Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “IFA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMed1986

Immunofluorescence detection of Cryptosporidium oocysts in fecal smears.

An indirect fluorescent antibody (IFA) procedure was developed for the detection of Cryptosporidium sp. oocysts in human, nonhuman primate, and bovine fecal smears. The procedure, which takes about 90 min to perform, involves the use of a rabbit antiserum against Cryptosporidium oocysts isolated from dairy cattle. Cross-specificity testing of the IFA method revealed no reactivity with yeasts, various amoebae, Giardia lamblia, Chilomastix sp., or Blastocystis sp. and only very weak cross-reactivity with coccidian oocysts of other genera. IFA detection of oocysts in human and nonhuman primate fecal smears was far more sensitive than was dimethyl sulfoxide-carbolfuchsin staining. Moreover, IFA detection was comparable in sensitivity to auramine O staining with samples of high oocyst concentration and somewhat more sensitive than auramine O with samples containing relatively few oocysts. The IFA procedure may be useful in the clinical diagnosis of human and animal cryptosporidiosis and also in the detection of oocysts in environmental samples.

Animals↗
PubMed1987

Enzyme-linked immunosorbent assay for Potomac horse fever disease.

An enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) and IgM in natural and experimental infections of equids with Ehrlichia risticii was developed. Ehrlichial organisms purified from an infected mouse macrophage cell line were used as the antigen. IgM was separated from serum IgG by the expedient of spun-column chromatography, allowing the use of an indirect ELISA for quantitation of both IgG and IgM in the test sera. Among 16 paired sera from horses exhibiting clinical signs of Potomac horse fever, 8 were positive by the indirect fluorescent-antibody test (IFA), 11 were positive by the IgG ELISA, and 8 were positive by the IgM ELISA. All IFA-positive specimens were positive by the IgG ELISA, which appeared to be more sensitive than the IFA. In all cases, the IgG ELISA alone would have sufficed for diagnosis when acute- and convalescent-phase sera were available. When 26 single acute- or convalescent-phase serum samples were tested, the IFA detected 8, the IgG ELISA detected 10, and the IgM ELISA detected 6 positive serum specimens. The kinetics of IgG and IgM responses as determined by ELISA in two experimentally infected ponies which survived infection and challenges revealed that specific IgM was short-lived, falling to undetectable levels by day 60 postinoculation, whereas specific IgG persisted for more than 1 year. IgM and IgG were detected as early as days 1 and 10, respectively, postinoculation. The results suggest that the ELISA is more sensitive than the IFA and that the IgM ELISA may provide a means for early diagnosis of Potomac horse fever at or before the onset of clinical signs.

Animals↗
PubMed1987

Detection of Pneumocystis carinii by fluorescent-antibody stain using a combination of three monoclonal antibodies.

A combination of three monoclonal antibodies, two prepared against human and one against rat Pneumocystis carinii, was used in an indirect fluorescent-antibody stain (IFA) to diagnose P. carinii in both bronchoalveolar lavage and lung biopsy specimens. This combination of monoclonal antibodies was specific for P. carinii and yielded bright fluorescence of both P. carinii cysts and trophozoites. A total of 126 specimens from 93 patients were stained for P. carinii by a toluidine blue O stain and the monoclonal IFA. Forty-five (35.7%) of these were positive for P. carinii by toluidine blue O, and 43 (34.1%) were positive by IFA. There was 98.4% agreement between both methods, with no false-positive and two false-negative occurrences by IFA. An IFA procedure with monoclonal antibodies such as those used in these studies can provide a simple, fast, and sensitive method for diagnosing P. carinii pneumonia by microbiology laboratories.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Evaluation of MUREX SUDS Toxo test.

The SUDS Toxo test (MUREX Corp., Norcross, Ga.) was compared with the indirect hemagglutination test (IHA) and the indirect fluorescent-antibody test (IFA) by examining 404 serum specimens, including 64 (15.8%) specimens with IFA titers of greater than or equal to 1:2. When SUDS was compared with IHA, sensitivity (96.4%), specificity (97.9%), and negative predictive value (99.4%) indicated that there were similar reactivities between the two tests. When an IFA titer of greater than or equal to 1:16 was considered significant and IHA and SUDS were compared with IFA, IHA was slightly less sensitive but had a higher positive predictive value than did SUDS; however, there was no statistical difference between the tests. When SUDS was compared with IFA, in which a titer of greater than or equal to 1:16 was considered significant, the high negative predictive value (100%), excellent sensitivity (100%) and specificity (98.3%), and ease of performance made SUDS an attractive alternative to IHA for screening single serum specimens for toxoplasmosis.

