Commercial Latex Agglutination Kit Research Articles

Isolation and identification of Escherichia coli O157:H7 from houseflies (Musca domestica L) at cattle barns in Al-Qadisiyah Province, Iraq

Recent studies identified that Escherichia coli O157:H7 (ECO157H7) causes hemorrhagic colitis in humans, a rare spectrum of diarrheal illness. According to the findings of epidemiological investigations, cattle serve as the principal reservoirs for this bacterium. This study was conducted to understand the incidence of ECO157H7 in houseflies (HFs), a key disease vector. HFs (n = 40) were collected from cattle barns. The HFs were cultured on MacConkey (MC) agars, and any suspected colonies were grown on Eosin Methylene Blue (EMB) agar. EMB-based metallic sheen colonies were grown on specific media, such as sorbitol Chromagar (SCA) and cefixime tellurite sorbitol-MacConkey (CT–SMAC) agar. Sorbitol non-fermenting (SNF) isolates were subjected to a commercial latex agglutination kit to identify the existence of O157 group. The results recorded 31/40 (77.5%) E. coli isolates identified from HF samples. The findings revealed that only 18/31 (58%) were from the SNF isolates. The identities of the isolates were further examined by targeting the rfbO157 and fliCH7 genes, as genetic markers in a PCR method. The PCR results reported 10/18 (55.5%) and 12/18 (66.6%) isolates that carried the rfbO157 and fliCH7 genes, respectively. Our research revealed that HFs represent a harbor for the pathogenic E. coli. The ecology and way this bacterium spreads among animals and across the environment may depend heavily on the presence of ECO157H7 in agricultural environments.

Seroprevalence of Toxoplasma gondii in sheep and goats in Rahim Yar Khan (Punjab), Pakistan

Toxoplasmosis, an infection caused by Toxoplasma (T.) gondii Apicomplexa protozoan, is widespread in humans and other animal species, having already been reported in many countries and different climates. In Pakistan, no data is available on this aspect among food animals. This study was undertaken to determine the seroprevalence of T. gondii infection in sheep and goats. A total of 200 serum samples from sheep and goats, were collected from urban area of Rahim Yar Khan (Punjab), Pakistan and tested for Toxoplasmosis with a commercial latex agglutination kit (Eiken Chemical Co., Ltd. Japan). The overall seroprevalence of Toxoplasmosis was 19%. Goats had a significantly higher (p < 0.01) prevalence (25.4%) as compared to the sheep (11.2%); and higher (p < 0.01) in the female (24%) than in the males (19%) for both species. In the present study the male (both in sheep and goat) are found less seropositive T. gondii (OR = 0.23; 99% C.I. = 0.01, 1.81) as compared to female sheep and goat. The prevalence was significantly higher (p < 0.01) in adult sheep than younger animals. Among both the sheep and goats the group from 1-1.5 years are highly seropositive (OR = 1.75; 99% C.I. = 0.47, 6.51) as compared to the group less than one year of age followed by the 2-2.5 years age group (OR = 1.63; 99% C.I. = 0.50, 5.74) whereas group with more than 3 years of age least seropositive.

Evaluation of three commercial latex agglutination kits and a commercial enzyme immunoassay for the detection of cryptococcal antigen

We compared the performance of the Meridian CALAS, Wampole Crypto-LA, Murex Cryptococcus latex agglutination assay, and the Meridian Premier EIA for the detection of cryptococcal antigen in serum and CSF. The assays demonstrated similar performance characteristics based on concordance values > or = 93% but important differences were noted in endpoint titers.

