Diagnosis of Cryptococcosis in Dogs by Latex Agglutination Test and Enzyme Immunoassay

Cryptococcus spp. is a pathogenic fungus which is an increasingly important cause of infection, particularly in the immunocompromised hosts. Diagnosis of cryptococcosis in animals can be carried out by isolation of the fungus but this requires several days to detect and identify the organism. Detection of cryptococcal antigen by latex agglutination test and enzyme immunoassay in serum is a rapid and easy method for diagnosis of cryptococcosis. In the present study, a total of 142 blood samples were collected from apparently healthy (n=89) and diseased dogs (n=53) for diagnosis of cryptococcosis. Latex agglutination test and enzyme immunosorbent assay (EIA) were carried out for the detection of cryptococcal antigen in serum. Of the 142 serum samples tested, six samples tested positive by Latex agglutination test while one sample tested positive by EIA. The sample which was positive by EIA was also positive by Latex agglutination test. The serum samples of dogs that tested positive for cryptococcal antigen were obtained from dogs suffering from symptoms like bloody faeces and vomit, emesis, chronic ear infection and discharge. Based on our findings, we conclude that the latex agglutination test in combination with the enzyme immunoassay can be used for the diagnosis of Cryptococcosis in dogs

Toxoplasma gondii infection: seroprevalence and associated risk factors among primary schoolchildren in Lagos City, Southern Nigeria

INTRODUCTION: Toxoplasma gondii infection has been described as the most widespread zoonotic infection of humans and other animals. Information concerning T. gondii infection among schoolchildren is unavailable in Lagos City, Nigeria. METHODS: This cross-sectional study investigated the seroprevalence and risk factors associated with T. gondii infection among primary schoolchildren (PSC) from a community located in the center of Lagos, southern Nigeria, from November 2013 to March 2014. A total of 382 PSC were screened for the presence of sera anti-T. gondii antibodies using a latex agglutination test (TOXO Test-MT, Tokyo, Japan). A cutoff titer of ≥ 1:32 was considered positive, while titers ≥ 1:1,024 indicated high responders. Questionnaires were also used to obtain data on possible risk factors from parents/guardians. RESULTS: The overall seroprevalence was 24% (91/382), and 83.5% (76/91) of seropositive PSC were classified as high responders. Among the risk factors tested, including contact with cats and soil, consumption of raw meat and vegetables, and drinking unboiled water, none showed statistical significance after multivariate adjustment. No associations were observed among age, gender, body mass index (BMI), and parents' occupation/educational level. CONCLUSIONS: The findings in this study show evidence of active infection, and hence, there is need for urgent preventive measures in this city. Further investigation is required to clarify the transmission routes. Policy makers also need to initiate prevention and control programs to protect pregnant women and immunocompromised patients in particular because they are more severely affected by T. gondii infection. .

Development of a peptide based latex agglutination assay for serotype identification of foot and mouth disease virus.

Out of 200 serum samples collected from cattle (142) and buffaloes (58) of various ages and sexand subjected to latex agglutination test (LAT) using serotype specific peptides (O, A, Asia 1) and also with peptide for non-structural protein 2B (NSP-2B), 114 (70%) samples were positive against FMDV type ‘O’, 102 (51%) against serotype ‘A’ and 104 (52%) against serotype ‘Asia 1’. With NSP-2B peptide a total of 71 (35.5%) samples were positive. The results suggest that LAT could be used for the diagnosis of foot and mouth disease virus as it is easy, cheap and effective test.

Comparative study between immunoturbidimetric and latex agglutination methods for the detection of rheumatoid factor / Estudo comparativo entre as técnicas de aglutinação em látex e de imunoturbidimetria para a detecção de fator reumatoide

INTRODUCTION: The rheumatoid factor (RF) is the most common antibody found in patients with rheumatoid arthritis. It is an inflammatory chronic disease characterized by articular involvement, inflammation of synovial fluid, tissue infiltration by leucocytes and joint destruction, which ultimately determine articular deformities. The rheumatoid factor is found in 70%-80% of the adult population and in 10% of the young population. OBJECTIVE: The aim of this research was to compare immunoturbidimetric and latex agglutination methods for the detection of RF in serum. RESULTS: The immunoturbidimetric method displayed sensitivity (95.2%), specificity (89.4%) and high positive correlation (R² = 0,8077) with the latex agglutination method in positive serum samples. CONCLUSION: The study allowed to demonstrate that both immunoturbidimetric and latex agglutination methods equally discriminate between negative and positive serum samples for RF.

