Latex Agglutination Test Results Research Articles

Information value of latex test for pathogenic burkholderia serological diagnostics using microscopy and video digital recording system

Objective: the purpose of the work is assessment of the possibility of using instrumental assay to record the results of the latex test in the detection of pathogenic burkholderia. Monoclonal based latex agglutination test was prepared according to a previously developed technique. The latex agglutination test results were obtained using a “Nikon Eclipse TE 2000-U HMC/System microscope”, as w ell as the video-digital hardware-software com plex “Expert-lab”. The results of an objective assessment of the latex agglutination test were obtained using statistical analysis. The use of “Nikon Eclipse” microscope for visual accounting of microagglutination increased the sensitivity of the latex test to 1•107 CFU/ml. The “Expert-lab” make arrangements for quantitative assessment of the scanned image of the latex test results, which makes it possible to determine the threshold values for discrimination between positive and negative samples. Objective information about the presence or absence of agglutination is recorded. Numerical values of the latex test intensity between samples and controls are compared using system software. Also we can a possibility to save protocols and images of the study, to archive the obtained data. The use of “Nikon Eclipse TE 2000-U HMC/System” microscope for visual recording of the results and on the “Expert-lab” video digital system for objective evaluation of data when searching for pathogenic burkholderia allow s us to document and to archive the data obtained, to conduct in-laboratory quality control of studies and increase the sensitivity of the latex-agglutination reaction.

Evaluation of Real-Time Polymerase Chain Reaction in Culture-Negative Cerebrospinal Fluid Samples of Bacterial meningitis Patients

Background: Meningitis is a rigorous childhood disease with high morbidity and mortality. It is the main cause of under five mortality in India. Mainly three bacteria Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae are responsible. In low economic set up country like India, documented bacterial meningitis mainly depend on gram staining, cerebrospinal fluid (CSF) culture results or latex agglutination test resulting in less number of positive due to the prior antimicrobial intake which affects culture and latex agglutination test results. This study was taken up rapid and accurate molecular method like RT PCR to diagnose bacterial meningitis in culture-negative CSF samples.
 Materials and Methods: Fifty culture-negative CSF samples from suspected cases of bacterial meningitis were examined by real-time polymerase chain reaction (real-time PCR) for the presence of lytA, bexA, and ctrA genes specific for Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis respectively.
 Results: Positive real-time PCR results for Streptococcus pneumoniae were detected in 36 (72%) of culture-negative CSF samples while 10% positive results for Haemophilus influenzae type b. Nine (18%) samples were negative by real-time PCR for all tested organisms.
 Conclusion: The use of molecular techniques as real-time PCR can provide a valuable addition to the proportion of diagnosed cases of bacterial meningitis especially in settings with high rates of culture-negative results.

Identification of Common Bacterial Pathogens Causing Meningitis in Culture-Negative Cerebrospinal Fluid Samples Using Real-Time Polymerase Chain Reaction.

Background. Meningitis is a serious communicable disease with high morbidity and mortality rates. It is an endemic disease in Egypt caused mainly by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. In some settings, bacterial meningitis is documented depending mainly on positive cerebrospinal fluid (CSF) culture results or CSF positive latex agglutination test, missing the important role of prior antimicrobial intake which can yield negative culture and latex agglutination test results. This study aimed to utilize molecular technology in order to diagnose bacterial meningitis in culture-negative CSF samples. Materials and Methods. Forty culture-negative CSF samples from suspected cases of bacterial meningitis were examined by real-time polymerase chain reaction (real-time PCR) for the presence of lytA, bexA, and ctrA genes specific for Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, respectively. Results. Positive real-time PCR results for Streptococcus pneumoniae were detected in 36 (90%) of culture-negative CSF samples while no positive results for Haemophilus influenzae or Neisseria meningitidis were detected. Four (10%) samples were negative by real-time PCR for all tested organisms. Conclusion. The use of molecular techniques as real-time PCR can provide a valuable addition to the proportion of diagnosed cases of bacterial meningitis especially in settings with high rates of culture-negative results.

