Indirect Fluorescent Antibody Titers Research Articles

Community-acquired bacterial pneumonia requiring admission to hospital

Patients who develop bacterial pneumonia in the community often require admission to acute-care hospitals. Knowledge of the incidence of pneumonia due to different pathogens that are brought into an institution from the community may play a role in determining the patterns of infecting organisms responsible for hospital-acquired pneumonia. For 1 year, we prospectively reviewed the records of patients admitted to our 1000-bed community hospital with community-acquired bacterial pneumonia (CABP). Patients had clinical signs and symptoms, positive radiologic findings, and pure cultures of potential pathogens from sputum, blood, pleural fluid, lung aspirate, lung biopsy, or transtracheal aspirate. Pneumonia due to Legionella pneumophila was diagnosed by serum indirect fluorescent antibody (IFA) titer ≥ 1: 256 and clinical signs and symptoms along with response to erythromycin. Of 204 patients with bacterial pneumonia, the following pathogens were implicated: Streptococcus pneumoniae, Haemophilus species, L. pneumophila, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, oral anaerobic bacteria, Psuedomonas aeruginosa, Serratia marcescens, and others. Most patients were more than 50 years of age and many had evidence of underlying pulmonary disease. The etiology of CABP may not be as predictable as in the past. Empiric antimicrobial therapy for CABP should include agents with activity against the pathogens prevalent in the community.

A Case Report of Transfusion-Induced Babesiosis

An elderly woman contracted transfusion-induced babesiosis, accompanied by disseminated intravascular coagulopathy. Her parasitemia cleared after treatment with several antibiotic and antimalarial drugs, but she died of cardiopulmonary failure. One of the transfusion donors had a high indirect fluorescent antibody titer against Babesia microti but was asymptomatic; his parasitemia was detected only by hamster inoculation, illustrating the difficulty in detecting the carrier state. ( JAMA 1982;248:465-467)

Staphylococcal protein A in the serologic diagnosis of congenital rubella and toxoplasmosis.

Staphylococcal protein A (SPA) has been used to remove maternal IgG from cord or neonatal sera to make serologic testing for congenital infection more IgM specific. To evaluate the clinical usefulness of this procedure, sera sent for TORCH titers that had rubella hemagglutination inhibition (RHI) reciprocal titers greater than or equal to 8 or toxoplasmosis indirect fluorescent antibody (TFA) titers greater than or equal to 16 were adsorbed with SPA and retested. Nine of 109 sera were TFA positive by routine testing, and all but one from an infant with congenital toxoplasmosis became negative after SPA adsorption. A repeat TFA at 4 to 26 months of age was negative in all six children without evidence of toxoplasmosis who returned for follow-up. Fifty of 55 sera were RHI positive by routine testing, and all but one from an infant with congenital rubella became negative after SPA adsorption. The repeat routine RHI was negative in 32 of 35 children whose sera were initially negative after SPA adsorption. SPA adsorption greatly increased the specificity of routine RHI and TFA tests in the diagnosis of congenital rubella and toxoplasmosis.

Development of a solid-phase radioimmunoassay for antibody to antigens of Babesia bovis infected bovine erythrocytes

Kahl L. P., Anders R. F., Callow L. L., Rodwell B. J. and Mitchell G. F. 1982. Development of a solid-phase radioimmunoassay for antibody to antigens of Babesia bovis infected bovine erythrocytes. International Journal for Parasitology 12: 103–109. A quantitative solid-phase radioimmunoassay (RIA) has been developed for the purpose of ranking sera from exposed animals according to their titre of anti- B. bovis antibody. The antigen was a sonicate of lysed infected blood cells, and antibody binding was detected with 125I-labelled anti-bovine IgG. The assay was tested using sera from experimentally infected splenectomized and intact cattle and from animals resident in an endemic area. A high specificity for B. bovis was demonstrated. There was good agreement in identifying exposed cattle when the test was compared with an indirect fluorescent antibody (IFA) test although no correlation was seen between titres obtained in the two tests. Analysis of the effects of challenge infection with B. bovis on IFA and RIA titres in previously exposed animals illustrated that the RIA was a more sensitive test for detecting changes in antibody titre.

