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Biomedical subjects

D W Scheifele

Publications and source records attributed to D W Scheifele.

At least 55 records · Page 3Linked to original sources
PubMed1984

Variant postpartum toxic shock syndrome with probable intrapartum transmission to the neonate.

We report a unique mother-infant pair with variant staphylococcal toxic shock syndrome and probable intrapartum transmission to the neonate. Diagnosis of probable toxic shock was supported by the finding of fever, desquamative skin rash, multi-organ system involvement, and pronounced mucocutaneous manifestations, including strawberry tongue, dermal swelling, pharyngitis, and vulvar edema, although hypotension was absent. Staphylococcus aureus was isolated from the vagina, placenta, chorioamnion, and surface swabs and gastric aspirates of the infant. The isolates produced enterotoxin C but not enterotoxin F, and illness developed in both mother and infant despite preexisting high antibody titers to enterotoxin F and enterotoxin C. This unique mother-infant pair highlights our present lack of knowledge of the precise etiology and pathogenesis of toxic shock syndrome and illustrates the consequent difficulty in clinical diagnosis and laboratory confirmation of this disease in certain patients with atypical presentations.

Adult↗
PubMed1984

Bacterial endotoxins in umbilical cord blood of neonates.

We tested umbilical cord blood from 255 infants for evidence of bacterial endotoxins. Using a Limulus lysate gelation technique, endotoxin-like activity (ELA) was detected in 13 (9.1%) of 142 term infants and in 23 (20.3%) of 113 preterm infants (p less than 0.05), in concentrations ranging from 30 to 3,000 pg Escherichia coli equivalent activity per milliliter of plasma. No factors predisposing to endotoxemia could be detected in term pregnancies but among ELA+ premature infants, placental cultures more frequently revealed gram-negative species (p less than 0.05). Cord blood endotoxemia in the concentrations observed was without obvious consequence in mothers and term infants. Our data confirm the existence of natal endotoxemia, a potential mechanism of perinatal injury.

Endotoxins↗
PubMed1983

Potential significance of colonization with beta-lactamase-producing Haemophilus parainfluenzae in children.

Recent surveys in Vancouver showed most healthy children were colonized with beta-lactamase-producing Haemophilus parainfluenzae. Such organisms might alter the effects of penicillins on throat bacteria by local inactivation. To test this hypothesis in vitro, three isolates of beta-lactamase-producing Haemophilus parainfluenzae were each mixed on a membrane with ampicillin-sensitive strains of Haemophilus influenzae type b or group A Streptococcus pyogenes and exposed to ampicillin. When tested alone, susceptible strains were rapidly killed but when tested together with a beta-lactamase producer, they were protected, indicating efficient ampicillin degradation by Haemophilus parainfluenzae strains. If similar interactions occur in vivo, the effects of beta-lactams on throat bacteria could be significantly altered in the presence of beta-lactamase-producing Haemophilus parainfluenzae.

Ampicillin↗
PubMed1982

Characterization of ampicillin-resistant Haemophilus parainfluenzae.

Carriage of ampicillin-resistant (Ampr) Haemophilus parainfluenzae has become frequent among children in our community, although carriage of Ampr Haemophilus influenzae remains uncommon. In this study we characterized the mechanism of ampicillin resistance in 27 representative isolates of H. parainfluenzae. As determined by isoelectric focusing, each isolate had a TEM-1 beta-lactamase; substrate profiles assessed for enzymes from 10 strains were also consistent with TEM-1 enzyme. Agarose gel electrophoresis revealed a plasmid of 23 to 34 megadaltons in each isolate and a small plasmid (less than or equal to 4 megadaltons) in 14 isolates. Transfer of ampicillin resistance to H. influenzae Rd was achieved during membrane mating with 14 of 15 donors. The transconjugants exhibited high-level ampicillin resistance (greater than or equal to 50 micrograms/ml), which was stable despite serial passage of isolates on antibiotic-free media. The transconjugants tested retained fertility. Cryptic plasmids were discovered in 7 of 25 antibiotic-susceptible H. parainfluenzae isolates. Our data suggest that H. parainfluenzae may play an important role in the exchange of Ampr genes among throat bacteria.

Ampicillin↗
PubMed1981

Ampicillin-resistant Haemophilus influenzae colonizing ambulatory children.

The prevalence of ampicillin sodium-resistant Haemophilus influenzae was determined from throat cultures of 305 ambulatory children. Resistant strains were detected in 3% of children, amounting to 12% of Haemophilus isolates. Factors associated with carriage of ampicillin-resistant strains were sought: only ampicillin exposure was significant. Among children who had received ampicillin or amoxicillin trihydrate within six months, 9% harbored ampicillin-resistant strains compared with 1.4% among those not exposed. Colonization with H influenzae was more frequent following the use of ampicillin, and a higher proportion of isolates was resistant rates was observed with other antibiotics or with factors such as age, sex, otitis history, or day-care center exposure. The association between ampicillin/amoxicillin usage and carriage of ampicillin-resistant strains is increasingly clear. It remains to be determined whether the use of newer antibiotics for otitis also will encourage the development of resistance in H influenzae.