Using species-specific PCR technique to detect Toxoplasma gondii in broiler chickens

Two groups of broiler chickens were used in this study. One was reared under typical conditions at the animal house of Veterinary Medicine College/Mosul University- Iraq, while the other group was reared under common commercial farm conditions. Fifty and 80 birds from the two respective groups were sacrificed at 49 days of age for detecting Toxoplasma gondii by using Species-specific PCR technique. Results of Latex agglutination test indicated, principally, that 29.3% and 49.2% of the serum samples were positive for the birds of both groups, respectively. Titer figures ranged between 1:20 to 1:320 where the highest value was 1:160 (39.3%) and the lowest was 1:20 (5.8%). Confirmation of 38 and 64 serum samples, using Latex agglutination test was performed by PCR technique, from the two respective groups of chickens. Of those, 8 samples from the college birds and 35 from the commercial farm birds were confirmed positive by giving band of 133 bp, according to specific primers designated on gene B1.Based on these results, pursuing the PCR technique is considered, so far, a most sensitive method for Toxoplasma gondii detection. Also, positive PCR results are counted on as an early marker for reactivation and useful means in monitoring therapies.

Direct Detection of Methicillin-ResistantStaphylococcus aureusfrom Blood Cultures Using Three Non-Molecular Methods: PBP2a Latex Agglutination, PBP2a Rapid Immunochromatographic Assay and MRSA-Chromogenic Medium

Background: This study compared three non-molecular methods for the detection of methicillin-resistance directly from blood cultures containing Staphylococcus aureus: penicillin-binding protein (PBP) 2a latex agglutination (LA), PBP2a immunochromatographic assay (ICA) and MRSA chromogenic medium (CM). Methods: Fifty methicillin-resistant S. aureus (MRSA) and 50 methicillin-susceptible S. aureus (MSSA) were seeded into blood-culture bottles. When isolates returned a positive signal, 5 mL of culture was added to serum separator tubes and centrifuged at 1,300 g for 10 min. The pellets were then used as the inoculum for the PBP2a LA, MRSA-CM and PBP2a ICA. The pure colony was used for PBP2a LA test, additionally. Results: The respective sensitivities and specificities were 98 and 100% for PBP2a ICA, and 100 and 100% for MRSA-CM in direct detection of MRSA from positive blood culture. The results of PBP2a LA test using pure colony were entirely compatible with those by mecA gene PCR but the PBP2a LA test using the pellets directly isolated from positive blood culture showed sometimes ambiguous agglutination; its sensitivity and specificity were 78 and 100%, if ambiguous results were scored as negative, and were 90 and 92%, if ambiguous results were scored as positive, respectively. Conclusion: For direct detection of MRSA in positive blood culture, MRSA-CM and PBP2a ICA provided excellent results. The PBP2a LA test using pure colony also gave excellent results but the PBP2a LA test by the direct method using pellet of positive blood culture was slightly less sensitive than the other two methods. (Korean J Clin Microbiol 2012;15:27-31)

Detection of Toxoplasma gondii Antibodies in Different Meat Juices

Toxoplasmosis is one of the most important zoonotic diseases worldwide and it is caused by the protozoan Toxoplasma gondii, humans can get infected post-naturally either by uptake of sporulated toxoplasma oocysts or by ingestion of tissue cysts upon consumption of raw or undercooked meat. The study included cattle, sheep and chicken of different age groups and housing conditions whenever possible and applicable. Direct Latex Agglutination test was used to detect T. gondii specific antibodies and to determine seroprevalences in meat juice of slaughtered animals. The total samples are 300 of domestic animals (cattle, sheep and chicken 100 samples each of them). The results of Latex agglutination test are positive in 17% of cattle, 37% of sheep and 9% of chicken from meat juice. The examination of specific IgG and IgM antibodies was detected by Hydroxy ethylmercaptan (2-ME) test with used of meat juices and Compound of 2- Hydroxy ethylmercaptan which appear in cattle 17.9% of IgM and 82.1% IgG, in sheep 16.2% of IgM and 83.8% IgG and in chicken 11.1% of IgM and 88.9% IgG. The aim of this study was to approximate the risk of human infection via meat consumption by estimating the seroprevalence of T. gondii in slaughtered animals in Hamdania.

