Capsular Polysaccharide Antigen Research Articles

CCCerebral cryptococcosis regarding two clinical cases and bibliographic review

Cryptococcosis is a life-threatening infection, the species complexes Cryptococcus neoformans and Cryptococcus gattii are yeasts with a polysaccharide capsule, metabolize urea and catecholamines; It is transmitted by inhalation of bird droppings, mainly pigeons, and is capable of causing outbreaks in both immunocompromised and immunocompetent hosts. In Latin America, cryptococcal meningitis is a health threat. The initial infection is localized to the lungs and spreads to other organs, such as the central nervous system, where it causes meningoencephalitis and rarely focal granulomatous lesions such as cryptococcomas. The diagnosis must be made early, with serological tests for the cryptococcal polysaccharide capsular antigen. Treatment is divided into induction, consolidation and maintenance. Below, two clinical cases are presented, the first case is a 68-year-old female with a history of tuberculosis 15 years ago; 10 days, with holocranial headache, nausea and vomiting; on physical examination with superficial stupor, nuchal rigidity; kerning sign (+); lumbar puncture with identification of cryptococcal meningitis, induction treatment with fluconazole was started. The second case, a 60-year-old male with a history of acute lymphoblastic leukemia with chemotherapy 1 month ago, suddenly presented with altered consciousness, a lumbar puncture was performed, which reported cryptococcal meningitis by PCR, induction treatment with fluconazole was started; Both patients were admitted to the Intensive Care Unit, however, they had an unfavorable outcome.

Identification of Burkholderia cepacia strains that express a Burkholderia pseudomallei-like capsular polysaccharide.

Burkholderia pseudomallei and Burkholderia cepacia are Gram-negative, soil-dwelling bacteria that are found in a wide variety of environmental niches. While B. pseudomallei is the causative agent of melioidosis in humans and animals, members of the B. cepacia complex typically only cause disease in immunocompromised hosts. In this study, we report the identification of B. cepacia strains isolated from either patients or soil in Laos and Thailand that express a B. pseudomallei-like 6-deoxyheptan capsular polysaccharide (CPS). These B. cepacia strains were initially identified based on their positive reactivity in a latex agglutination assay that uses the CPS-specific monoclonal antibody (mAb) 4B11. Mass spectrometry and recA sequencing confirmed the identity of these isolates as B. cepacia (formerly genomovar I). Total carbohydrates extracted from B. cepacia cell pellets reacted with B. pseudomallei CPS-specific mAbs MCA147, 3C5, and 4C4, but did not react with the B. pseudomallei lipopolysaccharide-specific mAb Pp-PS-W. Whole genome sequencing of the B. cepacia isolates revealed the presence of genes demonstrating significant homology to those comprising the B. pseudomallei CPS biosynthetic gene cluster. Collectively, our results provide compelling evidence that B. cepacia strains expressing the same CPS as B. pseudomallei co-exist in the environment alongside B. pseudomallei. Since CPS is a target that is often used for presumptive identification of B. pseudomallei, it is possible that the occurrence of these unique B. cepacia strains may complicate the diagnosis of melioidosis.IMPORTANCEBurkholderia pseudomallei, the etiologic agent of melioidosis, is an important cause of morbidity and mortality in tropical and subtropical regions worldwide. The 6-deoxyheptan capsular polysaccharide (CPS) expressed by this bacterial pathogen is a promising target antigen that is useful for rapidly diagnosing melioidosis. Using assays incorporating CPS-specific monoclonal antibodies, we identified both clinical and environmental isolates of Burkholderia cepacia that express the same CPS antigen as B. pseudomallei. Because of this, it is important that staff working in melioidosis-endemic areas are aware that these strains co-exist in the same niches as B. pseudomallei and do not solely rely on CPS-based assays such as latex-agglutination, AMD Plus Rapid Tests, or immunofluorescence tests for the definitive identification of B. pseudomallei isolates.

Naturally acquired antibodies against 4 Streptococcus pneumoniae serotypes in Pakistani adults with type 2 diabetes mellitus.

