Development of a latex agglutination test based on VH antibody fragment for detection of Streptococcus suis serotype 2.

Streptococcus suis serotype 2 (SS2) is an important porcine pathogen that causes diseases in both swine and human. For rapid SS2 identification, a novel latex agglutination test (LAT) based on heavy-chain variable domain antibody (VH) was developed. Firstly, the soluble 47B3 VH antibody fragment from a phage display library, in which cysteine residues were engineered at the C-terminus, was expressed in Escherichia coli. The purified protein was then gently reduced to form monomeric soluble 47B3 VH subsequently used to coat with latex beads by means of site-specific conjugation. The resulting VH-coated beads gave a good agglutination reaction with SS2. The LAT was able to distinguish S. suis serotype 2 from serotype 1/2, which shares some common sugar residues, and showed no cross-reaction with other serotypes of S. suis or other related bacteria. The detection sensitivity was found to be as high as 1.85x106 cells. The LAT was stable at 4°C for at least six months without loss of activity. To the best of our knowledge, this is the first LAT based on a VH antibody fragment that can be considered as an alternative for conventional antibody-based LAT where VHs are the most favored recombinant antibody.

Measurement of serum hepcidin-25 by latex agglutination in healthy volunteers and patients with hematologic disorders.

Iron is an essential trace metal, vital for various physiologic processes, but excess levels can harm health. Maintaining iron homeostasis is critical, with hepcidin playing a key role. The isoform hepcidin-25 exerts the most significant influence on iron metabolism, making its serum levels a valuable diagnostic tool. However, mass-spectrometry and other conventional measurement methods can be difficult to perform, and some immunoassays lack reliability. In this study, we employed a recently developed latex agglutination method integrated with a readily available automated analyzer to quantify serum hepcidin-25 levels in both volunteers recruited from personnel of our hospital (n = 93) and patients with various hematological disorders (n = 112). Our findings unveiled a robust positive correlation between serum hepcidin-25 and ferritin, as well as C-reactive protein levels, in both volunteers and patients. Among the patients with hematological disorders, there was a noteworthy negative correlation between hepcidin-25 levels and hemoglobin concentrations, as well as reticulocyte counts. Interestingly, the hepcidin-25/ferritin ratio was remarkably low in patients with hemolytic anemia and myelodysplastic syndromes with ring sideroblasts. Our findings suggest that quantifying serum hepcidin-25 and the hepcidin-25/ferritin ratio using this method may be valuable for screening of hematopoietic diseases and other iron metabolism disorders.

Utilization of an Automated Latex Agglutination Turbidity Assay for Assessing Gastric Mucosal Alteration during Helicobacter pylori Infection.

Background/Aims: : A latex agglutination turbidity (LA) assay to test for serum antibodies has been approved in Japan and Korea for mass screening of Helicobacter pylori infection. In this study, we evaluated the LA assay for diagnosing H. pylori infection and predicting gastric mucosal changes in a Mongolian population. Methods: : In total, 484 individuals were classified into H. pylori-positive (n=356) and H. pylori-negative (n=128) groups, as determined by histology and H. pylori culture. Results: : The best cutoff, sensitivity, and specificity values for the LA assay were 18.35 U/mL, 74.2%, and 65.6%, respectively. The LA values in the atrophic gastritis group were statistically higher than those in the other groups (healthy, chronic gastritis, intestinal metaplasia, and gastric cancer, p<0.0001). The cutoff value to distinguish the atrophic gastritis group from the other four groups was 32.0 U/mL, and its area under the curve was 0.673, which was the highest among the E-plate, pepsinogen (PG) I, PG II, and PG I/II ratio tests in our data. The odds ratios for atrophic gastritis determined by the LA assay and PG I test in multiple logistic regression were 2.5 and 1.9, respectively, which were significantly higher than for the other tests. Conclusions: : The LA assay can determine the risk of atrophic gastritis, which in turn is a considerable risk factor for gastric cancer. We propose using this assay in combination with the PG I/II ratio to avoid missing gastric cancer patients who have a low LA value (less than 32.0 U/mL).

