Infectious diseases are transmissible or communicable illnesses and can spread quickly in some areas and become epidemics. It is critical to quickly diagnose initial infections and prevent further spread through in vitro diagnosis. However, current detection strategies have exhibited a lack of balance with regard to accuracy, time consumption, and portability until recently (e.g. serology, culturing, molecular tests, etc.). Alternatively, many studies have focused on point-of-care testing (POCT), which combines simple, rapid, and exact on-site diagnostic platforms. Moreover, multiplex detectability is necessary for emergency treatment depending on the stage of the disease or interactional infections. The lateral flow assay (LFA) is the most popular diagnostic tool that meets the required standards for colorimetric assays. Here, we review lateral flow assays based on the immune reactions for the simultaneous diagnosis of infectious diseases as the POC test. The assays employed various forms and approaches in terms of the multiplexing level system for improving the sensitivity and specificity. We briefly describe the state-of-the-art infection diagnostic methods and published performances that have been classified into three categories based on the application forms of the lateral flow immunoassay. Also, we discuss further uses of LFA and other technologies for more effective infectious disease POCT.

Clinically relevant categorization of antimicrobial resistance is critical to mitigating the threat it poses. Difficult-to-treat resistance (DTR) is a recently proposed category defined as non-susceptibility to all first-line antibiotic agents. A retrospective study was conducted with non-duplicate cases of gram-negative bloodstream infection (GNBSI) caused by four major taxa (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter species) identified from a nationwide surveillance database. DTR was defined as non-susceptibility to all the β-lactams and fluoroquinolones tested. Patient characteristics and mortality were compared between DTR GNBSI and GNBSI caused by carbapenem-resistant (CR+/DTR-) and extended-spectrum cephalosporin-resistant (ESCR+/DTR-) isolates using CDC definitions. Adjusted odds ratios (aORs) for 30-day in-hospital mortality were examined for DTR in overall and in propensity score-matched cohorts. A total of 1,167 episodes of monomicrobial GNBSI were identified, and 147 (12.6%) of the isolates were DTR. The majority of DTR isolates were Acinetobacter spp. (79.6%) and P. aeruginosa (17.7%). DTR infections were associated with previous antibiotic use, healthcare contact, ventilator use, and lower respiratory tract infection. Crude mortality for GNBSI caused by DTR was 50.3%. A multivariable model showed that only DTR, but not other categories, was significantly associated with mortality (aOR, 3.58; 95% CI, 1.27–10.19). DTR was also a significant predictor for mortality in the analysis of propensity score–matched cohorts (aOR, 3.48; 1.82–6.79). In patients with GNBSI, DTR were associated with higher mortality than those in other resistance categories. Our findings suggest that DTR could be useful for surveillance and prognostication.