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Human spermatozoa were exposed to concentrations of 10(2) to 10(7) organisms per ml. Candida albicans. A subsequent striking decrease in spermatozoal motility and significant agglutination were observed. The possible role of mycotic genital tract infections in human infertility is considered.
Routine microscopical examination of stool specimens for diagnosis of strongyloidiasis is insensitive and serological methods using Strongyloides stercoralis antigen are at present not available for field studies. We evaluated 2 techniques, enzyme-linked immunosorbent assay (ELISA) and gelatin particle indirect agglutination (GPIA), using an antigen obtained from the rodent parasite, S. venezuelensis. Fifty-four Peruvian patients with different clinical forms of strongyloidiasis were studied: 12 asymptomatic, 31 symptomatic, and 11 hyperinfection cases. Our results demonstrate that both ELISA and GPIA using S. venezuelensis antigen are useful for diagnosis of strongyloidiasis, with sensitivities of 74.1% and 98.2%, respectively and a specificity of 100% for both techniques. We found that GPIA is a highly sensitive test for patients with suspected chronic infection and/or hyperinfection. In the hyperinfection cases, significantly lower concentrations of specific immunoglobulin antibodies and eosinophils (P < 0.001) were found compared with the asymptomatic and symptomatic cases.
Agglutination assays detect antibodies to variant parasite antigens expressed on the surface of Plasmodium falciparum-infected erythrocytes. Standard techniques require immediate analysis limiting the number of samples that can be processed simultaneously and preclude re-examination of slides. Fixed Giemsa-stained smears allow long-term storage and re-examination, without fluorescence microscopy.
The co-agglutination (Co-A) procedure was standardized and evaluated to detect hydatid antigen in fluid samples aspirated from hydatid cysts. Samples were collected from 14 hydatid cysts in different organs (liver, 7; lung, 5; multiple abdominal cysts, 1; and kidney, 1) by surgery. Echinococcus granulosus scolices and hooklets were seen in only 6 (42.85%) samples by routine microscopy. In contrast, hydatid antigen was demonstrated in all the samples by Co-A (100% sensitivity). Co-A could be employed as a simple and rapid diagnostic procedure, as an alternative to microscopy, to confirm the hydatid aetiology of a suspected cyst.
The performance of the direct agglutination test (DAT) was evaluated under field conditions in an endemic area of visceral leishmaniasis in eastern Sudan, using aqueous (Aq) antigen which has to be kept refrigerated and a newly developed freeze-dried (FD) antigen which is stable at ambient temperature. Both antigens compared well, with 92-98% of readings being identical or only with one dilution difference in titre. FD antigen gave titres that were identical with Aq antigen in 73% of samples, higher in 19%, and lower in 8%. Owing to high ambient temperatures and low humidity, microtitre plate wells dried out during the standard procedures for elution and incubation. However, shortening the elution time from 12 to 4 h proved possible for both antigens; incubation could be reduced from 24 to 10 h for Aq antigen, after which the plates could still be read. Incubation with FD antigen required 18 h and the plates needed to be kept cool because of evaporation. Despite the longer procedure with the FD antigen, the DAT can be completed in 24 h and the use of this stable antigen, that does not require refrigeration, is a major improvement in performing the DAT under unfavourable field conditions.
Human capillary blood drawn by finger pricking was absorbed on Whatman no. 4 filter paper and tested for anti-Leishmania antibodies using the direct agglutination test (DAT). Over 1400 filter paper samples were collected from L. infantum endemic areas in northern Pakistan and compared with 569 serum samples obtained from the same area. Eleven filter paper samples (0.8%) gave positive results (antibody titre > or = 1:3200), compared with 8 serum samples (1.4%); the difference was not statistically significant (P = 0.35). The filter paper eluates compared well with their homologous sera, and were strongly correlated with respect to antibody titre (r = 0.7, P < 0.0001).
Tests on a panel of 421 serum samples from Ethiopia and 11 from Europe with the direct agglutination test (DAT) and freeze-dried antigen (Leishmania donovani 1S) showed that a cut-off titre of 1:200 or 1:400 could be employed. Using a cut-off titre of 1:400, 181 (88.3%) of 205 serum samples from visceral leishmaniasis (VL) patients tested positive, as did 5 (13.9%) of 36 sera from patients with localized cutaneous leishmaniasis, 5 (71.4%) sera from 7 patients with diffuse cutaneous leishmaniasis and 8 (89.9%) sera from 9 HIV-positive VL patients. We also found that 19 (57.6%) sera from 33 treated VL patients were still positive in the DAT at 1.5 to 5 years after treatment.
Aqueous extracts from lyophilized albumen glands of the garden snail (Cepaea hortensis) exhibit, after separation from a second lectin, a specificity against sialic acid-containing polymers. In agglutination studies with bacteria, the lectin interacts with all strains of group B streptococci (Streptococcus agalactiae) containing type-specific polysaccharides. In contrast, group B streptococci containing only protein type antigens as well as all strains of other Lancefield streptococcal groups and several other bacterial strains did not react.
A micromethod has been developed for the standard agglutination and antihuman globulin tests for serum antibodies to Brucella abortus. The test uses a haematoxylin-stained antigen. The test is simple and quick to perform and, in a comparison at two centres involving 367 sera, the micromethod was found to be more sensitive than the classical test. It is highly suitable both for routine serological screening and for large-scale surveys of occupationally exposed industrial groups.
