[Latex Agglutination as an Alternative to the Hemagglutination Reaction of Influenza Viruses].

As an alternative to the classical method of erythrocyte hemagglutination, a latex agglutination assay based on the interaction of influenza viruses with the sialoglycoprotein fetuin immobilized on the surface of polystyrene microspheres has been developed. Twelve influenza A virus strains of different subtypes and two influenza B viruses of different lines were tested. Simultaneous titration of viruses using the classical hemagglutination test and the proposed latex agglutination assay showed similar sensitivity and a high degree of correlation (R = 0.94). The obtained microspheres can be used for titration of viruses that recognize and bind sialylated glycans as receptors. In particular, latex aggregation was also induced by the Newcastle disease virus.

Evaluation of Latex Agglutination Test for Rapid Identification of Staphylococcus aureus Isolated from Pyogenic Wound Infections at a Tertiary Care Hospital.

Background Staphylococcus aureus infections are increasingly reported worldwide. It is a major clinical problem and imposes significant morbidity and mortality due to widespread emergence of multidrug resistant pathogens like methicillin resistant Staphylococcus aureus. Thus, rapid and reliable identification of Staphylococcus aureus is essential for timely and effective management of patient. Objective The performance of Latex agglutination test (Staphaurex Plus) was compared to conventional method tube coagulase test which is gold standard too for the identification of Staphylococcus aureus. Method This study was conducted at B.P. Koirala Institute of Health Sciences. Following standard microbiological methods, isolation and identification was done in the Department of Microbiology. MRSA detection was performed following Clinical and Laboratory Standard Institute. All the isolates of Staphylococci were subjected for Latex agglutination test and was performed according to manufacturer's instructions using Staphaurex Plus kit. Result Out of 377 (methicillin sensitive Staphylococcus aureus - 142; methicillin resistant Staphylococcus aureus - 233; Coagulase Negative Staphylococci -2) isolates of Staphylococci, Latex agglutination test was found to be positive in 138 (97.1%) of methicillin sensitive Staphylococcus aureus (MSSA) and 220 (94.4%) of methicillin resistant Staphylococcus aureus (MRSA). Overall sensitivity, specificity, positive predictive value and negative predictive value of Latex agglutination test was found to be 95.46%, 100%, 100%, 10.52% respectively. Conclusion In conclusion, Latex agglutination test is a rapid and reliable test for the identification of Staphylococcus aureus.

Asymptomatic latent syphilis in geriatric patients in association with stoke: Analysis using routine syphilis tests.

INTRODUCTION: We investigated the association between stroke and asymptomatic latent syphilis (ALS) in geriatric patients. METHODS: This retrospective observational study included patients aged >65 years who underwent routine qualitative rapid plasma reagin (RPR) and Treponema pallidum Latex Agglutination (TPLA) tests at a 161-bed community acute care hospital with long-term care facilities in Kamakura, Japan, from August 2014 to February 2019. Asymptomatic patients with a positive TPLA test result were diagnosed with ALS. Ninety-six patients with ALS were included in the study. Fifty-one patients (53.1%) had a positive RPR test. Comorbidities included hypertension (n = 44; 45.8%), chronic kidney disease (n = 44; 45.8%), and fracture (n = 29; 30.2%). No significant differences were found in sex, age, or comorbidities in univariate analyses. Multivariate analysis of the TPLA-positive geriatric patients revealed that a positive RPR test (odds ratio = 9.06; 95% confidence interval = 1.69-48.5; p = 0.01) was associated with a history of stroke. CONCLUSIONS: For geriatric patients with ALS, a positive qualitative RPR test was associated with a history of stroke. Medical evaluation and management of the risk factors for stroke are more necessary for ALS with a positive RPR qualitative test.

Rapid Clinical Screening of Burkholderia pseudomallei Colonies by a Bacteriophage Tail Fiber-Based Latex Agglutination Assay.