Immune response elicited during pneumococcal carriage has been shown to protect against subsequent colonization and infection by Streptococcus pneumoniae. The study was designed to measure the baseline serotype-specific anti-capsular IgG concentration and opsonic titers elicited in response to asymptomatic carriage in adults with and without type 2-diabetes. Level of IgG to capsular polysaccharide was measured in a total of 176 samples (124 with type 2 diabetes and 52 without type 2 diabetes) against serotype 1, 19F, 9V, and 18C. From within 176 samples, a nested cohort of 39 samples was selected for measuring the functional capacity of antibodies by measuring opsonic titer to serotypes 19F, 9V, and 18C. Next, we measured levels of IgG to PspA in 90 samples from individuals with and without diabetes (22 non-diabetes and 68 diabetes). Our results demonstrated comparable IgG titers against all serotypes between those with and without type 2-diabetes. Overall, we observed higher opsonic titers in those without diabetes as compared to individuals with diabetes for serotypes 19F and 9V. The opsonic titers for 19F and 9V significantly negatively correlated with HbA1c. For 19F, 41.66% (n = 10) showed opsonic titers ≥ 1:8 in the diabetes group as compared to 66.66% (n = 10) in the non-diabetes group. The percentage was 29.6% (n = 7) vs 66.66% (n = 10) for 9V and 70.83% (n = 17) vs 80% (n = 12) for 18C in diabetes and non-diabetes groups respectively. A comparable anti-PspA IgG (p = 0.409) was observed in those with and without diabetes, indicating that response to protein antigen is likely to remain intact in those with diabetes. In conclusion, we demonstrated comparable IgG titers to both capsular polysaccharide and protein antigens in those with and without diabetes, however, the protective capacity of antibodies differed between the two groups.

Quantification of antigen of Mycoplasma capricolum subsp. capripneumoniae by optical assay

Mycoplasma capricolum subsp. capripneumoniae (Mccp) is the cause of contagious caprine pleuropneumonia (CCPP) in goats. Inactivated vaccines and capsular polysaccharide (CPS) indirect hemagglutination reagents are available for prevention and serological detection, but high culture costs and complex antigen quantification have been plagued by production staff. In order to solve these problems in production practice, a sugar fermentation medium with an initial pH value of 7.8, which could improve the production of two antigens simultaneously, was screened out by changing the initial pH value based on previous Mccp metabolomics analysis. Since phenol red can be identified by UV absorption spectrum and cetyltrimethylammonium bromide (CTAB) can bind to anionic capsular polysaccharide, a UV spectrum measurement method for analyzing the culture stage reached by Mccp and a CTAB precipitation test for relative quantification of capsular polysaccharide antigen content in the fermentation broth were established. The UV spectrum observation method can guide the production of Mccp according to the growth curve of Mccp, which greatly reduces the monitoring time of the traditional CCU method and improves the accuracy of the original eye-observation method. The established CTAB precipitation test can complete the monitoring of CPS content within 5 hours, which greatly reduces the time required compared with the traditional differential technique, and its accuracy was verified by the phenol-sulfuric acid method. The optimized culture medium and the two correlation comparison methods established in this study can effectively reduce the production cost of Mccp and improve the production efficiency. The two assays have been used in the research at our laboratory, which provides experimental data for further improvement of the production process of CCPP inactivated vaccine and capsular polysaccharide as well as rapid quantification.

Cryptococcal meningoencephalitis with Actinomyces odontolyticus sepsis: a case report and literature review

BackgroundThe combined infection of actinomyces odontolyticus sepsis and cryptococcal encephalitis is rare in routine clinical practice. Thus, we presented this case report and literature review to provide clues to improve such patients' diagnoses and treatment processes.Case presentationThe main clinical manifestations of the patient were high fever and intracranial hypertension. Then, we completed the routine cerebrospinal fluid examination, biochemical detection, cytological examination, bacterial culture, and India ink staining. Firstly, the blood culture suggested actinomyces odontolyticus infection, considering the possibility of actinomyces odontolyticus sepsis and intracranial actinomyces odontolyticus infection. Accordingly, the patient was administered penicillin for treatment. Although the fever was slightly relieved, the symptoms of intracranial hypertension did not relieve. After 7 days, the characteristics of brain magnetic resonance imaging and the results of pathogenic metagenomics sequencing and cryptococcal capsular polysaccharide antigen suggested that cryptococcal infection. Based on the above results, the patient was diagnosed with a combined infection of cryptococcal meningoencephalitis and actinomyces odontolyticus sepsis. Anti-infection therapy with ‘penicillin, amphotericin, and fluconazole’ was provided, improving the clinical manifestations and objective indexes.ConclusionThe combined infection of Actinomyces odontolyticus sepsis and cryptococcal encephalitis is first reported in this case report, and combined antibiotics with ‘penicillin, amphotericin, and fluconazole’ are effective.

