Proof of Concept for a Quick and Highly Sensitive On-Site Detection of SARS-CoV-2 by Plasmonic Optical Fibers and Molecularly Imprinted Polymers.

The rapid spread of the Coronavirus Disease 2019 (COVID-19) pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pathogen has generated a huge international public health emergency. Currently the reference diagnostic technique for virus determination is Reverse Transcription Polymerase Chain Reaction (RT-PCR) real time analysis that requires specialized equipment, reagents and facilities and typically 3-4 h to perform. Thus, the realization of simple, low-cost, small-size, rapid and point-of-care diagnostics tests has become a global priority. In response to the current need for quick, highly sensitive and on-site detection of the SARS-CoV-2 virus in several aqueous solutions, a specific molecularly imprinted polymer (MIP) receptor has been designed, realized, and combined with an optical sensor. More specifically, the proof of concept of a SARS-CoV-2 sensor has been demonstrated by exploiting a plasmonic plastic optical fiber sensor coupled with a novel kind of synthetic MIP nano-layer, especially designed for the specific recognition of Subunit 1 of the SARS-CoV-2 Spike protein. First, we have tested the effectiveness of the developed MIP receptor to bind the Subunit 1 of the SARS-CoV-2 spike protein, then the results of preliminary tests on SARS-CoV-2 virions, performed on samples of nasopharyngeal (NP) swabs in universal transport medium (UTM) and physiological solution (0.9% NaCl), were compared with those obtained with RT-PCR. According to these preliminary results, the sensitivity of the proposed optical-chemical sensor proved to be higher than the RT-PCR one. Furthermore, a relatively fast response time (about 10 min) to the virus was obtained without the use of additional reagents.

Oral gentamicin therapy for Carbapenem-resistant Klebsiella pneumoniae gut colonization in hematologic patients: a single center experience.

The mortality for carbapenem-resistant Klebsiella pneumoniae (KPC-Kp) infection ranges from 18 to 48% depending on the type of therapy. Mortality rates in hematologic patients are even higher, up to 85%. Gut decontamination with oral gentamicin might be an option to avoid a subsequent KPC-Kp infection in colonized patients. We treated 14 hematologic patients with oral gentamicin, 80 mg four times daily, for 7 to 25 days in order to eradicate KPC-Kp from the gut, starting oral gentamicin therapy when possible after the discontinuation of systemic antibiotic therapy. The overall decontamination rate in the entire study population was 71% (10/14). Out of the 4 patients who did not respond to oral gentamicin therapy, 1 KPC-Kp strain was gentamicin resistant and 4 patients received concomitant systemic antibiotic therapy (CSAT). One of these patients died from KPC-Kp sepsis. The decontamination rate was 90% (9/10) in patients receiving oral gentamicin only, versus 25% (1/4) in those also treated with CSAT. No new gentamicin-resistant KPC-Kp strain was isolated during oral gentamicin therapy Oral gentamicin might be useful for gut decontamination and prevention of KPC-Kp infection. This option should be considered in patients colonized by a gentamicin-susceptible KPC-Kp strain and not receiving CSAT.

Evaluation of the commercial AD fosfomycin test for susceptibility testing of multidrug-resistant Enterobacterales and Pseudomonas aeruginosa.

OBJECTIVES: To compare fosfomycin susceptibility testing with the commercial agar dilution (AD) test, AD Fosfomycin (Liofilchem, Roseto degli Abruzzi, Italy) and the reference AD method, using a collection of multidrug-resistant (MDR) Enterobacterales and Pseudomonas aeruginosa clinical isolates. METHODS: The collection included 119 carbapenemase-producing Enterobacterales, 53 Enterobacterales producing acquired AmpC-type and/or extended-spectrum ß-lactamases and 38 carbapenemase-producing P. aeruginosa, including representatives of different high-risk clones. AD Fosfomycin and AD reference method (ISO 20776-1:2019) were performed starting from the same microbial suspension. Results were interpreted according to EUCAST clinical breakpoints (10.0). Essential agreement (EA), category agreement (CA) and error rates were calculated as described by the International Organization for Standardization. RESULTS: Of 172 Enterobacterales, 143 (83.1%, including 92.9% (52 of 56) of the NDM-producers and 84.2% (48 of 57) of the KPC-producers) were susceptible to fosfomycin using reference AD. A CA of 91.9% (158 of 172; 95% CI 87.1%-95.3%) and an EA of 92.5% (136 of 147; 95% CI 87.4%-96.0%), respectively, were calculated for the commercial AD Fosfomycin test, with 9.8% (14 of 128) of major errors and no very major errors (0 of 29). Overall, 86.8% (33 of 38) of P. aeruginosa showed a fosfomycin MIC ≤128 mg/L using reference AD. An EA of 84.8% (95% CI 66.3%-92.0%) was calculated for the commercial AD Fosfomycin test, with a CA of 100% (95% CI 93.6%-100%) when considering a tentative breakpoint at 128 mg/L. CONCLUSIONS: AD Fosfomycin showed an overall good concordance compared with reference AD.