Melioidosis is a life-threatening disease in humans caused by the Gram-negative bacterium Burkholderia pseudomallei. As severe septicemic melioidosis can lead to death within 24 to 48 h, a rapid diagnosis of melioidosis is critical for ensuring that an optimal antibiotic course is prescribed to patients. Here, we report the development and evaluation of a bacteriophage tail fiber-based latex agglutination assay for rapid detection of B. pseudomallei infection. Burkholderia phage E094 was isolated from rice paddy fields in northeast Thailand, and the whole genome was sequenced to identify its tail fiber (94TF). The 94TF complex was structurally characterized, which involved identification of a tail assembly protein that forms an essential component of the mature fiber. Recombinant 94TF was conjugated to latex beads and developed into an agglutination-based assay (94TF-LAA). 94TF-LAA was initially tested against a large library of Burkholderia and other bacterial strains before a field evaluation was performed during routine clinical testing. The sensitivity and specificity of the 94TF-LAA were assessed alongside standard biochemical analyses on 300 patient specimens collected from an area of melioidosis endemicity over 11 months. The 94TF-LAA took less than 5 min to produce positive agglutination, demonstrating 98% (95% confidence interval [CI] of 94.2% to 99.59%) sensitivity and 83% (95% CI of 75.64% to 88.35%) specificity compared to biochemical-based detection. Overall, we show how a Burkholderia-specific phage tail fiber can be exploited for rapid detection of B. pseudomallei. The 94TF-LAA has the potential for further development as a supplementary diagnostic to assist in clinical identification of this life-threatening pathogen. IMPORTANCE Rapid diagnosis of melioidosis is essential for ensuring that optimal antibiotic courses are prescribed to patients and thus warrants the development of cost-effective and easy-to-use tests for implementation in underresourced areas such as northeastern Thailand and other tropical regions. Phage tail fibers are an interesting alternative to antibodies for use in various diagnostic assays for different pathogenic bacteria. As exposed appendages of phages, tail fibers are physically robust and easy to manufacture, with many tail fibers (such as 94TF investigated here) capable of targeting a given bacterial species with remarkable specificity. Here, we demonstrate the effectiveness of a latex agglutination assay using a Burkholderia-specific tail fiber 94TF against biochemical-based detection methods that are the standard diagnostic in many areas where melioidosis is endemic.

Nasopharyngeal carriage of Streptococcus pneumoniae among healthy children in Kassena-Nankana districts of Northern Ghana.

BACKGROUND: Pneumococcal vaccine immunizations may be responsible for alterations in serotype epidemiology within a region. This study investigated the pneumococcal carriage prevalence and the impact of the 13-valent pneumococcal conjugate vaccine (PCV-13) on circulating serotypes among healthy children in Northern Ghana. METHODS: This was a cross sectional study conducted in the Kassena-Nankana districts of Northern Ghana from November to December during the dry season of 2018. Nasopharyngeal swabs collected from 193 participants were cultured per standard microbiological protocols and pneumococcal isolates were serotyped using the latex agglutination technique and the capsular Quellung reaction test. We examined for any association between the demographic characteristics of study participants and pneumococcal carriage using chi-square test and logistic regression. RESULTS: Of the 193 participants that were enrolled the mean age was 8.6 years and 54.4% were females. The carriage rate among the participants was 32.6% (63/193), and twenty different serotypes were identified. These included both vaccine serotypes (VT), 35% (7/20) and non-vaccine serotypes (NVT), 65% (13/20). The predominant serotypes (34 and 11A), both of which were NVT, accounted for a prevalence of 12.8%. PCV-13 covered only 35% of serotypes identified whiles 40% of serotypes are covered by PPV 23. CONCLUSION: Post-vaccination carriage of S. pneumoniae is high and is dominated by non-vaccine serotypes. There is therefore a need for the conduct of invasive pneumococcal disease surveillance (IPD) to find out if the high non-vaccine serotype carriage translates to disease. And in addition, a review of the currently used PCV-13 vaccine in the country would be considered relevant.

Serum Helicobacter pylori antibody reactivity in seven Asian countries using an automated latex aggregation turbidity assay.