Animals↗
PubMed1987

Indirect immunofluorescence assay for antibodies to human immunodeficiency virus.

We compared an indirect immunofluorescence assay (IFA) with a commercial enzyme-linked immunosorbent assay (ELISA) screening procedure for the detection of antibodies to the human immunodeficiency virus (HIV). The IFA assay was as sensitive and specific as the ELISA. No false results were observed with IFA on single testing of 181 sera, while the ELISA produced five false-positive results which required retesting for resolution. In addition, the IFA was suitable for quantitation of anti-HIV responses. The IFA was superior to the ELISA for its reliability, simplicity, and rapidity in the diagnostic laboratory.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Interlaboratory and intralaboratory comparisons of indirect immunofluorescence assays for serodiagnosis of Lyme disease.

A conventional indirect immunofluorescence assay (IFA) and an anticomplement indirect immunofluorescence assay (ACIF) for detecting serum antibodies to Borrelia burgdorferi in humans were evaluated during a prevalence survey in northern California. Sera obtained from 119 current or former residents of an area in which Lyme disease is endemic were split and tested by the IFA in two laboratories and the ACIF in a third. The seropositivity rate ranged from 15 to 20% with 88 to 93% agreement among laboratories. Interlaboratory agreement was statistically highly significant in each of the three pairwise comparisons and was positively associated with clinical manifestations of Lyme disease. Intralaboratory agreement ranged from 93 to 96% in two laboratories and was also statistically highly significant. Immunoblotting confirmed 100 of 101 of the nondiscrepant immunofluorescence test results and likewise was positively correlated with the degree of interlaboratory agreement. The ACIF was found to be a highly specific test (100% specificity) with a much lower cutoff titer (1:8) than the conventional IFA (determined to be 1:128 or 1:256 in two laboratories) for detecting antibodies to B. burgdorferi. It also appeared to be more sensitive (80 versus 68%) than the IFA as determined by comparative immunoblotting, though the absolute sensitivity of the ACIF for serodiagnosis of early Lyme disease has yet to be determined. Significant serologic cross-reactivity was demonstrated between B. burgdorferi, Borrelia coriaceae, and Borrelia hermsii by the IFA, which may confound spirochetal serosurveys in California where all three spirochetes are known to coexist.

Antibodies, Bacterial↗
PubMed1991

Specific immunofluorescence staining of Treponema pallidum in smears and tissues.

To date, tissue sections prepared from Formalin-fixed tissues have not been successfully stained with Treponema pallidum subspecies-specific antibody in a direct fluorescent-antibody assay. While current methods stain T. pallidum, they do not distinguish T. pallidum from other spirochetes such as Borrelia burgdorferi (E. F. Hunter, P. W. Greer, B. L. Swisher, A. R. Simons, C. E. Farshy, J. A. Crawford, and K. R. Sulzer, Arch. Pathol. Lab. Med. 108:878-880, 1984). Because trypsin pretreatment of tissue sections has enhanced other immunofluorescent-antibody (IFA) applications, we compared the use of the trypsin digestion method with the current 1% ammonium hydroxide (NH4OH) method as a means to obtain specific staining of T. pallidum in tissues by both direct and indirect IFA techniques. Pretreated T. pallidum-infected tissues sections from rabbits, hamsters, and humans were quantitatively examined with the direct fluorescent-antibody-T. pallidum test conjugate absorbed with Treponema phagedenis, the Reiter treponeme. For indirect staining, a serum specimen from a patients with syphilis absorbed by affinity chromatography with T. phagedenis was used as the primary reagent, and a fluorescein isothiocyanate-labeled rabbit anti-human globulin was used as the secondary reagent. Serum specificity was established first by examining antigen smears of T. pallidum subsp. pallidum, T. pallidum subsp. pertenue, B. burgdorferi, T. phagedenis, and Treponema denticola MRB and then by examining tissues infected with these pathogens plus those infected with four Leptospira serovars. When we stained tissue using the direct IFA method that is currently a standard method for the examination of chancre smears, we found it to be unsuitable for use with tissue. Trypsin digestion did not offer an improvement over the NH4OH pretreatment method in the specific identification of T. pallidum by direct IFA. However, specific identification of T. pallidum in tissue sections was obtained by the indirect IFA technique after either trypsin or NH4OH pretreatment.

