Diagnostic accuracy of indirect immunofluorescence assay for intestinal invasive amebiasis and impact of HIV infection in a non-endemic country

Establishment and evaluation of an indirect ELISA for detection of antibodies to goat Klebsiella pneumonia

BACKGROUND

Klebsiella pneumonia, a Gram-negative bacterium belonging to the genus Enterobacter, causes many human and livestock diseases. Notably, infected goats may develop pneumonia, septicemia, which can lead to occasional death, resulting in great economic losses in goat-farming industry. However, there are little systematic methods for detection of goat Klebsiella pneumoniae in livestock production.

RESULTS

In this study, we developed a Klebsiella pneumoniae goat polyclonal antibody and established an indirect ELISA method to detect the Klebsiella pneumoniae. After screening and optimizing the conditions for detection, we determined the optimal working dilutions of the coated-bacterial antigen, the polyclonal antibody, and the enzyme-labeled secondary antibody that were 1:800 (2.99 × 10⁷ CFU/ml), 1:6400, and 1:5000, respectively. The optimal condition of coating and blocking were both 4 °C for 12 h. The optimal dilution buffers of bacterial antigen, the antibodies, and the blocking buffer were 0.05 mol/L carbonate buffer, 1% BSA phosphate buffer, and 1.5% BSA carbonate buffer, respectively. The cut-off value was determined to be 0.28, and the analytical sensitivity was 1:800 (dilution of a positive sample). Furthermore, there was no cross-reaction between the coated antigen and goat serum positive for antibodies against other bacteria, indicating that indirect ELISA could detect Klebsiella pneumoniae specifically in most cases. The average coefficients of variation of intra-assay and inter-assay were 4.37 and 5.17% indicating favorable reproducibility of indirect ELISA. In the detection of clinical veterinary samples, the positive rate of indirect ELISA was 6.74%, higher than that of conventional agglutination assays.

CONCLUSIONS

Taken together, we successfully established an indirect ELISA method for detecting antibodies against Klebsiella pneumoniae in goats, which can be applied in production.

Increases in Entamoeba histolytica Antibody-Positive Rates in Human Immunodeficiency Virus-Infected and Noninfected Patients in Japan: A 10-Year Hospital-Based Study of 3,514 Patients

Serological evidence of the epidemiological trends in Entamoeba histolytica infection is scarce, especially in nonendemic countries. We aimed to determine the antibody-positive rates over a 10-year period, and compare the trends between human immunodeficiency virus (HIV)–infected and –noninfected patients. We reviewed 3,514 patients who underwent antibody testing during the study periods, which were divided into five annual categories: 2004–2005, 2006–2007, 2008–2009, 2010–2011, and 2012–2013. Anti-E. histolytica antibody was assessed by indirect immunofluorescence assay. The antibody-positive rate increased yearly from 2004–2005 to 2012–2013 (P < 0.001), although there was no increase in the annual number of antibody tests. This trend was seen among males (18.6–28.3%; P < 0.01), females (5.4–28.2%; P < 0.01), HIV-infected patients (18.4–26.9%; P < 0.001), and non-HIV-infected patients (14.6–36.8%; P < 0.001), and HIV-infected men who have sex with men (19.4–29.1%; P < 0.001). Among antibody-positive patients, there was a significant increase in the proportion of patients with high (≥ 1,600) titers (0.7–12.9%; P < 0.001), whereas this trend was not seen in patients with low (100) or intermediate (200–800) titers (P = 0.282 and 0.409, respectively). This large hospital-based study demonstrated that positive anti-E. histolytica antibody rates increased over 10 years, even though the annual number of antibody tests remained constant. Moreover, this trend was identified in non-high-risk patients (females and non-HIV-infected patients) as well as in high-risk patients. The proportion of patients with high antibody titers significantly increased among the antibody-positive patients.

