Comparative evaluation of three recombinant antigen-based enzyme immunoassays for detection of IgM and IgG antibodies to human parvovirus B19.

BACKGROUND: Diagnosis of acute and past infection with parvovirus B19 is based on detection of IgM and IgG antibodies. OBJECTIVES: To evaluate two commercial recombinant antigen-based enzyme immunoassay (EIA) test kits for detection of IgM and IgG antibodies to parvovirus B19 and to compare the commercial EIAs to in-house EIA test procedures. STUDY DESIGN: A panel of 121 sera was used to compare the three IgM EIAs. The panel included 84 sera submitted for parvovirus B19 testing and 37 sera that were IgM positive for other viral pathogens. The same serum panel plus an additional 14 sera submitted for B19 testing was used to compare the three IgG EIAs. The commercial EIAs were performed according to manufacturers' instructions. Using the in-house EIA test procedures as the reference, sensitivity and specificity for each of the commercial EIAs was determined. RESULTS: The commercial B19 IgM EIAs showed agreements of 95.0 and 93.4% to the in-house IgM EIA. Compared to the in-house B19 IgM EIA, the commercial B19 IgM EIAs were 97.4 and 97.5% sensitive, respectively. Specificities were 93.5 and 91.4%, respectively. Sensitivities for the commercial IgG EIAs, compared to in-house IgG EIA, were 88.0 and 85.2%, respectively, and specificities were 94.1 and 98.0%. CONCLUSION: We found that the commercial parvovirus B19 IgM and IgG EIAs are comparable to standard in-house EIAs and are suitable for testing for B19 antibodies in human sera.

Negotiating. Biases physicians bring to the table.

What are some of the obstacles that physicians face as they seek to become more effective at the bargaining table? The author's thesis, based on experience in both the classroom and the front lines of medical practice, is that physicians face a set of systematic "biases" derived from physician training and professional culture that make negotiation especially difficult for them. They outline the biases they have observed, explore some possible explanations, and suggest solutions for physicians who wish to negotiate more effectively.

Detection of the human immunodeficiency virus genome with a biotinylated DNA probe generated by polymerase chain reaction.

A non-radiolabelled DNA probe was developed for detection of the human immunodeficiency virus type 1 (HIV-1) genome using the polymerase chain reaction (PCR) technology. Primers amplifying a 395 base pair segment of a portion of the polymerase region of the HIV-1 genome were used both to amplify sample target DNA and to generate a biotinylated DNA probe used in Southern blot hybridization. This probe performed as well as one produced by nick translation using biotinylated nucleotides or an enzyme labelled oligonucleotide probe.

Comparison of detection of antibody to the acquired immune deficiency syndrome virus by enzyme immunoassay, immunofluorescence, and Western blot methods.

There was 100% agreement between enzyme immunoassay (EIA) (Abbott Laboratories), Western blot, and indirect immunofluorescence (IF) when these three methods were used to measure antibody to the acquired immune deficiency syndrome (AIDS) virus in sera from 142 high-risk individuals, indicating that IF was a sensitive alternative method for detecting antibody to this agent. Thirty-two (64%) of 50 EIA-positive plasma specimens from a blood bank and 6 (21%) of 28 EIA-positive sera from alternative testing sites were negative by IF. In addition, two EIA-negative sera from the latter group were positive by IF. Western blotting agreed with IF on those 40 specimens which gave discrepant results by EIA and IF. The IF method was determined to be equal to Western blotting in sensitivity and specificity for detection of AIDS antibody, and it was found to be useful for confirming positive EIA results, especially in specimens from individuals in low-risk groups.

Enzyme immunoassay versus plaque neutralization and other methods for determination of immune status to measles and varicella-zoster viruses and versus complement fixation for serodiagnosis of infections with those viruses.

