Impact of GeneXpert MTB/RIF assay on triage of respiratory isolation rooms for inpatients with presumed tuberculosis: a hypothetical trial.

BACKGROUND: Placing inpatients with presumed active pulmonary tuberculosis in respiratory isolation pending results of serial sputum acid-fast bacilli (AFB) smear microscopy is standard practice in high-income countries. However, this diagnostic strategy is slow and yields few tuberculosis diagnoses. We sought to determine if replacing microscopy with the GeneXpert MTB/RIF (Xpert) nucleic acid amplification assay could reduce testing time and usage of isolation rooms. METHODS: We prospectively followed inpatients at San Francisco General Hospital undergoing tuberculosis evaluation. We performed smear microscopy and Xpert testing on concentrated sputum, and calculated diagnostic accuracy for both strategies in reference to serial sputum mycobacterial culture. We measured turnaround time for microscopy and estimated hypothetical turnaround times for Xpert on concentrated and unconcentrated sputum. We compared median and total isolation times for microscopy to those estimated for the 2 Xpert strategies. RESULTS: Among 139 patients with 142 admissions, median age was 54 years (interquartile range [IQR], 43-60 years); 32 (23%) patients were female, and 42 (30%) were HIV seropositive. Serial sputum smear microscopy and a single concentrated sputum Xpert had identical sensitivity (89%; 95% confidence interval [CI], 52%-100%) and similar specificity (99% [95% CI, 96%-100%] vs 100% [95% CI, 97%-100%]). A single concentrated sputum Xpert could have saved a median of 35 hours (IQR, 24-36 hours) in unnecessary isolation compared with microscopy, and a single unconcentrated sputum Xpert, 45 hours (IQR, 35-46 hours). CONCLUSIONS: Replacing serial sputum smear microscopy with a single sputum Xpert could eliminate most unnecessary isolation for inpatients with presumed tuberculosis, greatly benefiting patients and hospitals.

Association of Rapid Molecular Testing With Duration of Respiratory Isolation for Patients With Possible Tuberculosis in a US Hospital.

Importance: New guidelines recommend that molecular testing replace sputum-smear microscopy to guide discontinuation of respiratory isolation in patients undergoing evaluation for active tuberculosis (TB) in health care settings. Objective: To evaluate the implementation and impact of a molecular testing strategy to guide discontinuation of isolation. Design, Setting, and Participants: Prospective cohort study with a pragmatic, before-and-after-implementation design of 621 consecutive patients hospitalized at Zuckerberg San Francisco General Hospital and Trauma Center who were undergoing sputum examination for evaluation for active pulmonary TB from January 2014 to January 2016. Interventions: Implementation of a sputum molecular testing algorithm using GeneXpert MTB/RIF (Xpert; Cepheid) to guide discontinuation of isolation. Main Outcomes and Measures: We measured the proportion of patients with molecular testing ordered and completed; the accuracy of the molecular testing algorithm in reference to mycobacterial culture; the duration of each component of the testing and isolation processes; length of stay; mean days in isolation and in hospital; and mean cost. We extracted data from hospital records and compared measures before and after implementation. Results: Clinicians ordered sputum testing for TB for 621 patients at ZSFG during the 2-year study period. Of 301 patients in the preimplementation period with at least 1 sputum microscopy and culture ordered, clinicians completed the rapid TB testing evaluation process for 233 (77%).Among 320 patients evaluated in the postimplementation period, clinicians ordered molecular testing for 234 (73%) patients and received results for 295 of 302 (98%) tests ordered. Median age was 54 years (interquartile range, 44-63 years), and 161 (26%) were women. The molecular testing algorithm accurately diagnosed all 7 patients with culture-confirmed TB and excluded TB in all 251 patients with Mycobacterium tuberculosis (MTB) culture-negative results. Compared with the preimplementation period, there were significant decreases in median times to final rapid test result (39.1 vs 22.4 hours, P < .001), discontinuation of isolation (2.9 vs 2.5 days, P = .001), and hospital discharge (6.0 vs 4.9 days, P = .003), on average saving $13 347 per isolated TB-negative patient. Conclusions and Relevance: A sputum molecular testing algorithm to guide discontinuation of respiratory isolation for patients undergoing evaluation for active TB was safe, feasible, widely and sustainably adopted, and provided substantial clinical and economic benefits. Molecular testing may facilitate more efficient, patient-centered evaluation for possible TB in US hospitals.

Real-world performance of the new US HIV testing algorithm in medical settings.