Seroprevalence of Toxoplasma gondii in Cats and Pigs from Thua Thien Hue Province in Vietnam

The traditional small scale pig farmers in Vietnam keep animals in open backyard stalls and usually keep cats to catch rats and mice. Under these conditions, controlling for the exposure of pigs to toxoplasmosis, a significant zoonoses, is difficult. The purpose of this study is to investigate the seroprevalence of Toxoplasma gondii antibodies in domestic cats and pigs in T.T. Hue Province, Vietnam with commercial latex agglutination kits (Eiken-Toxocheck). A total of 155 cat and 260 pig sera samples (110 from a slaughterhouse and 150 from 6 pig farms) were collected in 2007. Among them, 112 (72.3%) cats, 62 (41.3%) live pigs and 76 (69.1%) slaughtered pigs tested positive for T. gondii antibodies (1 : 64 cut-off). The seroprevalence increases as the pig grows ; the seroprevalence of piglets less than 15kg was 16.7% and 71.0% for those over 50kg (OR=12.26, 95%CI=3.31, 45.34). We also have collected sera from the same herds of 6 farmers 2 times with 2 month interval. Of which, the prevalence rate at the first sampling was 28.4% (88 samples) and 2 months later in the 2nd sampling it was 64.0% (50 samples) (OR=4.48, 95%CI=2.14, 9.39). The results indicate a high prevalence of T. gondii in pigs under the current farming system in T.T. Hue Province, Vietnam.

Peak Rotavirus Activity Shifted From Winter to Early Spring in Japan

Since 1910, there have been many studies on acute gastroenteritis in children in Japan. These diseases, namely Kasei-shoni-kolera (pseudocholera infantum) or banshu-otosho (late autumn vomiting disease), are historically known to occur in the cooler season with a peak in November or December. Earlier we confirmed their causation by rotaviruses but found peaks in January or February from 1974 to 1981. The aim of the present study was to confirm the temporal shift in peak rotavirus activity. Under the National Epidemiological Surveillance of Infectious Diseases program from 1983 through 2003, rotavirus positive patients 0-3 years old and clinically diagnosed with "infantile vomiting and diarrhea" at sentinel clinics were examined. Fecal samples were screened by electron microscopy and/or using commercial latex agglutination kits at prefectural/municipal Public Health Institutes, and we determined the trend for the "peak" month during 21 seasons. Peak rotavirus activity shifted gradually from January to March during the 21 consecutive seasons. The mean duration from December to the peak month (mean beginning peak duration) of the rotavirus season significantly varied among 3 periods of 7 consecutive seasons (1.7 +/- 0.5 months in 1982/1983-1988/1989, 2.3+/-0.8 months in 1989/1980-1995/1996, and 3.1 +/- 0.7 months in 1996/1997-2002/2003, respectively; P = 0.0026 by 1-way analysis of variance). This time series shift in the peak rotavirus infection was statistically significant (P = 0.0003 for trend). Our findings confirmed that the temporal trend in peak rotavirus activity in Japan has shifted gradually from winter to early spring for unknown reasons.

Ordinary and opportunistic enteropathogens associated with diarrhea in senegalese adults in relation to human immunodeficiency virus serostatus

