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Biomedical subjects

D A Goldmann

Publications and source records attributed to D A Goldmann.

At least 91 records · Page 5Linked to original sources

Performance of a solid phase enzyme immunoassay for detection of group A streptococci in a pediatric office laboratory as refereed by a hospital laboratory.

We evaluated the performance of a new rapid solid phase enzyme immunoassay, SUDS Group A Strep (MUREX Corp., Norcross, GA) for the detection of Group A beta-hemolytic streptococci in a pediatric office practice. Duplicate throat swabs were obtained from 341 children with pharyngitis. One swab was used in the SUDS test and the other was cultured in the office laboratory. Office SUDS and culture (sheep blood agar plate, aerobic 24-hour incubation) were compared with culture using reference techniques (sheep blood agar plate, anaerobic 48-hour incubation) in a hospital laboratory. Compared with hospital laboratory culture, the sensitivity of office SUDS (73.8%) was superior to that of office culture (66.6%) at P = 0.05. Specificities were 93.1 and 98.6%, respectively; positive predictive values were 86.1 and 96.6%; and negative predictive values were 85.9 and 83.5%. The sensitivity and specificity of SUDS compared with office culture were 88.5 and 87.8%, respectively, but would have been 93 and 94% had hemolyzed media not been used on several occasions in the office culture procedure. We conclude that SUDS Group A Strep was significantly more sensitive than throat cultures as performed in a typical pediatric practice although the performance of office cultures could have been improved by standard quality control techniques.

Bacteriological Techniques↗

Fifteen-year experience with bloodstream isolates of coagulase-negative staphylococci in neonatal intensive care.

Investigators worldwide, as well as the neonatologists and infection control team at our hospital, have reported that the incidence of coagulase-negative staphylococcal bacteremia in critically ill neonates has increased dramatically in recent years. To investigate these claims, we examined the results of all blood cultures obtained from 1970 to 1984 in our neonatal intensive care unit. Throughout this study period, coagulase-negative staphylococci were prominent blood culture isolates (crude overall incidence of 4.4 positive bacteremia workups per 100 neonates admitted; range, 2.5 to 6.7), representing 26.3 to 69.6% of all positive cultures. There was no significant increase in incidence over time by analysis of linear trend. Detailed analysis of data from 1976 and 1982 (two selected years for which complete information concerning culturing practices and patient characteristics was available) revealed that these observations were not explained by changes in the frequency of blood culturing. In both 1976 and 1982, the probability that a blood culture would grow coagulase-negative staphylococci increased steadily from 2 to 3% shortly after admission to reach a level of about 12% in week 3 of hospitalization, before declining to an intermediate level thereafter. This pattern is more consistent with nosocomial bacteremia than with contamination of blood cultures. Contrary to clinical reports, coagulase-negative staphylococci have been the principal pathogens isolated from blood cultures in our neonatal intensive care unit since at least 1970, with no measurable increase over the subsequent 14 years.

Coagulase↗

Effect of preoperative shampoos with chlorhexidine or iodophor on emergence of resident scalp flora in neurosurgery.

Wound contamination with endogenous bacterial scalp flora plays an important role in the pathogenesis of postoperative neurosurgical infections. To assess the effect of preoperative antiseptic shampoos on the emergence of resident scalp flora during surgery and subsequent wound contamination, we randomized 151 neurosurgical procedures into four study groups: group A--preoperative shampoos with chlorhexidine, surgical scalp preparation with chlorhexidine; group B--no shampoos, surgical preparation with chlorhexidine; group C--shampoos with iodophor, surgical preparation with iodophor; group D--no shampoos, surgical preparation with iodophor. Quantitative cultures of the scalp were obtained preoperatively and at the end of surgery, and qualitative wound cultures were taken prior to wound closure. Group A had the lowest concentration of bacteria on the scalp both preoperatively and postoperatively (median range = 30 [0-5.7 x 10(5)] and 0 [0-2.5 x 10(3)] respectively). Group A also had significantly fewer positive postoperative scalp cultures (29%) than groups B (51%), C (58%), and D (53%) (P less than 0.05), as well as fewer positive wound cultures (20% v 25%, 42%, and 30% respectively). A density of bacteria on the scalp of greater than 10(2)/4cm2 best predicted the presence of bacteria in the wound. Repeated preoperative shampoos with chlorhexidine reduce intraoperative emergence of resident skin flora and subsequent contamination of the wound.

Adolescent↗

Coagulase-negative staphylococcal bacteremia in the changing neonatal intensive care unit population. Is there an epidemic?