BACKGROUND AND AIM: To determine the application range of diagnostic kits utilizing anti-Helicobacter pylori antibody, we tested a newly developed latex aggregation turbidity assay (latex) and a conventional enzyme-linked immunosorbent assay (E-plate), both containing Japanese H. pylori protein lysates as antigens, using sera from seven Asian countries. METHODS: Serum samples (1797) were obtained, and standard H. pylori infection status and atrophy status were determined by culture and histology (immunohistochemistry) using gastric biopsy samples from the same individuals. The two tests (enzyme-linked immunosorbent assay and latex) were applied, and receiver operating characteristics analysis was performed. RESULTS: Area under the curve (AUC) from the receiver operating characteristic of E-plate and latex curves were almost the same and the highest in Vietnam. The latex AUC was slightly lower than the E-plate AUC in other countries, and the difference became statistically significant in Myanmar and then Bangladesh as the lowest. To consider past infection cases, atrophy was additionally evaluated. Most of the AUCs decreased using this atrophy-evaluated status; however, the difference between the two kits was not significant in each country, but the latex AUC was better using all samples. Practical cut-off values were 3.0 U/mL in the E-test and 3.5 U/mL in the latex test, to avoid missing gastric cancer patients to the greatest extent possible. CONCLUSIONS: The kits were applicable in all countries, but new kits using regional H. pylori strains are recommended for Myanmar and Bangladesh. Use of a cut-off value lower than the best cut-off value is essential for screening gastric cancer patients.

Comparison of a Lateral Flow Assay and a Latex Agglutination Test for the Diagnosis of Cryptococcus Neoformans Infection.

Infections by the basidiomycete yeast Cryptococcus neoformans are life-threatening diseases claiming more than 600,000 lives every year. The most common manifestation is cryptococcal meningitis in AIDS patients. Diagnosis primarily relies on antigen testing from serum and cerebrospinal fluid (CSF). Current guidelines recommend rapid antigen testing with a focus on point-of-care assays. Over the recent years, a range of new lateral flow assays (LFAs) was launched. There is still a lack of data evaluating the CE-certified Biosynex RDT CryptoPS LFA. We compared the performance of this LFA with a latex agglutination assay (LAA; Latex-Cryptococcus Antigen Detection System, IMMY) from blood and CSF samples. Blood and/or CSF samples of 27 patients with proven cryptococcal infections caused by different species and blood-CSF pairs of 20 controls were tested applying LFA and LAA. Upon combined analysis of blood and CSF, both assays were able to identify all C. neoformans infections. Based on CSF analysis only, the LFA and the LAA had sensitivities of 100% and 93%. Neither test gave false-positive results nor was reactive in two cases of C. non-neoformans/non-gattii species infections. Both assays have high sensitivities and specificities for the diagnosis of C. neoformans infection. Contrarily to the IMMY LAA, the RDT CryptoPS LFA is suitable as a point-of-care test but is limited in the quantification of antigen reactivity.

Evaluation of the diagnostic potential of recombinant leptospiral OMP A-like protein (Loa22) and transmembrane (OmpL37) protein in latex agglutination test for serodiagnosis of leptospirosis in animals.

Leptospirosis is a re-emerging zoonotic disease of animals and humans caused by pathogenic Leptospira, which has major public health concerns. The study is aimed to express the recombinant outer membrane protein (OMP) A-like protein (rLoa22) and transmembrane (rOmpL37) protein of Leptospira interrogans serovar Hardjo in the Escherichia coli and their evaluation as a diagnostic antigen in the latex agglutination test (LAT) to detect anti-leptospiral antibodies in the sera of animals. The Loa22 and OmpL37 genes lacking signal peptide coding sequences were individually amplified (522 and 963 bp), by polymerase chain reaction, and directionally cloned into a pETite N-His Kan vector for expression. The expressed purified proteins were characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblot, which confirmed leptospiral specific reactive protein with a molecular weight of ~19 and 36 kDa, respectively. The sensitized latex beads coated with these OM proteins separately were evaluated in LAT using cattle sera of microscopic agglutination test (MAT) confirmed positive (n = 53) and negative (n = 52) cases of leptospirosis. The rLoa22 LAT and rOmpL37 LAT revealed the relative diagnostic sensitivity of 94·34 and 96·23%, diagnostic specificity of 92·31 and 96·15% and accuracy of 93·33 and 96·19%, with the excellent agreement of Cohen's kappa value of 0·87 and 0·92, respectively. After extensive evaluation, this rapid recombinant protein-based field diagnostic test can be applied as a screening test for the detection of anti-leptospiral antibodies in the sera of animals in the field conditions.