P325 Trend of cryptococcal meningitis in patients attending a teaching hospital in north-east india — a single center study

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM ObjectiveTo determine the changing trend of Cryptococcal meningitis in patients attending Regional Institute of Medical Sciences Hospital, Imphal.MethodsA total of 142 cerebrospinal fluid (CSF) samples collected from patients with suspected meningitis from January 2013 to January 2022 were analyzed in the department of Microbiology, Regional Institute of Medical Sciences, Imphal. The samples were subjected to India ink preparation (IIP), Gram stain, Cryptococcal antigen (CrAg) testing, fungal culture in Sabouraud Dextrose agar (SDA) medium, and Bird Seed Agar.ResultsOut of 142 CSF samples received, direct examination by IIP revealed Cryptococcus in 28 cases (19.7%) whereas, capsular polysaccharide antigen testing using lateral flow immunochromatography kit (CRYPTO-PS) detected a total of 40 cases (28.2%). Culture showed growth of fungus in 22 samples and all were from CrAg positive samples. Maximum number of cases were detected in the year 2019 followed by 2018. Immunosuppression (AIDS) was an important underlying factor. Recurrence was seen in three patients and two cases who were on Cycloserine succumbed while undergoing treatment.ConclusionCryptococcosis continues to be a serious fungal infection among AIDS patients in spite of HAART. High index of clinical suspicion and microbiological examination is necessary to improve clinical outcomes. Whenever immunosuppressive drugs are administered in HIV patients treated earlier for cryptococcosis, monitoring the patient for likely recurrence is to be borne in mind to improve the overall clinical outcome. CrAg testing is an additional armamentarium for the diagnosis of cryptococcosis in the absence of culture positivity.

Clinical utility of cryptococcal antigen detection in transthoracic needle aspirate by lateral flow assay for diagnosing non-HIV pulmonary cryptococcosis: A multicenter retrospective study.

Lateral flow immunoassay (LFA) detection of cryptococcal capsular polysaccharide antigen (CrAg) is reported to be the most rapid and convenient laboratory method for diagnosing cryptococcosis. Its clinical diagnostic use, however, is not well studied. We retrospectively analyzed the data from 97 patients with suspected pulmonary cryptococcosis (PC) at 2 tertiary care centers. CrAg in both serum and lung aspirate specimens were examined by LFA. We divided the patients who were diagnosed with PC into group I, patients positive for CrAg in both the serum and lung aspirate, and group II, patients positive for CrAg in the lung aspirate but not in the serum. We analyzed the differences in imaging distribution, morphological characteristics, and concomitant signs between the 2 groups. Of all 97 patients, 47 were diagnosed with PC. Lung aspirates were positive for CrAg in 46/47 patients with PC (sensitivity 97.9%, specificity 100%, positive predictive value = 100%, negative predictive value = 98%). There were no false positive results in the noncryptococcosis patients, revealing a diagnostic accuracy of 99%. Serum CrAg tests were positive in 36/47 patients with PC (sensitivity 76.6%, specificity 100%, accuracy 88.7%, positive predictive value = 100%, negative predictive value = 82%). Chest imaging data showed a statistically significant greater number of single lesions in group II than in group I (P < .05). More lesions accompanied by halo signs were showed in group I (P < .01), whereas more accompanied by pleural stretch signs were found in group II (P < .01). The LFA-positive rate of CrAg in lung aspirate samples was higher than that of the serum samples, especially in patients with single pulmonary lesion or in those accompanied by pleural stretch. The direct measurement of CrAg in lung aspirate is a rapid, useful alternative diagnostic method for PC confirmation.

