Rapid Detection of Resistant Bacteria Based on β-lactamase Activity

Author: admin     Date: February 22, 2024

Bacterial resistance to antibiotics poses a significant clinical challenge in combating serious infectious diseases due to complicated resistance mechanisms and time-consuming test methods. Among the many molecular mechanisms that confer antibiotic resistance, the production of β-lactamase, which catalyzes the hydrolysis of β-lactam antibiotics, is a major and threatening mechanism. Additionally, it has been reported that individuals could be simultaneously infected with multiple strains of different susceptibility levels. Traditional detection methods cannot detect minority populations of antibiotic-resistant bacteria. Advanced tools are urgently needed to quickly diagnose antibiotic-resistant infections to initiate appropriate treatment. The hydrolyzed probes LBRL1 could attach to the enzyme, β-lactamase, and thus facilitate the covalent labeling of drug-resistant bacterial strains. Moreover, this β-lactamase-induced covalent labeling provides quantitative analysis of the resistant bacterial population (down to 5%) by the Flow NanoAnalyzer.

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Figure 1. Analysis of bacteria resistance in single gram-negative bacterial cell. 

(A) Bacteria are labeled with LBRL1.(B)Unlabeled B.

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Figure 2. Differentiation of resistant E. coli JM109/pUC19 cells in bacterial mixtures.

The Flow NanoAnalyzer allows rapid single-cell detection and quantitative observation of the resistant bacterial population (down to 5%) through fluorescent probe LBRL1.

Chem. Eur. J., 2013, 19(33), 10903-10910.

Clinical Diagnosis of Bacterial Infection and Resistance

Author: admin     Date: February 22, 2024

It has been reported that individuals could be simultaneously infected with multiple strains of different susceptibility levels, and the population of resistant bacteria could be very low. However, if the minority population of resistant bacteria cannot be detected in time, an inappropriate prescription of antibiotics is usually the result. Therefore, detecting the minority population of antibiotic-resistant bacteria is crucial for clinical diagnosis. By employing a monoclonal antibody against TEM-1 β-lactamase and an Alexa Fluor 488-conjugated secondary antibody to selectively label resistant bacteria in green, and using the nucleic acid dye SYTO 62 to stain all the bacteria, the Flow NanoAnalyzer is able to detect and quantify as low as 0.1% of antibiotic-resistant bacteria. Furthermore, this approach is applied to detect antibiotic-resistant infection in clinical urine samples without cultivation, and the bacterial load of susceptible and resistant strains can be reliably quantified. This method provides a powerful tool for the fundamental studies of antibiotic resistance and holds the potential to offer rapid and precise guidance in clinical therapies.

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Figure 1. Tracking of the dynamic population change of antibiotic-resistant bacteria with and without antibiotics.

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Figure 2. Analysis of E. coli ATCC 35218 (positive control) and two β-lactamase positive clinical urine samples upon dual fluorescent staining

Through fluorescent immunolabeling and nucleic acid staining of bacteria, detection of minority population of antibiotic-resistant bacteria is achieved.

Biosen. Bioelectron., 2016, 80, 323-330.