Results by an enzyme immunoassay method (EIA) performed at one serum dilution and results by indirect immunofluorescence (IFA) and hemagglutination inhibition (HI) tests performed at step dilutions were correlated with results by a neutralization test (50% plaque neutralization [PN]) performed at step dilutions on single serum samples for serologic evaluation of immunity status to measles virus. PN results were taken as true indicators of immunity, and the other tests were evaluated on that basis. The predictive value of a positive result being positive also by PN was 95.3% for HI and 93.3% for EIA and IFA. The predictive value of a negative result being negative also by PN was 81.1% for HI, 100% for EIA, and 75.0% for IFA. A similar study on immunity status to varicella-zoster virus by EIA and by an anticomplement immunofluorescence test versus PN showed a 100% predictive value of a positive or negative result by EIA. By the anticomplement immunofluorescence test, the predictive value of a positive result was 97.7%, and that of a negative result was 88.5%. Studies on the comparative ability of EIA versus complement fixation (CF) to detect significant changes in antibody concentration between acute-phase and convalescent-phase serum samples indicative of a current infection were also done. Both tests were satisfactory for the serodiagnosis of measles or varicella-zoster virus infections. However, EIA was preferable to CF because it was less technically difficult, less labor intensive, and could be performed on sera that were anticomplementary in CF reactions.

Antibody response to cytomegalovirus polypeptides captured by monoclonal antibodies on the solid phase in enzyme immunoassays.

Antibodies to different cytomegalovirus (CMV) polypeptide antigens, captured by monoclonal antibodies coated on the solid phase of an enzyme immunoassay test, were analyzed in 42 serum pairs submitted for serodiagnosis of CMV infection. Three CMV antigens, captured on the solid phase by three monoclonal antibodies of different specificities, designated CH92-1, CH65-1, and CH16-1, were glycoproteins A (gA), gC, and gD, respectively; and one antigen, captured by CH23, was a polypeptide with an apparent molecular weight of 150,000, possibly associated with the nucleocapsid. Of these four CMV antigens, gA captured by CH92-1 was most effective in eliciting an antibody response. Antibody to this antigen was present in serum samples at a higher concentration in primary and reactivated infection and persisted longer than did antibody to the other tested antigens. In contrast, antibody to antigen captured by CH23 was at a lower concentration, rose more slowly in infection, and persisted for a shorter time than did antibody to the other antigens. Antibody response to gC and gD was intermediate in concentration and temporal appearance compared with the antibody response to gA and to the polypeptide bound by CH23. An enzyme immunoassay on paired serum samples with the captured glycoproteins as antigen was equal for the detection of current infection to an enzyme immunoassay with the whole CMV antigen from infected cell lysates. Enzyme immunoassays with either the CMV glycoproteins or the whole CMV antigen from infected cell lysates were superior to a complement fixation test with a glycine extract antigen for serodiagnosis of current infection.

Evaluation and reporting of enzyme immunoassay determinations of antibody to herpes simplex virus in sera and cerebrospinal fluid.

Several methods for evaluating and reporting enzyme immunoassay (EIA) determinations of antibody to herpes simplex virus derived from one dilution of single serum samples were studied. An EIA ratio method for serological evidence of current infection from paired serum samples was also evaluated. Optical density (OD) of the reaction at a 1:100 serum dilution and estimated titers obtained by reference of the OD of the serum dilution to a standard curve were compared to the corresponding plotted EIA titer obtained by titration to endpoint. Neither the OD per se nor the estimated titer was completely predictive of the plotted titer (correlation coefficient [r] of 0.824 and 0.817, respectively), and they provided only a semiquantitative measurement of antibody concentration. For an antibody status report, however, OD would be sufficient if related to the cutoff value as an EIA index (OD of sample divided by cutoff OD for positive specimens). The OD of the EIA reaction at a single dilution (1:5) of cerebrospinal fluid, on the other hand, correlated quite well with the titer obtained by titration (r = 0.950). For serological diagnosis of current infection, the OD ratio of convalescence-phase/acute-phase sera was determined at several dilutions. A ratio of greater than or equal to 1.54 was calculated as a reliable index for a significant rise in antibody concentration and compatible with current infection. By determining the convalescent-phase/acute-phase serum ratio at two dilutions, 1:100 and 1:1,000, the EIA ratio method appeared to be a sensitive as or more sensitive than, complement fixation in diagnosing current infection.

Upper and lower respiratory tract infections. Nursing intervention.

Proper nursing intervention can assist in the reduction of nosocomial respiratory tract infections. Maintaining the integrity of the patient's respiratory defense mechanisms and/or augmenting those that are impaired helps to control endogenous factors that can contribute to infection. Nursing implications in controlling endogenous factors include mobilization of secretions, prevention of aspiration, and reduction of oral resident microorganisms. Strict aseptic technique in caring for artificial airways and respiratory assistance equipment is essential. Advocacy of a patient's right to protection from harm should be exercised if breaks in proper technique by others are observed. The care that nurses provide is relevant to infection control.