Indian Journal of Pathology and Microbiology

: 2014  |  Volume : 57  |  Issue : 1  |  Page : 159--160

Biofilm production in Gram-positive isolates causing urinary tract infection in a tertiary care hospital

Pragyan Swagatika Panda1, Uma Choudhary1, Sarita Yadav1, Surya K Dube2,  
1 Department of Microbiology, Pt. B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
2 Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi, India

Correspondence Address:
Pragyan Swagatika Panda
Department of Microbiology, Pt. B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana

How to cite this article:
Panda PS, Choudhary U, Yadav S, Dube SK. Biofilm production in Gram-positive isolates causing urinary tract infection in a tertiary care hospital.Indian J Pathol Microbiol 2014;57:159-160

How to cite this URL:
Panda PS, Choudhary U, Yadav S, Dube SK. Biofilm production in Gram-positive isolates causing urinary tract infection in a tertiary care hospital. Indian J Pathol Microbiol [serial online] 2014 [cited 2021 Sep 26 ];57:159-160
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Biofilm production by uropathogens may promote colonization leading to recurrent and multi drug resistant urinary tract infection (UTI).Owing to high-level natural resistance to current antibiotics infections caused by Staphylococcus epidermidis, Staphylococcus aureus and the enterococci, are difficult to treat. Furthermore, these organisms become resistant to the highest deliverable levels of antibiotics when growing in a biofilm. It is estimated that 60% of nosocomial infections are derived from biofilm-related infections, many of which are caused by coagulase-negative staphylococci (CONS). [1] Enterococcal UTIs occur primarily in older man, particularly in association with urinary tract manipulation or instrumentation or prostatic hypertrophy. [2] S. epidermidis, which is a common urinary isolate hospitalized patients older than 50 years of age is associated with UTI in about 20% of cases. [2] Staphylococcus saprophyticus accounts for 10-15% of acute symptomatic UTIs in young female patients. Isolation of S. aureus from the urine is very often related bacteremia infection of the kidney. [3] Unfortunately in current literature studies on biofilm formation in Enterococcus spp (which is a very important cause of UTI) and by other UTI causing Gram-positive cocci (GPC) are scarce. Hence, the present study was prospectively carried out to investigate the biofilm production by UTI causing GPC.

A total of 35 non-repetitive clinical isolates (26 of S. aureus; 4 of CONS; 4 of Enterococcus faecalis and 1 of E. faecium) isolated from cases of UTIs, were prospectively investigated for biofilm production. The isolates were identified by standard microbiological techniques. All the isolates were then screened for biofilm production by using tissue culture plate (TCP), [4] tube method (TM), [5] Congo red agar (CRA) [5] and modified Congo red agar method (MCRA) [6] American Type Culture Collection (ATCC) strain S. aureus (ATCC 25923) was used as the positive control. [7]

Out of the 35 isolates all the CONS were isolated from female patients. Biofilm production was detected in 54.2% (19/35) cases by TCP, followed by 51.4% (18/35), 34.2% (12/35) and 22.8% (8/35) cases by TM, MCRA and CRA method respectively [Table 1].Considering the TCP method as the gold-standard sensitivity, specificity for other three method is shown in [Table 2]. In their study on 152 isolates of Staphylococci Mathur et al., have reported biofilm production in 47.3%, 41.4% and 5.2% isolates by TCP, TM and CRA method respectively. [5] They reported the modified TCP method as the most sensitive (96.2%) and specific (94.5%) method for biofilm detection as compared to TM (77.9% and 96.0%) and CRA method (7.6% and 97.2%). [5] Oliviera and associates, [8] observed the biofilm production in 82% cases by TM followed by 81% and 73% cases by TCP and CRA method respectively among 100 isolates of CONS. Our findings are similar to that of Mathur et al., [5] but in contrast to the findings by Oliviera et al., [8] where TM had higher biofilm detection rate than the TCP. The difference in the results could be attributable to the difference in interpretation of results of TM which require subjective visual interpretation. In a study by Mariana et al., [6] among the 100 methicillin resistant Staphlococcus aureus (MRSA) clinical strains investigated, 78% of isolates produced strong biofilm on standard CRA while in the MCRA, all of MRSA strains formed strong biofilm. Our study findings are in accordance with the above with more biofilm production by MCRA method compared with CRA. Dworniczek et al., [9] have reported biofilm production in 59% of E. faecalis isolates from different clinical specimens by Tissue culture method which was less when compared to our study (75%).{Table 1}{Table 2}

In our study, we conclude that biofilm formation in UTI causing GPCs is high and TCP is the most sensitive method for biofilm detection, but CRA is a simple method that could be used to determine whether an isolate has the potential for biofilm production or not, i.e., for the screening of the isolates. However, MCRA is a better method compared with CRA for S. aureus [Table 1] which can set the stage for future work focused on these methods.


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