Sensitivity and Specificity of the Indirect Fluorescent Antibody Test in the Study of Four Murine Coccidia1

The sensitivity and specificity of the indirect fluorescent antibody (IFA) test for the detection of serum antibodies were examined in mice that were infected with Eimeria falciformis, E. ferrisi, E. papillata, or E. vermiformis. For the study of each species, five groups of mice were given graded inoculation doses of 10, 10(2), 10(3), 10(4), or 10(5) sporulated oocysts in a primary infection. The sixth group was infected with three sequential doses of 1.5 x 10(3), 1.5 x 10(4), and 1.5 x 10(5) sporulated oocysts per mouse at two- to three-week intervals. All groups of infected mice developed serum antibodies. Sera were titrated by the IFA test with purified sporozoites. Strong fluorescence and high IFA titers were observed with homologous reactions mainly with the sera from mice infected with the higher inoculation dose levels in primary infections and from those given three sequential inoculation doses. Immunological cross reaction among the four species of Eimeria occurred at dilutions of 1:10 to 1:160. Very weak or no fluorescence of free sporozoites was observed with sera from noninfected mice, and there was no fluorescence of sporozoites contained in intact sporocysts.

Transmission of scrub typhus to human volunteers by laboratory-reared chiggers.

Laboratory-reared, Rickettsia tsutsugamushi-infected Leptotrombidium arenicola and L. fletcheri chiggers were fed on 1 and 2 human volunteers respectively. All subjects developed typical clinical signs and symptoms of scrub typhus beginning days 8-10 post chigger attachment (PCA); these included fever, severe headache, myalgia, regional lymphadenopathy, and eschar. The two L. fletcheri subjects developed a transient generalized rash on days 3-4 after the onset of fever, and these two individuals also appeared to suffer a more severe clinical disease. Rickettsemias were detected in all three volunteers beginning on day 7 PCA, 1-3 days before the onset of clinical disease. Rises in indirect fluorescent antibody titers occurred starting on days 13-19 PCA (day 4-11 post fever) and in Weil-Felix OXK titers starting on days 26-22 PCA (days 7-14 post fever). These results strongly suggest that the use of laboratory-reared chiggers is a reliable means of transmitting scrub typhus infections to volunteers.

Rocky Mountain Spotted Fever

Serological tests for Rocky Mountain spotted fever were performed on single serum specimens from sixth graders from Forsyth County, North Carolina, an area highly endemic for this disease. Five of 508 *.098%) sera were positive (titer greater than or equal to 1:64) using the indirect fluorescent antibody method. Elevated Proteus agglutination antibody titers (greater than 1:160) to OX-19, but not ot OX-2, were common (19.6%) in these children. No correlation of those with positive OX-19 titers could be made with the cases demonstrating elevated indirect fluorescent antibody titers or with a history of urinary tract infection. These data suggest that the increased prevalence of elevated Proteus OX-19 antibody levels makes a single high titer unreliable in the diagnosis of Rocky Mountain spotted fever and that naturally acquired mild or asymptomatic subclinical cases of Rickettsia rickttsii infection occur.

A fifth serogroup of Legionella pneumophila.

Brief Reports1 July 1980A Fifth Serogroup of Legionella pneumophilaALBERT C. ENGLAND III, M.D., ROGER M. McKINNEY, Ph.D., PETER SKALIY, Ph.D., GEORGE W. GORMAN, B.S.ALBERT C. ENGLAND III, M.D.Search for more papers by this author, ROGER M. McKINNEY, Ph.D.Search for more papers by this author, PETER SKALIY, Ph.D.Search for more papers by this author, GEORGE W. GORMAN, B.S.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-93-1-58 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptIn September 1978, the Center for Disease Control (CDC) investigated an outbreak of Legionnaires' disease among persons who had attended the national Veterans of Foreign Wars convention held in Dallas, Texas, 17 to 25 August 1978 (1). Among 45 conventioneers who had radiographically diagnosed pneumonia, in seven there was seroconversion toLegionella pneumophilaserogroup 1, 11 had single indirect fluorescent (IF) antibody titers of 256 or greater, and one had lung tissue positive by direct fluorescent (DF) antibody to serogroup 1 but not to serogroups 2 to 4 (2); 26 others had pneumonia without apparent bacterial cause and did not...

Transfer factor and cellular reactivity to varicella-zoster antigen in childhood leukemia

The present studies were designed to evaluate possible efficacy of specific human transfer factor (TF) in preventing or attenuating varicella-zoster (VZ) infection in children with acute lymphocytic leukemia (ALL). TF was prepared following leukapheresis of adult donors who were convalescing from chicken pox. Recipients were VZ seronegative children with ALL, 12 in remission and 3 in relapse; a single injection of TF was given equivalent to 10 8 lymphocytes per 7 kg body wt. The following VZ-specific parameters were measured: lymphocyte blastogenesis, cytotoxicity and leukocyte inhibitory factor (LIF) production, and indirect fluorescent and CF antibody titers. No patients in relapse converted immune response while 10 12 in remission developed positive reactivity in at least one assay of cell-mediated immunity (CMI); 3 12 were positive in all three parameters of CMI and 8 12 in two assays. Cytotoxicity was the most consistently positive test following TF administration. No patients developed VZ antibody. Seventeen months follow-up has demonstrated persistent cellular immunity.