Prevalence of Anal Human Papillomavirus Infection and Risk Factors among HIV-positive Patients in Tokyo, Japan

Background

Oncogenic human papillomavirus (HPV) infection, particularly multiple HPV types, is recognized as a necessary cause of anal cancer. However, a limited number of studies have reported the prevalence of anal HPV infection in Asia. We determined the prevalence, genotypes, and risk factors for anal HPV infection in Japanese HIV-positive men who have sex with men (MSM), heterosexual men, and women.

Methods

This cross-sectional study included 421 HIV-positive patients. At enrollment, we collected data on smoking, alcohol, co-morbidities, drugs, CD4 cell counts, HIV RNA levels, highly active anti-retroviral therapy (HAART) duration, sexually transmitted infections (STIs), and serological screening (syphilis, hepatitis B virus, Chlamydia trachomatis, Entamoeba histolytica). Anal swabs were collected for oncogenic HPV genotyping.

Results

Oncogenic HPV rate was 75.9% in MSM, 20.6% in heterosexual men, and 19.2% in women. HPV 16/18 types were detected in 34.9% of MSM, 17.7% of heterosexual men, and 11.5% of women. Multiple oncogenic HPV (≥2 oncogenic types) rate was 54.6% in MSM, 8.8% in heterosexual men, and 0% in women. In univariate analysis, younger age, male sex, MSM, CD4 <100, HIV viral load >50,000, no administration of HAART, and having ≥2 sexually transmitted infections (STIs) were significantly associated with oncogenic HPV infection, whereas higher smoking index and corticosteroid use were marginally associated with oncogenic HPV infection. In multivariate analysis, younger age (OR, 0.98 [0.96–0.99]), MSM (OR, 5.85 [2.33–14.71]), CD4 <100 (OR, 2.24 [1.00–5.01]), and having ≥2 STIs (OR, 2.81 [1.72–4.61]) were independently associated with oncogenic HPV infection. These 4 variables were also significant risk factors for multiple oncogenic HPV infection.

Conclusions

Among Japanese HIV-infected patients, approximately two-thirds of MSM, one-fifth of heterosexual men, and one-fifth of women have anal oncogenic HPV infection. Younger age, MSM, ≥2 STIs, and immunosuppression confer a higher risk of infection with oncogenic HPV and multiple oncogenic types.

Colonoscopic diagnosis of amebiasis: a case series and systematic review

PURPOSE

Nonspecific gastrointestinal symptoms make diagnosis of amebiasis difficult. Certain colonoscopic findings predict amebic colitis while others suggest different diagnoses. We aimed to evaluate the diagnostic capability of colonic evaluation of amebiasis.

METHODS

We retrospectively reviewed data of all amebiasis cases admitted to our institution between 2003 and 2012. Cases were diagnosed by clinical presentation, laboratory examinations, and colonoscopy with biopsy and microscopic examination. Patients were stratified as right-sided colitis and proctosigmoiditis. A systematic review was conducted by searching Medline, Cochrane, EMBASE, and Google Scholar using key words amebiasis, amebic colitis, amebic proctosigmoiditis, colonoscopy, and Entamoeba histolytica. Data were extracted from articles meeting the inclusion criteria. Colonoscopic findings were described and studies were assessed for quality.

RESULTS

The current series included 20 patients (5 male, 15 female, median age 51), 7 with amebic liver abscess and 13 with amebic colitis. Colonoscopic findings of right-sided colitis included aphthae or erosions, ulcers, exudates, or edematous swollen mucosa in cecum, and findings for proctosigmoiditis were edematous swollen mucosa with bloody exudate. In 25 studies, colonoscopic findings of 41 patients (36 male, 5 female, median age 43.39 years) included mainly ulcers in the cecum and rectum, ulcerated mass, and edematous mucosa; and in fewer patients, submucosal invasion suggestive of colon cancer, bleeding ulcers, proctitis, and ulcers with aphthae in rectum.

CONCLUSIONS

Colonic evaluation of suspected amebiasis is of diagnostic value when accompanied by biopsy and microscopic identification of Entamoeba species. Colonoscopic manifestations vary between right-sided colitis and proctosigmoiditis.