Animals↗
PubMed1991

Indirect immunofluorescence assay for detection of Helicobacter pylori in human gastric mucosal biopsies.

To determine sensitivity and specificity of immunofluorescence assay (IFA) for detection of Helicobacter pylori, we studied 151 patients. Biopsies of gastric mucosae were obtained for culture, histological testing, and IFA. H. pylori serum antibodies were tested by enzyme-linked immunosorbent assay. IFA was done on Formalin-preserved, paraffin-embedded biopsies by using rabbit anti-H. pylori and goat anti-rabbit gamma globulin-fluorescein isothiocyanate conjugate. The sensitivity and specificity of IFA compared with culture and Warthin-Starry stain were 93 and 95%, respectively. IFA is an accurate method for the diagnosis of H. pylori infection.

Adolescent↗
PubMed1993

Detection of microsporidian spores in clinical samples by indirect fluorescent-antibody assay using whole-cell antisera to Encephalitozoon cuniculi and Encephalitozoon hellem.

Three polyclonal mouse antisera, to Encephalitozoon cuniculi, Nosema algerae, and Nosema corneum, and two polyclonal rabbit antisera, to E. cuniculi and Encephalitozoon hellem, were used in an indirect fluorescent-antibody assay (IFA) with Enterocytozoon bieneusi, E. cuniculi, and Encephalitgozoon. hellem spores (spores of the last two were taken from culture). Enterocytozoon bieneusi cannot be cultured. By IFA, antisera to E. cuniculi and E. hellem reacted strongly and equally with each other's spores. The mouse antisera reacted strongly with the homologous species, but for these there was segmental and particulate or "dot" staining of heterologous microsporidian spores, indicating cross-reactions with more selected antigens. In fecal samples, cross-reactions with both mouse and rabbit antisera were sometimes seen with different yeast species, with species of streptococci, and species of gram-negative rods. There were no cross-reactions to staphylococci. Enterocytozoon bieneusi was easily identified in duodenal and colonic biopsies, duodenal and colonic fluids, and feces of symptomatic AIDS patients by IFA. In a study of 12 AIDS patients with diarrhea, the new IFA identified microsporidia in all of 11 fecal samples, three colon fluids, six duodenal fluids, and three duodenal biopsy touch preparations. Although the fecal sample of 1 of the 12 was negative, the patient's duodenal fluid contained microsporidian spores by IFA.

Animals↗
PubMed1994

Comparison of rapid detection methods for influenza A virus and their value in health-care management of institutionalized geriatric patients.

Respiratory specimens from 160 geriatric patients with suspected influenza illness were used to evaluate the abilities of two enzyme immunoassays (EIAs; Directigen FLU-A [Becton Dickinson Microbiology Systems, Cockeysville, Md.] and Prima EIA [Baxter/Bartels Diagnostics, Inc., Issaquah, Wash.]) and direct immunofluorescence testing (immunofluorescence assay [IFA]) to identify influenza A virus. In comparison with culture isolation, the sensitivities and specificities of the IFA, Directigen FLU-A, and Prima EIA were 92.5 and 97.2%, 86.8 and 99.1%, and 92.5 and 98.1%, respectively. In contrast to EIA, IFA was labor intensive and required a high degree of technical expertise, and the results of IFA were difficult to interpret. These factors may preclude the use of IFA for testing large numbers of specimens. A retrospective epidemiologic survey of influenza infection was done in six geriatric institutions which had used either rapid and culture testing or culture alone. Preventable cases of influenza A virus infection ranged from 9 to 38% of all cases in facilities which used culture testing only and which had not instituted amantadine prophylaxis. The use of direct specimen testing is recommended as an adjunct to culture isolation for the identification of influenza A virus. Use of a combination of these methods permits the timely administration of appropriate antiviral therapy and infection control measures, while it also permits the antigenic surveillance of circulating influenza strains, which is necessary for present vaccine efficacy evaluations and the creation of future effective vaccine formulations.

Aged↗
PubMed1998

Use of monoclonal antibodies to identify serotypes of enterovirus isolates.

