A Study of Antibacterial Effect of Nigella sativa Seed Extracts on Bacterial Isolates from Cases of Wound Infection.

BACKGROUND: With an increasing trend of pathogenic bacteria developing resistance to the existing drugs, there is a need for newer therapeutic measures. Nigella sativa seeds and oil have been used for decades as Ayurveda, Unani Tibb and other forms of traditional medicine for various disorders. Thymoquinone is one of the active components of the N. sativa seeds. OBJECTIVE: The present study determines the antibacterial effect of crude methanolic extract N. sativa seeds and thymoquinone against bacteria causing wound infection. METHODS: Samples obtained from cases of wound infection received at a Microbiology laboratory attached to a tertiary care hospital over a period of six months were included in the study. The antibacterial effect of crude methanolic extract of N. sativa seeds was determined by the Punch Well method. The minimum inhibitory concentration (MIC) of thymoquinone against bacteria isolated from cases of wound infection was determined by the Micro Broth Dilution technique. RESULTS: A total of 60 isolates were collected from 60 samples of wound infection. By the Punch Well method, Staphylococcus aureus showed varying zones of inhibition whereas all gram-negative bacilli and Enterococcus faecalis did not show any zone of inhibition. Thymoquinone showed good antibacterial activity against S. aureus with MIC values ranging from 2-8µg/ml for most of the isolates. Uniformly, MIC of thymoquinone against all gram-negative bacilli and E. faecalis was >128µg/ml, p<0.001. It was found that methicillin-resistant S. aureus (MRSA) isolates showed higher MIC than methicillin sensitive S. aureus (MSSA) isolates p<0.05. CONCLUSION: Antibacterial activity of thymoquinone was very good against S. aureus but showed limited activity against Enterobacteriaceae members and E. faecalis isolated from patients with wound infection. Thymoquinone may be considered a potential antibacterial agent against wound infection caused by S. aureus.

Genotypic and Phenotypic Expression of Antibiotic Resistance Patterns of Uropathogenic Enterobacteriaceae.

Aim: To determine the antibiotic resistance patterns, detection of carbapenemase genes in uropathogenic bacilli belonging to the Enterobacteriaceae family and to correlate it with clinical data. Materials and Methods: Identification and antibiotic sensitivity testing of the uropathogenic Enterobacteriaceae was done by using VITEK2 Compact (C) system. Multiplex PCR was used to detect blaIMP, blaKPC, blaNDM1, blaOXA -48, and blaVIM genes. Results: Out of 1602 urine samples, 417 (26%) showed significant growth, and in these 311 (74.6%) belonged to the Enterobacteriaceae family. Escherichia coli showed a relatively low rate of resistance to nitrofurantoin (17/205; 8.3%), with the majority of the isolates showing a MIC value of ≤16 µg/mL when compared to Klebsiella spp. (55/86; 64%), with MIC values for the majority of isolates being 128 µg/mL. Klebsiella spp. showed a relatively low rate of resistance to nalidixic acid (48/86; 55.8%) when compared with E. coli isolates (179/205; 87.3%). Out of 145 isolates tested, we found blaNDM in 11 (7.58%), bla OXA -48 in 8 (5.51%), bla VIM in 4 (2.75%), bla KPC in one (0.6%) and blaIMP in none of the isolates. Of these 3 isolates were carbapenem sensitive, the rest were resistant. Conclusion: Most of the isolates were sensitive to fosfomycin, carbapenems and resistant to cephalosporins and nalidixic acid. We detected carbapenemase genes in 13 (59%) out of 22 carbapenem resistant isolates and 3 (2.4%) out of 123 carbapenem sensitive isolates.

Comparative analysis of virulence factors & biotypes of Gardnerella vaginalis isolated from the genital tract of women with & without bacterial vaginosis.

BACKGROUND & OBJECTIVES: : Bacterial vaginosis (BV) involves the presence of a thick vaginal multispecies biofilm, where Gardnerella vaginalis is the predominant species. The reason for an increase in the number of G. vaginalis which are usually present as normal flora of the female genital tract in cases of BV, is not known. Hence, the objective of the present study was to compare the biotypes and virulence factors of G. vaginalis isolated from the genital tract of women with and without BV. METHODS: : High vaginal swabs collected from 811 women of reproductive age were cultured. G. vaginalis isolates were biotyped and tested for adherence to vaginal epithelial cells, biofilm formation, agglutination of human red blood cells (RBCs), protease production, phospholipase production and surface hydrophobicity. RESULTS: : Of the isolates from women with BV, 83.3 per cent (60/72) showed good adherence, 78.4 per cent (58/74) produced biofilm, 82.9 per cent (63/76) produced phospholipase, 67.1 per cent (51/76) produced protease, 77.3 per cent (58/75) were positive for surface hydrophobicity and 61.6 per cent (45/73) were positive for haemagglutination of human RBC. In case of G. vaginalis from non-BV women, 25 per cent (15/60) isolates showed good adherence, 18.4 per cent (9/49) biofilm production, 35 per cent (21/60) phospholipase, 36.6 per cent (22/60) protease, 41.7 per cent (25/60) surface hydrophobicity and 10.1 per cent (6/59) agglutination of human RBCs. Maximum number of isolates belonged to biotypes 6, 2 and 3. Biotype 3 was more associated with non-BV rather than BV; biotype 6, 2 and 1 were more associated with cases of BV. Maximum virulence factors were expressed by biotypes 6, 2 and 1. INTERPRETATION & CONCLUSIONS: : Virulence factors were more expressed by G. vaginalis isolates obtained from women with BV rather than from non-BV. Biotypes 6, 2 and 1 were more associated with cases of BV and expressed maximum virulence factors.