*¹Otaru, B. M., 2Aikhomu V., and ¹Oladele, R. O.
¹Department of Medical Microbiology and Parasitology, College of Medicine, University of Lagos, Lagos, Nigeria
2Department of Medical Microbiology, Lagos University Teaching Hospital (LUTH), Lagos, Nigeria
*Correspondence to: otaruboluwatife@gmail.com; Tel: +2348140528910; ORCID: 0009-0003-9413-7832
Abstract:
Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections pose a major challenge due to limited therapeutic options. Biofilm formation has been proposed as a potential contributor to antimicrobial resistance; however, evidence regarding its association with carbapenem resistance in K. pneumoniae remains conflicting. Notably, data from Nigeria are scarce. The objective of this study is to compare biofilm formation between carbapenem-resistant and carbapenem susceptible K. pneumoniae (CRKP and CSKP) isolated from blood samples.
Methodology: This comparative laboratory-based study analysed 46 stored blood culture isolates of K. pneumoniae from a tertiary hospital in Nigeria. Re-identification was done using VITEK® 2 automated system and carbapenem susceptibility testing was carried out using Kirby-Bauer disc diffusion method. Two methods of biofilm formation assessment; Congo Red Agar (CRA) and microtiter plate assay, were used. Statistical analysis was done using Fisher Exact test, with Odds ratio and 95% confidence interval, and p<0.05 considered statistical significance. For statistical analysis of biofilm strength determined by the microtiter plate assay, isolates were dichotomised into strong and non-strong biofilm producers.
Results: A total of 46 K. pneumoniae blood isolates were studied, of which 30 (65.2%) were CSKP and 16 (34.8%) were CRKP. Using the CRA method, 16 isolates (34.8%) were biofilm-positive, while 30 (65.2%) were negative; 6 of 16 (37.5%) CRKP and 10 of 30 (33.3%) CSKP isolates were biofilm formers, but the difference was not statistically significant (OR=1.200; 95% CI=0.3385-4.254; p=1.000). Similarly, the microtiter plate assay identified 42 isolates (91.3%) as strong biofilm producers and 4 (8.7%) as non-strong biofilm producers; 14 of 16 (87.5%) CRKP and 28 of 30 (93.3%) CSKP isolates were strong biofilm producers, but the difference was also not statistically significant (OR=0.500; 95% CI=0.06355-3.934; p=0.6019).
Conclusion: Our study found no significant association between carbapenem resistance and biofilm formation, suggesting that biofilm formation may act as an independent bacterial survival strategy rather than a direct contributor to carbapenem resistance.
Keywords: Klebsiella pneumoniae, Biofilm formation, Carbapenem resistance, Congo Red Agar, Microtiter plate assay
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