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Biomedical subjects

J D Nelson

Publications and source records attributed to J D Nelson.

At least 199 records · Page 11Linked to original sources
PubMed1975

Breast abscess during the neonatal period. A review.

Thirty-nine infants ranging in age from 1 to 7 weeks had breast abscess. The lesion occurred more frequently in girls (girl/boy ratio, 1.8:1), but this was due to cases developing after 2 weeks of age. During the first two weeks, the sex incidence was equal. No bilateral lesions were recorded. Eighty-four percent of the abscesses developed during the first three weeks of life. In general, there was a lack of systemic manifestations; a body temperature of 38.3 C (101 F) or more was found in only 25.7% of the patients and constitutional signs were found in four patients. Abscess cultures were obtained in 36 cases: 32 yielded Staphylococcus aureus, two Salmonella, one Escherichia coli, and one yielded both S aureus and E coli. Of six patients available for follow-up, decreased breast tissue was noted in two.

Abscess↗
PubMed1975

Osteomyelitis in infants and children. A review of 163 cases.

One hundred sixty-three cases of osteomyelitis in infants and children were seen at our hospital during the past 15 years. There were twice as many boys as girls. Staphylococcus aureus was the major etiologic agent, being identified in 61% of the cases. Gram-negative bacteria were responsible for only 14 cases (9%). The femur, the tibia, or the humerus were affected in 103 of the 152 patients with single bone involvement. Ostoemyelitis of more than one bone was seen in 11 cases (7%). Associated joint infectin was confirmed in 29 patients. There were no deaths. Surgical drainage was carried out in 81 cases (50%). Ten patients had recurrent or persistent drainage and one developed a Brodie abscess. Of the patients with S aureus osteomyelitis, chronic disease occurred in 19% of those receiving parenterally administered antibiotics for three weeks or less, but in only one patient (2%) of those who received parenteral antibiotics longer than three weeks.

Acute Disease↗
PubMed1975

Clinical pharmacology of ticarcillin in the newborn infant: relation to age, gestational age, and weight.

Ticarcillin, a new penicillin derivative with greater in vitro activity against Pseudomonas than carbenicillin, was given as a single dose of 50 mg/kg intramuscularly on 61 occasions to 54 neonates and young infants. The serum concentrations and rate of elimination varied considerably depending upon gestational age, chronological age, and body weight. Peak serum concentrations depended principally upon the volume of distribution which approximated the extracellular fluid volume of the neonate. The plasma clearance and serum half-life of the drug were determined. From these pharmacokinetic data appropriate groupings according to age and body weight were made and dosages and intervals of administration predicted for clinical trials of efficacy with repeated doses.

Age Factors↗
PubMed1975

Colicin types of Shigella sonnei in relation to antibiotic resistance.

Colicin typing of 436 strains of Shigella sonnei isolated in Dallas during a 10-year period was performed to determine whether resistance to ampicillin was associated with a single strain or was widespread among all S. sonnei types. One hundred ninety-three strains collected during a period of eight and one-half years when ampicillin resistance was 1.6% were available for retrospective review. During the last one and one-half years of study, 20.6% of the 243 strains that represented almost all S. sonnei isolated in Dallas were resistant to ampicillin. More than 50% of the strains collected annually were colicin type 9,22% were untypable, and seven other types were less frequently encountered. Resistance to ampicillin increased slightly from 1.5% to 9.5% among the type 9 strains, and one type 8 strain (2.9%) was resistaiple resistance to seven antibiotics tested was found mainly in untypable strains. Thus it appears that the abrupt increase in ampicillin resistance in mid-1972 was due principally to resistance in a single biotype, and that resistance is not widespread among all types of S. sonnei.

Adult↗
PubMed1975

Comparative efficacy of cephalexin and ampicillin for shigellosis and other types of acute diarrhea in infants and children.

Most ampicillin-resistant Shigella are susceptible to cephalexin. Randomized treatment with cephalexin or ampicillin was given to 154 infants and children with acute diarrhea. Rectal swab cultures revealed Shigella in 42%, Salmonella in 6%, enteropathogenic Escherichia coli in 2%, and no pathogen in 50%. Cephalexin failed to eradicate Shigella after 5 days of treatment in 76% of patients as contrasted with 28% of ampicillin-treated patients with susceptible organisms. Shigella persisted in 78% of ampicillin-treated patients with resistant organisms. Diarrhea lasted more than 5 days in 43% of cephalexin-treated patients, in 56% of the ampicillin group with resistant organisms, but in only 9% of ampicillin-treated patients with susceptible organisms. The failure of cephalexin was due to the relatively high minimal inhibitory concentrations and minimal bacterial concentrations of 5 or 10 mug/ml and, although serum concentrations were twice the minimal bacterial concentration, they were not sufficient to demonstrate killing by the serum dilution method. In vitro susceptibility or resistance of Shigella to ampicillin correlated with clinical success or failure. Cephalexin is not a suitable drug for treatment of shigellosis in patients with ampicillin-resistant organisms.

