Development of a Colloidal Gold-Based Immunochromatographic Strip for Rapid Detection of Klebsiella pneumoniae Serotypes K1 and K2

Abstract

eIn this study, a novel colloidal gold-based immunochromatographic strip (ICS) containing anti-Klebsiella pneumoniae capsular polysaccharide polyclonal antibodies was developed to specifically detect K. pneumoniae serotypes K1 and K2. Capsular polysaccharide K1 and K2 antigens were first used to produce polyclonal anti-K1 and anti-K2 antibodies. Reference strains with different serotypes, nontypeable K. pneumoniae strains, and other bacterial species were then used to assess the sensitivity and specificity of these test strips. The detection limit was found to be 10 5 CFU, and the ICSs were stable for 6 months when stored at room temperature. No false-positive or false-negative results were observed, and equivalent results were obtained compared to those of more conventional test methods, such as PCR or serum agglutination. In conclusion, the ICS developed here requires no technical expertise and allows for the specific, rapid, and simultaneous detection of K. pneumoniae serotypes K1 and K2.K lebsiella pneumoniae is a Gram-negative, rod-shaped bacterium that is found in the normal flora of the mouth, skin, and intestines. Recently, a new type of invasive infection caused by K. pneumoniae has emerged as a global disease (1). There are 77 different serotypes of the capsular polysaccharides (CPSs) of K. pneumoniae (2), with K2 and K21 being the most prevalent in western countries (3). Recently, by genotyping capsular polysaccharide genes, 79 capsular types were distinguished (4, 5). In contrast, the K1 and K2 serotypes are most often associated with bacteremia, liver abscess, and community-acquired pneumonia in Asia (3). However, reports of this new invasive syndrome have recently been on the rise in western countries (6, 7). In addition to causing human disease, K. pneumoniae serotypes K1 and K2 have also been detected in contaminated animal milk (8). Capsular serotypes have typically been identified by using either a capsular swelling test or countercurrent immunoelectrophoresis (3, 9). However, these conventional methods are time-consuming, require extensive materials and manpower, and often produce falsepositive or false-negative results that are caused by cross-reactions. Another option is PCR, but this analysis requires a long time for preparation, expensive equipment, and skilled technicians, and previous studies have recommended that rapid detection is ideal for early clinical diagnosis and treatment (1).To address these concerns, this study involved the development of a colloidal gold-based immunochromatographic strip (ICS) that contained anti-K. pneumoniae capsular polysaccharide polyclonal antibodies (pAbs) and was able to detect K. pneumoniae serotypes K1 and K2. This testing kit provides a sensitive, rapid, and simultaneous method to detect K. pneumoniae serotypes K1 and K2. MATERIALS AND METHODSBacterial strains. The various serotypes of K. pneumoniae that were used here were obtained from our previous studies in Taiwan and at the Serum Institute in Denmark. The panel of bacterial strains contained al...

Development of risk factor-based scoring system for detection of hypervirulent Klebsiella pneumoniae bloodstream infections.

“…PCR method is usually employed to determine the capsular serotype but is laborious and not logistically applicable to all hospital settings. Compared to these methods, the immunochromatographic method [13] is very simple to perform and is possible to obtain the result within a few minutes. Even though the commercial product of this method is currently approved only in Taiwan for the clinical diagnosis of HVKp infections, and it can detect only capsular serotypes K1 and K2, it is an attractive tool to quickly identify capsular serotype K1.…”

A Novel Diagnostic Method to Detect Duck Tembusu Virus: A Colloidal Gold-Based Immunochromatographic Assay

“…The rapid and accurate detection is crucial to help determine whether to initiate treatment, and it will also reduce economic losses in the animal industry ( Kim et al, 2015 ). In our study, in order to evaluate how practical for detecting DTMUV, we detected 50 samples with ICS and RT-PCR ( Zhang et al, 2015b ; Siu et al, 2016 ; Zeng et al, 2016 ; Zhao et al, 2016 ). As expected, the results detected by ICS were generated within 10 min, which was significantly shorter than the time taken to do RT-PCR (about 5 h).…”

“…For the coincidence rate of ICS and reverse-transcription polymerase chain reaction (RT-PCR) ( Sun et al, 2014 ; Zhang et al, 2015a ; Siu et al, 2016 ; Zeng et al, 2016 ), a total of 50 clinical samples (i.e., 35 clinical samples and 15 positive allantoic fluid samples) collected in the field from different duck farms were tested by the ICS. Before detection, the samples were homogenized with an electrical tissue homogenizer (ARTMICCRA D-9, Germany) in PBS containing antibiotics (20% w/v).…”

Virulence Differences in Hypervirulent Klebsiella pneumoniae between Isolates with Multi-Locus Sequence Type (MLST)-11 and Serotype K1 or K2 Strains

“…Isolates were collected from a previous study [14]. Serotyping K1 and K2 was performed by a rapid testing cassette and PCR [15,16]. For nonserotype K1/K2 from rapid testing, serotyping was performed by using wzi and wzc sequencing [17,18] and capsule-speci c primers for serotyping [19].…”