Seroepidemiological studies of malaria in pregnant women and newborns from coastal El Salvador.

A cohort of 113 women and their newborns from the coastal area of El Salvador were studied longitudinally to estimate malaria incidence and indirect fluorescent antibody (IFA) response to malaria infection. The district in which the study was conducted had an estimated annual parasite index of 600/1,000 inhabitants, and all malaria infections were treated immediately with a 4-aminoquinoline. In the third trimester of pregnancy, the IFA response to Plasmodium falciparum was significantly depressed. As a result of antimalarial therapy and depressed immune responsiveness, 49% (P. vivax) and 53% (P. falciparum) of the pregnant subjects had a malaria IFA titer less than 1:20 at the time of delivery. Malaria IFA crossed the placenta to the fetus with a step-down of approximately a 4-fold dilution, except for the step-up noted in the P. falciparum titer for 17 of 116 newborns. Due to the overall low prevalence and intensity of maternal IFA, a titer of at least 1:20 was passed to only 23% (P. vivax) and 45% (P. falciparum) of newborns. Passively-acquired malaria IFA degraded with a half-life estimated between 43 and 52 days. During follow-up of infants to 6 months of age, no protection from malaria resulting from passively-acquired antibody could be demonstrated. Because of the limited transplacental immunization of these newborns with antimalarial antibody, it appears that passive immunity can exert little effect on the incidence of infant malaria in coastal El Salvador.

Serum Antibody Levels as Risk Factors in the Dissemination of Herpes Zoster

Serum antibody levels against varicella-zoster virus (VZV) were examined by immune adherence hemagglutination assay (IAHA), indirect fluorescent antibody (IFA) assay, and complement fixation techniques in 67 immunocompromised patients with localized and disseminated herpes zoster. In the serum obtained initially, undetectable IAHA titers were found in 56.5% of the patients with disseminated zoster compared with 18.2% of those with localized zoster. When serum obtained within the first seven days of illness was analyzed, undetectable IAHA titers and IFA titers of less than 32 were noted in 77.8% of those with disseminated zoster but in only 18.5% of those with localized disease. Peak serum antibody titers in patients with disseminated zoster were eventually equal to or greater than those in localized zoster. The patient groups were comparable in age, underlying disease, and therapy, although Hodgkin's disease was more frequent in patients with disseminated zoster. Thus, the absent IAHA or low IFA levels of circulating antibody early in illness were highly significant risk factors in dissemination of virus in herpes zoster.

Prevalence of Antibody to Legionella pneumophila in Middle-Aged and Elderly Americans

An indirect fluorescent antibody (IFA) test was used to establish the background prevalence of antibody to Legionella pneumophila in single serum specimens from 1,143 persons. The serum specimens had been obtained from volunteers 46 years of age and older who were not acutely ill and who resided in the areas of Atlanta, Georgia; Washington, D.C.; Houston, Texas; and Rochester, New York. The overall prevalence of seropositivity (reciprocal titer, greater than or equal to 64) was 1.7%. The prevalence of seropositivity did not vary with age, sex, or geographic location. Groups of persons in which the prevalence of reciprocal titers of greater than or equal to 64 is significantly higher than 1.7% may have unusually great exposure to L. pneumophila. In the population tested, a reciprocal IFA titer of greater than or equal to 64 would have a specificity of 98.3% in the diagnosis of an acute illness as Legonnnaires' disease.

Plasmodium fragile and Macaca mulatta monkeys as a model system for the study of malaria vaccines.

Pladmodium fragile and the Macaca mulatta monkey are presented as a model system for the study of malarial vaccines. Four animals were immunized with culture-grown P. fragile merozoites and subsequently challenged with culture-produced parasites. One animal failed to develop a detectable parasitemia following primary challenge. Two other immunized animals had primary infections which were short-term. the parasitemias in these three monkeys following secondary challenge were short-term and the immunity was apparently sterilizing. The fourth immunized monkeys had recrudescences of the primary and secondary infection but differed markedly from the four control animals. Indirect fluorescent antibody titers increased as a result of the immunization and were indicative of the level of immunity. Because of the many similarities to the human-P. falciparum model system, the P. fragile-M. mulatta system appears to be particularly well suited for a number of malaria vaccine studies.