Clinical features of cryptococcosis in patients with different immune statuses: a multicenter study in Jiangsu Province\u2013China

BackgroundCurrent guidelines support different management of cryptococcosis between severely immunodeficient and immunocompetent populations. However, few studies have focused on cryptococcosis patients with mild-to-moderate immunodeficiency. We performed this study to determine the clinical features of pulmonary (PC) and extrapulmonary cryptococcosis (EPC) and compared them among populations with different immune statuses to support appropriate clinical management of this public health threat.MethodsAll cases were reported by 14 tertiary teaching hospitals in Jiangsu Province, China from January 2013 to December 2018. The trends in incidence, demographic data, medical history, clinical symptoms, laboratory test indicators, imaging characteristics and diagnostic method of these patients were then stratified by immune status, namely immunocompetent (IC, patients with no recognized underlying disease or those with an underlying disease that does not influence immunity, such as hypertension), mild-to-moderate immunodeficiency (MID, patients with diabetes mellitus, end-stage liver or kidney disease, autoimmune diseases treated with low-dose glucocorticoid therapy, and cancer treated with chemotherapy) and severe immunodeficiency (SID, patients with acquired immunodeficiency syndrome, haematologic malignancies, solid organ transplantation or haematologic stem cell transplantation, idiopathic CD4 lymphocytosis, agranulocytosis, aggressive glucocorticoid or immunosuppressive therapy and other conditions or treatments that result in severe immunosuppression).ResultsThe clinical data of 255 cryptococcosis patients were collected. In total, 66.3% of patients (169) were IC, 16.9% (43) had MID, and 16.9% (43) had SID. 10.1% of the patients (17) with IC were EPC, 18.6% of the patients (8) with MID were EPC, and 74.4% of patients (32) were EPC (IC/MID vs. SID, p < 0.001). Fever was more common in the SID group than in the IC and MID groups (69.8% vs. 14.8% vs. 37.2%, p < 0.001). Of chest CT scan, most lesions were distributed under the pleura (72.7%), presenting as nodules/lumps (90.3%) or consolidations (10.7%). Pleural effusion was more common in SID group compared to IC group (33.3% vs. 2.4%, p < 0.001). Positivity rate on the serum capsular polysaccharide antigen detection (CrAg) test was higher in the SID group than in the other two groups [100.0% vs. 84.4% (MID) vs. 78.2% (IC), p = 0.013]. Positivity rate on the serum CrAg test was also higher in cryptococcal meningitis patients than in PC patients (100.0% vs. 79.5%, p = 0.015).ConclusionsThe clinical presentation of MID patients is intermediate between SID and IC patients and is similar to that of IC patients. The serum CrAg test is more sensitive for the identification of SID or EPC patients.

A Porphyromonas gingivalis Capsule-Conjugate Vaccine Protects From Experimental Oral Bone Loss.

Periodontal diseases are chronic inflammatory diseases of the periodontium that result in progressive destruction of the soft and hard tissues supporting the teeth, and it is the most common cause of tooth loss among adults. In the US alone, over 100 million individuals are estimated to have periodontal disease. Subgingival bacteria initiate and sustain inflammation, and, although several bacteria have been associated with periodontitis, Porphyromonas gingivalis has emerged as the key etiological organism significantly contributing to the disease. Currently, intensive clinical maintenance strategies are deployed to mitigate the further progression of disease in afflicted individuals; however, these treatments often fail to stop disease progression, and, as such, the development of an effective vaccine for periodontal disease is highly desirable. We generated a conjugate vaccine, comprising of the purified capsular polysaccharide of P. gingivalis conjugated to eCRM®, a proprietary and enhanced version of the CRM197 carrier protein with predetermined conjugation sites (Pg-CV). Mice immunized with alum adjuvanted Pg-CV developed robust serum levels of whole organism-specific IgG in comparison to animals immunized with unconjugated capsular polysaccharide alone. Using the murine oral bone loss model, we observed that mice immunized with the capsule-conjugate vaccine were significantly protected from the effects of P. gingivalis-elicited oral bone loss. Employing a preclinical model of infection-elicited oral bone loss, our data support that a conjugate vaccine incorporating capsular polysaccharide antigen is effective in reducing the main clinical endpoint of periodontal disease—oral bone destruction. Further development of a P. gingivalis capsule-based conjugate vaccine for preventing periodontal diseases is supported.

