Abstract
BackgroundIn Asia, serotype K1/K2 Klebsiella pneumoniae are the major capsular serotypes that cause liver abscess or bacteremia in patients. The purpose of this study was to compare novel immunochromatographic strips (ICSs), which can rapidly detect K. pneumoniae serotypes K1/K2 in clinical samples, to conventional capsular serotyping methods.MethodsPus drainage samples from 16 patients with a liver abscess caused by K. pneumoniae, blood samples from 112 positive flagged blood culture bottle and a subsequent single colony in the medium were tested with the ICS. The results were then compared to findings of capsular swelling tests. Samples subjected to the polymerase chain reaction (PCR) analysis were used as reference.ResultsThe identification of K. pneumoniae via the traditional bacterial culture from pus samples took 3.4 days on average (ranging from 2.2 to 5.5 days). Further capsular serotyping of K. pneumoniae by the capsular swelling test of pure isolates lasted 5–10 min, and the PCR method took ~ 4 h. As for ICSs, the time for direct identification of the K. pneumoniae capsular serotype K1/K2 in pus was < 4 min (ranging from 2 to 4 min). The results of ICSs were consistent with capsular swelling tests and PCR methods. Testing of 112 blood culture samples and subsequent single colonies in the medium with ICSs yielded consistent results for most samples.ConclusionsThis study indicates that ICSs can rapidly detect K. pneumoniae serotypes K1 and K2 in pus or positive flagged blood culture broth samples within 5 min. Their accuracy is comparable to that of the conventional capsular serotyping methods such as a serum agglutination assay or PCR.
Highlights
In Asia, serotype K1/K2 Klebsiella pneumoniae are the major capsular serotypes that cause liver abscess or bacteremia in patients
The direct detection of K. pneumoniae capsular serotypes in clinical samples is possibly based on the polymerase chain reaction (PCR) assay, false negatives may sometimes occur due to interference from a non purified DNA samples
immunochromatographic strips (ICSs) immunochromatographic strip a Two non-K1/K2 isolates from blood culture broth samples were identified as the K2 serotype in subsequent single colony broth samples and further serotyping by PCR confirmed serotype K5
Summary
In Asia, serotype K1/K2 Klebsiella pneumoniae are the major capsular serotypes that cause liver abscess or bacteremia in patients. Appropriate early antibiotic treatment—with the aim of decreasing mortality and morbidity related to pyogenic liver abscesses caused by K. pneumoniae—is an important clinical task It usually takes at least 3 days to isolate K. pneumoniae from pus and identify it via blood cultures in the traditional clinical laboratory setting, and serotyping is not routinely performed. The capsular swelling test via anti-capsular type sera, countercurrent immunoelectrophoresis from pure isolates, or polymerase chain reactions (PCRs) have been used to identify K. pneumoniae capsular serotypes. They take hours to days when bacterial cultures or direct clinical samples are used [5, 6]. Preparation of purified DNA may be needed to increase the accuracy of detection in a PCR assay
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