A fivefold increase in the number of cases of nosocomial coagulase-negative staphylococcal bacteremia was investigated in a neonatal intensive care unit between 1975 and 1982. This apparent outbreak was not the result of increased isolation of coagulase-negative staphylococci from blood cultures nor an increased frequency with which blood cultures were obtained. Rather, it was attributable to a dramatic increase in the overall probability that a positive blood culture would be interpreted as "bacteremia" as opposed to a contaminant by both physicians and infection control staff. Specifically, there had been a 62.3% increase in neonatal intensive care unit bed use by very-low-birth-weight (less than 1000-g) infants between 1975 and 1982, and in both years, positive blood cultures were 3.8 times as likely to be perceived as clinically significant if obtained from such tiny infants. The growing number of very-low-birth-weight babies occupying neonatal intensive care unit beds, coupled with the observation that blood cultures positive for coagulase-negative staphylococci are almost four times as likely to be perceived as clinically significant if obtained from extremely premature infants, may account for the reported increase in nosocomial coagulase-negative staphylococcal bacteremia.

Boston↗

Prevention of nosocomial respiratory syncytial virus infections through compliance with glove and gown isolation precautions.

To determine whether increased compliance with a policy of glove and gown isolation precautions could reduce the high rate of nosocomial respiratory syncytial virus (RSV) infection on an infant and toddler ward, we conducted a longitudinal intervention trial during three RSV seasons, from 1982 to 1985, with an intervention to increase compliance introduced midway through the second season. The risk of acquiring RSV infection in the hospital was adjusted for the intensity of nosocomial exposure to the virus by assigning each study week to one of five strata, defined by the proportion of hospital days on which virus was shed by children on the ward. Overall, 37 patients acquired nosocomial RSV infections during 7547 days at risk. The adjusted relative risk, comparing the infection rate in the period before the intervention (when compliance with isolation precautions was noted in only 38.5 percent of the observed patient contacts) with the infection rate in the postintervention period (when compliance more than doubled) was 2.9 (95 percent confidence interval, 1.5 to 5.7). Rates of nosocomial RSV infection increased linearly with increasing levels of exposure to patients shedding virus, but the rise in the infection rate with increasing exposure was less than one fourth as great (P less than 0.001) in the period after the intervention as it was before. We conclude that glove and gown precautions can substantially reduce the nosocomial transmission of RSV, particularly with increasing exposure to patients shedding the virus.

Cross Infection↗

New microbiological techniques for hospital epidemiology.

Infection control teams rely on microbiology laboratories for accurate, reproducible data to trace the spread of microorganisms in the hospital. Since few problems are recognized immediately, laboratories should save important nosocomial pathogens so that outbreak strains will be available for analysis by more sophisticated techniques, particularly since automation has reduced the amount of epidemiologically useful data generated by routine procedures. Traditional supplemental reference procedures include phage typing, biotyping, serotyping and bacteriocin typing. Recently, analysis of antibiotic resistance determinants has provided the hospital epidemiologist with additional tools. Resistant strains have been characterized by their production of specific antibiotic inactivating enzymes. Agarose gel electrophoresis and restriction endonuclease analysis of plasmid DNA have permitted precise characterization of nosocomial strains, and the spread of antibiotic resistance genes can now be followed by sensitive and specific DNA probes. DNA probes also show promise for distinguishing nosocomial strains bearing known virulence factors from strains with less pathogenic potential. Molecular genetics techniques have found an additional role in elucidating the epidemiology of nosocomial viruses, especially the herpesviruses.

Bacteriological Techniques↗

Confounding and the analysis of multiple variables in hospital epidemiology.

Most information in hospital epidemiology comes from observational studies of hospitalized patients rather than planned experiments, and in such observational studies the characteristics of study patients may vary widely, even within a single hospital. Any comparison between hospital populations will usually contain additional, unintended contrasts among patients with varying degrees of health. Adult patients, for example, may have vastly different underlying diseases, and infants may be of substantially different birth weights. We used both underlying disease and birth weight as indices of the basic severity of illness in order to adjust for confounding by differences in underlying disease in reanalyses of several published studies. We give an example in which differing birth weights among groups of infants compared artifactually double the apparent effect of nosocomial infections as a cause of mortality, and another example in which differing degrees of severity of underlying illness artifactually halve the apparent effect of appropriate antibiotics in preventing death from bacteremia with gram-negative bacilli. We describe simple intuitive methods based on stratification, adapted from chronic disease epidemiology, to remove confounding effects during analyses.

Birth Weight↗

Impact of rapid antigen tests for group A streptococcal pharyngitis on physician use of antibiotics and throat cultures.