Intraerythrocytic Parasites in Rodent Populations of Connecticut: Babesia and Grahamella Species

A total of 612 Peromyscus leucopus, 11 Microtus pennsylvanicus, 21 Clethrionomys gapperi, and 4 Tamias striatus was collected in Connecticut and examined for Babesia and Grahamella during 1976 and 1977. Babesia antibodies were detected in sera of 9 P. leucopus collected from 4 sites. Babesia parasites were not detected in the blood smears of captured rodents. Subsequent splenectomy and subinoculation of blood from these rodents into susceptible animals failed to induce disease and no Babesia was isolated. Six of 10 P. leucopus inoculated with a Shelter Island, New York strain of B. microti remained infected for 3 1/2 months. Indirect fluorescent antibody titers of experimentally infected P. leucopus ranged from 1:8 to 1:256. Prevalence of Grahamella peromysci infection, as determined from examinations of blood smears of P. leucopus, was 13%. This infection rate is a conservative estimate because parasitemia is difficult to detect in intact animals. Twenty of 58 P. leucopus, taken at 2 sites and with negative blood smears for G. peromysci, developed parasitemia after splenectomy.

Characteristics of Theileria species (eland) infections in eland and cattle

A stabilste of Theileria sp (eland) was prepared from adult Rhipicephalus appendiculatus ticks which had fed as nymphs on a parasitaemic eland. This stabilate proved infective to eland and cattle which developed macroschizont, and, in most cases, piroplasm parasitoses. The reactions of cattle and eland to this stabilate challenge were variable but lower numbers of piroplasms were produced in cattle. Theileria sp (eland) appeared to have low pathogenicity for eland and cattle although one eland died on challenge, showing a 50 per cent piroplasm para-sitaemla. Eland and cattle recovered from Theileria sp (eland) infection were immune to challenge with the homologous stabilate. However, eland infected previously with blood developed macroschizonts when challenged with stabilate. Cattle recovered from Theileria sp (eland) were fully susceptible to T parva stabilate challenge. Sera from cattle infected with Theileria sp (eland) only showed a significant rise in indirect fluorescent antibody titres when Theileria sp (eland) piroplasm antigen was used. Sera from cattle reacting to Theileria sp (Idobogo) and Theileria sp (Mwanza), other species with low pathogenicity, also showed an antibody response to Theileria sp (eland) piroplasm antigen. In two cases it proved possible to transmit Theileria sp (eland) between cattle using R appendiculatus. The establishment of lymphoblastoid cell lines infected with schizonts was achieved from eland but not from cattle. One infected cell line from eland grew as a monolayer. The development of this parasite was compared with other Theileria spp and it is proposed that Theileria sp (eland) be designated T taurotragl(Martin and Brocklesby 1960).

Abnormal haemoglobins in the Sudan savanna of Nigeria

Children born in areas hyperendemic for Plasmodium falciparum are protected by maternal antibodies for up to about five months of life, after which they are subject to intense infection until they acquire sufficient immunity--by about five years of age. Children with sickle cell trait (Hb.AS) are at an advantage during these critical years, probably because of preferential phagocytosis of parasitized red cells. This could lead to either (i) early processing of antigen by macrophages and an accelerated immune response, or (ii) less antigenic stimulus and hence lower antibody production. Immunoglobulin (Ig)G and IgM determinations, agar gel diffusion (Ouchterlony) against soluble P. falciparum antigen, the indirect fluorescent antibody (IFA) test using P. falciparum and P. malariae antigens, and the indirect haemagglutination (IHA) test with P. falciparum antigen were performed on sera from a population with different Hb electrophoretic types in the hyperendemic malarial area of Garki, Kano State, Nigeria. Plasma immunoglobulins and antimalarial antibodies rose with age. After the first year of life, lower mean concentrations of immunoglobulins (especially IgM), and lower mean titres of antibodies specific against P. falciparum (Ouchterlony, IHA and less significantly IFA) were present in Hb.AS compared to Hb.AA; these differences increased with age. Antimalarial intervention was followed by a decline of all values and final levels showed little difference between haemoglobin types. It was unlikely that either a relative inability to produce antibody or a more rapid catabolism of immunoglobulins was responsible for the lower levels in sickle cell trait. The observations are more easily explained by the hypothesis that Hb.AS persons have less antigenic stimulus due to the early removal of parasitized sickled cells by macrophages, which then degrade the antigens. The antibody difference between Hb.AA and Hb.AS increased throughout life, suggesting that this process remained a feature of sickle cell trait even after parasite frequencies and densities were similar in the two Hb groups. These observations have implications in the aetiology of tropical splenomegaly syndrome, which is rarely seen in sickle cell trait subjects. Mean IgG and IgM were slightly higher in Hb.AS than Hb.AA infants, the difference for IgG achieving significance. This suggested that during infancy early phagocytosis of parasitized cells had led to enhanced processing of antigen and hence an earlier immune response in Hb.AS, but this was unlikely to be a major factor in survival. IFA titres against P. malariae were slightly but not significantly lower in Hb.AS, possibly as a result of cross-reaction with P. falciparum antibody or of a slight degree of protection against P. malariae.

