Detection Of Capsular Polysaccharide Antigen Research Articles

Cryptococcal meningitis in HIV (AIDS) patients: A Mini Review

Meningitis is a major health problem causing inflammation of the protective membranes covering the brain and spinal cord, collectively known as the meninges . Meningitis is generally caused by Meningococcus , Streptococcus pyogenes bacterial species causing bacterial meningitis: BM), Mycobacterium tuberculosis (Tubercular meningitis: TBM), Cryptococcus neoformans (fungal meningitis: CM). In recent times the CM and TBM are two most common types of chronic infectious meningitis. In adults, HIV-associated Cryptococcal meningitis has been reported in many areas of the world having high HIV seroprevalence i.e. in Sub-Saharan Africa. Cryptococcal meningitis is the fourth most commonly recognized cause of life-threatening infection among AIDS patients.Despite availability of antiretroviral therapy, the rise in rate of infections due to HIV/AIDS, suppress the cell mediated immune system and subjects are predisposed for opportunistic infections. Additionally, In AIDS patients, it is characterized by lack of meningeal signs and diminished inflammatory response. Diagnosis of CM is generally based on the collection of CSF sample and/or blood samples. Initially the CSF samples are processed for ‘gold standard’ culture methods, microscopy and India ink preparation. Serologically, Latex agglutination test (LAT) is the most commonly used for detection of Cryptococcal capsular antigen. Enzyme immunoassay (EIA) is another serological tool for detection of capsular polysaccharide antigens of C. neoformans in CSF. DOI: 10.21276/AABS.2017.1344

Detection of Cryptococcus Neoformans Amongst HIV Patients Attending Comprehensive Care Clinic At Kapkatet District Hospital, Kenya

Cryptococcal meningitis is the most common lethal opportunistic fungal infection caused by a fungus (yeast) - Cryptococcus neoformans in people with HIV and AIDS. Cryptococcal infection affects approximately one million HIV-infected patients worldwide each year, and is associated with high mortality. In Sub-Saharan Africa, Cryptococcal disease has been associated with 17% of all deaths among HIV-infected patients and 75% of deaths from opportunistic infections in men with pulmonary tuberculosis. Prompt treatment depends on awareness of the common symptoms. In Sub-Saharan Africa, Kenya included, data on the prevalence of Cryptococcal infection is scanty. This cross-sectional study carried out at Kapkatet District Hospital Comprehensive Care Clinic (CCC) using 300 selected HIV patients enrolled for review at the CCC from June to August 2012 sought to identify HIV infected patients who also had Cryptococcus neoformans as detected from their blood samples. Serum samples were studied for the detection of capsular polysaccharide antigen of Cryptococcus neoformans usinglatex agglutination technique with pronase pre-treatment (IMMY, Crypto-Latex Antigen Detection System, Immunomycologics Inc., OK, USA). Results showed that 1% of the patients were confirmed to have Cryptococcus Neoformans. Of those found positive, 25% were males and 75% were females and were distributed between ages 21 and 50 years which also showed that 73% of all patients who participated in the study were in this age range. Since Cryptococcosis is highly lethal once contracted, health care workers managing people living with HIV/AIDS need to have ahigh index of suspicion so as to initiate prompt treatment immediately the disease is confirmed. Abbreviations And Acronyms

La cryptococcose au cours de l’infection à VIH

Cryptococcosis is a cosmopolitan fungal serious condition due to an encapsulated yeast Cryptococcus neoformans. This is the systemic fungal infection the most common in HIV infection. This yeast is present in the environment and its main entrance in the body is the respiratory tract. Its gravity is linked to its tropism for the central nervous system. It generally affects subjects with severe deficit of cellular immunity and in particular, patients living with HIV. The diagnosis of neuromeningeal cryptococcosis is based on the detection of encapsulated yeasts at microscopic examination of cerebrospinal fluid, the detection of capsular polysaccharide antigen in serum or cerebrospinal fluid, but especially on the culture. A staging is always essential. The prognosis is severe. The control of intracranial hypertension is a major element of prognosis.