Objectives: A survey was conducted in Dakar, Senegal, to identify major types and prevalences of bacteria, parasites, fungi, and Rotaviruses associated with diarrhea in relation to human immunodeficieny virus (HIV) serostatus with the goal to provide guidance to physicians for case management. Methods: Etiologic agents were identified in a case-control study: cases were HIV-infected patients with diarrhea (HIV+ D+) and HIV seronegative patients with diarrhea (HIV− D+); controls were HIV-infected patients without diarrhea (HIV+ D−) and seronegative controls without diarrhea (HID− D−). Ordinary enteric pathogens were identified by conventional methods. Different Escherichia coli pathotypes were characterized by polymerase chain reaction (PCR), identification of HEp-2 cell adherence pattern, Sereny test, GIvl1-ELISA, and the suckling mouse assay. Opportunistic parasites, such as Cryptosporidium and Microsporidium, were identified by the Kinyoun method and trichromic stain of Weber, respectively. Rotaviruses were identified with a commercial latex agglutination kit. Antimicrobial susceptibility testing was carried out by the disk diffusion method. Results: Among the 594 patients examined, 158 were HIV+ D+, 121 were HIV− D+, 160 were HIV+ D−, and 155 were HIV− D−. The main etiologies of diarrhea were different according to HIV serostatus of patients. In immunocompetent adults the main causes of diarrhea were Shigella sp (12.4%), Entamoeba histolytica (10.7%), Salmonella enterica (6.6%), and Giardia (4.9%). In the immunocompromised host the more frequent pathogens were enteroaggregative E. coli (19.6%), Microsporidium (9.4%), Cryptosporidium sp (8.2%), Rotavirus (8.2%), Shigella sp (7.6%), Candida albicans (7.6%), E. histolytica (5.1%), S. enterica (4.4%), and Isospora belli (4.4%). Also, Blastocystis hominis has to be considered as an opportunistic parasite, because it was identified only in HIV-infected patients, with higher prevalence in adults with diarrhea (2.5% in HIV+ D+ patients; 0.6% in HIV+ D− patients). High level of asymptomatic carriage of Ascaris lumbricoides and Trichuris trichiura and some cases of multiple infections were observed. Fungi, Cryptosporidium sp and Microsporidium sp, were often identified in patients with low CD4 counts (range, 79–250 cells/mL). Independently from HIV-serostatus, CD4 count was lower in diarrheic persons, suggesting that diarrhea is a debilitating illness and that effective management of diarrhea can prevent immunosuppression. Isolated enteropathogenic strains displayed high resistance to most antibiotics used in Senegal for treating diarrhea (ampicillin, tetracycline, cotrimoxazole); they were susceptible to amikacin, gentamicin, and norfloxacin. Conclusion: These epidemiologic data suggest that guidelines for the management of diarrhea during HIV infection in Dakar should be updated.

Evaluation of Kits for the Detection of Fibrin(ogen) Degradation Products in Dogs

The sensitivities and specificities of 3 commercial serum fibrin(ogen) degradation product (FDP) kits and 1 plasma FDP kit for the detection of FDPs in dogs were determined. Blood was collected for measurement of serum and plasma FDP concentrations from 30 healthy dogs and from 20 dogs that fulfilled clinical and laboratory criteria for disseminated intravascular coagulation. To determine the effect of hemolysis on FDP results, blood was collected simultaneously into Bothrops atrox venom‐based and thrombin‐based serum collection tubes for measurement of FDPs using a single serum FDP kit. The sensitivity (80–95%) and specificity (90–100%) for a positive or negative FDP result, regardless of concentration, was similar for all kits. Kits yielded discordant results in individual dogs and FDP concentrations obtained from 1 serum FDP kit were consistently higher than those from the other kits. Serum prepared from venom‐based collection tubes was significantly more hemolyzed than serum prepared from thrombin‐based collection tubes or citrated plasma. Hemolysis did not affect the FDP results. On the basis of these results, we conclude that commercial latex agglutination kits for detection of FDPs in serum and plasma samples from human patients are valid for use in dogs. The plasma FDP assay is a viable alternative to currently used serum FDP assays and has the advantage of using a single (citrated plasma) sample for measuring coagulation parameters and FDP concentration.

Evaluation of kits for the detection of fibrin(ogen) degradation products in dogs.

The sensitivities and specificities of 3 commercial serum fibrin(ogen) degradation product (FDP) kits and 1 plasma FDP kit for the detection of FDPs in dogs were determined. Blood was collected for measurement of serum and plasma FDP concentrations from 30 healthy dogs and from 20 dogs that fulfilled clinical and laboratory criteria for disseminated intravascular coagulation. To determine the effect of hemolysis on FDP results, blood was collected simultaneously into Bothrops atrox venom-based and thrombin-based serum collection tubes for measurement of FDPs using a single serum FDP kit. The sensitivity (80-95%) and specificity (90-100%) for a positive or negative FDP result, regardless of concentration, was similar for all kits. Kits yielded discordant results in individual dogs and FDP concentrations obtained from 1 serum FDP kit were consistently higher than those from the other kits. Serum prepared from venom-based collection tubes was significantly more hemolyzed than serum prepared from thrombin-based collection tubes or citrated plasma. Hemolysis did not affect the FDP results. On the basis of these results, we conclude that commercial latex agglutination kits for detection of FDPs in serum and plasma samples from human patients are valid for use in dogs. The plasma FDP assay is a viable alternative to currently used serum FDP assays and has the advantage of using a single (citrated plasma) sample for measuring coagulation parameters and FDP concentration.