A Novel, Inexpensive In-House Immunochromatographic Strip Test for Cryptococcosis Based on the Cryptococcal Glucuronoxylomannan Specific Monoclonal Antibody 18B7.

The aim of this study was to develop a novel lateral flow immunochromatoghaphic strip test (ICT) for detecting cryptococcal polysaccharide capsular antigens using only a single specific monoclonal antibody, mAb 18B7. The mAb 18B7 is a well characterized antibody that specifically binds repeating epitopes displayed on the cryptococcal polysaccharide glucuronoxylomannan (GXM). We validated the immunoreactivities of mAb 18B7 against capsular antigens of different cryptococcal serotypes. The mAb 18B7 ICT was constructed as a sandwich ICT strip and the antibody serving in the mobile phase (colloidal gold conjugated mAb 18B7) to bind one of the GXM epitopes while the stationary phase antibody (immobilized mAb18B7 on test line) binding to other remaining unoccupied epitopes to generate a positive visual readout. The lower limit of detection of capsular antigens for each of the Cryptococcus serotypes tested was 0.63 ng/mL. No cross-reaction was found against a panel of antigens isolated from cultures of other pathogenic fungal, except the crude antigen of Trichosporon sp. with the lower limit of detection of 500 ng/mL (~800 times higher than that for cryptococcal GXM). The performance of the mAb 18B7 ICT strip was studied using cerebrospinal fluid (CSF) and serum and compared to commercial diagnostic kits (latex agglutination CALAS and CrAg IMMY). The sensitivity, specificity and accuracy of the mAb18B7 ICT with CSF from patients with confirmed cryptococcal meningitis were 92.86%, 100% and 96.23%, respectively. No false positives were observed with samples from non-cryptococcosis patients. With serum samples, the mAb 18B7 ICT gave a sensitivity, specificity and accuracy of 96.15%, 97.78% and 96.91%, respectively. Our results show that the mAb 18B7 based ICT was reliable, reproducible, and cost-effective as a point-of-care immunodiagnostic test for cryptococcosis. The mAb 18B7 ICT may be particularly useful in countries where commercial kits are not available or affordable.

A half-century of meningococcal vaccines

The first safe and effective vaccine for the prevention of invasive meningococcal disease was created fifty years ago. The vaccine employed a novel platform, polysaccharide capsular antigen, based on the discovery that anticapsular antibody conferred protective immunity in humans. As with most new paradigms in vaccinology, it derived from important basic research from other scientific disciplines over the preceding years. The success of the first monovalent polysaccharide vaccine in nearly eliminating invasive meningococcal disease in military settings led to accelerated advances in polysaccharide vaccine development against other serogroups of meningococcus and other encapsulated pathogens. As gaps in vaccine efficacy arose over the past half-century, new vaccine technologies and approaches were developed to address the challenges. Several of these, including conjugate vaccines and “reverse vaccinology” led to other novel, successful vaccines that have had a significant, favorable global impact on invasive meningococcal disease. The history of meningococcal vaccine discovery may provide insights into the future of vaccine efforts against other infectious threats.

The Diversity of Lipopolysaccharide (O) and Capsular Polysaccharide (K) Antigens of Invasive Klebsiella pneumoniae in a Multi-Country Collection.