Nonpoliovirus enteroviruses cause a variety of diseases that are common in young children and adults. The "gold standard" for laboratory diagnosis of enteroviruses is cell culture isolation, followed by serotype identification by neutralization assay. These procedures are time-consuming and expensive. Rapid serotype identification of enteroviruses is important in differentiating nonpoliovirus enterovirus pathogens from vaccine strain polioviruses that can be shed for some time after vaccination. In the present investigation, we evaluated a rapid method for serotype identification of enteroviruses by indirect immunofluorescence assay (IFA) using commercially available monoclonal antibodies for polioviruses, coxsackieviruses type B, and six serotypes of commonly circulating echoviruses. Of 291 isolates of enteroviruses included in the study, 95 were polioviruses and 196 were nonpoliovirus enteroviruses. Two hundred thirty-four of these (38 polioviruses and 196 nonpoliovirus enteroviruses) were consecutively grown in the laboratory over a 5-year period. IFA identified the serotypes of 74% of the consecutive isolates and 71% of all enterovirus isolates by yielding a positive staining result. The levels of agreement in the identification of the enterovirus group between IFA and neutralization tests were 92% for consecutively grown isolates and 85% for all enterovirus isolates. The sensitivity of the IFA for the detection of viruses for which specific monoclonal antibodies were applied was 73% for polioviruses, 85% for coxsackieviruses type B, and 94% for echoviruses. Specificity was near 100% for polioviruses and coxsackieviruses type B and 94% for echoviruses. We conclude that IFA can be helpful as a preliminary test for serotype identification of enteroviruses. The results are most accurate when the test identifies the isolate as a poliovirus.

Antibodies, Monoclonal↗
PubMed1999

Inter- and intralaboratory comparison of Ehrlichia equi and human granulocytic ehrlichiosis (HGE) agent strains for serodiagnosis of HGE by the immunofluorescent-antibody test.

Human granulocytic ehrlichiosis (HGE) is usually diagnosed by immunofluorescent antibody (IFA) serology with Ehrlichia equi-infected neutrophils or HGE agent-infected cultured HL60 cells. The HGE agent and E. equi are antigenically diverse, and interpretation of serologic results is also often variable. Thus, we investigated the sensitivity and specificity of various HGE agent and E. equi antigens used for IFA diagnosis by three different laboratories. Serum samples from 28 patients with well-characterized HGE and 9 patients with suspected HGE who were investigated by PCR, blood smear examinations, and serology were used, along with 9 serum samples from patients with other rickettsial and ehrlichial infections. Each serum sample was tested with up to 10 different antigen preparations. Overall, qualitative IFA results agreed in 70% of the samples. Titers among antigens were similar (r = 0.89 to 0. 96), but titers of individual samples varied by fourfold or more in 5 of 81 (6%) of the serum samples. Sensitivity ranged from 100% to 82%, and specificity varied from 100% to 67%, but these differences were not significant, even among those tested in the same laboratory or between two different laboratories. Antibodies were detected in 14 to 44% of acute-phase sera from confirmed HGE patients. Most false-positive reactions resulted with Ehrlichia chaffeensis; when these sera were excluded, the specificity of most antigens was 91 to 100%. These data indicate that IFA results often agree and that IFA is useful for diagnosis of HGE in convalescence. However, without further standardization, variability among serologic tests using E. equi and HGE agent isolates for diagnosis of HGE will occasionally provide discrepant results and confound diagnosis.

Antibodies, Bacterial↗
PubMed2000

Expression of a gene encoding the major antigenic protein 2 homolog of ehrlichia chaffeensis and potential application for serodiagnosis.

The major antigenic protein 2 (MAP2) homolog of Ehrlichia chaffeensis was cloned and expressed. The recombinant protein was characterized and tested in an enzyme-linked immunosorbent assay (ELISA) format for potential application in the serodiagnosis of human monocytic ehrlichiosis. The recombinant protein, which contained a C-terminal polyhistidine tag, had a molecular mass of approximately 26 kDa. The antigen was clearly identified by Western immunoblotting using antihistidine antibody. However, immune sera failed to react with the recombinant on immunoblots when the antigen was denatured by heat or reduced using beta-mercaptoethanol. The recombinant MAP2 (rMAP2) was used in an ELISA format with 60 blinded serum samples. Twenty of the serum samples were previously demonstrated to contain antibodies reactive with E. chaffeensis by indirect immunofluorescence assays (IFAs). The remaining 40 samples were seronegative. All samples negative by IFA were also found to be negative for antibodies against the rMAP2 of E. chaffeensis by using the ELISA. Only 1 of 20 IFA-positive samples tested negative in the rMAP2 ELISA. There was 100% agreement using IFA-negative samples and 95% agreement using IFA-positive samples, resulting in a 97.5% overall agreement between the two assays. These data suggest that the rMAP2 homolog of E. chaffeensis may have potential as a test antigen for the serodiagnosis of human monocytic ehrlichiosis. To our knowledge, this recombinant is unique because it is thus far the only E. chaffeensis recombinant antigen that has been shown to work in an ELISA format.