The Effect of a Rapid Kit for Detection of Streptococcal Pharyngitis on the Accuracy of the Physicians' Diagnoses

In the last decade, the accuracy of rapid tests for detection of group A streptococcal antigen was evaluated in laboratory and clinical settings, and the tests were suggested as an alternative to the traditional throat culture. We evaluated 19 patients with a preliminary diagnosis of nonstreptococcal pharyngitis and 13 patients with a preliminary diagnosis of streptococcal pharyngitis. The physician performed a rapid latex agglutination test (Detect A Strep), took throat culture from all of the patients, reconsidered the preliminary diagnosis, and made a working diagnosis. A clinical score was calculated for each patient during data analysis. The accuracy of the physicians' preliminary diagnoses was compared with the accuracy of the scoring system, with the accuracy of the latex agglutination test, and with the accuracy of the physicians' working diagnoses. The scoring system, the physicians' preliminary diagnoses, the latex agglutination test, and the physicians' working diagnoses correlated significantly with throat culture results (p < or = 0.05). The efficiency of the physicians' preliminary diagnoses was 75% compared with an efficiency of 69% of the clinical scoring system, an efficiency of 66% of the latex agglutination test, and an efficiency of 69% of the physicians' working diagnoses. The physician changed the preliminary diagnosis only for two patients as a result of the latex agglutination test results; ironically, however, the preliminary diagnosis was correct in both of these cases. The use of a rapid test for the diagnosis of group A streptococcal antigen under normal working conditions did not improve the accuracy of the physician's diagnosis, so the use of the latex agglutination test in this study was not cost-effective.

Evaluation of suprapubic bladder aspiration for detection of group B streptococcal antigen by latex agglutination in neonatal urine.

Our objective was to determine whether urine collection by suprapubic bladder aspiration (SBA) improves the specificity of the group B streptococcal (GBS) latex agglutination (LA) test by avoiding contamination of urine with GBS from perineal and rectal colonization that can result in a positive LA test in an uninfected infant when the urine is collected by bag. Part 1 consists of a retrospective review of the medical records of 113 infants who had urine collected by SBA for GBS LA testing as part of evaluation for possible sepsis. The sensitivity and specificity of the urine LA test was assessed by comparing it with blood culture results. In part 2, a prospective analysis was performed of 19 newborns who had rectal and vaginal/penile cultures as well as urine by SBA and bag for GBS cultures and LA. Results of LA testing on urine collected by both of these methods were compared with results of urine, perineal, and rectal cultures. In the retrospective review of GBS LA testing performed on 113 consecutive urine specimens collected by SBA from neonates being evaluated for suspected sepsis, the sensitivity and specificity were 67% and 89%, respectively, when compared with blood culture results. Twelve infants who had a positive LA test result but a sterile blood culture (BC-,LA+) were compared with 95 infants with both blood cultures and urine LA tests negative for GBS (BC-, LA-). BC-, LA+ infants were more likely than those with BC-, LA- to have an immature to total neutrophil (I/T) ratio > or = 0.16 at 12 and 24 hours (p = 0.04 and 0.02, respectively). In the prospective study, we found that a positive GBS LA test can be due to perineal contamination and possibly to gastrointestinal absorption of GBS antigen. No false positive LA test results occurred on urine obtained by SBA; however, use of this method failed to detect the one infant with GBS bacteremia. Because of suboptimal sensitivity and specificity, use of the GBS LA test on urine obtained either by SBA or bag cannot be recommended for diagnosis of early onset GBS disease.

Use of the Pastorex aspergillus antigen latex agglutination test for the diagnosis of invasive aspergillosis.

