Background: This study investigated the diagnostic utility of the BioFire FilmArray Pneumonia Panel (PN panel), an automated and multiplexed nucleic acid detection system that rapidly detects 26 pathogens (18 bacteria and eight viruses) and seven antimicrobial resistance markers in a single assay. Methods: We analyzed the targets in lower respiratory tract specimens using the PN panel and compared the detection results with those of bacterial culture methods and antimicrobial susceptibility testing. Results: Of the 57 samples analyzed, the PN panel detected 97 targets (84 bacteria, four viruses, and nine antimicrobial resistance markers). Detection of bacteria and antimicrobial resistance was three times greater than that of the bacterial culture (25 bacteria and two resistant isolates) against the targets available in the panel. The overall positive and negative percent agreements between the PN panel and culture methods for bacterial detection were 100.0% and 92.9%, respectively. Multiple pathogens were detected by the PN panel in 24 samples (42.1%), ranging from two pathogens in 11 samples (19.3%) to six pathogens in one sample (1.8%). The PN panel semiquantitatively detected higher copies (≥ 10⁶ copies/mL) of bacterial targets if the bacteria were positive by the culture method. In contrast, the semiquantitative values obtained by the panel varied (10⁴ to 10⁷ ≤ copies/mL) among bacteria that were negative by the culture method. Conclusions: The PN panel enhanced the detection of pathogens and antimicrobial resistance markers in lower respiratory tract specimens.

Plasma levels of high mobility group box chromosomal protein-1 (HMGB-1), as well as of other inflammatory molecules such as interleukin-6 (IL-6), regulated on activation normal T-cell expressed and secreted (RANTES), and soluble intercellular adhesion molecule-1 (sICAM-1), were determined in patients with bacterial pneumonia coinfected with influenza virus. HMGB-1 levels were significantly elevated in these patients compared to patients undergoing mild bacterial pneumonia alone (p<0.01). Among cases of coinfection, we found a significant correlation between the concentration of HMGB-1 and white blood cell counts (p<0.05, r=0.612). Levels of IL-6 were also higher in these patients than in patients with bacterial pneumonia alone (p<0.05), despite similar levels of RANTES and sICAM-1 in the 2 groups. These data suggest that HMGB-1 is involved in the pathogenesis of severe bacterial pneumonia coinfected with influenza virus.

The MALDI Biotyper Selective Testing of Antibiotic Resistance-β-Lactamase (MBT STAR-BL) assay, which analyzes bacterial induced hydrolysis of cefotaxime using MALDI-TOF MS, correctly identified 100.0% of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae as positive and 94.7% of non-ESBL producers as negative in 80 strains tested.

We investigated the clinical features of bloodstream infections (BSIs) caused by Klebsiella pneumoniae harboring rmpA and molecular characteristics of the bacteria. We retrospectively investigated adult patients with K. pneumoniae BSI from January 2010 to March 2021 at Nagasaki University Hospital. A matched case–control study in a 1:3 ratio was conducted to clarify the clinical and bacterial characteristics of BSI caused by rmpA-positive K. pneumoniae compared with those caused by rmpA-negative isolates. Antimicrobial susceptibility testing and multilocus sequence typing (MLST) were performed for rmpA-positive isolates. The rmpA was detected in 36 (13.4%) of the 268 isolates. Of these 36 isolates, 31 (86.1%) harbored iucA and 35 (97.2%) each possessed peg-344 and iroB; capsular types were identified as K1 in 9 (25.0%) and K2 in 10 isolates (27.8%). Contrarily, of the 108 rmpA-negative isolates, which were matched for case–control studies, 5 isolates (4.6%) harbored iucA and 1 (0.9%) each possessed peg-344 and iroB; 2 (1.9%) and 3 isolates (2.8%) had K1 and K2 capsular types, respectively. Among the rmpA-positive isolates, ST23/K1 (eight isolates) was the most frequent, followed by ST412/non-K1/K2 (seven isolates), ST86/K2 (five isolates), and ST268/non-K1/K2 (four isolates). In a multivariate analysis using clinical factors, liver abscess positively correlated with rmpA-positive isolates, whereas biliary tract infection and use of anticancer drugs negatively correlated with rmpA-positive isolates in patients with K. pneumoniae BSI. Considering the correlation between rmpA-positive isolates and clinical features, rmpA can be used as a marker for understanding the pathophysiology of K. pneumoniae BSI.