The sensitivity, specificity, accuracy and predictive values of counter immunoelectrophoresis (CIE), latex agglutination (LA) and coagglutination (CoAg) tests were compared for detection of pneumococcal antigen in cerebrospinal fluid (CSF) of patients suspected of meningitis. A total of 95 CSF samples comprising 15 culture proven, 47 clinically suspected but culture negative cases of meningitis and 33 controls were screened by above tests. Among three tests, LA was found to have high sensitivity and moderately high negative predictive value than CIE and CoAg tests. However, CIE had slightly better specificity than LA and CoAg tests. Accuracywise CIE and LA tests were comparable than CoAg test. CIE and LA tests had high positive predictive value than CoAg test.
Serum samples from North Atlantic populations of harp seal, Phoca groenlandica (n = 316), ringed seal, Phoca hispida (n = 48), hooded seal, Cystophora cristata (n = 78), and minke whale, Balaenoptera acutorostrata (n = 202), were tested for Toxoplasma gondii-specific IgG. The modified agglutination test (MAT) was slightly modified to be more user-friendly by replacing the 0.2 M 2-mercaptoethanol with 10 mM dithiothreitol. No positive samples were found at 1:40 dilution.
A new co-agglutination assay for the identification of Pseudomonas aeruginosa from culture was developed and evaluated. A total of 232 P. aeruginosa isolates, and 36 oxidase-positive, Gram-negative clinical isolates were tested. The sensitivity of the assay was 96%, and the specificity was 91.9%. The assay took <15 min to perform.
A peptide (m.w. 1157.5 Da) able to prevent the agglutination of K562(S) cells induced by the peptic-tryptic prolamine digests of the cereals toxic in coeliac disease (i.e. bread wheat, rye, barley and oat) was characterized as one of the components of the peptic-tryptic digest of durum wheat gliadin. This peptide was synthesized in a high degree of purity with the solid phase method with the Applied Biosystem 431A. An amino acid sequence was identified in the 1157.5 Da peptide as being related to the largest common sequences previously detected in a series of bread wheat toxic peptides by other authors.
Trypanosomosis due to Trypanosoma evansi (surra) is a major enzootic disease of the dromedary camel. Thus, the purpose of the present study was to assess seroprevalence and infection rates in the Canary Islands using antibody(-card agglutination test-CATT/T. evansi) and parasite detection tests (micro-Haematocrit Centrifugation technique, Giemsa stained blood smears, microscopic examination of lymph node aspirates and mouse inoculation). PCV was also determined. 745 dromedary camels (483 females and 262 males) were examined. Trypanosomes were detected in seven animals. 36 animals yielded CATT positive results while 709 animals were negative. All parasitologically positive animals were also CATT positive. Results showed a good correlation between CATT positive and low PCV and a higher seroprevalence in older animals. Trypanocidal drugs have not been registered in Spain and, consequently, if vigilance is not exercised the prevalence could be increased in the future.
Equine protozoal myeloencephalitis (EPM) is a serious neurological disease of horses in the Americas. The apicomplexan protozoan most commonly associated with EPM is Sarcocystis neurona. A direct agglutination test (SAT) was developed to detect antibodies to S. neurona in experimentally infected animals. Merozoites of the SN6 strain of S. neurona collected from cell culture were used as antigen and 2-mercaptoethanol was added to the antigen suspension to destroy IgM antibodies when mixed with test sera. Mice fed sporocysts of S. speeri or S. falcatula-like sporocysts from opossums did not seroconvert in the SAT. The sensitivity of the SAT was 100% and the specificity was 90% in mice.
The present study aimed to develop Dot-ELISA, complement fixation test (CFT) and capillary tube agglutination test (CAT) for serodiagnosis of Babesia equi infection and to compare their sensitivity with each other. For this study, sequential serum samples were collected from four donkeys experimentally infected with B. equi up to 90 days post infection (P.I.). B. equi antigen was prepared from the blood of a donkey showing more than 80% parasitaemia. Dot-ELISA, CF and CA tests were standardized as per the standard method. While performing CFT, it was observed that CFT standardized for the donkey system could not be applied to the horse system, and different units of the same antigen and complement were required for each. Dot-ELISA detected antibodies from 3-6 days P.I. onwards, whereas CF and CA tests could detect antibodies from the 6th day P.I. indicating that Dot-ELISA is the more sensitive. The efficacy of these three tests was also determined by testing 211 field serum samples of apparently healthy horses. By Dot-ELISA 49.76%, by CAT 42.18% and by CFT 27.86% of the serum samples were found positive. As the results of Dot-ELISA and CAT are comparable, it is proposed that CAT may be used as a screening test.
Serum samples from Toxoplasma gondii-negative pigs infected with protozoa, helminths and viruses, and from fetal pigs were examined for cross reacting antibodies to T. gondii by the use of the modified agglutination test (MAT). Nonspecific reactions with T. gondii antigen were not found in 1:10 dilutions of sera from eight pigs experimentally infected with Sarcocystis miescheriana, 11 pigs infected with Ascaris suum, three pigs infected with Trichuris suis, ten pigs infected with Trichinella spiralis, nine pigs infected with various porcine viruses, six gnotobiotic pigs, and 82 fetal pigs. Antibodies were also not found in 1:25 dilution of sera from 200 naturally aborted fetal pigs. Thus, evidence for cross reactivity to T. gondii with unrelated or related organisms using the MAT was not found.
Carbohydrate-binding components were shown to be present at the surface of Listeria monocytogenes by means of a panel of neoglycoproteins using direct agglutination. These lectin-like components bind on neoglycoproteins bearing D-glucosamine, L-fucosylamine, or para-amino-phenyl-alpha-D-mannopyrannoside residues. The interactions were inhibited by the carbohydrate moieties specific to the neoglycoproteins. The protein nature of the lectin-like components of L. monocytogenes was ascertained by the loss of carbohydrate-binding capacity following protease treatment.