Correlation between Biofilm Formation and Multi-Drug Resistance among Clinical Isolates

Biofilms are often found in communities of microorganisms in chronic and persistent infections, exhibiting high resistance against antimicrobial agents. Biofilm serves as a barrier, impeding the penetration of drugs and constraining their effectiveness. Multiple methods, such as the Tissue Culture Plate method, Congo Red Agar method, Tube method, bioluminescent assay, and fluorescent microscopic examination, can be used to evaluate biofilm production.

The study included a total of 300 clinical isolates representing a range of bacterial species, including Acinetobacter baumannii (n=9), Coagulase Negative Staphylococcus (n=7), Enterobacter aerogenes (n=7), Enterococcus faecalis (n=15), Escherichia coli (n=137), Klebsiella pneumoniae (n=23), Proteus mirabilis (n=4), Pseudomonas aeruginosa (n=16), Salmonella typhi (n=11), and Staphylococcus aureus (n=68). Associations among isolates capable and incapable of biofilm formation and their multidrug resistance phenotypes were evaluated.

Among the 300 clinical isolates tested, 289 isolates (96.3%) exhibited biofilm formation. The most prevalent biofilm-forming organisms were A. baumannii (n=9), Citrobacter koseri (n=1), Coagulase Negative Staphylococcus (CONS) (n=7), E. aerogenes (n=7), E. faecalis (n=15), E. coli (n=137), Klebsiella oxytoca (n=1), K. pneumoniae (n=23), P. mirabilis (n=4), P. aeruginosa (n=16), S. typhi (n=11), S. aureus (n=68), and Streptococcus pneumoniae (n=1). The biofilm-forming isolates demonstrated increased resistance compared to isolates that did not form biofilms.

Antimicrobial resistance represents a critical characteristic of infections involving biofilms. The study identified biofilm production in 92.7% of the isolates tested via TCP and in 72.3% of the isolates using the CRA. Furthermore, it was observed that pathogens with multidrug resistance (MDR) exhibited a higher biofilm production tendency than non-producing pathogens.