Escherichia coli O15 : H7 from Food of Animal Origin in Arsi: Occurrence at Catering Establishments and Antimicrobial Susceptibility Profile.

Escherichia coli O157 : H7 (E. coli O157 : H7) has been found to be the major cause of food-borne diseases and a serious public health problem in the world, with an increasing concern for the emergence and spread of antimicrobial-resistant strains. Hitherto, little is known about the carriage of E. coli O157 : H7 and its antimicrobial susceptibility profile in the food of animal origin in Ethiopia. This study aimed to determine the occurrence and multidrug resistance profile of E. coli O157 : H7 from food of animal origin at different catering establishments in the selected study settings of Arsi Zone. One hundred ninety-two animal origin food items, namely, raw/minced meat (locally known as "Kitfo," "Kurt," and "Dulet"), raw milk, egg sandwich, and cream cake samples were collected and processed for microbiological detection of E. coli O157 : H7. Out of 192 samples, 2.1% (4/192) were positive for E. coli O157 : H7. Two E. coli O157 : H7 isolates were obtained from "Dulet" (6.3%) followed by "Kurt" (3.1%, 1/32) and raw milk (3.1%, 1/32), whereas no isolate was obtained from "Kitfo," egg sandwich, and cream cake samples. Of the 4 E. coli O157 : H7 isolates subjected to 10 panels of antimicrobial discs, 3 (75%) were highly resistant to kanamycin, streptomycin, and nitrofurantoin. Besides, all the isolates displayed multidrug resistance phenotypes, 3 to 5 antimicrobial resistance, amid kanamycin, streptomycin, nitrofurantoin, tetracycline, and chloramphenicol. The occurrence of multidrug-resistant E. coli O157 : H7 isolates from foods of animal origin sampled from different catering establishments reveals that the general sanitary condition of the catering establishments, utensils used, and personnel hygienic practices did not comply with the recommended standards. Thus, this finding calls for urgent attention toward appropriate controls and good hygienic practices in different catering establishments dealing with consuming raw/undercooked foods of animal origin.

An infantile late-onset case Group of B Streptococcus meningitis diagnosed with a rapid latex kit.

Globally, vaccination has reduced the prevalence of meningitis caused by Streptococcus pneumoniae Neisseria meningitidis, and Haemophilus influenzae. However, neonatal Group B Streptococcus (GBS) meningitis continues to remain a problematic infection of the central nervous system. Here, we report a case of bacterial meningitis in a 34-day old male baby who presented with fever. A cerebrospinal fluid (CSF) test on the day of admission showed an increase in cell count with decreased glucose level. A rapid latex test of the CSF using a commercial kit diagnosed the causative pathogen as GBS. We administered the antibiotics ampicillin, cefotaxime, gentamicin and panipenem/betamipron to the patient for over 14 days. Partial seizures were frequently observed during the course and were well-controlled with midazolam and phenobarbital. Brain magnetic resonance imaging on day 17 showed subdural hygroma in the frontal region, and 99mTc ethyl-cysteinate dimer-single photon emission computed tomography confirmed a decreased cerebral blood flow predominantly in the left frontal region. After three years of follow-up, the condition of the patient improved without any neurological sequelae. Our report highlights that rapid identification of the causative organism is essential in infantile late-onset meningitis. In addition, we consider that the latex kit-based rapid testing of CSF is beneficial for identifying the causative agent of bacterial meningitis.

Staphylococcal aureus bacteraemia: Clinical characteristic & evaluation of Prolex Staph Xtra latex agglutination test in the rapid identification of Staphylococcus aureus.