Klebsiella pneumoniae is a common cause of sepsis and is particularly associated with healthcare-associated infections. New strategies are needed to prevent or treat infections due to the emergence of multi-drug resistant K. pneumoniae. The goal of this study was to determine the diversity and distribution of O (lipopolysaccharide) and K (capsular polysaccharide) antigens on a large (>500) global collection of K. pneumoniae strains isolated from blood to inform vaccine development efforts. A total of 645 K. pneumoniae isolates were collected from the blood of patients in 13 countries during 2005–2017. Antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method. O antigen types including the presence of modified O galactan types were determined by PCR. K types were determined by multiplex PCR and wzi capsular typing. Sequence types of isolates were determined by multilocus sequence typing (MLST) targeting seven housekeeping genes. Among 591 isolates tested for antimicrobial resistance, we observed that 19.3% of isolates were non-susceptible to carbapenems and 62.1% of isolates were multidrug resistant (from as low as 16% in Sweden to 94% in Pakistan). Among 645 isolates, four serotypes, O1, O2, O3, and O5, accounted for 90.1% of K. pneumoniae strains. Serotype O1 was associated with multidrug resistance. Fifty percent of 199 tested O1 and O2 strains were gmlABC-positive, indicating the presence of the modified polysaccharide subunit D-galactan III. The most common K type was K2 by both multiplex PCR and wzi capsular typing. Of 39 strains tested by MLST, 36 strains were assigned to 26 known sequence types of which ST14, ST25, and ST258 were the most common. Given the limited number of O antigen types, diverse K antigen types and the high multidrug resistance, we believe that an O antigen-based vaccine would offer an excellent prophylactic strategy to prevent K. pneumoniae invasive infection.

Clinicopathological features of isolated pulmonary cryptococcosis in HIV-negative patients.

ObjectiveTo analyse the clinicopathological features of isolated pulmonary cryptococcosis in human immunodeficiency virus (HIV)-negative patients.MethodsThis retrospective study analysed the following data from HIV-negative patients diagnosed with pulmonary cryptococcosis: demographics, underlying diseases, clinical manifestations on admission, laboratory tests, imaging data, results of histopathology, treatment options and outcomes. Sputum samples from all patients were collected and assessed for the presence of yeast or fungi. Cryptococcal antigen testing was performed for some patients. Histopathological analysis was also undertaken for some samples of lung tissue.ResultsThe study analysed 37 patients (22 males). Thirteen (35.14%) patients were asymptomatic, 24 (64.86%) were symptomatic and 17 (45.95%) patients had no underlying disease. Out of 25 tested patients, 23 (92.00%) tested positive on the serum cryptococcal capsular polysaccharide antigen test. During 6 to 24 months of follow-up, all 37 patients that were either treated with or without antifungal therapy alone or combined with surgical resection showed complete recovery. One patient made a full recovery without any treatment.ConclusionEarly identification of pulmonary cryptococcosis in HIV-negative patients and timely detection of cryptococcal antigens in serum or respiratory specimens may help to improve diagnosis, prognosis and treatment of the disease.

Clinical and Radiological Features of Patients With Pulmonary Cryptococcosis in a Hospital of North China.

Objective: The increasing incidence has led to more focus on pulmonary cryptococcosis in HIV-negative patients. We conducted a retrospective analysis of pulmonary cryptococcosis to understand the clinical characteristics, imaging features, diagnosis, treatment and prognosis of this disease in HIV-negative patients in respiratory department of a tertiary hospital in north China.Method: We identified retrospectively those diagnosed with pulmonary cryptococcosis in the first medical center of Chinese People’s Liberation Army General Hospital since 2009 to 2019. The clinical and image data were collected and analyzed.Results: The study involved 34 patients with pulmonary cryptococcosis. All patients were diagnosed by histopathology. It accounted for 0.93‰ of the total number of patients admitted to respiratory department in the same period. The mean age was 49 years; 26 patients (76.5%) were male. Patients were predominantly immunocompetent (30, 88.2%), and there was no underlying disease for most patients (26, 76.5%). The most frequent symptoms were cough and expectoration. Fourteen (41.2%) patients showed no symptom or sign. Multiple lesions (21, 61.8%) and subpleural lesions (23, 67.6%) were the most common. Nodule was the most common abnormality on chest computed tomography image. Eight (23.5%) patients received serum Cryptococcus capsular polysaccharide antigen test, and seven patients showed positive result. All patients recovered after antifungal treatment.Conclusions: Most patients of HIV-negative pulmonary cryptococcosis were mainly immunocompetent patients younger than 60 years without underlying diseases. There was lack of specificity in clinical manifestations and imaging findings. The prognosis of pulmonary cryptococcosis in HIV-negative patients was good.