To evaluate the Pastorex aspergillus antigen latex agglutination test for the diagnosis of invasive aspergillosis in patients undergoing liver or bone marrow transplantation. Serum samples were taken at least twice weekly post-transplant and tested for Aspergillus antigen. Latex agglutination test results were compared with microbiological examination of respiratory, urine and bile specimens. Serum samples from liver transplant patients were also tested for antibodies to Aspergillus fumigatus by counter immunoelectrophoresis. Eight of the 91 patients studied developed invasive aspergillosis. Positive latex agglutination tests were obtained in eight of 187 (4.3%) serum samples from four of these eight patients. The other four patients with invasive aspergillosis gave consistently negative latex agglutination tests. A positive latex agglutination test was the first indication of invasive aspergillosis in two patients; these patients were already on amphotericin B. Positive latex agglutination tests were the only evidence of invasive aspergillosis in one patient who subsequently died of the infection. False positive latex agglutination tests were obtained in five of 83 (6%) patients with no evidence of invasive aspergillosis and misleading positive cultures seen in nine of 83 (10.8%). No antibodies were detected in three of four liver transplant patients with invasive aspergillosis. Conversely, antibodies were detected in 63 of 262 (24%) serum samples from 43 liver transplant patients with no evidence of invasive aspergillosis; one of these patients had an antibody titre of 1:2 on four separate occasions. The Pastorex aspergillus antigen latex agglutination test, when used alone, lacks sensitivity and specificity for the early diagnosis of invasive aspergillosis. A diagnosis was made in all patients with invasive aspergillosis when both culture and antigen tests were performed although using these criteria a false positive diagnosis would have been made in 13 of 83 (15.6%) patients. Microbiological and serial serological investigations for antigen should both be performed and the results considered in conjunction with radiological and clinical evidence.

Comparison of a dot immunobinding assay, latex agglutination, and cytotoxin assay for laboratory diagnosis of Clostridium difficile-associated diarrhea

C. diff-CUBE, a dot immunobinding assay (DIA) (Difco Laboratories, Ann Arbor, Mich.) for detection of Clostridium difficile toxin A in stool specimens, was compared with latex agglutination (LA) (Marion Laboratories, Kansas City, Mo.) and cytotoxin assay (CTA) for the laboratory diagnosis of C. difficile-associated diarrhea. A total of 200 stool specimens collected from 169 patients with suspected C. difficile diarrhea were tested. Of the 198 specimens evaluated by all three methods, 36 (18%) from 36 patients were positive by one or more of the tests. Twenty-five, 26, and 23 specimens were positive by CTA, DIA, and LA, respectively; 14 were positive by all three methods. Eight specimens yielded nonspecific LA test results; all eight were negative by CTA, and one was positive by DIA. DIA results agreed with CTA results in 183 (92%) cases and with LA results in 175 (88%) cases. CTA and LA results agreed in 179 (90%) cases. Freezing of the specimen did not appear to adversely affect either the DIA or LA test. These preliminary results suggest that C. diff-CUBE may be useful as a rapid screen for the diagnosis of C. difficile-associated diarrhea. However, for optimum laboratory diagnosis, further testing of all stools that are negative by DIA is warranted.

Significance of a positive urine group B streptococcal latex agglutination test in neonates

We assessed the clinical significance of a reactive urine latex agglutination (LA) test in neonates without bacteriologically confirmed group B streptococcal (GBS) infection. In a retrospective review of a 3 1/2-month period, during which 367 urine specimens from newborn infants evaluated for suspected sepsis were tested by LA, 25 infants (6.9%) with sterile blood cultures but positive urine LA test results were compared with a control group of 112 infants with both blood cultures and urine LA test results negative for GBS. When the data were studied with stepwise discriminant analysis, the only variables significantly associated with a positive urine LA test result were immature to total neutrophil ratios greater than or equal to 0.16 at 0 and 12 hours. The influence of mucosal GBS colonization on urine LA test results was then investigated prospectively in 98 healthy infants (83 born to mothers colonized with GBS and 15 born to mothers with negative GBS cultures). Eight (8.2%) of the infants studied, or 8 of 52 (15.4%) infants colonized with GBS, had a positive urine LA test result. GBS was isolated from urine cultures of all infants with a positive urine LA test result. A positive urine LA test result was associated with positive GBS rectal and vaginal cultures and with increased density of colonization at those sites. We conclude that contamination of bag specimens of urine with GBS from perineal and rectal colonization may produce a positive urine LA test result in an infant with no systemic sign of infection.