BACKGROUND: Staphylococcus aureus is a leading cause of community as well as healthcare-associated bacteraemia. This study aimed to describe clinical characteristics of S. aureus bacteraemia (SAB) and to evaluate the performance of the Prolex Staph Xtra Latex agglutination test in the identification of Staphylococcus aureus. METHODS: Cross-sectional study was conducted from Jun 2018 to May 2019. Isolates from first-positive peripheral blood cultures were tested with Prolex Staph Xtra Latex agglutination test, together with routine tube coagulase and DNase test. All isolates were further confirmed with Vitek2 GP. RESULTS: Hundred isolates were tested with Prolex Staph Xtra Latex. Twelve isolates were excluded due to incomplete medical records. Eighty-eight isolates were analysed, yielded sensitivities, specificities, positive and negative predictive values of 100%, 91.7%, 98.7%, and 100%, respectively. Of these, 76 were identified as S. aureus and 12 CoNS. Seventy-six patients were included in the SAB analysis. Fifty-nine out of 76 (78.6%) had underlying comorbidities. Thirty-four percent of the episodes were considered as primary SAB. Skin and soft tissue infection were accounted for the highest source of bacteraemia, 24(31.6%). Both MRSA and MSSA bacteraemia were seen mostly among healthcare-associated bacteraemia (HCA) (7/16, 43.8% and 28/60, 46.7%). Liver cirrhosis was significantly associated with MRSA bacteraemia (P=0.048). Metastatic infection & complicated SAB were identified in 13(17.1%) and 30(39.5%) of cases, respectively. All-cause mortality was 22.4%. CONCLUSION: S. aureus bacteraemia is a serious infection associated with significant metastatic complications and mortality. Prolex Staph Xtra Latex agglutination test has excellent sensitivity and specificity with 100% and 91.7% respectively.

Performance of the Lateral Flow Assay and the Latex Agglutination Serum Cryptococcal Antigen Test in Cryptococcal Disease in Patients with and without HIV.

Cryptococcal epidemiology is shifting toward HIV-negative populations who have diverse presentations. Cryptococcal antigen (CrAg) testing is also changing, with development of the lateral flow assay (LFA) having reported increased sensitivity and specificity, but with minimal knowledge in the HIV-negative population. In this study, we evaluate the real-life performance of CrAg testing in patients with cryptococcal disease. We conducted a retrospective review of patients with cryptococcosis from 2002 to 2019 at Barnes-Jewish Hospital. Latex agglutination (LA) was used exclusively until April 2016, at which point LFA was used exclusively. Demographics, presentations, and testing outcomes were evaluated. Serum CrAg testing was completed in 227 patients with cryptococcosis. Of 141 HIV-negative patients, 107 had LA testing and 34 had LFA testing. In patients with disseminated disease, serum CrAg sensitivity by LA was 78.1% compared to 82.6% for LFA. In patients with localized pulmonary disease, serum CrAg sensitivity was 23.5% compared to 90.9% for LFA. Of 86 people living with HIV (PLWH), 76 had LA testing, and 10 had LFA testing. Serum CrAg sensitivity for LA was 94.7% compared to 100% for LFA in patients with disseminated disease. We noted a significant improvement in sensitivity from LA testing to LFA testing, predominantly in those with localized pulmonary disease. However, both LFA and LA appear to be less sensitive in HIV-negative patients than previously described in PLWH.

Evaluation of Pneumococcal Serotyping of Nasopharyngeal-Carriage Isolates by Latex Agglutination, Whole-Genome Sequencing (PneumoCaT), and DNA Microarray in a High-Pneumococcal-Carriage-Prevalence Population in Malawi.