INTRODUÇÃO: O fator reumatoide (FR) é o autoanticorpo mais comum encontrado em pacientes com artrite reumatoide, uma doença crônica inflamatória caracterizada pelo envolvimento articular com inflamação do líquido sinovial, infiltração de tecido por leucócitos e destruição das articulações, que acaba por determinar deformidades articulares. O FR é encontrado em 70%-80% da população adulta e em 10% da população juvenil. OBJETIVO: Comparar os métodos de imunoturbidimetria e aglutinação (prova do látex) para a determinação de FR em soro. RESULTADO: Foi possível observar que o método imunoturbidimétrico apresenta sensibilidade (95,2%), especificidade (89,4%) e correlação positiva elevada (R² = 0,8077) com o método de aglutinação pelo látex em amostras de soro positivas. CONCLUSÃO: O estudo permitiu demonstrar que o método imunoturbidimétrico e o método de aglutinação pelo látex são igualmente capazes de discriminar amostras negativas e positivas para FR.

Effect of serum sample inactivation on the performance of latex agglutination test for paracoccidioidomycosis serodiagnosis

Paracoccidioidomycosis is diagnosed from the direct observation of the causative agent, but serology can facilitate and decrease the time required for diagnosis. The objective of this study was to determine the influence of serum sample inactivation on the performance of the latex agglutination test (LAT) for detecting antibodies against Paracoccidioides brasiliensis. The sensitivity of LAT from inactivated or non-inactivated samples was 73% and 83%, respectively and the LAT selectivity was 79% and 90%, respectively. The LAT evaluated here was no more specific than the double-immunodiffusion assay. We suggest the investigation of other methods for improving the LAT, such as the use of deglycosylated antigen.

Comparison of an in-house latex agglutination test with IgM ELISA and MAT in the diagnosis of leptospirosis.

The laboratory diagnosis of leptospirosis is fraught with several problems. Isolation of Leptospira by culture has a low sensitivity and the microscopic agglutination test (MAT) is time consuming To overcome these problems, a rapid latex agglutination test (LAT) has been standardized for the detection of antileptospiral antibodies in serum samples from suspected cases of leptospirosis. We compared the efficiency of the LAT to a commercially available IgM ELISA and MAT. A total of 150 serum samples were tested by LAT, IgM ELISA, and MAT. The positivity was 26.7%, 26% and 24% respectively. The sensitivity and specificity of LAT as compared to MAT was 90.62 and 91.96% respectively. Even though LAT and ELISA showed similar results, its rapidity and simplicity made latex agglutination test more suitable as a rapid screening test.

Enzyme-linked immunospot assay combined with serum latex agglutination test for diagnosis of pulmonary tuberculosis and concomitant pulmonary cryptococcosis / 中国感染与化疗杂志

Objective To evaluate the value of enzyme-linked immunospot assay (TB ELISPOT) combined with serum latex agglutination test (LA) for diagnosis of pulmonary tuberculosis plus pulmonary cryptococcosis.Methods Serum and biopsy specimens of 76 patients, who were suspected of pulmonary tuberculosis and/or pulmonary cryptococcosis based on clinical and imaging features, were collected from March 2006 to September 2008 in Shanghai Public Health Clinical Center. TB ELISPOT assay, LA and histopathological examination were performed in all the patients. Results Histopathological and pathogenic examination confirmed pulmonary cryptococcosis in 15 cases and pulmonary tuberculosis in 22 cases, pulmonary tuberculosis plus pulmonary cryptococcosis in 8 cases. The sensitivity and specificity of TB ELISPOT were 91% and 94.4%. The sensitivity and specificity of LA were both 100%. TB ELISPOT assay and LA test were both positive in the 8 cases of pulmonary tuberculosis plus pulmonary cryptococcosis.Conclusions The value of enzyme-linked immunospot assay combined with serum latex agglutination test is high for diagnosis of pulmonary tuberculosis plus pulmonary cryptococcosis.

The characteristics of CT imaging and diagnosis of pulmonary cryptococcosis in 42 cases with non-acquired immune deficiency syndrome / 中华内科杂志

