The Evaluation of a Lateral Flow Strip Based on the Covalently Fixed "End-On" Orientation of an Antibody for Listeria monocytogenes Detection.

In this study, the covalently fixed "end-on" orientation of a monoclonal Listeria monocytogenes antibody (mAb-Lis) to amino terminated oligo (ethylene glycol)-capped gold nanoparticles (NH2-TEG-AuNPs) was used to fabricate an in-house lateral flow strip (LFS), namely, the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS. The aim was to evaluate the performance of the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS in detecting L. monocytogenes. The proposed LFS enabled the sensitive detection of L. monocytogenes in 15 min with a visual limit of detection of 102 CFU/mL. Quantitative analysis indicated an LOD at 10 CFU/mL. The fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS showed no cross-reactivity with other pathogenic bacteria and practical performance across different food matrices, including human blood, milk, and mushroom samples. Furthermore, the clinical performance of the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS for detecting L. monocytogenes was evaluated by using 12 clinical samples validated by the hemoculture method. It demonstrated excellent concordance with the reference methods, with no false-positive or false-negative results observed. Therefore, the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS serves as a promising candidate for a point-of-care test (POCT), enabling the rapid, precise, and highly sensitive detection of L. monocytogenes in clinical samples and contaminated food.

The CREPE Score: A Predictive Tool for Third-Generation Cephalosporin-Resistant Enterobacterales Pneumonia in Community Settings.

Purpose: To evaluate risk factors and develop a prediction score for community-acquired pneumonia caused by third-generation cephalosporin-resistant Enterobacterales (3GCR EB-CAP). Patients and Methods: A retrospective study was conducted by reviewing the medical records of patients hospitalized with community-acquired pneumonia caused by Enterobacterales (EB-CAP) between January 2015 and August 2021 at Srinagarind Hospital, Khon Kaen University, Thailand. Logistic regression was used to analyze clinical parameters associated with 3GCR EB-CAP. The coefficients of significant parameters were simplified to the nearest whole number for a prediction score, called the CREPE (third-generation Cephalosporin Resistant Enterobacterales community-acquired Pneumonia Evaluation). Results: A total of 245 patients with microbiologically confirmed EB-CAP (100 in the 3GCR EB group) were analyzed. Independent risk factors for 3GCR EB-CAP included in the CREPE score were (1) recent hospitalization within the past month (1 point), (2) multidrug-resistant EB colonization (1 point), and (3) recent intravenous antibiotic use (2 points for within the past month or 1.5 points for between one and twelve months). The CREPE score had an area under the receiver operating characteristic curve (ROC) of 0.88 (95% CI 0.84-0.93). Using a cut-off point of 1.75, the score had a sensitivity and specificity of 73.5% and 84.6%, respectively. Conclusion: In areas with high prevalence of EB-CAP, the CREPE score can assist clinicians in selecting appropriate empirical therapy and reducing overuse of broad-spectrum antibiotics.

Multi Evaluation of a Modified GoldNano Carb Test for Carbapenemase Detection in Clinical Isolates of Gram-Negative Bacilli.

Carbapenemase-producing Gram-negative bacteria have been increasingly reported. Simple and sensitive methods for carbapenemase detection are still needed. In this study, a gold nanoparticle (AuNP) solution was modified by the addition of zinc sulfate (ZnSO4) for improving the conventional GoldNano Carb (cGoldC) test, and the modified GoldC (mGoldC) test was then evaluated for phenotypic detection of carbapenemase production in Gram-negative bacilli clinical isolates. ZnSO4 was added to give final concentrations of 0.25, 0.5, 0.75, and 1 mM. The performance of the mGoldC test was evaluated in Enterobacterales, Acinetobacter spp., and Pseudomonas aeruginosa isolates from six hospitals in different regions using polymerase chain reaction (PCR) as a gold standard. The AuNP solution with 0.25 mM ZnSO4 was used for the mGoldC test. Evaluation of the mGoldC test in 495 Enterobacterales, 212 Acinetobacter spp., and 125 P. aeruginosa isolates (including 444 carbapenemase producers and 388 non-carbapenemase producers) revealed sensitivity, specificity, a positive likelihood ratio, and a negative likelihood ratio of 98.6%, 98.2%, 54.7, and 0.01, respectively. This test is fast, easy to perform, cost-effective (~0.25 USD per test), and highly sensitive and specific for routine carbapenemase detection, thus leading to effective antimicrobial therapy and infection control measures.

Colistin heteroresistance in carbapenem-resistant Acinetobacter baumannii clinical isolates from a Thai university hospital.

Colistin is the last resort for the treatment of infections with carbapenem-resistant (CR) Gram-negative bacteria particularly Acinetobacter baumannii (CRAB). Currently, both colistin-resistant and -heteroresistant A. baumannii isolates have been reported globally. We therefore investigated the colistin heteroresistance rate in 75 non-duplicate colistin-susceptible CRAB clinical isolates from a Thai university collected in 2016. Minimum inhibitory concentrations (MICs) of colistin for all isolates were determined by broth microdilution method and carbapenemase genes were detected by PCR methods. All isolates were genotyped by ERIC-PCR method and screened for colistin heteroresistance by modified population analysis profile (PAP) method. The colistin MIC range for the 75 isolates was 0.5-2 µg/mL, with MIC50 and MIC90 of 1 and 2 µg/mL, respectively. Thirty-three isolates (44%) were considered colistin-heteroresistant with subpopulations growing at 3-8 µg/mL of colistin. After three daily passages of the subpopulations on antibiotic-free medium, their colistin MICs ranged from 4 to > 32 µg/mL, with MIC50 and MIC90 of 32 and > 32 µg/mL, respectively. Eight different ERIC-PCR profiles were obtained among the 33 isolates and all carried blaOXA-23-like. The high rate of colistin heteroresistance in the CRAB isolates highlights the possibility of treatment failure of CRAB infections by colistin due to the selection of colistin-resistant subpopulations.