SARS-CoV-2 Inactivation on Hard Non-porous Airplane Cabin Material Surfaces was Limited After Exposure to Far UV-C (222 nm) Radiation.

AIMS: To test the efficacy of 222 nm Far UV-C for surface disinfection of SARS-CoV-2 on inanimate surfaces from airplane cabins. METHODS AND RESULTS: Two far ultraviolet (UV-C) irradiation light systems were evaluated for disinfection of SARS-CoV-2. Materials used for carriers (test surfaces) included polished stainless steel and used airplane materials including seatbelt latches, window dust covers, sidewall laminates, and tray tables. CONCLUSIONS: While demonstrating reasonable efficacy under some experimental conditions, the data indicated that 222 nm Far UV-C disinfection alone does not reliably provide a 3 log10 or 99.9% reduction of SARS-CoV-2 on inanimate surfaces from an airplane cabin. An Ushio (Cypress, CA) 1.7" x 2.3" Care222® 12W 222nm BI lamp module tested in triplicate at a low (⁓ 1.5 mJ cm-2), medium (⁓ 3.0 mJ cm-2), and high (⁓ 6 to 9 mJ cm-2) fluence did not provide a ≥ 3 log10 or 99.9% reduction of SARS-CoV-2. The reduction of SARS-CoV-2 was greatest on stainless steel. The result was a log10 reduction of 2.83, 1.33, 2.58, and 2.21 logs for virus samples containing saline, saline with 2.5 mg BSA, saline with 0.25 mg BSA, and artificial saliva respectively at a dosage of 5 to 9 mJ cm-2. The log10 reduction of SARS-CoV-2 in saline with 2.5 mg bovine serum albumin was lowest with 1.33 for stainless steel, 0.93 for belt latch, and 0.61 for tray table at a dosage of 5 to 6 mJ cm-2.The second UV lighting system tested was a prototype mobile wand with a built-in short-pass filtered krypton-chloride cylindrical lamp. One pass of the wand over a tray holding carriers inoculated with SARS-CoV-2 in artificial saliva at a rate of approximately 1 foot (1') per second (sec) exposed the carriers to 7.3 mJ cm-2. The log10 reductions determined for the single pass were 2.97, 3.75, 1.78, 1.91, and 1.28 logs for stainless steel, belt latch, dust cover, sidewall, and tray table respectively. Two passes of the wand generated 17.2 mJ cm-2 and resulted in log10 reductions of 4.04, 3.74, 4.24, 3.68, and 1.66 logs for stainless steel, belt latch, dust cover, sidewall, and tray table respectively. The combination of higher fluence from multiple passes of the wand, the close proximity (10 cm wand to the carrier), the exposure to elevated temperatures up to 35°C, and ozone from the bulb being blown directly onto the carriers contributed to effective viral inactivation on all surfaces except the airplane tray table. The impact of temperature and ozone on viral inactivation should be determined for future testing of the 222 nm UV-C wand.

Detection of cyclic lipopeptide biomarkers from Bacillus species using atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry.

A novel approach to microbial detection using atmospheric pressure matrix-assisted laser desorption/ionization with an ion trap mass spectrometer to analyze whole cell bacteria is introduced. This new approach was tested with lyophilized spores and cultures of Bacillus globigii (BG) grown on agar media for 4 days or longer. At each stage of growth, it was found that biomarkers, identified as cyclic lipopeptides known as fengycin and surfactin, could be detected by pulsed ultraviolet laser irradiation of intact BG cells (approximately 5 mg) cocrystallized with alpha-cyano-4-hydroxycinnamic acid. Furthermore, definitive amino acid sequence information was obtained by performing tandem mass spectrometry on the precursor ions of the cyclic lipopeptides. The investigation was broadened to include the examination of aerosolized BG spores collected from the atmosphere and directly deposited onto double-sided tape. Subsequent analysis of the recovered spores resulted in the production of mass peaks consistent with fengycin. Other Bacillus species were analyzed for comparison and showed mass spectral peaks also identified as originating from various cyclic lipopeptides. Further studies were conducted using a pulsed infrared laser as the excitation source to analyze BG cells (approximately 5 mg) suspended in a matrix of 0.03 M ammonium citrate and glycerol resulting in the production of ions characteristic of fengycin and surfactin.