Farmer’s Lung Disease in Vermont

Several Vermont population groups were surveyed for the occurrence of antibodies to thermophilic actinomycetes. Antibodies to M. faeni and T. vulgaris were measured by the precipitin method in all subjects and, in 124 subjects, M. faeni antibodies were also measured by the indirect fluorescent antibody (IFA) technique. There was relatively good correlation between the two techniques (r 0.48, p less than 0.01). Hospital employees, blood donors and patients with chronic bronchitis were generally negative for precipitins to thermophilic actinomycetes. Of the 258 Vermont dairy farmers surveyed, 14 (5.4%) had precipitins to M. faeni, 3 (1.2%) had precipitins to T. vulgaris but only 1 farmer with antibodies to M. faeni had symptoms of possible farmer's lung disease (FLD). On the other hand, 10 (4.1%) precipitin-negative farmers had symptoms possibly consistent with FLD. The IFA test did not correlate any better with symptoms. 7 (5.6%) patients with pulmonary fibrosis had precipitins to M. faeni 5 of these were diagnosed as having FLD. 18 (14.4%) had precipitins to T. vulgaris and only 3 of these patients were felt to have hypersensitivity pneumonitis. Patients with pulmonary fibrosis and FLD hat IFA titers of greater than or equal to 1/128, but so did asymptomatic farmers.

Acquired Chorioretinitis Due to Toxoplasmosis

Brief Reports1 January 1979Acquired Chorioretinitis Due to ToxoplasmosisDIETER W. GUMP, M.D., ROBERT A. HOLDEN, M.D.DIETER W. GUMP, M.D.Search for more papers by this author, ROBERT A. HOLDEN, M.D.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-90-1-58 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptChorioretinitis due toToxoplasma gondiiin the adult is generally a late sequela of congenital infection (1). Perkins (2), in an extensive review of ocular toxoplasmosis, concluded that almost all cases of toxoplasmic chorioretinitis seen in the United Kingdom were of congenital origin. Unless a serial two-tube rise to high titers by any serologic test occurs or a single high IgM indirect fluorescent antibody titer is present, acute toxoplasmosis cannot be confirmed (1). Considerable controversy remains about whether chorioretinitis can occur with acquired disease, although reports by Saari and colleagues (3), Masur and associates (4), and our case here seem...

Experimental Trypanosoma cruzi infection in rhesus monkeys III. Electrocardiographic and histopathological findings

In five rhesus monkeys surviving ‘Peru strain’ or ‘strain 7’ Trypanosoma cruzi infection for six to eight years, positive xenodiagnosis results and high indirect fluorescent antibody titres (4096 — 65536) persisted until the animals were killed. Abnormal electrocardiograph patterns in two monkeys (H and K) were possibly compatible with myocardial damage. Histopathological changes attributable to T. cruzi infection were minor in four monkeys but severe in one (R). In this animal, infected with what was judged previously to be the less virulent of the two T. cruzi stocks used (‘strain 7’), there was severe myocarditis, with myofibre degeneration, and lesions of the oesophagus. Elevated serum levels of five enzymes were not detected in any of the chronically infected monkeys.

Cultured Plasmodium falciparum used as antigen in a malaria indirect fluorescent antibody test.

Human sera obtained from persons infected with Plasmodium falciparum were tested by a standard indirect fluorescent antibody (IFA) technique using antigen obtained from long term in vitro cultures of two strains of P. falciparum, and antibody in high titer was reproducibly detected. Sera from uninfected persons had undetectable or very low titers of antibody. The use of cultured parasites offers a convenient, stable source of antigens from different P. falciparum strains without requiring their adaptation to primates. Differences observed in IFA titers obtained by reacting immune serum with two different P. falciparum strains suggests the need for further evaluation of strain specificity.