery diarrhea in one, and mild transient elevation of alanine aminotransferase levels in three. Because of imipenem and cilastatin's unusually broad spectrum of activity and its relative safety, this drug combination can be used for the initial, empiric therapy of acute bone and joint infections in pediatric patients.

Acute Disease↗
PubMed1987

Function of the adrenal cortex in patients with major depression.

Failure to suppress cortisol secretion after administration of dexamethasone occurs in up to 50% of depressed patients. To test whether this hypothalamic-pituitary-adrenal (HPA) overactivity is associated with adrenocortical hyperresponsiveness, we performed dexamethasone suppression tests (DSTs) and adrenocorticotropic hormone (ACTH) stimulation tests in depressed subjects and subjects with other psychiatric disorders. Three groups were defined: depressed nonsuppressors, depressed suppressors, and other suppressors. While predexamethasone and postdexamethasone cortisol concentrations were greater in the depressed nonsuppressor group, ACTH concentrations did not differ among groups. After receiving alpha-ACTH[1-24] (4.2 micrograms/kg), depressed nonsuppressors had greater increases in stimulated cortisol secretion than the other groups. These results demonstrate that in a subgroup of depressed patients, HPA overactivity is associated with adrenocortical hyperresponsiveness.

Adrenal Cortex↗
PubMed1985

Comparative treatment trial of augmentin versus cefaclor for acute otitis media with effusion.

A total of 150 children with acute otitis media were randomly allocated to treatment with amoxicillin-potassium clavulanate (Augmentin) or with cefaclor. Each drug was given in a daily dosage of approximately 40 mg/kg in three divided doses for ten days. Tympanocentesis done before treatment yielded specimens that contained pneumococcus or Haemophilus sp or both in 67% of specimens. Viridans group streptococci were isolated from 10% of specimens and Branhamella catarrhalis from 6%. Patients were scheduled for follow-up examinations at midtreatment, end of therapy, and at 30, 60, and 90 days. Of the 150 children, 130 were evaluable. Five of 60 patients (8%) treated with cefaclor were considered therapeutic failures because of persistent purulent drainage and isolation of the original pathogen or suprainfection. There were no failures among patients treated with Augmentin (P = .019). Rates of relapse, recurrent acute otitis media with effusion, and persistent middle ear effusion were comparable in the two groups of patients. Diaper rash, or loose stools, or both were significantly more common in children treated with Augmentin (34%) than in those taking cefaclor (12%), but in no case was it necessary to discontinue medication because of these mild side effects (P = .002). Cefaclor therapy was discontinued in one patient because of severe abdominal pain and vomiting. In this study, treatment with Augmentin was superior to treatment with cefaclor in the acute phase of acute otitis media with effusion, but Augmentin produced more adverse effects. The rates of persistent middle ear effusion and recurrent acute otitis media with effusion were comparable with the two regimens.

Acute Disease↗
PubMed1984

Pharmacokinetics and bacteriological efficacies of apalcillin and cefpiramide in experimental pneumococcal meningitis.

Rabbits with experimentally induced pneumococcal meningitis were given single 25-mg/kg doses of apalcillin or cefpiramide. Mean percentages of the drug concentration in cerebrospinal fluid versus that in blood serum were 7.6% with apalcillin and 3.9% with cefpiramide. Bactericidal activity in cerebrospinal fluid resulted in mean reductions of from 4 to 5 log10 CFU/ml, and cerebrospinal fluid cultures became sterile for four of six animals treated with each drug.

Ampicillin↗
PubMed1983

Randomized trial of cefamandole plus amdinocillin versus cefamandole in serious pediatric infections.

In a randomized, prospective clinical trial cefamandole therapy was compared with cefamandole plus amdinocillin in infants and children with suspected bacterial infections. Fifty-two infections in 50 patients with bone and joint (19 infections), pulmonary (19 infections), soft tissue (eight infections), and urinary tract (6 infections) diseases were treated. Bacterial infection was documented in 31 patients. All isolates were susceptible to cefamandole except one strain of Serratia marcescens, which was susceptible to the combination. In vitro synergy was demonstrated in all coliform bacilli, in three of seven Haemophilus strains, and in six of 16 gram-positive cocci. No correlation between degree of serum bactericidal activity and presence or absence of synergy could be demonstrated. One patient treated with cefamandole died; all other patients responded promptly to therapy without serious adverse drug effects.

Amdinocillin↗
PubMed1983

Ceftriaxone versus ampicillin and chloramphenicol for treatment of bacterial meningitis in children.

78 patients with bacterial meningitis were evaluated in a prospective, randomised study comparing twice-daily ceftriaxone as single-drug therapy with ampicillin and chloramphenicol given every 6 h. The groups were comparable in age, sex, days of illness before admission, and bacterial colony counts in cerebrospinal fluid (CSF). The pathogens were Haemophilus influenzae type b (54 cases), streptococci (9 cases), meningococci (9 cases), and unknown (6 cases). In 40 CSF specimens obtained 4-12 h after initiation of therapy, cultures were negative in 57% of the ceftriaxone patients and in 42% of the others. The mean falls in the CSF bacterial colony counts were 4.7 and 5.0 log10 colony-forming units/ml, respectively. Mean bactericidal activity in CSF was significantly greater in the ceftriaxone than in the conventional treatment group at the beginning and end of therapy. There were no significant differences in clinical responses or in frequency of complications, except for mild diarrhoea, which occurred in 16 ceftriaxone patients and in 8 in the other group (p less than 0.05).

Adolescent↗