Detection of Escherichia coli using immunomagnetic separation and bacteriophage amplification coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The application of whole cell analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has emerged as a valuable tool for rapidly identifying/detecting bacteria. This technique requires minimal sample preparation and is simple to perform, but is generally limited to purified samples of bacteria at concentrations greater than 1.0 x 10(6) cells/mL. In this paper, we describe a bacterial detection method that integrates immunomagnetic separation with bacteriophage amplification prior to MALDI-MS analysis. The developed method consists of three main stages: (1) isolation of a target bacterium by immunomagnetic separation; (2) infection of the immuno-captured bacterium with a lytic bacteriophage; and (3) assay of infected medium for bacteriophage progeny using MALDI-MS to produce a molecular weight signal for the virus capsid protein. With this technique, the presence of Escherichia coli in broth was determined in less then 2 h total analysis time at a concentration of approximately 5.0 x 10(4) cells/mL.

Rapid analysis of intact phospholipids from whole bacterial cells by matrix-assisted laser desorption/ionization mass spectrometry combined with on-probe sample pretreatment.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), utilizing an on-probe sample pretreatment, was applied to the rapid and direct detection of intact phospholipids from whole bacterial cells. The sample preparation procedure involved depositing growing bacterial colonies from culture dishes directly onto the MALDI probe followed by treatment of the sample spot with a 3 micro L aliquot of an aqueous 0.05 M solution of sodium iodide prior to the addition of a 2,5-dihydroxybenzoic acid (DHB) matrix solution (ca. 8 mg dissolved in 70% acetonitrile/30% H(2)O containing 0.1% of trifluoroacetic acid). The MALDI spectra obtained from whole bacteria cells showed a series of ions generated from bacterial phospholipids, such as phosphatidylethanol-amines (PEs) and phosphatidylglycerols (PGs), which were clearly observed as well-resolved peaks. The ranges of the observed total carbon numbers in two acyl groups for PEs and PGs (30-36 and 33-36, respectively) were in good agreement with those reported previously. Furthermore, the distinct discrimination of four species of the Enterobacteriaceae family cultured identically was achieved by using principal components analysis (PCA) conducted on the relative peak intensities of phospholipids observed from the MALDI spectra.

Rapid detection of taxonomically important fatty acid methyl ester and steroid biomarkers using in situ thermal hydrolysis/methylation mass spectrometry (THM-MS): implications for bioaerosol detection.

Implications for the rapid interrogation of biological materials collected from the atmosphere using a simple, one step, sample preparation technique was explored. For this purpose, various samples of whole bacteria, fungi, pollen, media contaminated with viruses, and proteins were treated with an aliquot of methanolic tetramethylammonium hydroxide prior to thermal introduction into the ion source of a triple quadrupole mass spectrometer. Molecular and fragment ions, consistent with fatty acid methyl esters (FAMEs) and steroids (non-methylated and methylated), generated during electron ionization (70 eV) of the volatile hydrolysates were subsequently detected. The varying distributions and relative intensities of these ions were used to discriminate between the different biological samples. More specifically, it was found that polyunsaturated FAMEs and steroids could be used to differentiate eukaryotic cells from prokaryotic cells since the latter do not generally synthesize either of these lipid membrane constituents. Further discrimination of the different eukaryotic samples was made based on the detection of ergosterol for fungi, cholesterol for the viral media, and C18:3Me for pollen. Multivariate statistical analysis was employed to evaluate and compare the large set of mass spectra generated during the study and to build a trained model for predicting the class membership of test samples entered as unknowns. Of 132 different samples subjected to the model as unknowns, 131 were correctly classified into their proper biological categories. Moreover, 29 out of 30 bacteria test samples representing five species of pathogenic bacteria were correctly classified at the species level.