Jim Nomura

Clostridium difficile Testing in the Clinical Laboratory by Use of Multiple Testing Algorithms

ABSTRACT The incidence of Clostridium difficile infection (CDI) has risen almost 3-fold in the United States over the past decade, emphasizing the need for rapid and accurate tests for CDI. The Cepheid Xpert C. difficile assay is an integrated, closed, nucleic acid amplification system that automates sample preparation and real-time PCR detection of the toxin B gene (tcdB). A total of 432 stool specimens from symptomatic patients were tested by a glutamate dehydrogenase (GDH) assay, a toxin A and B enzyme immunoassay (EIA), the Xpert C. difficile assay, and a cell culture cytotoxicity neutralization assay (CCCN). The results of these methods, used individually and in combination, were compared to those of toxigenic culture. Results for the Xpert C. difficile assay alone showed a sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 94.4, 96.3, 84.0, and 98.8%, while the EIA alone gave corresponding values of 58.3, 94.7, 68.9, and 91.9%, respectively. An algorithm using the GDH assay and the EIA (plus the CCCN if the EIA was negative) showed corresponding values of 83.1, 96.7, 83.1, and 96.1%. The Xpert C. difficile assay was statistically superior to the EIA (P, <0.001 by Fishers exact test) and to the GDH-EIA-CCCN algorithm (P, 0.0363). Combining the GDH and Xpert C. difficile assays lowered both the sensitivity and the NPV of the Xpert assay. The GDH-EIA-CCCN procedure required, on average, 2 days to complete testing on GDH-positive results, while testing by the Xpert C. difficile assay was completed, on average, in less than 1 h. Xpert C. difficile testing yielded the highest sensitivity and NPV, in the least amount of time, of the individual- and multiple-test algorithms evaluated in this study.

Mucormycosis of the vulva following bone marrow transplantation

Mucormycosis is uncommon in bone marrow transplant recipients. Primary cutaneous mucor in any setting is unusual. It may mimic necrotizing bacterial infection particularly in patients with severe neutropenia. We report a case of vulvar mucormycosis in a transplant recipient. Diagnosis depends on histological identification of fungal hyphae invading tissue and blood vessels.

Hepatitis B Testing and Vaccination Among Adults With Sexually Transmitted Infections in a Large Managed Care Organization

Data on viral hepatitis B (HBV) testing and vaccination in primary care settings among persons at sexual risk for HBV infection have been sparse. We examined rates and factors associated with HBV serologic testing and vaccination rates in adults infected with sexually transmitted infections. We conducted a retrospective cohort study of adults diagnosed with chlamydia, gonorrhea, or syphilis in Kaiser Permanente Southern California in 2008-2011. The vaccine series initiation was examined in subjects who were tested susceptible. The 90-day hepatitis B surface antigen (HBsAg) testing rate was 28.1% in 15 357 adults. Testing rates increased through the study period. Only 8.8% of patients received both HBsAg and hepatitis B surface antibody tests to determine prior exposure and susceptibility to HBV. Among those who were tested susceptible, 116 (10.6%) subjects initiated the vaccine series. In multivariable logistic regression analysis, the odds of receiving testing was inversely associated with female sex, black race, other/unknown race, or having prespecified chronic comorbidities. In survival analysis, adults aged 25-34 years and ≥55 years were more likely to initiate hepatitis B vaccine series compared with those aged 18-24 years. There are missed opportunities in HBV testing and vaccination in primary care. Implementation of provider decision-making support tools in the electronic medical record system may potentially improve hepatitis B testing and vaccination rates.

Performance of Treponemal Tests for the Diagnosis of Syphilis

BACKGROUND Treponemal immunoassays are increasingly used for syphilis screening with the reverse sequence algorithm. There are few data describing performance of treponemal immunoassays compared to traditional treponemal tests in patients with and without syphilis. METHODS We calculated sensitivity and specificity of 7 treponemal assays: (1) ADVIA Centaur (chemiluminescence immunoassay [CIA]); (2) Bioplex 2200 (microbead immunoassay); (3) fluorescent treponemal antibody absorption test (FTA-ABS); (4) INNO-LIA (line immunoassay); (5) LIAISON CIA; (6) Treponema pallidum particle agglutination assay (TPPA); and (7) Trep-Sure (enzyme immunoassay [EIA]), using a reference standard combining clinical diagnosis and serology results. Sera were collected between May 2012-January 2013. Cases were characterized as: (1) current clinical diagnosis of syphilis: primary, secondary, early latent, late latent; (2) prior treated syphilis only; (3) no evidence of current syphilis, no prior history of syphilis, and at least 4 of 7 treponemal tests negative. RESULTS Among 959 participants, 262 had current syphilis, 294 had prior syphilis, and 403 did not have syphilis. FTA-ABS was less sensitive for primary syphilis (78.2%) than the immunoassays or TPPA (94.5%-96.4%) (all P ≤ .01). All immunoassays were 100% sensitive for secondary syphilis, 95.2%-100% sensitive for early latent disease, and 86.8%-98.5% sensitive in late latent disease. TPPA had 100% specificity. CONCLUSIONS Treponemal immunoassays demonstrated excellent sensitivity for secondary, early latent, and seropositive primary syphilis. Sensitivity of FTA-ABS in primary syphilis was poor. Given its high specificity and superior sensitivity, TPPA is preferred to adjudicate discordant results with the reverse sequence algorithm over the FTA-ABS.

A Case of Fulminant Endophthalmitis

Diagnosis: Clostridium septicum endophthalmitis associated with underlying colon cancer. The gram stain shows pleomorphic gram-positive bacilli and growth on the egg yolk media demonstrates the characteristic spreading morphology of Clostridium septicum. Our patient developed a case of fulminant endogenous endophthalmitis due to Clostridium septicum. Although most cases of endogenous endophthalimitis occur in the setting of a systemic infection and/or positive blood cultures, up to 18% can develop in the absence of constitutional symptoms [1]. Once the microbiologic diagnosis was made, the patient was referred for colonoscopy. This was performed 6 weeks after evisceration and revealed a mass in the right colon with biopsy showing adenocarcinoma. One month later, he successfully underwent a right hemicolectomy with margins free of tumor cells.

Cytomegalovirus sinusitis complicated by orbital apex syndrome in an immunocompromised host

Sinusitis in immunocompromised patients can be caused by a wide variety of pathogens, primarily bacterial and fungal in nature. Tissue invasion can extend into the orbital apex and result in ophthalmoplegia and blindness. We report the first histologically proven case, to our knowledge, caused by cytomegalovirus infection.