Antigens, Bacterial↗
PubMed2000

Comparison of a baculovirus-based VP2 enzyme immunoassay (EIA) to an Escherichia coli-based VP1 EIA for detection of human parvovirus B19 immunoglobulin M and immunoglobulin G in sera of pregnant women.

A split-sample study was conducted to evaluate the clinical performance of an enzyme immunoassay that detects the human parvovirus B19 virus (B19V) immunoglobulin M (IgM) or IgG in the sera of pregnant women. The initial study compared a baculovirus-expressed VP2 enzyme immunoassay (BVP2 EIA) (Biotrin International Inc., Dublin, Ireland) with the currently available and commonly used Escherichia coli-expressed VP1 enzyme immunoassay (EVP1 EIA) (MRL Diagnostics, Cypress, Calif.). There was a high degree of agreement between the two assays in the detection of IgM antibodies (283 of 307 [92.2%]) or IgG antibodies (279 of 311 [89. 7%]), with the majority of discrepancies (IgM, 17 of 24 [71%]; IgG, 16 of 31 [50%]) being due to equivocal data obtained with the EVP1 EIA. Specimens with discordant BVP2 EIA and EVP1 EIA results (23 of 24 IgM and 32 of 32 IgG results) were analyzed further by baculovirus-based VP1 immunofluorescence assays (BVP1 IFAs) (Biotrin International). The BVP2 EIA and BVP1 IFA results for 20 of 23 and 28 of 32 specimens for IgM and IgG, respectively, were concordant. In contrast, the EVP1 EIA and BVP1 IFA data for only 3 of 23 and 4 of 32 specimens for IgM and IgG, respectively, were in agreement, despite the fact that the same capsid antigen was used. Both the BVP2 EIAs and BVP1 IFAs utilize a conformational viral capsid antigen, while the EVP1 EIA uses a denatured viral capsid antigen. In conclusion, the BVP2 EIAs produced far fewer equivocal results for IgM and IgG, correlating more closely to the confirmatory BVP IFAs, than did the EVP1 EIAs and proved to be more accurate for detecting B19V antibodies in the sera of pregnant women.

Antibodies, Viral↗
PubMed2003

Comparison of two commercial enzyme-linked immunosorbent assays with an immunofluorescence assay for detection of Legionella pneumophila types 1 to 6.

Members of the genus Legionella are characterized as gram-negative, motile, freshwater-dwelling bacteria that were responsible for a pneumonia outbreak among American Legion members in 1976. Because clinicians routinely order serologic testing for Legionella pneumophila serogroups 1 to 6 as a screen for possible L. pneumophila infections, we evaluated the Wampole Laboratories L. pneumophila type 1 to 6 immunoglobulin G (IgG) and IgM combined enzyme-linked immunosorbent assay (ELISA) and the Zeus Scientific L. pneumophila type 1 to 6 IgG-IgM-IgA multispecific combined ELISA systems and compared them to an IgG-specific immunofluorescence assay (IFA) for L. pneumophila serogroups 1 to 6. The Centers for Disease Control and Prevention recommends that the positive titer cutoff for an IFA be 1:256. Regardless of where the positive IFA cutoff titer is placed, however, the sensitivity of both commercial assays was below what would be acceptable for a screening assay. With a 1:256 IFA titer as the positive cutoff, the agreement, sensitivity, and specificity of the Wampole ELISA were 74.6, 21.4, and 98.4%, respectively. The agreement, sensitivity, and specificity of the Zeus ELISA were 72.6, 10.5, and 100.0%, respectively. We recommend that any laboratories attempting to replace an IFA type 1 to 6 screen with an alternative ELISA carefully investigate the sensitivity of the replacement assay.

Antibodies, Bacterial↗
PubMed2001

An intradermal skin test for determination of immunity to varicella.