Enhancing leptospirosis control with nanosensing technology: A critical analysis.

Leptospirosis is a serious health problem in tropical areas; thus, animals shed leptospires in the environment. Humans are accidental hosts infected through exposure to contaminating bacteria in the environment. One health strategy can be applied to protect and eliminate leptospirosis because this cooperates and coordinates activities between doctors, veterinarians, and ecologists. However, conventional methods still have limitations. Therefore, the main challenges of leptospirosis control are the high sensing of detection methods to screen and control the pathogens. Interestingly, nano sensing combined with a leptospirosis detection approach can increase the sensitivity and eliminate some limitations. This article reviews nanomaterial development for an advanced leptospirosis detection method, e.g., latex beads-based agglutination test, magnetic nanoparticles enrichment, and gold-nanoparticles-based immunochromatographic assay. Thus, nanomaterials can be functionalized with biomolecules or sensing molecules utilized in various mechanisms such as biosensors. Over the last decade, many biosensors have been developed for Leptospira spp. pathogen and others. The evolution of biosensors for leptospirosis detection was designed for high efficiency and might be an alternative tool. In addition, the high-sensing fabrications are useful for leptospires screening in very low levels, for example, soil or water from the environment.

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.

[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.

Comparative evaluation of in-house developed latex agglutination test (LAT) with World Organisation for Animal Health (WOAH) -recommended methods for the detection of Bacillus anthracis spores from the soil.

In-house developed Bacillus anthracis-specific synthetic peptide-based latex agglutination test (LAT) assay was comparatively evaluated with World Organisation for Animal Health (WOAH)-recommended polymerase chain reaction (PCR)/real-time PCR (qPCR) methods for the screening of B. anthracis spores from the soil to provide a simple, rapid, and economical immunodiagnostic test for field application.

Detection and Isolation of Escherichia coli O157:H7 in Beef from Food Markets and Fecal Samples of Dairy Calves in the Peruvian Central Highlands.

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a food and waterborne pathogen with severe public health implications. We report the first-time isolation of this pathogen in the Central Highlands of Peru through standardized culture procedures and polymerase chain reaction (PCR). Escherichia coli strains were cultured from rectal-anal swabs from dairy calves and beef from food markets. The latex agglutination test was used to detect O157 and H7 antigens, and multiplex real-time PCR was carried out to detect virulence-related genes. The STEC O157:H7 strains were isolated from 3.5% (1/28) of beef samples and from 6.0% (3/50) of dairy calves that also carried both eaeA and stx1 genes. Therefore, this pathogen is a potential cause of food/waterborne disease in the region, and its surveillance in both livestock and their products should be improved to characterize the impact of its zoonotic transmission. From 2010 to 2020, E. coli was suspected in 10 outbreaks reported to the Peruvian Ministry of Health. Isolates from future outbreaks should be characterized to assess the burden posed by STEC O157:H7 in Peru.

An efficient and convenient Fiber -2- based latex agglutination test for the detection of antibodies against fowl adenovirus serotype 4 in clinical samples.