Accurate assessment of the serotype distribution associated with pneumococcal colonization and disease is essential for evaluating and formulating pneumococcal vaccines and for informing vaccine policy. For this reason, we evaluated the concordance between pneumococcal serotyping results by latex agglutination, whole-genome sequencing (WGS) with PneumoCaT, and DNA microarray for samples from community carriage surveillance in Blantyre, Malawi. Nasopharyngeal swabs were collected according to WHO recommendations between 2015 and 2017 by using stratified random sampling among study populations. Participants included healthy children 3 to 6 years old (vaccinated with the 13-valent pneumococcal conjugate vaccine [PCV13] as part of the Expanded Program on Immunization [EPI]), healthy children 5 to 10 years old (age-ineligible for PCV13), and HIV-infected adults (18 to 40 years old) on antiretroviral therapy (ART). For phenotypic serotyping, we used a 13-valent latex kit (Statens Serum Institut [SSI], Denmark). For genomic serotyping, we applied the PneumoCaT pipeline to whole-genome sequence libraries. For molecular serotyping by microarray, we used the BUGS Bioscience Senti-SP microarray. A total of 1,347 samples were analyzed. Concordance was 90.7% (95% confidence interval [CI], 89.0 to 92.2%) between latex agglutination and PneumoCaT, 95.2% (95% CI, 93.9 to 96.3%) between latex agglutination and the microarray, and 96.6% (95% CI, 95.5 to 97.5%) between the microarray and PneumoCaT. By detecting additional vaccine serotype (VT) pneumococci carried at low relative abundances (median, 8%), the microarray increased VT detection by 31.5% over that by latex serotyping. To conclude, all three serotyping methods were highly concordant in identifying dominant serotypes. Latex serotyping is accurate in identifying vaccine serotypes and requires the least expertise and resources for field implementation and analysis. However, WGS, which adds population structure, and microarray, which adds multiple-serotype carriage, should be considered at regional reference laboratories for investigating the importance of vaccine serotypes at low relative abundances in transmission and disease.

Inflammatory markers in saliva for diagnosis of sepsis of hospitalizes patients.

BACKGROUND: Inflammatory/immunological serum markers are useful for the early detection of organ dysfunction, helping the diagnosis of sepsis. Although the detection of blood biomarkers is a standard practice, the use of noninvasive samples (eg saliva) would be beneficial. AIM: To investigate the saliva of hospitalized patients with and without sepsis and identify the levels of inflammatory markers such as C-reactive protein (CRP), procalcitonin (PCT), interleukin 6 (IL-6) and nitric oxide (NO). METHODS: Saliva samples were collected from 26 patients in intensive care unit with diagnosis of sepsis and from 26 without sepsis (control). The levels of CRP were determined by using latex agglutination test, whereas those of procalcitonin and IL-6 by ELISA and NO by the Griess reaction. RESULTS: Of 26 patients with sepsis, 14 were males (54%) with a mean age of 63.81 ± 3.48 years. The control group had the same distribution for gender, with mean age 65.04 ± 4.07 years. Sepsis group showed higher salivary concentrations of CRP, PCT, IL-6 and NO, with only levels of IL-6 being statistically different (P = .0001). CONCLUSIONS: Patients with sepsis had significantly higher levels of IL-6 in their saliva, suggesting that this biological sample could be useful in the diagnosis of this condition.

Prevalence of cryptococcal antigenemia in hospitalized patients with liver cirrhosis.

The benefits of screening for cryptococcal antigenemia and of preemptive antifungal treatment in HIV-infected patients have been proven. Liver cirrhosis is an important risk factor for cryptococcal infections. Cryptococcal infections are rapidly fatal in patients with liver cirrhosis, especially when diagnosis is delayed. However, screening for cryptococcal antigenemia has not been investigated in these patients. The aim of this study was to investigate the prevalence of cryptococcal antigenemia in hospitalized patients with liver cirrhosis. This prospective study was conducted at Seoul National University Hospital from July 2017 to January 2018. We included patients with liver cirrhosis who were admitted regardless of symptoms or signs suggesting cryptococcal infections. The severity of cirrhosis was evaluated from Child-Pugh and model for end-stage liver disease (MELD) scores. Serum cryptococcal antigenemia was determined using a latex agglutination test. A total of 294 patients were included in the analysis, comprising 104 (35.4%), 100 (34.0%), and 90 (30.6%) patients in Child-Pugh classes A, B, and C, respectively. There were 21 cases of spontaneous bacterial peritonitis, and 14 of hepatic encephalopathy, but none of cryptococcal peritonitis or meningitis. In addition, none of the patient specimens tested positive in the serum cryptococcal latex agglutination test (one-sided 97.5% confidence interval, 0% ∼ 1.2%). Liver cirrhosis is a major risk factor for cryptococcal infections, but the prevalence of serum cryptococcal antigen positivity in patients with liver cirrhosis is very low. Therefore, screening for cryptococcal antigenemia and preemptive antifungal treatment in cirrhotic patients might not be beneficial.