Ultrasound-enhanced latex immunoagglutination test (USELAT) for detection of capsular polysaccharide antigen of Neisseria meningitidis from CSF and plasma

Aims An ultrasonic instrument, the Immunosonic, was used to evaluate ultrasound-enhanced latex immunoagglutination testing (USELAT) for detection and serogroup determination of Neisseria meningitidis in clinical specimens. Methods Eighty-two CSF and EDTA blood specimens from patients with suspected meningococcal disease (MD) were tested by USELAT. Results were compared with routine laboratory tests for confirmation of MD and discrepant results were resolved by analysis of further laboratory and clinical data. Results Using the Wellcogen Bacterial Antigen Kit, USELAT was positive in 20 (24%) specimens. The resolved sensitivity of USELAT was 49% compared with 67% for PCR. There were no discrepancies between serogroups indicated by USELAT and serogroups confirmed by PCR or culture grouping. Conclusions Although USELAT could be performed in laboratories without facilities for PCR testing, a specific ultrasonic instrument is necessary and some experience is required in interpreting results. The lower resolved sensitivity makes USELAT unsuitable as a stand-alone rapid test, and it added little value to standard laboratory culture with PCR testing. An ultrasonic instrument, the Immunosonic, was used to evaluate ultrasound-enhanced latex immunoagglutination testing (USELAT) for detection and serogroup determination of Neisseria meningitidis in clinical specimens. Eighty-two CSF and EDTA blood specimens from patients with suspected meningococcal disease (MD) were tested by USELAT. Results were compared with routine laboratory tests for confirmation of MD and discrepant results were resolved by analysis of further laboratory and clinical data. Using the Wellcogen Bacterial Antigen Kit, USELAT was positive in 20 (24%) specimens. The resolved sensitivity of USELAT was 49% compared with 67% for PCR. There were no discrepancies between serogroups indicated by USELAT and serogroups confirmed by PCR or culture grouping. Although USELAT could be performed in laboratories without facilities for PCR testing, a specific ultrasonic instrument is necessary and some experience is required in interpreting results. The lower resolved sensitivity makes USELAT unsuitable as a stand-alone rapid test, and it added little value to standard laboratory culture with PCR testing.

Ultrasound-enhanced latex immunoagglutination test (USELAT) for detection of capsular polysaccharide antigen of Neisseria meningitidis from CSF and plasma

Ultrasound-enhanced latex immunoagglutination test (USELAT) for detection of capsular polysaccharide antigen of Neisseria meningitidis from CSF and plasma

Ultrasound-enhanced latex immunoagglutination test (USELAT) for detection of capsular polysaccharide antigen of Neisseria meningitidis from CSF and plasma

An ultrasonic instrument, the Immunosonic, was used to evaluate ultrasound-enhanced latex immunoagglutination testing (USELAT) for detection and serogroup determination of Neisseria meningitidis in clinical specimens. Eighty-two CSF and EDTA blood specimens from patients with suspected meningococcal disease (MD) were tested by USELAT. Results were compared with routine laboratory tests for confirmation of MD and discrepant results were resolved by analysis of further laboratory and clinical data. Using the Wellcogen Bacterial Antigen Kit, USELAT was positive in 20 (24%) specimens. The resolved sensitivity of USELAT was 49% compared with 67% for PCR. There were no discrepancies between serogroups indicated by USELAT and serogroups confirmed by PCR or culture grouping. Although USELAT could be performed in laboratories without facilities for PCR testing, a specific ultrasonic instrument is necessary and some experience is required in interpreting results. The lower resolved sensitivity makes USELAT unsuitable as a stand-alone rapid test, and it added little value to standard laboratory culture with PCR testing.