Utility of a rapid fecal latex agglutination test detecting the neutrophil protein, lactoferrin, for diagnosing inflammatory causes of chronic diarrhea

Objective: The utility of tests for fecal neutrophils in the setting of chronic diarrhea has not been established. The purpose of this study was to determine the causes of chronic diarrhea associated with fecal neutrophils. Methods: One fecal specimen from each of 10 normal subjects, 26 patients with known microscopic colitis, 13 with celiac sprue, eight with Crohn’s disease, four with ulcerative colitis, and 103 with chronic diarrhea of unknown origin, as well as 10 fecal specimens from a patient with chronic nongranulomatous enterocolitis were analyzed blindly for the presence of a neutrophil granule protein called lactoferrin using a commercial latex agglutination kit. Diagnostic evaluation of the 103 patients with chronic diarrhea was carried out to determine the diagnostic accuracy of this test for chronic inflammatory bowel disease. Results: None of the normal control subjects, three of 39 patients with microscopic colitis or celiac sprue, all 10 specimens from the patient with enterocolitis, and all 12 control patients with ulcerative colitis or Crohn’s disease had a positive fecal lactoferrin test. Eleven of 103 patients with chronic diarrhea presenting without a diagnosis had a positive test, and all were diagnosed with an inflammatory condition of the colon (five-, ulcerative colitis; four-, Crohn’s disease; one-, ischemic colitis; and one-, microscopic colitis). Only one patient with inflammatory bowel disease had a negative lactoferrin test. The sensitivity, specificity, and positive and negative predictive values of the fecal lactoferrin test for ulcerative or Crohn’s colitis were 90%, 98%, 82%, and 99%, respectively. Conclusion: The major cause of fecal neutrophils in patients with chronic diarrhea is chronic inflammatory bowel disease of the colon. The latex agglutination test for fecal lactoferrin offers a highly sensitive, specific, and simple means for detection of fecal neutrophils in these patients.

Comparative evaluation of cryptococcal latex tests

One hundred and seven specimens (24 CSF and 83 sera) from 90 patients were tested for the presence of Cryptococcus neoformans antigen using the Fairfield Hospital in-house latex agglutination technique and the IMMY and Meridian commercial latex agglutination kits. Forty one specimens (14 CSF and 27 sera) from 27 patients with culture-proven cryptococcosis were positive by both the Fairfield and IMMY latex tests. Thirty nine of these specimens were positive by the Meridian latex test. Two were negative. Sixty six specimens (10 CSF and 56 sera) from 63 patients not known to have cryptococcosis were negative by all 3 tests.

Commercial Latex Agglutination Kits for the Detection of Food borne Salmonella

The ability of the Bactigen® Salmonella Shigella (BSST), the Microscreen® (MS), and the Spectate® (SPECT) latex agglutination kits to detect Salmonella in pure cultures and in naturally contaminated foods was examined. Of 190 Salmonella strains tested, the MS, BSST, and SPECT systems correctly identified 89.5, 81.6, and 66.3% of the test cultures, respectively. The sensitivity of SPECT increased to 92.7% when only strains belonging to the targeted serogroups (somatic A to E plus G) and strains harboring the Vi antigen were considered. The lack of specificity of the MS (3.4%), SPECT (17.0%), and BSST (33.9%) systems with 59 cultures of nonsalmonellae varied widely, with Citrobacter freundii and Escherichia coli accounting for many of the false-positive reactions. Examination of foods according to the prescribed MS and SPECT analytical test protocols identified respectively, 18 (75%) and 19 (79.2%) of the 24 food samples found to contain Salmonella spp. by a standard cultural method. Although instructions with the BSST kit indicate that the product is intended for the analysis of clinical samples, the system nevertheless identified 21 (87.5%) contaminated food samples under homologous MS and SPECT test conditions. The concurrent use of TBG43 with enrichment media recommended by kit manufactures enhanced the sensitivities of MS (83.3%), SPECT (91.7%), and BSST (91.7%). Attempts to effect greater method brevity through the application of latex kits at various stages of the standard cultural procedure were counterproductive.