To detect the antibody against fowl adenovirus serotype 4 (FAdV-4) in clinical practice, the latex agglutination test (LAT) was developed by using the Fiber-2 protein of FAdV-4 as an antigen bound to sensitized latex microspheres. The concentration, time, and temperature of sensitization latex microspheres by the Fiber-2 protein were studied and optimized; the specificity, sensitivity, and repeatability of LAT were tested; and the method developed in the study was applied. The results showed that the optimum sensitization concentration of Fiber-2 protein was 0.8 mg/mL, the time was 120 min, and the temperature was 37 â„ƒ. Except for antiserum against FAdV-4 and FAdV-10, LAT developed in the study could not agglutinate antisera against FAdV-1, FAdV-2, FAdV-3, FAdV-4, FAdV-5, FAdV-6, FAdV-8a, FAdV-8b, FAdV-11, Newcastle disease virus, infectious bronchitis virus, egg drop syndrome virus and Clostridium perfringens. Compared with the commercial FAdV-4 ELISA Kit, the titers in 21 clinical samples were low when tested by the developed LAT method, but there was no significant difference. The coefficients of variation among different batches and the same batch of latex-sensitized particles were between 0 % and 13.3 % and 0-8.7 %, respectively. The critical value of immune protective antibody against FAdV-4 was 25, and the titers in 40.9 % of clinical samples were higher than the immune critical point. The results showed that the Fiber-2-based LAT developed in the study has the characteristics of high specificity, sensitivity and repeatability, has the advantages of free equipment, long shelf life, and fast and easy operation, and is an effective and convenient method for serological diagnosis of FAdV-4 infection and evaluating the efficacy of vaccines.

Comparative analysis of diagnostic methods for the detection of Cryptococcus neoformans meningitis.

BACKGROUND: Cryptococcosis is a devastating opportunistic infection in immunocompromised individuals, primarily in people living with HIV/AIDS. This study evaluated a protocol for the early diagnosis of meningitis due to C. neoformans, utilizing established molecular techniques from serum and CSF samples. METHODS: The 18S and 5.8S (rDNA-ITS) sequence-specific nested PCR assays were compared with direct India ink staining and the latex agglutination test for detection of C. neoformans in serum and cerebrospinal fluid (CSF) from 49 Brazilian suspected meningitis patients. Results were validated with samples obtained from 10 patients negative for cryptococcosis and HIV, and by analysis of standard C. neoformans strains. PRINCIPAL FINDINGS: The 5.8S DNA-ITS PCR was more sensitive (89-100%) and specific (100%) than the 18S rDNA PCR and conventional tests (India ink staining and latex agglutination) for identification of C. neoformans. While the 18S PCR exhibited a sensitivity (72%) similar to that of the latex agglutination assay in serum samples, it was superior to the latex agglutination assay when testing CSF, with a sensitivity of 84%. However, the latex agglutination was superior to the 18SrDNA PCR in specificity in CSF (92%). The 5.8S DNA-ITS PCR yielded the highest levels of accuracy (96-100%) of any test for detection (serological and mycological) of C. neoformans in both serum and CSF. CONCLUSION: Use of the nested 5.8S PCR was superior to other techniques for the diagnosis of cryptococcosis. The possibility of using serum, a non-invasively collected material, in a targeted 5.8S PCR analysis to identify Cryptococcus spp. is recommended, especially in immunosuppressed patients. Our results indicate that nested 5.8S PCR can increase the diagnostic capability of cryptococcosis, and we suggest its use to monitor patients in the future.

Evaluation of three commercial kits effective identification of menstrual blood based on the D-dimer.