AIMS: To evaluate the usefulness of a diluted, inactivated solution of attenuated varicella vaccine in predicting susceptibility to varicella and its correlation with specific antibody titre to varicella. METHODS: In a prospective blinded study, 63 healthy subjects (aged 2-43 years) were studied. Skin test solution was prepared from vials of OKA strain virus which was inactivated by exposure of the vials to room temperature for 10 days; solution was diluted at 1/50 with normal saline and kept at 4 degrees C until used for skin testing. The material was injected intradermally. Serum samples were drawn prior to skin testing and kept at -70 degrees C until analysis for antibody assay by the indirect fluorescent antibody (IFA) method. RESULTS: Forty three patients were IFA antibody positive; 41 of them reacted to the skin test. One of the 20 IFA negative patients reacted to the skin test. Sixteen patients had two serological tests performed, one month apart. Four out of these 16 patients tested negative with the skin test. All four had negative serology on both samples. Six of the 12 IFA positive patients showed a boost in the antibody titre one month after application of the skin test. The specificity and sensitivity of the skin test compared to the IFA assay were both 95%, and the positive and negative predictive values were 97% and 90% respectively. CONCLUSIONS: Results suggest that a varicella skin test prepared using this simple and relatively cheap method is a safe, sensitive, and specific tool by which to assess immunity to varicella.

Adolescent↗
PubMed1993

Use of recombinant human parvovirus B19 antigens in serological assays.

AIMS--To compare the sensitivity, specificity, and practicality of recombinant proteins in serological tests for the detection of human parvovirus B19 IgG and IgM. METHODS--Indirect enzyme linked immunosorbent assays using B19 structural proteins expressed in Escherichia coli were developed for the detection of B19 specific IgG and IgM (rELISA-G and rELISA-M). Cells infected with baculovirus expressing B19 structural proteins were also used in an indirect immunofluorescence assay for IgG and IgM antibodies (IFA-G and IFA-M). Antibody capture radioimmunoassays for IgG and IgM (GACRIA and MACRIA) were used as comparative assays. RESULTS--Twenty nine pools of intravenous immunoglobulin were clearly positive for B19 IgG by rELISA-G and contained low IgG titres by GACRIA. From 113 samples tested by all methods, sensitivities of 92% (77/84) and 97% (68/70) were obtained for ELISA and immunofluorescence, respectively, when compared with GACRIA. One hundred and sixteen samples from patients presenting with rash or arthralgia were compared by MACRIA, rELISA-M, and IFA-M. Sensitivities of both recombinant tests were more than 95%. Despite pretreatment to remove IgG or rheumatoid factor, false positive results were a problem in the rELISA-M but were not seen with the IFA-M. CONCLUSIONS--The limited supply of native antigen has severely restricted the wide application of serology for parvovirus B19. The use of recombinant antigens permitted the introduction of local screening tests which had many advantages, including quicker results and relief of the burden on the Reference Laboratory. The use of rELISA-M for sensitivity and IFA-M for specificity and confirmation proved a useful and practical combination for diagnosis of recent infection with B19, and rELISA-G allowed the immune response to be determined in selected populations.

Adolescent↗
PubMed1995

The role of a nested polymerase chain reaction in the diagnosis of Pneumocystis carinii pneumonia.

Aim-To compare the techniques and results of a nested PCR and an immunofluorescence assay (IFA) for the detection of Pneumocystis carinii infection; to consider the role of the nested PCR in the diagnosis of P carinii pneumonia (PCP).Methods-Serial dilutions of two known P carinii positive samples were tested by IFA and PCR to determine their relative sensitivities. Seventy eight respiratory samples (15 from 11 patients with HIV infection/acquired immunodeficiency syndrome (AIDS) and 63 from 42 patients with other forms of immunodeficiency) were tested using both assays, and the costs and technical requirements of each assay were assessed.Results-The PCR had a greater relative sensitivity over the IFA of 2 x 10(1) to 2 x 10(3) fold in a postmortem lung sample and 2 x 10(5) to 2 x 10(6) fold in a bronchoalveolar lavage sample from a patient with PCP. P carinii was detected in all 15 samples from the patients with HIV/AIDS by both IFA and PCR. Of the 63 samples from the patients with immunodeficiencies other than HIV/AIDS, the PCR was more sensitive than IFA.Conclusions-The nested PCR is a more sensitive assay than the IFA. It may be useful in the diagnosis of PCP in patients with immunodeficiencies other than HIV/AIDS. Similarly, PCR may be of benefit for this patient group as less invasive specimens are needed. PCR has an increasing role to play in the diagnosis of PCP in the routine laboratory.

Journal Article↗