Comparing immunochromatography with latex antigen agglutination testing for the diagnosis of cryptococcosis in cats, dogs and koalas.

Although the point-of-care cryptococcal antigen lateral flow assay (LFA) has revolutionized the diagnosis of cryptococcosis in human patients, to date there has been no large-scale examination of this test in animals. We therefore assessed the LFA in cats, dogs and koalas suspected of having cryptococcosis. In sum, 528 serum specimens (129 from cats, 108 from dogs, 291 from koalas) were tested using the LFA and one of two commercially available latex cryptococcal antigen agglutination test (LCAT) kits. The LCAT is a proven and well-accepted method in veterinary patients and therefore taken as the "gold standard" against which the LFA was compared. The LFA achieved a sensitivity of 92%, 100%, and 98% in cats, dogs, and koalas, respectively, with corresponding negative predictive values of 94%, 100%, and 98%. The specificity of the LFA was 81%, 84%, and 62% for cats, dogs, and koalas, respectively, with corresponding positive predictive values of 76%, 48%, and 69%. These findings suggest the most appropriate role for the LFA is as a screening test to rule out a diagnosis of cryptococcosis in cats, dogs, and koalas. Point-of-care accessibility makes it equally suited for use in the field and as a cage-side test in veterinary hospitals. The suboptimal specificity of the LFA makes it less suited to definitive confirmation of cryptococcosis in animals; therefore, all LFA-positive test results should be confirmed by LCAT testing. The discrepancy between these observations and the high specificity of the LFA in humans may reflect differences in the host-pathogen interactions amongst the species.

Changes in pneumococcal carriage prevalence and factors associated with carriage in Norwegian children, four years after introduction of PCV13.

BACKGROUND: Streptococcus pneumoniae carriage is often asymptomatic but can cause invasive pneumococcal disease. Pneumococcal carriage is a prerequisite for disease, with children as main reservoir and transmitters. Childhood carriage can therefore be used to determine which serotypes circulate in the population and which may cause disease in the non-vaccinated population. In 2006, a pneumococcal conjugate vaccine (PCV7) was introduced into the Norwegian Childhood Immunisation Programme, which was replaced by the more valent PCV13 in 2011. We investigated changes in pneumococcal carriage prevalence 4 years after switching to PCV13 compared to three previous surveys, and analysed factors associated with carriage in children. METHODS: We conducted a cross-sectional study in Norway, autumn 2015, among children attending day-care centres. We collected questionnaire data and nasopharyngeal swabs to identify pneumococcal serotypes. We compared the carriage prevalence in 2015 with surveys conducted in the same setting performed before widespread vaccination (2006; n = 610), 2 years after PCV7 introduction (2008; n = 600), and 2 years after switching to PCV13 (2013; n = 874). Using multilevel logistic regression we determined the association between pneumococcal carriage and previously associated factors. RESULTS: In 2015, 896 children participated, with age ranging from 8 to 80 months. The overall carriage prevalence was 48/100 children [95%CI 44-53] in 2015, 38% [29-46] lower than in 2006 pre-PCV7, and 23% [12-32] lower than in 2013, 2 years after switching to PCV13. The PCV13 carriage prevalence was 2.8/100 children [1.9-4.2] in 2015. Increasing age (p < 0.001), recent antimicrobial use (odds ratio = 0.42 [0.21-0.57]) and being vaccinated (odds ratio = 0.37 [0.29-0.47]) were negatively associated with carriage. CONCLUSIONS: Our study showed a continued decrease in overall pneumococcal carriage, mainly fuelled by the decline in vaccine serotypes after vaccine introduction. Childhood vaccination with PCV13 should be continued to keep low PCV13 carriage, transmission and disease. Furthermore, the low prevalence of PCV13-type carriage in children endorse the choice of not recommending PCV13 in addition to the 23-valent pneumococcal polysaccharide vaccine to most medical risk groups in Norway, as little disease caused by these serotypes can be expected.

Contrasting Results from Two Commercial Kits Testing for the Presence of Clostridium perfringens Enterotoxin in Feces from Norovirus-Infected Human Patients.