Practical approaches to diagnosing fungal infections in immunocompromised patients

Karin L. McGowan, Ph.D. from human skin and stool. Prior to sively to IC hosts. Burn patients are Director of Microbiology the 1980s, they were rarely reported to also at increased risk of acquiring disChildren's Hospital of Philadelphia cause infection (14, 16). Sepsis due to seminated Fusarium infections. AIDepartment of Pediatrics University of Pennsylvania Medical School Rhodotorula spp. occurs in IC pediatric though not all Fusarium infections in Philadelphia, Pennsylvania 19104 patients, especially children on longthe IC patients become disseminated, term steroid therapy who appear to be all of these infections are extremely predisposed to acquiring serious Rhodifficult to treat. Most isolates are reFungal infections frequently prove dotorula infection. A positive blood sistant to 5-fluorocytosine and require fatal to immunocompromised (IC) paculture from an IC patient that yields amphotericin B therapy. The prognosis tients. They are a frustration for both Rhodotorula is reason for concern, befor these patients is poor, and early iniclinicians and laboratorians because cause the overall mortality rate for this tiation of therapy offers the best chance they are difficult to diagnose, even with infection is 50 to 60%. for cure. Early therapy depends upon the best laboratory methods available. Trichosporon beigelii, the cause of laboratory awareness and rapid reMicrobiologists can, however, take white piedra, a superficial infection of porting of the results. practical steps to minimize the the hair shaft, is another yeast that The most common fungal infections problems encountered when dealing causes serious infections in IC patients in the immunocompromised are those with fungal infections in IC patients, or patients with hematologic maligcaused by Candida spp., Aspergillus nancies. T. beigelii can cause invasive spp., the Mucorales, and C. neoL a b o r a t o r y Awareness disease of the respiratory and gastroinformans, but significant changes in the The first step is to understand which testinal tracts, which leads to dissemipatterns of infection have occurred (3, organisms cause serious fungal infecnation (9). This organism shares 10). The incidence of candidemia at tions in IC patients, and in which cirantigenic determinants with the capsular cumstances they occur (Table 1). polysaccharide of Cryptococcus neoFungi that commonly cause infections formans (12, 13). Thus, compromised In This Issue in IC patients rarely cause serious inpatients with T. beigelii infections can fections in normal hosts. Many were have false positive serum cryptococcal once considered harmless colonizers, or antigen latex agglutination test results. Diagnosis of Fungai Infections. . . 33 saprophytes. Organisms such as Early detection of this pathogen is critImportance of direct microscopic, Drechslera, Cunninghamella, Penicilical, because a number of reported exam and serologic tests lium, and Pseudallescheria boydii are isolates have been resistant to amphoDiagnostic Significance of CMV now reported as causative agents in intericin B. fections that usually involve the In normal hosts, Fusarium infections Serology . . . . . . . . . . . . . . . . . . . . . 36 sinuses, lungs, and bloodstream. Neuare limited primarily to local infections Pitfalls in interpretation tropenia appears to be the most imporof the skin, nails and cornea. In bone Eschericheria hermannii Wound tant predisposing factor in these marrow transplant patients, Fusarium Infection . . . . . . . . . . . . . . . . . . . . . 38 patients, spp. frequently cause invasive fungal A rare, yellow-pigmented species Rhodotorula spp. have always been disease (2). In fact, invasive disease considered normal flora when recovered with this genus has been limited excluLetter to the Editors . . . . . . . . . . . 39

Clinical performance and effect on treatment rates of latex agglutination testing for streptococcal pharyngitis in an emergency department.

