Direct-from-Blood-Culture Disk Diffusion To Determine Antimicrobial Susceptibility of Gram-Negative Bacteria: Preliminary Report from the Clinical and Laboratory Standards Institute Methods Development and Standardization Working Group.

The performance of a disk diffusion test using broth from positive blood cultures as inoculum (direct disk diffusion [dDD]) was evaluated for a collection of 20 challenge isolates of Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa Isolates seeded into human blood were inoculated into Bactec Plus Aerobic/F, VersaTREK Redox 1, and BacT/Alert FA Plus bottles and incubated in the respective automated blood culture systems. Disk diffusion results were compared to reference disk diffusion results. Categorical agreement (CA) values for dDD, after removal of random errors due to natural MIC variation, were 87.8%, 88.4%, and 92.2% for the BacT/Alert, Bactec, and VersaTREK systems, respectively. No very major errors (VME) were observed, and major error (ME) rates were 3.0%, 2.3%, and 1.7%, respectively. Incubation of the dDD test samples for 6 h compared to incubation for 16 to 18 h resulted in 19.9% of tests having too light of growth to allow reading of zones of inhibition. Among the evaluable dDD tests, CA values were 58.9%, 76.6%, and 73.2% for the isolates seeded into the BacT/Alert, Bactec, and VersaTREK systems, respectively. VME rates for isolates seeded into these systems were 2.2%, 1.8%, and 3.0%, respectively, and ME rates were 25.4%, 6.1%, and 2.8%, respectively, at the 6-h reading. The best performance of dDD was found for blood cultures with bacterial concentrations in the range of 7.6 × 107 to 5.0 × 108 CFU/ml; CA values ranged from 94.7 to 96.2% for these concentrations after 18 h of incubation and from 76.9 to 84.1% after 6 h of incubation. These preliminary data demonstrate the potential accuracy of dDD testing by the clinical laboratory.

High nasal burden of methicillin-resistant Staphylococcus aureus increases risk of invasive disease.

In a retrospective cohort study of 1,140 patients harboring methicillin-resistant Staphylococcus aureus, the nasal burden was low in 31%, category 1+ to 2+ in 54%, and category 3+ to 4+ in 15%. There was a significant trend in infection risk with increasing nasal burden (P = 0.007). In multivariate models, high nasal burden remained significantly associated with invasive infection.

Time to Detection in Culture Supports Prediction of Low Transmissibility of Tuberculosis and Discontinuation of Isolation for Low-Risk Patients With A Single AFB-Negative and NAAT-Negative Respiratory Specimen.

For 94 patients with culture-positive pulmonary tuberculosis, time-to-detection (TTD), acid-fast bacilli (AFB) smear, and nucleic acid amplification test (NAAT) results were reviewed. All 12 patients whose first specimen was negative by AFB smear and NAAT had prolonged TTD, indicating low transmissibility and supporting discontinuing isolation for low-risk patients.Infect Control Hosp Epidemiol 2018;39:619-621.

Tuberculosis prevention and control in long-term-care facilities for older adults.

In the United States, older adults comprise 22% of cases of tuberculous disease but only 12% of the population. Most cases of tuberculosis (TB) occur in community dwellers, but attack rates are highest among frail residents of long-term-care facilities. The detection and treatment of latent TB infection and TB disease can pose special challenges in older adults. Rapid recognition of possible disease, diagnosis, and implementation of airborne precautions are essential to prevent spread. It is the intent of this evidence-based guideline to assist healthcare providers in the prevention and control of TB, specifically in skilled nursing facilities for the elderly.

Antibacterial activity of vegetables and juices.

OBJECTIVE: We evaluated the antibacterial activities of various fruit and vegetable extracts on common potential pathogens including antibiotic-resistant strains. METHODS: Standardized bacterial inocula were added to serial dilutions of sterile vegetable and fruit extracts in broth, with final bacterial concentrations of 10(4-5) cells/mL. After overnight incubation at 35 degrees C, antibacterial activity was measured by minimum inhibitory and minimum bactericidal dilutions (for raw juices) or concentrations (for tea). RESULTS: Among the vegetable and fruit extracts tested, all green vegetables showed no antibacterial activity on Staphylococcus epidermidis and Klebsiella pneumoniae. All purple and red vegetable and fruit juices had antibacterial activities in dilutions ranging from 1:2 to 1:16. Garlic juice had significant activity, with bactericidal action in dilutions ranging up to 1:128 of the original juice. Tea also had significant activity, with bactericidal action in concentrations ranging up to 1.6 mg/mL, against a spectrum of pathogens including resistant strains such as methicillin- and ciprofloxacin-resistant staphylococci, vancomycin-resistant enterococci, and ciprofloxacin-resistant Pseudomonas aeruginosa. CONCLUSIONS: Tea and garlic have the potential for exploration of broader applications as antibacterial agents.

Antibacterial activity of citrate and acetate.

OBJECTIVE: We evaluated citrate salt, acetate salt, and their combinations for antibacterial activity against a sample of common pathogens. METHODS: Bacterial suspensions were added to serial microdilutions of the salts in broth, with final cell concentrations of 10(4-5) colony-forming units per milliliter. After overnight incubation at 35 degrees C, the minimum inhibitory concentration was recorded. Bactericidal activity was screened by quantitative subcultures from the minimum inhibitory concentration dilution. RESULTS: Citrate salt was active against gram-positive species and Candida albicans but showed little activity against gram-negative species; acetate salt showed the opposite results. Their combination did not show synergism or antagonism. CONCLUSION: It may be feasible to take advantage of the different antibacterial spectra of these two agents and combine them for possible application such as food or medical preservative agents.

Voluntary to mandatory: evolution of strategies and attitudes toward influenza vaccination of healthcare personnel.

BACKGROUND: Assessing the relative success of serial strategies for increasing healthcare personnel (HCP) influenza vaccination rates is important to guide hospital policies to increase vaccine uptake. OBJECTIVE: To evaluate serial campaigns that include a mandatory HCP vaccination policy and to describe HCP attitudes toward vaccination and reasons for declination. DESIGN: Retrospective cohort study. METHODS: We assessed the impact of serial vaccination campaigns on the proportions of HCP who received influenza vaccination during the 2006-2011 influenza seasons. In addition, declination data over these 5 seasons and a 2007 survey of HCP attitudes toward vaccination were collected. RESULTS: HCP influenza vaccination rates increased from 44.0% (2,863 of 6,510 HCP) to 62.9% (4,037 of 6,414 HCP) after institution of mobile carts, mandatory declination, and peer-to-peer vaccination efforts. Despite maximal attempts to improve accessibility and convenience, 27.2% (66 of 243) of the surveyed HCP were unwilling to wait more than 10 minutes for a free influenza vaccination, and 23.3% (55 of 236) would be indifferent if they were unable to be vaccinated. In this context, institution of a mandatory vaccination campaign requiring unvaccinated HCP to mask during the influenza season increased rates of compliance to over 90% and markedly reduced the proportion of HCP who declined vaccination as a result of preference. CONCLUSIONS: A mandatory influenza vaccination program for HCP was essential to achieving high vaccination rates, despite years of intensive vaccination campaigns focused on increasing accessibility and convenience. Mandatory vaccination policies appear to successfully capture a large portion of HCP who are not opposed to receipt of the vaccine but who have not made vaccination a priority.