Blood or bloodstains are encountered frequently in forensic investigations. Presumptive and more confirmatory tests for peripheral blood are well established, however, similar methods for menstrual blood identification are less so. D-dimer is a fibrin degradation product that occurs at high concentration in menstrual blood and therefore a potential target to screen for this body fluid. We evaluated three rapid tests to determine if they can discriminate menstrual blood from peripheral remote from a laboratory setting. Their sensitivity, specificity and robustness were also assessed. The assays were: a latex agglutination (Dade Dimertest Latex Assay), SERATEC PMB test and OneStep D-dimer RapidCard InstaTest, both of which are based on lateral flow immunochromatographic analysis. Of the three, greater sensitivity was observed using the OneStep D-dimer RapidCard InstaTest, regardless of whether liquid or a stain was used. This test also detected a result using the smallest volume of menstrual blood, 0.003125 µL. Specificity testing was based on six different body fluids (urine, saliva, peripheral blood, semen, sweats and vaginal fluid) resulting in all 30 samples testing negative for the D-dimer using the OneStep D-dimer RapidCard InstaTest. Mixtures at ratios 1:1, 1:3 and 1:9 (menstrual blood: the other biofluid or PBS) were tested and the results showed that D-dimer could be detected for all samples using either the Dade Dimertest Latex Assay or the OneStep D-dimer RapidCard InstaTest. The body fluids were exposed to environmental stresses such as various temperature (-20 °C, 4 °C, room temperature and 37 °C for 30, 90, 180 and 360 days) and fluctuations in humidity (42%, 76% and 100% humidity at room temperature for 1, 3, 5, 10 and 20 days): all samples were D-dimer positive using the OneStep D-dimer RapidCard InstaTest though the strength decreased relative to the increase of storage time and temperature or humidity. All 6 postmortem blood samples gave a positive result for D-dimer using the OneStep D-dimer RapidCard InstaTest and 2 samples gave a positive response using the Dade Dimertest Latex Assay and the SERATEC PMB test; peripheral blood postmortem samples can show an increase in D-dimer. Menstrual blood was recovered from the pads under the sample wells after testing using the two immunochromatographic assays from which STR alleles could be amplified successfully. The results presented here support the application of these commercial kits for effective identification of menstrual blood.

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.

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.

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.

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.

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.

[Biodiversity of isolated fungal flora at the reanimation service of the University Hospital Souro Sanou of Bobo-Dioulasso, Burkina Faso]. / Biodiversité de la flore fongique isolée au service de réanimation du Centre Hospitalo-Universitaire Souro Sanou de Bobo-Dioulasso, Burkina Faso.

INTRODUCTION: nosocomial diseases are a major public health problem in sub-Saharan Africa particularly in Burkina Faso. The purpose of this study was to determine the biodiversity of the fungal flora identified at the reanimation service of the University Hospital Souro Sanou of Bobo-Dioulasso. METHODS: we conducted a descriptive cross-sectional study from August 2016 to January 2017. The purpose of the study was to investigate the fungal flora in the ambient air and in the reanimation environment. Samples were seeded and incubated for 3-4 days at 37°C in the oven. The identification of colonies of filamentous fungi was macroscopic and microscopic. Blastesis test, chromogenic medium and latex agglutination test were used to identify Candida species. RESULTS: out of 200 samples collected, 176 grew in Sabouraud-Chloramphenicol agar. The overall prevalence of fungal flora was 88% (176/200). Molds were the most common fungal agents found (66.9%). Among the eight types of mold identified, Aspergillus was the most common family (48.9%) while Aspergillus fumigatus was the most detected species (32.9%). CONCLUSION: regular decontamination of fungal niches should be systematic at the reanimation service of the University Hospital Souro Sanou of Bobo-Dioulasso.

New and rapid strategies for the diagnosis of bovine paratuberculosis "in situ" using latex particles.

The chemical coupling of a protoplasmatic antigen from Mycobacterium avium subsp. paratubeculosis onto core-shell carboxylated particles was investigated with the aim of producing latex-protein complexes to be used in immunoagglutination assays capable of detecting bovine paratuberculosis disease. For this purpose, sensitizations were carried out using both colored and not colored carboxylated latexes as well as the protoplasmatic antigen at pH close to its isoelectric point to favor the antigenic protein to approach the particle surface. In all cases, higher fractions of proteins were chemically-bound to carboxyl groups on the surface of the particles. The assessment of the performance of the visual immunoagglutination assays consisted of evaluating 111 sera from healthy and infected bovines with Mycobacterium avium subsp. paratuberculosis. Complexes obtained from the colored latex allowed an acceptable visual discrimination between the studied positive and negative sera. Most of the positive samples showed strong to very strong agglutination and only a few samples reacted weakly, i.e. a sensitivity of 70%. The specificity of the assay, on the other hand, was 86%. Therefore, this rapid detection technique allows an easy and inexpensive identification of animals possibly infected with paratuberculosis "in situ" in the herds.

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.

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.