BACKGROUND: Detection of Clostridium perfringens enterotoxin (CPE) is critical for disease surveillance; however, commercial testing kits produce contrasting results. METHODS: We examined the cause of the differing results from a reversed passive latex agglutination (RPLA) assay (PET-RPLA Toxin Detection Kit) and an enzyme-linked immunosorbent assay (C. perfringens Enterotoxin ELISA Kit) using 73 human norovirus-positive fecal samples from gastroenteritis patients across 22 episodes in Japan. RESULTS: CPE was detected in 39/73 samples using the RPLA method; however, ELISA-based examination of 10 RPLA-positive samples produced negative results. Moreover, cpe was not detected in any of the RPLA-positive (n = 32) or -negative (n = 5) samples, and C. perfringens was only isolated from one RPLA-positive sample. CONCLUSIONS: An ELISA-based testing approach may be more reliable than RPLA assays for CPE detection from human fecal samples. These findings may also be applicable to the detection of other foodborne diseases.

Comparison of the specificity of rheumatoid factor detected by latex fixation with that of regulatory rheumatoid factor.

BACKGROUND: Rheumatoid factor (RF), originally defined as pathological autoantibodies to IgG that are detected in rheumatoid arthritis, turned out to be multi-specific antibodies, some of which exhibit immunoregulatory properties. Recently, we identified a RF, the production of which confers resistance to experimental autoimmune diseases and is associated with the remission of autoimmune diseases. To differentiate the RF, we discovered from the one associated with rheumatic disease onset or progression and to reflect its immunoregulatory properties, we named it regulatory rheumatoid factor (regRF). Immunization with conformers of Fc fragments that expose regRF neoepitopes reduces collagen-induced arthritis in rats. Certain information about the specificity of classical RF and regRF indicates that these populations may be one and the same. Therefore, the aim of this study was to determine whether there is a difference between the classical RF and regRF. METHODS: Classical RF was measured in diseased blood by the latex fixation method, and regRF was detected by the agglutination of human IgG-loaded tanned erythrocytes. Competitive analysis was used to determine the specificity of rheumatoid factors. RESULTS: It was found that regRF and pathology-associated RF constitute different antibody populations. Pathology-associated RF is specific for lyophilized IgG. RegRF does not interact with IgG. RegRF is specific to conformers of IgG Fc fragments that have a reduced hinge. In latex-positive rheumatoid arthritis sera, regRF may be present in addition to pathology-associated RF. The latex fixation method detects both rheumatoid factor populations. CONCLUSION: RegRF and classical pathology-associated RF have different specificity.

Evaluation of a commercial latex agglutination test for detecting rotavirus A and human adenovirus in children's stool specimens.

OBJECTIVES: Rotavirus A and human adenovirus are the two most common causes of infantile diarrhea; thus, it is of great importance to find out a rapid and accurate diagnostic method. This study aimed to evaluate the diagnostic significance of latex agglutination test for detection of rotavirus A and human adenovirus. METHODS: A prospective study was conducted on 214 diarrhea children from September 2018 to March 2019 in our hospital. Fresh stool samples were collected for detection of rotavirus A and human adenovirus by latex agglutination test and quantitative reverse transcription polymerase chain reaction (RT-qPCR). Then, the consistency of results detected by these two methods was analyzed． RESULTS: With performing the latex agglutination test, it was revealed that positive rates for detecting rotavirus A virus and human adenovirus were 23.83% (51/214) and 25.24% (54/214), respectively. Meanwhile, results of RT-qPCR showed that positive rates for detecting rotavirus A virus and human adenovirus were 58 (27.10%) and 59 (27.57%), respectively. Using RT-qPCR as the gold standard, the sensitivity and specificity of the latex agglutination test for detecting rotavirus A were 81.03% and 97.44%, and the corresponding values for detecting human adenovirus were 76.27% and 94.19%, respectively. CONCLUSION: This latex agglutination test showed a satisfactory consistency with RT-qPCR for detecting rotavirus A and human adenovirus. The mentioned commercial assay may be highly appropriate for rapid screening of rotavirus A and human adenovirus.