Ambulatory Care↗
PubMed1981

Evaluation of the Limulus test for endotoxemia in neonates with suspected sepsis.

A simplified test for endotoxemia was evaluated in parallel with 198 blood cultures from 115 neonates requiring transitional or intensive care. The Limulus assay disclosed endotoxemia in seven of eight patients with gram-negative bacteremia tested on one or two occasions. It was not specific for bacteremia, especially during the first week of life, when 37 of 112 tests from nonbacteremic infants (33%) were positive. In older infants, positive tests were obtained in only ten of 55 without bacteremia (18%) (P less than 0.07), six of whom had necrotizing enterocolitis as the likely source of endotoxemia. Gram-negative bacteremia existed in 5% of infants (two of 39) less than or equal to 7 days with positive tests and in 37% of older infants (six of 16) (P less than 0.01). Endotoxemia appears to be frequent among infants appearing to have sepsis and may contribute to neonatal morbidity. The Limulus assay may be a useful diagnostic test for coliform bacteremia and necrotizing enterocolitis beyond the first week of life.

Endotoxins↗
PubMed1981

Frequency of ampicillin-resistant Haemophilus parainfluenzae in children.

Ampicillin resistance has been described in Haemophilus species other than Haemophilus influenzae, but its frequency and significance are uncertain. In a throat-culture survey, beta-lactamase-producing Haemophilus parainfluenzae was detected in 192 (72%) of 266 ambulatory children. Ampicillin-resistant H. parainfluenzae was more frequently found in children from three to four years of age (88%) or in those who attended day-care programs (97%) and less frequently in older children and parents (33%). Colonization was unrelated to previous exposure to antibiotics or to a history of otitis media. Colonization with ampicillin-resistant H. parainfluenzae occurred in 88% of subjects with H. influenzae, including all of seven subjects carrying ampicillin-resistant H. influenzae. Colonization with beta-lactamase-producing H. parainfluenzae was 26 times more frequent than with H. influenzae. If the mechanisms and genetics of resistance are the same, H. parainfluenzae may prove to be a vector for spread of resistance genes of H. influenzae.

Ampicillin↗
PubMed1981

Loss of plasmid DNA coding for beta-lactamase during experimental infection with Haemophilus influenzae type b.

Apparent R factor-negative segregation was documented during infection of infant monkeys with two of three strains of ampicillin-resistant Haemophilus influenzae type b. In vitro the bacterial population of one strain (A-Sm) uniformly produced beta-lactamase. All bacteria isolated from blood or cerebrospinal fluid from both animals inoculated with strain A-Sm produced the enzyme. In contrast, 98% and 96% of bacteria from two other strains produced beta-lactamase in vitro. After intranasal inoculation of infant Macacca mulatta with these two strains, bacteria isolated from blood and cerebrospinal fluid uniformly did not produce beta-lactamase. Loss of the beta-lactamase-producing phenotype was associated with loss of plasmid DNA. Strains containing a mixed population of bacteria may undergo spontaneous loss of plasmid DNA during experimental infection. It is suggested that in these strains the bacteria carrying plasmids are less virulent.

Ampicillin↗
PubMed1979

Effect of inoculum size on the susceptibility of Haemophilus influenzae b to beta-lactam antibiotics.

The current prevalence of ampicillin-resistant Haemophilus influenzae b meningitis requires accurate knowledge of susceptibility to alternative antibiotics. One variable affecting susceptibility is inoculum size. We studied the susceptibility of 200 clinical isolates of H. influenzae b to ampicillin, carbenicillin, and cefamandole at inocula of 10(5) and 10(7) CFU by two techniques. Fifty ampicillin-susceptible and fifty ampicillin-resistant strains were tested for susceptibility to ampicillin by broth dilution while 100 of each were tested by agar dilution. An inoculum effect was found, being greatest with the ampicillin-resistant strains. The range of minimal inhibitory concentrations for the resistant strains was 25 to 800 microgram of ampicillin per ml at an inoculum of 10(5) and 2,000 to less than 6,000 microgram of ampicillin at 10(7); 1.0 to 150 microgram of carbenicillin per ml at 10(5) and 6.2 to 2,000 microgram of carbenicillin per ml at 10(7); 0.4 to 2.0 microgram of cefamandole at 10(5) and 1.0 to 125 microgram/ml at 10(7). Because of this inoculum effect, we would not recommend the use of carbenicillin or cefamandole for therapy of ampicillin-resistant H. influenzae meningitis.