Objective To further elucidate the CT characteristics and diagnostic approaches to non-acquired immune deficiency syndrome patients with pulmonary cryptococcosis. Methods The histories of forty-two pulmonary cryptococcosis (PC) patients diagnosed in Zhongshan Hospital from 2003 -2008 were collected and analyzed for demography data, underlying conditions, clinical symptoms, chest CT and diagnostic studies. Results None of the 42 PC patients had avian or its feces contacting history, and 71.4% (30/42) of them were immunocompetent. The most frequent CT lesions were multiple nodules (67. 9% ) with peripheral predominance (67. 9% ), and cavitations (50%) often presented within them. Masses/consolidation (31.4%) and patching lesions (2. 9% ) could exist occassionally. Positive detection rates of non-aggressive examinations including sputum, bronchoalveolar lavage fluid and bronchofibroscope aspiration were 4. 3%, 8. 3% and 6. 3% respectively, while those of aggressive approaches including transbrunchial lung biopsy (TBLB), thin needle aspiration biopsy (TNAB) and pneumonectomy by surgery were 64. 7%, 64. 3% and 100% respectively. Non-aggressive serum cryptococcus antigen test was performed in 14 patients who had been diagnosed by histopathology or pathogen culture, and all of them were positive. Conclusion Our study suggests that PC is common in immunocompetent population. Avian or its feces contacting is not so important as used opinion to PC differential diagnosis. CT characteristics of PC are diversiform and always change very slowly. Besides the most frequent multiple nodules with subpleural predominance, pulmonary lesions can present as masses, consolidation or patchings. Aggressive techniques such as TBLB and TNAB are benefit to clinical diagnosis of PC, and non-aggressive serum cryptococcus antigen test may be promising for its early diagnosis as well as clinical course follow-up and therapeutic effect evaluation.

A report of three cases and literature review of pulmonary cryptococcosis / 中国综合临床

Objective To improve the diagnosis and treatment of pulmonary cryptococcosis.Methods The clinical data of 3 cases of pulmonary cryptococcosis were analyzed and reviewed.Results The cases were tested by percutaneous lung biopsy and were confirmed by histopathologic examination.The sputum cultures were negative and serum latex cryptococcal antigen agglutination tests were positive.Two of them had mild to moderate symptoms and were treated by fluconazol;the other with meningitis had severe symptoms and was treated by amphotericin B.All of them were clinically cured.Conclusion Percutaneous lung biopsy combined with latex cryptococcal antigen agglutination tests is helpful for diagnosis of pulmonary cryptococcosis.Patients with mild to moderate symptoms should be firstly treated by fluconazol and those with severe symptoms or meningitis,by amphotericin B.

Prevalence of Toxoplasma gondii in Stray Cats of Gyeonggi-do, Korea

Toxoplasma gondii is an obligate intracellular zoonotic protozoan with a worldwide distribution. It infects humans as well as a broad spectrum of vertebrate hosts. Cats and wild felidae play crucial roles in the epidemiology of toxoplasmosis. This study was performed to survey the prevalence of T. gondii infection among stray cats in the Gyeonggi-do, Republic of Korea. A total of 174 stray cat blood samples were collected from Gwacheon-si (n = 20), Bucheon-si (82), and Yangju-si (72). Positive sera for T. gondii were identified in 14 samples (8.1%) exclusively via the latex agglutination test, 28 (16.1%) via ELISA, and 23 (13.2%) via PCR analysis. The overall infection rate of female stray cats (29.2%) presented as higher than that of male cats (24.0%). This study suggests that T. gondii is widespread in the stray cat population of Gyeonggi-do, Korea. It is urgently needed to control urban stray cat population and to reduce the risk of zoonotic transmission of toxoplasmosis to other animal hosts and humans.

Detección de meticilino-resistencia en Staphylococcus aureus: Comparación de métodos convencionales y aglutinación con mrsa-Screen latex / Methicillin resistance detection in Staphylococcus aureus: Comparison between conventional methods and Mrsa-Screen latex agglutination technique

Staphylococcus aureus meticilino-resistente (MRSA) es un patógeno que ha emergido en las últimas cuatro décadas causando tanto infecciones nosocomiales como de la comunidad. La rápida y precisa detección de MRSA es relevante para guiar una apropiada terapia antibiótica y evitar la diseminación nosocomial de MRSA.En este trabajo se evaluó la eficiencia de métodos convencionales para la detección de meticilino-resistencia como difusión por discos, CIM en medio sólido, screening de oxacilina, y el nuevo test de aglutinación MRSA-Screen latex sobre 100 aislamientos de S. aureus, 79 mecA positivos y 21 mecA negativos. El test de aglutinación MRSA-Screen latex (Denka Seiken, Niigata, Japón) detecta la presencia de la PLP-2a, producto del gen mecA en cepas de S. aureus. La detección del gen mecA por PCR se utilizó como gold standard para comparar los resultados de los diferentes métodos. La sensibilidad y especificidad fueron 97 y 100 % para el método de difusión, 97 y 95 % para la CIM en medio sólido, 100 y 100 % para el screening de oxacilina y 100 y 100 % para MRSA-Screen latex. Todos los métodos presentaron alta sensibilidad y especificidad, pero el “MRSA-Screen latex” mostró la ventaja de poder brindar un resultado confiable, equivalente a la PCR, en sólo 15 minutos.