PNEUMOLYSIN IN URINE: A RAPID ANTIGEN DETECTION METHOD TO DIAGNOSE PNEUMOCOCCAL PNEUMONIA IN CHILDREN

Purpose: Etiological diagnosis of pneumococcal pneumonia is difficult in small children in whom blood culture cannot be done or who have already been started on antibiotics. A simple technique which can be applied at the bedside or in the outpatient department may help in obviating this problem. Detection of pneumolysin, a product of invasive pneumococci is being exploited as a diagnostic tool. Methods: An attempt was made to detect this protein in urine of seventy children, clinically suspected and radiologically diagnosed cases of pneumonia. Seventy age and sex matched controls were included in the study. Purified pneumolysin was prepared from clinical isolates of invasive pneumococcal infections. This was used to raise polyclonal antisera in rabbits. The antisera was used to sensitise Cowan 1 Staphylococcus aureus (CoA). A slide agglutination was performed with 25 µL urine and equal quantity of the reagent. Results: Results were compared with CoA reagent sensitised with antisera raised against a genetically derived pneumolysoid and capsular polysaccharide for antigen detection in the urine. Pneumolysin could be detected in 42.9% (30/70) urine samples from cases with pneumonia by the genetically derived antigen and in 37.1% samples by the in house prepared antigen, in contrast to 2.1% in healthy controls and 4.2% in children with infections other than pneumonia. The result was statistically significant. Detection of pneumolysin was slightly better than detection of capsular polysaccharide antigen in urine although the result was not statistically significant. Blood culture proved to be positive in only 29.5% cases. Conclusions: Pneumolysin detection in urine showed promising results and was found to be simple and rapid. It will help in quickening the diagnosis of pneumococcal pneumonia.

Detection of Cryptococcus neoformans capsular polysaccharide antigen in asymptomatic HIV-infected patients.

Serum samples from 242 HIV-positive persons were studied for the detection of capsular polysaccharide antigen of Cryptococcus neoformans; 193 of these patients presented less than 300 CD4+ cells/microliters of blood and 49 patients had more than 300 CD4+ cells/microliters. None of them had symptoms or signs characteristic of cryptococcosis. The capsular antigen of C. neofarmans was detected by latex agglutination technique with pronase pretreatment (IMMY, Crypto-Latex Antigen Detection System, Immunomycologics Inc., OK, USA); in 61% of the samples, ELISA technique was also used (Premier, Cryptococcal Antigen, Meridian Diagnostic Inc., Cincinnati, Oh, USA). The comparative study of both methods showed that the results obtained were similar in 96.9% of the cases. The capsular antigen was detected in 13 out of 193 (6.7%) patients with less than 300 CD4+ cells/microliters. Cryptococcosis was confirmed mycologically in 3 of these 13 cases (23%) by the isolation of C. neoformans in CSF or blood cultures. Three patients, who had presented negative results of both tests for capsular antigen, suffered disseminated cryptococcosis 4 to 8 months later. The predictive diagnostic value of capsular antigen detection of C. neoformans seems to be low and we believe that it should not be done routinely in asymptomatic HIV-positive persons.

Pneumococci in nasopharyngeal samples from Filipino children with acute respiratory infections.

The presence of Streptococcus pneumoniae in the upper respiratory tract was studied in 318 Filipino children less than 5 years old with an acute lower respiratory tract infection. Nasopharyngeal samples were obtained from 292 children. With both quantitative bacterial culture and detection of capsular polysaccharide antigens by coagglutination, counterimmunoelectrophoresis, and latex agglutination, pneumococci were found in 160 (70%) of the 227 samples eligible for analysis. Culture was positive in 115 samples and antigen was positive in 140 samples. The culture isolation rate was significantly lower if the patient had received antimicrobial agents in the 48 h prior to the sampling. The seven most common types or groups of pneumococci were 6, 14, 19, 23, 15, 7, and 11, which together accounted for 64% of all pneumococcal findings.