Ampicillin↗
PubMed1975

Effects of mercuric chloride on growth and morphology of selected strains of mercury-resistant bacteria.

A survey of the comparative cytological effects of growth in the presence of mercury by a group of mercury-resistant bacterial cultures and a characterization of the process of bacterial adaptation to Hg2+ ion was accomplished. Mercury resistance was found to be dependent upon the ability to volatilize mercury from the medium and upon the amount of mercury accumulated by the cells. The results indicate that most cultures which adapt to growth in the presence of HgCl2 exhibit extensive morphological abnormalities. Significant effects are delay in the onset of growth and cell division and numerous structural irregularities associated with cell wall and cytoplasmic membrane synthesis and function. A detailed analysis of the adaptation process and the resulting effects on morphology was performed on an Enterobacter sp. During the period preceding active multiplication, a selection for mercury-resistant mutants occurred. It was also demonstrated that growth commenced only at a specific threshold concentration of HG2+.

Bacteria↗
PubMed1975

Role of bacteria in bioaccumulation of mercury in the oyster Crassostrea virginica.

An investigation of mercury-resistant bacteria was undertaken to determine their role in the accumulation of mercury in a simplified food chain. Oysters (Crassostrea virginica) were maintained in a closed system, sealed aquarium with stirred, aerated water containing 10 mug of 203-HgCl2 per liter. Uptake of 203-Hg by oysters held under control conditions was compared with that of 203-Hg uptake by oysters under similar conditions except that mercury-accumulating and mercury-metabolizing species of Pseudomonas, isolated from Chesapeake Bay, were added to the experimental oysters. After incubation for 4 days, the major portion ofthe 203-Hg in the water column was found to be associated with the microparticulate fraction, corresponding to a rise in total viable count. Mercury accumulation in the oysters was significantly higher in the gill and visceral tissue than other tissue. Mercury concentrations were 200 times greater in tissue fractions of oysters dosed with mercury-metabolizing bacteria compared with the oysters held under control conditions without mercury-metabolizing bacteria.

Analysis of Variance↗
PubMed1975

Distribution and significance of fecal indicator organisms in the Upper Chesapeake Bay.

Total viable aerobic, heterotrophic bacteria, total coliforms, fecal coliforms, and fecal streptococci were enumerated in samples collected at five stations located in the Upper Chesapeake Bay, December 1973 through December 1974. Significant levels of pollution indicator organisms were detected at all of the stations sampled. Highest counts were observed in samples collected at the confluence of the Susquehanna River and the Chesapeake Bay. The indicator organisms examined were observed to be quantitatively distributed independently of temperature and salinity. Counts were not found to be correlated with concentration of suspended sediment. However, significant proportions of both the total viable bacteria (53%) and fecal indicator organisms (greater than 80%) were directly associated with suspended sediments. Correlation coefficinets (r) for the indicator organisms examined in this study ranged from r = 0.80 to r = 0.99 for bottom water and suspended sediment, respectively. Prolonged survival of fecal streptococci in most of the sediment samples was observed, with concomitant reduction of the correlation coefficient from r = 0.99, fecal streptocicci to total coliforms in water, to r = 0.01, fecal streptococci to fecal coliforms in sediments. The results of this study compared favorably with fecal coliforms: fecal streptococci ratios for the various sample types. Characterization of organisms beyond the confirmed most-probable-number procedure provided good correlation between bacterial indicator groups.

Cell Count↗
PubMed1974

In vitro susceptibility of Shigella strains to trimethoprim and sulfamethoxazole.

Trimethoprim and sulfamethoxazole were tested alone and in combination against 227 recently isolated Shigella strains. Variations in medium constituents and inoculum size were used to determine the optimal testing conditions. The plate dilution method with addition of 5% lysed horse blood to the susceptibility test medium and an inoculum size of 10(2) organisms was found to provide satisfactory results. All 227 strains were inhibited by low concentrations of trimethoprim, and all were susceptible to the combination of 0.06 mug of trimethoprim per ml and 1.25 mug of sulfamethoxazole per ml. Sixteen percent of these strains were resistant to ampicillin, 33% to tetracycline, 15% to chloramphenicol, and 27% to cephalothin. Based on these in vitro observations, trimethoprim and sulfamethoxazole appear worth evaluating for treatment of shigellosis due to multiply antibiotic-resistant strains.

Drug Combinations↗