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen that has emerged over the last four decades, causing both nosocomial and community-acquired infections. Rapid and accurate detection of methicillin resistance in S. aureus is important for the use of appropriate antimicrobial therapy and for the control of nosocomial spread of MRSA strains. We evaluated the efficiency of conventional methods for detection of methicillin resistance such as the disk diffusion, agar dilution, oxacillin agar screen test, and the latex agglutination test MRSA-Screen latex, in 100 isolates of S. aureus, 79 mecA positive and 21 mecA negative. The MRSA-Screen latex (Denka Seiken, Niigata, Japón), is a latex agglutination method that detects the presence of PLP-2a, product of mecA gene in S. aureus. The PCR of the mecA gene was used as the “gold standard” for the evaluation of the different methods tested. The percentages of sensitivity and specificity were as follows: disk difusión 97 and 100 %, agar dilution 97 and 95 %, oxacillin agar screen test 100 and 100 %, and MRSA-Screen latex, 100 and 100 %. All methods presented high sensitivity and specificity, but MRSA-Screen latex had the advantage of giving a reliable result, equivalent to PCR, in only 15 minutes.

Latex Agglutination Test for Differentiating Neonatal Blood from the Maternal Blood in the Meconium / 대한진단검사의학회지

BACKGROUND: The Apt test is used for differentiating neonatal blood from the maternal blood in the meconium. The test requires a sufficient amount of blood to be detectable to the naked eyes. But many of the specimens in the hospital laboratory contain only a small amount of blood and is not detectable to the naked eyes and usually the results are reported 'impossible to determine' due to the small amount of blood. We developed a latex agglutination test to solve this problem and to differentiate the neonatal blood from the maternal blood in a small amount that was not detectable with the naked eyes. METHODS: Latex reagents for hemoglobin A (Hb A) and hemoglobin F (Hb F) were made. Ten milligrams of meconium were dissolved in 1mL of deionized water (DW). Ten milligrams of meconium that had shown negative results for both of the above reagents were mixed, each with 10microL of whole blood (WB) from 10 pregnant women and 10 neonates who had various hemoglobin concentrations (10-17 g/dL). Each of the 20 mixtures was dissolved in 1 mL of DW (WB 10microL/mL). Then, serial dilutions were made at a ratio of 1:10 until the final concentration of 10 pL/mL. Each of the six dilutes were tested with the two latex reagents. RESULTS: The dilutes of WB 10microL/mL looked red, WB 1microL/mL looked pink and all other dilutes showed no colors to the naked eyes. The reagent for Hb A showed agglutination in dilutes from WB 1microL to 1 nL/mL DW from all of the 20 persons. The reagent for Hb F reacted with dilutes from WB 1microL to 1 nL/mL DW from the ten neonates but did not react with those from any pregnant women. CONCLUSIONS: The latex agglutination test can be applied to the specimen with no color detectable to the naked eyes after dilution. The specimen reacted with both the Hb A and Hb F reagents could be determined as fetal blood and the one that reacted with the reagent only for Hb A could be determined as maternal blood.

Utility of Latex Agglutination Test in the Laboratory Diagnosis of Bacterial Meningitis / 대한임상병리학회지

BACKGROUND: Latex agglutination (LA) test has been ordered frequently on cerebrospinal fluid (CSF) specimens to identify etiologic agents of bacterial meningitis as early as possible, but its use is still controversial. To assess the clinical utility of LA tests, 54 consecutive cases of bacterial meningitis were reviewed retrospectively in a tertiary care hospital in Seoul. METHODS: A total of 54 patients with bacterial meningitis of Streptococcus pneumoniae (21 cases), Haemophilus influenzae (17), Neisseria meningitidis (5), Streptococcus agalactiae (11) were identified by a search of the hospital computer files from 1989 through 1997 in Asan Medical Center. The medical records of each patient were reviewed for CSF parameters (cell count, protein, glucose), the results of Gram stains, cultures, and LA tests, and history of antibiotics prior to the procurement of the CSF specimens. We also evaluated the yield of LA tests performed during the 12-month period from July 1996 through June 1997 and searched the hospital computer files for the CSF parameters of 215 patients on whom LA tests were done in the month of July 1997. RESULTS: Gram stains and cultures were positive in 21 (70.0%) and 29 (96.7%), respectively, of 30 cases without prior antibiotic treatment, compared to only 4 (16.7%) and 7 (29.2%), respectively, of 24 cases with prior antibiotic treatment (P OR =50/ L compared to 122 (56.7%) of 215 patients with LA tests performed in the month of July 1997. CONCLUSIONS: The LA test is highly sensitive for the laboratory diagnosis of bacterial meningitis. It is a valuable test, particularly when the patient has a history of prior antibiotic treatment. The low yields of the LA tests could be improved by limiting the tests to those specimens with leukocyte counts of > OR =50/ L.