Of 556 children with symptoms of streptococcal pharyngitis in a pediatric hospital emergency department, 38.8% had positive results on either a rapid latex agglutination test or throat culture for Group A Streptococcus. Twenty-six percent of patients with negative latex agglutination test results had growth on culture of a paired specimen. Under the best assumption rapid test sensitivity was 44.9%. The treatment rate (84%) for cases detected by the rapid test was markedly higher than the rate (44%) for cases detected only by culture (P less than 0.001), presumably because the rapid test result is available sooner. We conclude that: the rapid test had a lower sensitivity in routine use in our pediatric emergency department population than in previous reports from research settings; and using the rapid test in addition to culture can significantly increase treatment rates.

Immunodiagnostic confirmation of hydatid disease in patients with a presumptive diagnosis of infection.

Information obtained from the routine application of hydatid immunodiagnostic techniques in different clinical situations over a seven-year period is presented. The Immunoelectrophoresis test was used until it was replaced by the simpler, more sensitive and equally specific arc 5 double diffusion (DD5) test. Examination of sera from 1,888 patients with signs and/or symptoms compatible with hydatid disease revealed that the presurgical confirmation of Echinococcus granulosus infection is only obtained by detection of anti-antigen 5 antibodies. The latter were not found in 1,539 presumptive hydatidosis patients whose definitive diagnoses corresponded to other disease conditions. However, false positive latex agglutination test results were obtained in two cases. In all patients whose preoperative serum showed three or more uncharacteristic bands in the absence of anti-antigen 5 antibodies, hydatid cysts were found sur gically. DD5 testing of a fluid sample collected by puncture established its hydatid etiology. Post-operative monitoring of hydatidosis patients demonstrated that persistence of DD5-positivity two years after surgery established the presence of other cysts. Further evidence was obtained in patients with hydatid cysts in intrathoracic, abdominal or other locations associating cyst membrane integrity, antigen release and immunodiagnostic test positivity.

Beurteilung eines neuen latex-agglutinations-tests zur identifizierung von staphylococcus aureus

286 clinical isolates of staphylococci and 19 Micrococcus spp. were tested in a new latex agglutinating test to detect bound coagulase and protein A simultaneously. Coagulase-positive strains of staphylococci (n = 119) were all found to be latex-positive. Negative latex agglutination test results were obtained with 154 out of 167 coagulase-negative strains, the other 13 (7.8%) strains gave positive latex tests. Furthermore 3 out of 19 Micrococcus strains yielded positive agglutinating results. According to the results presented a negative latex test allows a rapid exclusion of S. aureus. A positive latex test requires the determination of further typical characteristics to differentiate among the staphylococcal isolates. Mit einem neuen Latextest, der den gleichzeitigen Nachweis von gebundener Koagulase und Protein A zur Identifizierung von Staphylococcus aureus ermöglicht, wurden 286 Staphylokokken- und 19 Mikrokokken-Stämme untersucht. Alle koagulasepositiven Staphylokokken-Stämme (n = 119) waren im Latextest positiv. Von den 167 koagulasenegativen Staphylokokkenstämmen bewirkten 13 (7,8%) eine Agglutination der Latexpartikel, 154 ergaben ein negatives Resultat. Auch 3 von 19 Micrococcus-Stämmen waren im Latextest positiv. Nach den vorliegenden Ergebnissen ermöglicht ein negativer Latextest einen raschen Ausschluß von S. aureus. Ein positiver Latextest erfordert zur Bestätigung die Beurteilung weiterer Merkmale zur Differenzierung von Staphylokokken.

Evaluation of a commercial latex agglutination test for identification of Staphylococcus aureus.

A new, commercially available latex agglutination test (SeroSTAT Staph; Scott Laboratories, Inc., Fiskeville, R.I.) was compared with the tube coagulase and slide coagulase tests as means for identifying Staphylococcus aureus. Of 160 clinical isolates of S. aureus, 159 (99.4%) yielded positive results with the latex agglutination test. Negative latex agglutination test results were obtained with 266 of 267 clinical isolates of Micrococcus spp. and staphylococcal species other than S. aureus (99.6%). The latex agglutination test was found to be a rapid, technically nondemanding method for identifying S. aureus. It was as accurate as the tube coagulase test and more accurate than the slide coagulase test.