Identification of Common Bacterial Infection and Detection of Biofilm Formation Associated with Exacerbation in Patients with Bronchiectasis

Document Type : Review articles

Authors

1 Medical Microbiology & Immunology, Faculty of Medicine, Tanta University, Egypt

2 Chest Diseases Department, Faculty of Medicine, Tanta University, Egypt

Abstract

Background: Bronchiectasis is a significant chronic clinical problem. Objective: this study aimed to identify bacteria causing acute exacerbations of bronchiectasis, determine their antibiotic resistance, evaluate the Diff-Quik stain for rapid pathogen detection, and assess biofilm formation. Methodology: A total of 50 samples were collected from hospitalized patients with acute bronchiectasis exacerbations. Standard bacteriological methods, Diff-Quik staining, CLSI-guided antimicrobial susceptibility testing, and tissue culture plate biofilm assays were performed. Results: In this study of 50 hospitalized patients with acute bronchiectasis exacerbations, P. aeruginosa was the most frequently isolated bacterium (31.1%) and was significantly associated with COPD and frequent exacerbations (>3/year). Of the P. aeruginosa isolates, 42.9% were MBL-positive by eCIM. Among those, 83.3% were aztreonam sensitive. Carbapenem resistance (CR) was significantly observed in K. pneumoniae, with 100% of tested CRKP positive for mCIM. ESBL and AmpC production were significant in K. pneumoniae and E. coli. Diff-Quik showed higher sensitivity (90%) and accuracy (81.4%) than Gram stain (68% and 68.6%, respectively), but lower specificity (60% vs. 70%). Regarding biofilm production in Gram-negative bacteria, 2.3% were strong producers (all P. aeruginosa), 22.7% were intermediate, and 56.8% were weak. Conclusion: Gram-negative bacteria, particularly P. aeruginosa and K. pneumoniae, were the predominant isolates. MDR strains, including ESBL, AmpC, and CR, were common in Gram-negative bacteria. Diff-Quik staining was more sensitive and accurate but less specific than Gram stain. Weak biofilm production was common in Gram-negative isolates, with strong biofilm formation observed only in P. aeruginosa.

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