BACKGROUND: Our medical center laboratory recently adapted its 24/7, two-hourly testing program to use an ARCHITECT-Multispot-viral load (AR-MS-VL) algorithm in place of a previous rapid test-immunofluorescence (RT-IF) algorithm. OBJECTIVES: We evaluated screening test performance, acute case detection, turnaround time and ability to resolve HIV status under the new algorithm. STUDY DESIGN: We considered consecutive HIV tests from January to November 2015. AR-MS-VL results at Zuckerberg San Francisco General Hospital and Trauma Center (ZSFG) were compared with RT-IF results at ZSFG and also with AR-MS-VL results in the recently completed CDC Screening Targeted Populations to Interrupt On-going Chains of HIV Transmission with Enhanced Partner Notification (STOP) Study for targeted testing of MSM at publicly funded testing sites in San Francisco. RESULTS: Among 21,985 HIV tests performed at ZSFG, 16,467 were tested by RT-IF and 5518 by AR-MS-VL. There were 321 HIV infections detected, of which 274 (84%) were known HIV+ cases, and 47 were newly identified HIV infections. Considering only patients of HIV-negative or -unknown status, prevalence was 0.22%. Under the AR-MS-VL algorithm, turnaround times for screening results and full algorithm results were 3 and 21h; status-unresolved cases were reduced (from 47% to 22%) compared with the RT-IF algorithm. The positive predictive value (PPV) of a new-positive AR screening test was low (0.44) at ZSFG, where no acute infections were detected. At STOP Study sites where HIV prevalence was higher and acute infection was more common, the AR PPV was higher (0.93). All 24 false-positive AR screening tests at ZSFG had a signal/cutoff (S/CO) ratio of <15 and all 88 true-positive tests had S/CO ratio >15. Of 62 acute infections in the STOP Study, 23 (37%) had an S/CO<15. DISCUSSION: An AR-MS-VL algorithm is feasible and can return rapid results in a large medical center. In this setting, reactive 4th generation assay tests that are negative for HIV antibodies are typically false-positive with low S/CO ratios.

Novel handwashes are superior to soap and water in removal of Clostridium difficile spores from the hands.

We examined the efficacy of 5 experimental handwash formulations in removing nontoxigenic Clostridium difficile spores from the hands of health care workers. Handwashing with sand resulted in an additional 0.5-log reduction in spore recovery compared with the current standard of soap and water.

Leveraging a rapid, round-the-clock HIV testing system to screen for acute HIV infection in a large urban public medical center.

OBJECTIVE: To describe the prevalence and location of new and acute HIV diagnoses in a large urban medical center. Secondary objectives were to evaluate rapid HIV test performance, the added yield of acute HIV screening, and linkage-to-care outcomes. DESIGN: Cross-sectional study from November 1, 2008, to April 30, 2009. METHODS: The hospital laboratory performed round-the-clock rapid HIV antibody testing on venipuncture specimens from patients undergoing HIV testing in hospital and community clinics, inpatient settings, and the emergency department (ED). For patients with negative results, a public health laboratory conducted pooled HIV RNA testing for acute HIV infection. The laboratories communicated positive results from the hospital campus to a linkage team. Linkage was defined as 1 outpatient HIV-related visit. RESULTS: Among 7927 patients, 8550 rapid tests resulted in 137 cases of HIV infection [1.7%, 95% confidence interval (CI): 1.5% to 2.0%], of whom 46 were new HIV diagnoses (0.58%, 95% CI: 0.43% to 0.77%). Pooled HIV RNA testing of 6704 specimens (78.4%) resulted in 3 cases of acute HIV infection (0.05%, 95% CI: 0.01% to 0.14%) and increased HIV case detection by 3.5%. Half of new HIV diagnoses and two thirds of acute infections were detected in the ED and urgent care clinic. Rapid test sensitivity was 98.9% (95% CI: 93.8% to 99.8%) and the specificity 99.9% (95% CI: 99.7% to 99.9%). More than 95% of newly diagnosed and out-of-care HIV-infected patients were linked to care. CONCLUSIONS: Patients undergoing HIV testing in EDs and urgent care clinics may benefit from being simultaneously screened for acute HIV infection.

Testing and linkage to care outcomes for a clinician-initiated rapid HIV testing program in an urban emergency department.

The urban emergency department is an important site for the detection of HIV infection. Current research has focused on strategies to increase HIV testing in the emergency department. As more emergency department HIV cases are identified, there need to be well-defined systems for linkage to care. We conducted a retrospective study of rapid HIV testing in an urban public emergency department and level I trauma center from June 1, 2008, to March 31, 2010. The objectives of this study were to evaluate the increase in the number of tests and new HIV diagnoses resulting from the addition of targeted testing to clinician-initiated diagnostic testing, describe the demographic and clinical characteristics of patients with newly diagnosed HIV infection, and assess the effectiveness of an HIV clinic based linkage to care team. Of 96,711 emergency department visits, there were 5340 (5.5%) rapid HIV tests performed, representing 4827 (91.3%) unique testers, of whom 62.4% were male and 60.8% were from racial/ethnic minority groups. After the change in testing strategy, the median number of tests per month increased from 114 to 273 (p=0.004), and the median number of new diagnoses per month increased from 1.5 to 4 (p=0.01). From all tests conducted, there were 65 new diagnoses of HIV infection (1.2%, 95% confidence interval [CI] 0.9%, 1.5%). The linkage team connected over 90% of newly diagnosed and out-of-care HIV-infected patients to care. In summary, the addition of targeted testing to diagnostic testing increased new HIV case identification, and an HIV clinic-based team was effective at linkage to care.

False-positive culture results from patient tissue specimens due to contamination of RPMI medium with Cryptococcus albidus.

Cryptococcus albidus, a rare opportunist, was isolated from biopsy specimens from three patients over 4 days. An investigation showed that the specimens had been contaminated by placement in RPMI medium. The importance of rapid communication between the microbiology laboratory, the infectious diseases/infection control division, and other involved parties in the event of unusual occurrences is highlighted.

A prospective, multicenter study of laboratory cross-contamination of Mycobacterium tuberculosis cultures.

A prospective study of false-positive cultures of Mycobacterium tuberculosis that resulted from laboratory cross-contamination was conducted at three laboratories in California. Laboratory cross-contamination accounted for 2% of the positive cultures. Cross-contamination should be a concern when an isolate matches the genotype of another sample processed during the same period.