Comparison of three latex agglutination kits and counterimmunoelectrophoresis for the detection of bacterial antigens in a pediatric population

Three commercial latex agglutination kits (Bactigen, Wampole Laboratories, Cranbury, NJ; Directigen, Hynson, Westcott & Dunning, Baltimore, MD; Wellcogen, Wellcome Diagnostics, Dartford, England) used for the detection of bacterial polysaccharide antigens (Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis) were compared with counterimmunoelectrophoresis and Gram stain for the identification of systemic bacterial disease in children. Urine and (when available) cerebrospinal fluid specimens were saved for all patients. Positive blood or cerebrospinal fluid culture isolates included 36 with H. influenzae type b, 11 with S. pneumoniae, 3 with N. meningitidis and 6 with other organisms. All latex kits performed similarly for the detection of H. influenzae type b antigen with a sensitivity range of 91 to 100%. The four methods performed poorly for the detection of S. pneumoniae (23 to 50%) and N. meningitidis (0%) antigen. Gram stain of cerebrospinal fluid appeared to be equally sensitive to the antigen detection methods for patients with meningitis. The false positive rates for the latex kits and counterimmunoelectrophoresis ranged from 2.8 to 9.2%, with Wellcogen having the lowest rates. The false negative rates ranged from 6.5% to 12% with Directigen having the lowest rate.

An evaluation of commercial latex agglutination kits for rotavirus detection

Three commerical latex agglutination kits for rotavirus detection in faeces, Rota Screen (Mercia Diagnostics Ltd), Slidex Rota-kit (bio Mérieux) and Rotalex (Orion Diagnostica) were evaluated and compared with electron microscopy (EM), enzymelinked immunosorbent assay (ELISA) and polyacrylamide gel electrophoresis (PAGE). Of all positives ( N = 102) RotaScreen detected 91%, Slidex 76%, Rotalex 87%, EM 88%, ELISA 99% and PAGE 100%. The detection rate with Slidex was low because many specimens gave non-specific agglutination. Results of the rotavirus negative specimens tested during the study confirmed the high non-specificity rate (14%) with Slidex compared with only 1–2% with RotaScreen and Rotalex. False positive reactions were low (1–3%) with all three latex tests. It was found that nonspecific agglutination and possibly false positive reactions could be removed by fluorocarbon treatment. The results and problems of interpretation of the latex tests are discussed as are user-acceptability and costs.

The clinical value of rapid C-reactive protein measurement in cerebro-spinal fluid

C-Reactive protein (CRP) has been measured in 90 consecutive CSF specimens using both latex agglutination and an immunoradiometric assay (IRMA). In the 60 CSF specimens otherwise normal by standard biochemical and microbiological criteria, the median CRP level was 32 μg/l (95% confidence limits, 0–108 μg/l) and in the remaining abnormal specimens the median level was 176 μg/l (95% confidence limits, 110–325 μg/l, p = 0.001). C-Reactive protein was detected by a commercial latex agglutination kit at a level of approximately 120 μg/l and all significant CNS bacterial infections were positive (7 bacterial meningitis, 2 infected shunts). In addition, viral encephalitis, extensive intracranial malignancy and sub-arachnoid haemorrhage gave positive agglutinations, but not in every case. A further nine specimens with a minor elevation of CRP level were detected by IRMA (median 76 μg/l), but this was of little practical significance. We have shown that normal CSF C-reactive protein levels are very low and we conclude that latex agglutination set at a sensitivity of 120 μg/l, although only semi-quantitative, is a rapid and useful method to assess CSF C-reactive protein in routine clinical practice and, when positive, is strong supporting evidence for bacterial infection.