Improving efficacy of glycoconjugate vaccines: from chemical conjugates to next generation constructs.

Glycoconjugate vaccines are among the safest and most successful vaccines developed during the past 30 years. Since the first semisynthetic chemical conjugate vaccine licensed in the 1980's to protect human against Haemophilus influenzae type b infection, conjugate vaccines against Neisseria meningitidis and Streptococcus pneumoniae have been developed and registered using the same approach (i.e. bacterial growth to produce capsular polysaccharide antigen and chemical coupling to carrier protein). Other types of conjugate vaccines have been recently developed and tested in clinical trials, prepared by coupling chemically synthesized oligosaccharides to proteins, by engineering Escherichia coli to directly produce bioconjugates or by delivering the native carbohydrate antigen in engineered membrane vesicles (i.e. Generalized Modules for Membrane Antigens, GMMA). Through this review, the reader will have an insight regarding the history and the characteristics of different types of conjugate vaccines, and the attributes that might affect their immunogenicity and their potential for future applications.

Indirect Detection of Burkholderia pseudomallei Infection in a US Marine After Training in Australia.

In 2012, the United States Marine Corps began annual deployments around Australia, including highly endemic areas for Burkholderia pseudomallei. B. pseudomallei infection, or melioidosis, is difficult to diagnose, and culture remains the gold standard. Accurate and timely diagnosis is essential, however, to ensuring appropriate therapy. Ten days after returning from Australia, a Marine presented to a community hospital with massive cervical lymphadenopathy, fever, and cough. Computed tomography demonstrated scattered pulmonary infiltrates with small cavitations; lymphadenopathy involving the cervical, supraclavicular, and mediastinal nodes; and splenomegaly. Sputum and blood cultures were negative. Empiric antimicrobial therapy with ceftazidime was initiated for suspected melioidosis. Retrospectively, a prototype iSTAT cartridge modified to detect B. pseudomallei capsular polysaccharide antigen was used to test a specimen of the patient's blood and was determined to be positive. Over the course of therapy, B. pseudomallei capsular antigen levels in blood declined as the patient improved. The leveraging of an existing point-of-care (POC) analyzer to create a rapid diagnostic assay for melioidosis provides a template for rapid POC diagnostics that could significantly improve the ability of clinicians to deliver timely and appropriate therapy for serious infections.

Dynamic research of serum cryptococcal capsular polysaccharide antigen titer and chest CT of pulmonary cryptococcosis after antifungal therapy

Objective: To observe the dynamic changes of serum cryptococcal capsular polysaccharide antigen (CrAg) titer and chest CT of pulmonary cryptococcosis (PC) after antifungal therapy. Methods: A retrospective study was performed for patients with PC admitted to the Department of Pulmonary and Critical Care Medicine of the First Affiliated Hospital of Wenzhou Medical University from January 2015 to April 2018. Serum CrAg titers and Chest CT examination were performed for all the cases before and after treatment. The difference between immunocompetent hosts group and immunocompromised hosts group were compared and analyzed. Results: Eighty-two patients with PC including 46 male (56.1%) and 36 (43.9%) female were enrolled. Fifty-two (63.4%) patients were proven PC and thirty (36.6%) patients were probable PC. Forty-five (54.9%) patients had underlying diseases. Fifty-four (65.9%) patients were immunocompetent hosts and twenty-eight (34.1%) patients were immunocompromised hosts. The mean duration of treatment was (7.9±2.4) months and the mean follow-up was (24.0±10.0) months. Improvement (≥75%) in chest CT were found in 64.8% of the cases in immunocompetent group and 67.9% in immunocompromised group after 6 months' treatment. Improvement (≥75%) was found in 88.9% of the cases with patchy infiltrates or consolidation and only 63.0% in nodular or mass-like type and mixed patterns of PC. The serum CrAg titer of 55 cases ranged from 1∶4 to 1∶160 before treatment (median 1∶40) and decreased for all cases after treatment. The serum CrAg titer became negative in 20 cases at last. Mean time of serum CrAg titer turning negative was (11.8±8.1) months. The serum CrAg titer became negative or decreased to 1∶1 in 24 cases after treatment cessation, of whom the serum CrAg titer ranged from 1∶5 to 1∶160 before treatment (median 1∶20). The serum CrAg titer of 31 cases ranged from 1∶4 to 1∶640 before treatment (median 1∶64), of whom the serum CrAg detections were still positive after treatment cessation, and CrAg titer was 1∶10 (ranged from 1∶2 to 1∶160). Conclusions: In PC, chest CT improves after antifungal treatment, and the infiltrates or consolidation type of PC resolves faster than nodular or mass-like shadows and mixed patterns in CT. The serum CrAg titer decreases after antifungal treatment.