Using case scenarios and an interview guided by a decision tree diagram, the clinical strategies of 150 physicians (50 private pediatricians, 50 health maintenance organization pediatricians and 50 pediatric residents) were assessed for the management of pharyngitis under three conditions: (1) no rapid antigen detection test available for diagnosing Group A streptococcal disease; (2) antigen test result available in 20 minutes; and (3) antigen test result available in 4 hours. The sensitivity of the antigen test was designated as 0.95 if the growth of rare or few Group A streptococci on throat culture was discounted and 0.82 if any growth was considered significant, and the specificity was set at 0.98. In a standardized pediatric case with a prior probability of Group A streptococcal disease of 0.58, 84% of clinicians would order a 20-minute test and 39% would order a 4-hour test. The 20-minute test would reduce throat culture use by 54%, reduce the proportion of patients exposed to antibiotics from 86% to 65% and reduce total antibiotic treatment days by 13.8%. Effects would be less pronounced for a low probability case or if results of antigen testing were not available for 4 hours. Provided a test with a documented high sensitivity and specificity were used, a rapid antigen test with results promptly available would substantially reduce throat culture use and unnecessary antibiotic exposures in children with a moderate prior probability of streptococcal disease.

Anti-Bacterial Agents↗

Pseudomonas cepacia: biology, mechanisms of virulence, epidemiology.

Pseudomonas cepacia, originally described as a plant pathogen, has emerged as an important cause of infection in altered hosts, particularly in the hospital setting. This organism's ability to survive and proliferate in a variety of solutions, medications, and even disinfectants and antiseptics has resulted in numerous clusters of common-source nosocomial infections. Many patients exposed to P. cepacia are merely colonized, but serious infections, including surgical and burn wound infections, bacteremia, meningitis, pneumonia, peritonitis, and urinary tract infections, are not rare. The virulence properties of this pathogen remain poorly characterized. Recently, P. cepacia has been reported in some cystic fibrosis centers as an increasingly frequent pulmonary pathogen. This trend has caused considerable concern because of reports of occasional cases of fulminant necrotizing pneumonia and bacteremia. Conversely, many patients with CF who become colonized with this organism have no ill effects. The epidemiology of P. cepacia in the CF population is unclear, but some patients probably acquire the organism from colonized siblings with CF. Circumstantial evidence suggests that the organism may also be acquired in the hospital. Treatment of infections is exceedingly difficult, particularly in patients with CF, because P. cepacia is resistant to a broad range of antibiotics.

Cross Infection↗

Risk of illness after exposure to a pediatric office.

To determine whether well children visiting a pediatrician's office are at risk of acquiring common communicable diseases, we conducted a prospective cohort study during the winter of 1983-1984. The occurrence of respiratory or gastrointestinal illness or fever in young children in the week after a visit to a pediatric office (office group) was compared with the occurrence of these illnesses in a similar group of children (home group) not exposed to the office during the study period. One home comparison subject was matched by age and sex to each of 127 children three years of age and under who were seen for well-child care in a private pediatric office with a common waiting room. The adjusted relative risk of the development of illness during the study week for the office group as compared with the home group was 0.95 (95 per cent confidence interval, 0.66 to 1.37), indicating no effect. We conclude that exposure to a pediatric office is not an important cause of the common infections in young children that have incubation periods of a week or less.

Child Health Services↗

Purification and characterization of Haemophilus influenzae pili, and their structural and serological relatedness to Escherichia coli P and mannose-sensitive pili.

Haemophilus influenzae pili were purified, and their physical and serological properties were examined. The solution properties of the pili were determined, and then a purification scheme involving repeated cycles of precipitation and solubilization was developed. The purified pili from one type b isolate (A02) were found to consist of multiple copies of a 25,000 mol wt subunit. Amino-terminal sequence analysis of A02 pili was carried out to 40 amino acid residues, and a remarkable degree of sequence homology was found with E. coli P and mannose-sensitive (MS) pili (27.5 and 25% homology, respectively). Purified A02 pili were found to be highly immunogenic, and serological analysis by enzyme-linked immunosorbent assay and whole piliated cell agglutination revealed significant cross-reactivity between A02 pilus antiserum and the pili of seven other H. influenzae strains tested (heterologous titers = 2-100% of the homologous titer). Cross-reactivity was also observed between the H. influenzae pili (five of eight strains tested) and the P pili from E. coli strains HU849 and 3669; no cross-reactivity was detected with MS pili from E. coli strain H10407 and C94. The structural similarities between H. influenzae and E. coli P and MS pili suggest a common gene ancestry.

