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Year : 2009  |  Volume : 52  |  Issue : 2  |  Page : 294
Biofilm production in uropathogenic Escherichia coli

Department of Microbiology, Pt. B.D. Sharma, PGIMS, Rohtak, India

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How to cite this article:
Sharma M, Aparna, Yadav S, Chaudhary U. Biofilm production in uropathogenic Escherichia coli. Indian J Pathol Microbiol 2009;52:294

How to cite this URL:
Sharma M, Aparna, Yadav S, Chaudhary U. Biofilm production in uropathogenic Escherichia coli. Indian J Pathol Microbiol [serial online] 2009 [cited 2022 Jan 28];52:294. Available from: https://www.ijpmonline.org/text.asp?2009/52/2/294/48960


Biofilms are the most common mode of bacterial growth in nature and are also important in clinical infections. Urinary tract infections (UTIs) are considered to be one of the most common bacterial infections. Uropathogenic strains of  Escherichia More Details coli account for 70-95% of the UTIs. Bacteria that invade the bladder cells and grow into structural colonies known as biofilms may be responsible for many recurrent UTIs. [1] The bacteria enclosed within the biofilm are extremely resistant to treatment. This may be because the drug concentrations obtained may be insufficient in certain areas of the film. The bacteria located at the base of the biofilm are metabolically inactive and are thus resistant to certain antibiotics and possess active antibiotic degradation mechanisms that contribute to avoid the accumulation of an effective drug concentration. [2]

Eighty non-repetitive, clinical isolates of E. coli isolated from cases of UTIs received in the Microbiology Department, Pt. B.D.S, PGIMS, Rohtak, were investigated. The clinical data were analyzed retrospectively. The patients were divided into three groups, namely: catheter-associated infections, asymptomatic bacteriuria and symptomatic bacteriuria. The organisms were identified by conventional microbiological methods. [3] The antibiotic susceptibility test was carried out by Kirby Bauer disc diffusion technique [4] using norfloxacin, nitrofurantoin, gatifloxacin, ceftizoxime, gentamycin, amoxyclav, cotrimoxazole and amoxicillin. All the isolates were then screened for biofilm production by using a crystal violet binding assay in a 96-well microtiter plate and the optical density values were determined using an enzyme-linked immunosorbant assay reader at 600 nm. [5] E. coli ATCC 25922 was used as a positive control.

In this study, of the 80 patients, 49 were males and 31 were females. Catheter-associated UTIs were the most common. Significant production of biofilm was seen in 54 (67.5%) isolates of E. coli whereas Suman et al. [6] have reported a higher rate of biofilm production (92.0%). Biofilm production was more in patients with catheters (70.3%) [Table 1]. Antibiotic sensitivity of the biofilm-producing isolates ranged from 16 to 57% while it was 38-76% for non-biofilm producers in our study. Non-biofilm-producing E. coli were sensitive to nitrofurantoin, amoxyclav and ceftizoxime. Amoxyclav and nitrofurantoin were the most effective antibiotics for E. coli growing as biofilms.

Biofilms producing E. coli are recalcitrant to immune factors and antibiotic therapy and are often responsible for chronic UTIs. Usually, floating cells are completely eradicated at the antibiotic levels predicted by laboratory minimum inhibitory concentration (MIC) studies. However, more than 100 times the MIC of antibiotics is required to eradicate cells within the biofilm. Therefore, an effectual control will need an intensive effort to build up newer therapeutic agents that aim to prevent the formation of biofilms or encourage the biofilm detachment.

   References Top

1.Ward DE. Biofilms may be responsible for recurring bladder infections. Record [serialonline]. 2003;28. Available from: http://record.wustl.edu/news/page/normal/2096.html. [last accessed on 2008 Jul 21].  Back to cited text no. 1    
2.Costerton JW, Stewart PS, Greenberg EP. Bacterial biofilms: A common cause of persistent infections. Science 1999;284:1318-22.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Collee JG, Duguid JP, Fraser AG, Marmion BP, Simmons A. Laboratory strategy in the diagnosis of infective syndromes. In: Collee JG, Fraser AG, Marmion BP, Simmons A, editors. Mackie and McCartney Practical Medical Microbiology. 14 th ed. Singapore: Churchill Livingstone; 1996. p. 53-94.  Back to cited text no. 3    
4.Bauer AW, Kirby WM, Sherris JC, Turck M. Antibiotic susceptibility testing by a standardized single disk method. Am J Clin Pathol 1966;45:493-6.  Back to cited text no. 4  [PUBMED]  
5.O'Toole GA, Kolter R. Initiation of biofilm formation in Pseudomonas fluorescens WCS365 proceeds via multiple, convergent signalling pathways: A genetic analysis. Mol Microbiol 1998;28:449-61.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]
6.Suman E, Jose J, Varghese S, Kotian MS. Study of biofilm production in Escherichia coli causing urinary tract infection. Indian J Med Microbiol 2007;25:305-6.  Back to cited text no. 6  [PUBMED]  Medknow Journal

Correspondence Address:
Madhu Sharma
74, Vijay Park, Sonepat Road, Rohtak -124 001, Haryana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.48960

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