Whole-Genome Sequences of Two Salmonella enterica Serovar Dublin Strains That Harbor the viaA, viaB, and ompB Loci of the Vi Antigen.

Here, we report the genome sequences of two Salmonella enterica serovar Dublin strains, 03EB8736SAL and 03EB8994SAL, isolated from raw-milk cheese and milk filtrate, respectively. Analysis of the draft genomes of the two isolates reveals the presence of the viaA, viaB, and ompB loci of the Vi capsular polysaccharide antigen (Vi antigen).

The performance of serum cryptococcal capsular polysaccharide antigen test, histopathology and culture of the lung tissue for diagnosis of pulmonary cryptococcosis in patients without HIV infection.

BackgroundClinicians may fail to make an early diagnosis of pulmonary cryptococcosis (PC) without HIV infection. Serum cryptococcal capsular polysaccharide antigen (CrAg) test, histopathology and culture of lung tissue play different roles in diagnosis of PC.ObjectiveTo investigate the performance of serum CrAg test, histopathology and culture of the lung tissue in diagnosis of PC without HIV infection.Patients/methodsFrom January 2011 to September 2017, patients with proven PC were recruited from a teaching hospital in southern China. Those patients with HIV infection, PC confirmed by surgery or PC with probable or possible diagnosis were excluded from the study. Latex agglutination test and CrAg lateral flow assay were used for detection of serum CrAg. Lung biopsy and needle aspiration were performed under computed tomography guidance.ResultsEighty-nine patients with proven PC including 41 male (46.1%) and 48 female (53.9%) were enrolled. Fifty-one (57.3%) patients had underlying disease. Positive CrAg test was found in 83 (93.3%) cases. Among six cases with negative CrAg test, PC was confirmed by histology in two cases and positive culture in four cases. The histopathological results of 77 (86.5%) cases revealed cryptococcal granuloma and 12 cases showed chronic inflammation, which was confirmed by positive culture. Among 65 cases, the diseased tissue of 46 (70.8%) cases presented Cryptococcus neoformans in the culture and one case was diagnosed with lung cancer coexisting with PC.ConclusionOur findings showed that serum CrAg test is rapid and sensitive in diagnosing PC, histology is important for confirming PC and culture plays a complementary role. Biopsied lung tissue should be submitted for cultures whenever feasible.

OxyR positively and directly regulates Vi polysaccharide capsular antigen in Salmonella enterica serovar Typhi

Salmonella enterica serovar Typhi (S. Typhi) is a human enteropathogen that can overcome oxidative stress and survive in macrophages. OxyR is an important part of the antioxidant defense system. S. Typhi expresses a virulence (Vi) polysaccharide capsular antigen, which provides the bacterium with the ability to avoid host defenses and suppress detection by the innate immune system. This study investigated the effect of OxyR on Vi antigen in S. Typhi. In the oxyR mutant strain, microarray analysis, quantitative real time PCR and β-galactosidase assay confirmed that the viaB operon was positively regulated by OxyR. The Vi enzyme-linked immunosorbent assay and flow cytometry results showed that Vi capsule level was decreased in the oxyR mutant strain. Also, the EMSA revealed that OxyR directly binds to the promoter region of tviA. Thus, we propose that S. Typhi OxyR positively regulates expression of Vi capsule antigen in a direct manner.