Adult↗

Comparison of a new, rapid enzyme-linked immunosorbent assay with latex particle agglutination for the detection of Haemophilus influenzae type b infections.

A new, rapid enzyme-linked immunosorbent assay (ELISA) for the detection of polyribosylribitol phosphate of Haemophilus influenzae type b was compared with a commercially available latex particle agglutination (LPA) system (Bactigen; Wampole Laboratories, Cranbury, N.J.). By adding specimens and the anti-polyribosylribitol phosphate immunoglobulin-enzyme conjugate to the solid phase in a single step, it was possible to complete the ELISA procedure in 30 min. The ELISA was capable of detecting 0.3 ng of polyribosylribitol phosphate per ml in cerebrospinal fluid, 0.6 ng/ml in urine, and 1.2 ng/ml in serum; the in vitro sensitivity of LPA in these body fluids was 0.6, 0.3, and 0.3 ng/ml, respectively. Both procedures detected polyribosylribitol phosphate in specimens from 25 patients with bacteriologically confirmed H. influenzae type b infections. The specificity of ELISA appeared to be superior to that of LPA. ELISA was positive in only one of seven patients who had a positive LPA test and a clinical illness that was not compatible with haemophilus infection. Moreover, five patients with bacteriologically confirmed infections due to other pathogens (Streptococcus pneumoniae type 14 [two patients], Neisseria meningitidis group C, Escherichia coli K100, and Staphylococcus aureus) had false-positive LPA tests; only two (E. coli and S. aureus) were positive by ELISA. A total of 108 samples from 61 patients who had no evidence of haemophilus infections were negative by both procedures. The ELISA is a rapid, sensitive, and specific alternative to LPA for the detection of haemophilus polyribosylribitol phosphate.

Animals↗

Empyema in children: clinical course and long-term follow-up.

Sixteen patients, aged 1 month to 15 years, were studied to determine the clinical course and long-term outcome of empyema in previously healthy children. The pathogens responsible were Haemophilus influenzae type b (seven patients), Staphylococcus aureus (five patients), Streptococcus pneumoniae (three patients), and viridans group Streptococcus (one patient). All patients had loculated fluid showing on chest roentgenographs. Chest tube drainage yielded 20 to 1,495 mL (mean 293 mL) during the first three days, accounting for 83% of total drainage. Chest tubes were removed after three to 17 days (mean ten days). Only slight roentgenographic improvement showed during chest tube drainage. Three patients required an open thoracotomy because of an unsatisfactory clinical response. Hospitalization ranged from eight to 77 days (mean 25 days). All patients had residual pleural thickening shown on chest roentgenographs taken at discharge. Thirteen patients were seen 5 to 140 months (mean 66 months) after discharge. Findings from physical examination were normal in 12 of the 13 patients. Pulmonary function tests in ten of the 13 patients revealed (mean percent predicted +/- 1 SD): vital capacity 92 +/- 12, residual volume 85 +/- 31, total lung capacity 92 +/- 13, peak flow rate 96 +/- 17, forced expiratory volume in 1 second 90 +/- 13, and maximal mid-expiratory flow rate 93 +/- 25. In all but one patient, findings on chest roentgenograms were normal or showed slight pleural thickening. Children with loculated empyema can be treated successfully with antibiotics and chest tube drainage. Few patients require open drainage, and further surgery is rarely required. The long-term outcome is excellent.

Adolescent↗

Clinical and bacteriological responses to three antibiotic regimens for acute exacerbations of cystic fibrosis: ticarcillin-tobramycin, azlocillin-tobramycin, and azlocillin-placebo.

In a randomized, double-blind study, cystic fibrosis patients 11-30 years of age with an acute exacerbation of their pulmonary disease were treated with either ticarcillin-tobramycin, azlocillin-tobramycin, or azlocillin-placebo for 10 days. There was significant improvement in Shwachman scores and pulmonary function tests. Concentrations of sputum bacteria were significantly reduced, but after therapy patients had a mean of 10(7) bacteria/ml of sputum. Pseudomonas was transiently eliminated in only one patient. The three regimens had similar impacts on pulmonary function and sputum bacterial concentration. Antibiotic resistance was noted more frequently in the azlocillin-placebo group, but this trend was not statistically significant. Improvement in pulmonary function did not correlate with bacteriological response. Four weeks after discharge, 62% of the improvement in forced expiratory volume in one second and 75% of the improvement in vital capacity remained, but concentrations of sputum bacteria had returned to pretreatment levels, and antibiotic-resistant bacteria persisted.

Acute Disease↗