Anti-Bacterial Agents↗
PubMed1979

Comparison of two antigen detection techniques in a primate model of Haemophilus influenzae type b infection.

Rapid diagnosis of Haemophilus influenzae type b meningitis is possible using immunological tests for capsular antigen (polyribophosphate, PRP), such as countercurrent immunoelectrophoresis (CIE) and latex particle agglutination (LPA). We compared two tests in monkeys with evolving, serially quantitated H. influenzae type b bacteremia (n = 23) and meningitis (n = 21). In vitro, the LPA test was sensitive to 0.5 ng of PRP/ml of saline, and the CIE test was sensitive to 1.0 ng/ml; in serum, however, CIE detected 5.0 ng of PRP/ml, whereas the sensitivity of LPA was unchanged. LPA detected PRP earlier in the course of bacteremia (mean, 12 h after onset; range, 4 to 36 h) than did CIE (mean, 45 h; range, 4 to 168 h) (P less than 0.01). A positive LPA test required greater than or equal to 100 bacteria per ml of blood, whereas CIE required greater than or equal to 1,000/ml. PRP accumulated with continuing blood stream infection, aiding detection of low-grade bacteremia. LPA detected antigen in cerebrospinal fluid (CSF) earlier in the course of meningitis and at a lower bacteria density than did CIE. Both methods detected antigen reliably with greater than or equal to 1,000 bacteria per ml of CSF. A close correlation existed between CSF concentrations of capsular antigen and bacteria (r = 0.90, P less than 0.001). We conclude that the LPA method permits earlier diagnosis of H. influenzae type b infection in part because of its greater sensitivity.

Animals↗
PubMed1978

Home-testing for recurrent bacteriuria, using nitrite strips.

Follow-up of children with recurrent urinary infections would be simplified by an accurate home-testing program for detection of infection. We provided nitrite test strips to the parents of 30 girls with recurrent urinary infection to determine if twice weekly home testing of first-voided urine could reliably detect infection. Infections were documented by dip slides or colony counts indicating more than 10(5) bacteria per milliliter of urine. Twenty-four families (80%) complied over a mean study period of 11 months, detecting 28 of 30 episodes of bacteriuria (93%). No false-positive tests occurred. Urinary nitrate, the substrate for nitrite production by bacteria, was universally present (greater than 100 microgram/ml) in 80 children. The nitrite test is useful for home follow-up observation of children at high risk of bacteriuria if applied repeatedly by motivated parents.

Adolescent↗
PubMed1978

Rapid diagnosis of Hemophilus influenzae type b infections by latex particle agglutination and counterimmunoelectrophoresis.

Latex particle agglutination and counterimmunoelectrophoresis techniques were compared in a clinical trial to demonstrate their sensitivity, specificity, and usefulness in the rapid diagnosis of invasive Hemophilus influenzae type b disease. LPA, a simplified LPA performed by house officers, and CIE used in this study detected 0.2, 0.5, and 1 to 10 ng/ml of Hib capsular antigen, respectively. One hundred-six illnesses suspected of being caused by Hib were evaluated prospectively by these assays. A total of 39 of these were confirmed by culture or detection of antigen or both. LPA and simplified LPA were more sensitive and specific than CIE in the diagnosis of Hib disease (P less than 0.01), especially in invasive disease other than meningitis. LPA is inexpensive, can be performed quickly, and detects all invasive Hib infections. The results emphasize the usefulness of antigen detection in the rapid diagnosis of Hib infections, demonstrate that LPA is more sensitive and specific than CIE, and can be conveniently performed by physicians.

Antigens, Bacterial↗
PubMed1978

Ventricular involvement in experimental Hemophilus influenzae meningitis.

We determined the frequency of ventricular involvement during Hemophilus influenzae type b meningitis in ten bacteremic infant rhesus monkeys. Meningitis was defined as cerebrospinal fluid obtained from the lumbar subarachnoid space or cisterna magna containing bacteria and ten or more leukocytes per mm3. HIB were cultured from 22 of 22 ventricular CSF samples. In 17 of 18 comparisons of bacterial density in ventricular and cisternal CSF, the values were within one log10: similarly, 5 of 8 quantitative ventricular-lumbar comparisons were within one log10. This concordance was present at bacterial densities of 2 x 10(1) to 1 x 10(9) CFU/ml. When discordance was present, the ventricular CSF contained more bacteria. In 15 of 20 comparisons of leukocyte density in ventricular and cisternal CSF, the ventricular pleocytosis was lower (mean ventricular/cisternal ratio 0.08). We conclude that infection of the lateral cerebral ventricle is a uniform feature of HIB meningitis in infant monkeys, but the cellular inflammatory component is less.

Animals↗