Impact of Choice of Test for Latent Tuberculosis Infection on Treatment Acceptance and Completion

OBJECTIVE

The aim of this study is to assess whether choice of test for tuberculosis (TB) infection affects decisions to accept and complete treatment among contacts to TB cases.

METHODS

Retrospective study is conducted in which TB contacts, ⩾15 years old during 2005 and 2009, were tested for infection with either a tuberculin skin test (TST) or an interferon-gamma release assay test, the QuantiFERON-TB Gold In-Tube (QFT-GIT).

RESULTS

Of 658 persons with valid test results, 185 (28%) had positive results, including 128 of 406 (32%) who had TST and 57 of 252 (23%) who received QFT-GIT. Treatment acceptance was 43 of 57 (75%) among QFT-GIT-positive and 97 of 128 (76%) among TST-positive persons (risk ratio [RR] = 1.0, 95% confidence interval [CI], 0.83-1.2). Treatment completion was 56% among QFT-GIT-positive (32 of 57) and 59% (75 of 128) among TST-positive persons (RR = 0.96, 95% CI, 0.73-1.26).

DISCUSSION

Our study showed no difference in proportions of TB contacts ⩾15 years old with positive TST results who accepted or completed LTBI treatment compared with those with positive QFT-GIT results. Future studies should include high-risk persons with no known TB exposure, who constitute the main reservoir for TB cases in the United States.

Videophone utilization as an alternative to directly observed therapy for tuberculosis

To demonstrate whether the use of videophone technology is an effective alternative method to direct observation of tuberculosis (TB) medication administration, a retrospective chart review and data analysis were performed on records for 57 patients with active TB in two Washington state counties who utilized videophone technology for the administration of medications from 2002 through 2006. A total of US$139,546 was saved in staff salaries, benefits and travel costs. The average cost savings per patient was US$2448. The use of videophone technology is a cost-effective alternative to in-home directly observed administration of TB medication.

Area income as a predictor of preventable hospitalizations in the Harris County Hospital District, Houston

This study assesses whether geographical area income based on census data is a good predictor of preventable (or ambulatory care-sensitive) hospitalizations in a large public hospital system in Texas, and how area income correlates with the socioeconomic status reported by patients. Documenting a correspondence between area and individual-level income, as well as meaningful variation in rates of avoidable hospitalizations across subgroups and areas with varying concentrations of low-income persons, points to the validity and utility of this approach for monitoring how well public hospital systems in Texas address the needs of those they most directly serve. Area income may not fully reflect the disproportionately lower socioeconomic status of patients seen in the public hospital system. Nonetheless, living in lower-income zip codes was associated with higher preventable hospitalization rates for the predominantly low-income population served by the public hospital system. A tenfold difference found in the adjusted rates of hospitalizations for preventable conditions compared with control (or marker) conditions among persons living in low-income areas signals the likelihood of substantial unmet needs in this population. Small-area analysis and related comparisons of rates of preventable hospitalizations in high- and low-income areas provide useful indicators for monitoring and assessing the performance of public hospital systems in Texas.

Bacteriophage surface display of an immunoglobulin-binding domain of Staphylococcus aureus protein A

As a model system for the optimization of separation ligands by bacteriophage surface display, we have constructed a phage surface expression system for a single immunoglobulin-binding domain of Protein A of Staphylococcus aureus. Protein A domain B is genetically fused to the gpIII adsorption protein of the filamentous bacteriophage M13, and hence displayed on the phage surface. Phage displaying the Protein A domain are selectively retained on human IgG-sepharose. Retention is due to specific Protein A-IgG interactions, as demonstrated by competitive inhibition by soluble Protein A or polyclonal human IgG. Polyclonal goat IgG, which is known to bind less well to Protein A than does human IgG, inhibits phage adsorption less effectively. Phage expressing Protein A can be purified in a few rounds of selective adsorption from a vast excess of wild type phage. Diverse libraries constructed by mutagenesis of this construct will allow massive screening of mutant forms of Protein A for alterations in binding and elution properties. We anticipate that phage display will prove to be a widely-applicable method of identification and optimization of affinity ligands for separations.