Whey powder: a potential anti-diarrheal agent through its biofilm formation.

Whey, the natural product resulting from coagulation of milk is reported to have diverse pharmaceutical credentials. In the present investigation the anti-diarrhoeal activity of the whey powder was investigated. The Whey powder which was prepared using rennet powder and lactic acid, was studied against Magnesium sulphate-induced Diarrhea in Swiss Albino mice. Castor oil-induced enteropooling studies and in vitro biofilm-forming potentials of the whey powder were also carried out, as this is believed to contribute to the anti-diarrhoeal activities of the preparation. Anti-diarrhoeal activity was more pronounced in mice which received 250 mg kg b.wt. of whey powder when compared to those which received 500 mg kg(-1) b.wt. The percentage inhibition of total number of feces in the 250 mg kg(-1) b.wt. drug-treated group was 56.14%,whereas the animals which received 500 mg kg(-1) b.wt. of whey powder showed 37.18% inhibition. The loperamide treated animal group showed 63.81% inhibition. In castor oil induced enteropooling, the percentage inhibition of intestinal content in the 250 mg kg(-1) b.wt. drug-treated group was 61.42% against atropine-treated animal group that showed 26.24% inhibition. The whey powder also exhibited strong biofilm forming capacity with increase in concentration. The anti-diarrhoeal activity of whey preparation established herein is believed to be owing to certain active principles present in it or due to biofilm-forming capacity, which inhibits the attachment of mediators of diarrhoea to mucosal walls of the GI tract or due to interaction of diarrhoea inducing chemicals with whey peptides, which needs further investigation.

Identification of natural compounds which inhibit biofilm formation in clinical isolates of Klebsiella pneumoniae.

Klebsiella pneumoniae, an important opportunistic pathogen, exists as a biofilm in persistent infections and in-dwelling medical devices. With the objective of identifying natural compounds inhibiting biofilm formation in K. pneumoniae, 35 clinical isolates were screened,out of which 7 strong biofilm producers were identified. Six natural compounds were tested for their inhibitory effects on bacterial growth and biofilm formation by determining the minimum inhibitory concentration and minimum concentration for biofilm inhibition (MBIC) for each compound. The results show that reserpine followed by linoleic acid, were the most potent biofilm inhibitors. Reserpine, an efflux pump inhibitor was effective at biofilm inhibition at a concentration of 0.0156 mg/mL, 64-fold lower concentration than its MIC. Linoleic acid, an essential fatty acid was effective as a biofilm inhibitor at 0.0312 mg/mL, which is 32-fold lower than its MIC. Berberine, another plant derived antimicrobial, chitosan and eugenol had an MBIC value of 0.0635 mg/mL. Curcumin, a natural phenolic compound was effective at biofilm inhibition at a concentration of 0.25 mg/mL, which is 50 fold less than its MIC. Notably, the MIC and MBIC data on these 6 natural compounds was reproducible in all seven high biofilm forming isolates of K. pneumoniae. The present report is a comprehensive comparative analysis of the dose dependent inhibition of various natural compounds on biofilm formation in K. pneumoniae.

Identification of plasmid-mediated quinolone resistance genes qnrA1, qnrB1 and aac(6')-1b-cr in a multiple drug-resistant isolate of Klebsiella pneumoniae from Chennai.

PURPOSE: Resistance to fluoroquinolones, a commonly prescribed antimicrobial for Gram-negative and Gram-positive microorganisms, is of importance in therapy. The purpose of this study was to screen for the presence of Plasmid-Mediated Quinolone Resistance (PMQR) determinants in clinical isolates of Klebsiella pneumoniae. MATERIALS AND METHODS: Extended-Spectrum Beta-Lactamase (ESBL) isolates of K. pneumoniae collected during October 2009 were screened by the antimicrobial susceptibility test. The plasmids from these isolates were analysed by specific Polymerase chain Reaction (PCR) for qnrA, qnrB and aac(6')-1b. The amplified products were sequenced to confirm the allele. RESULTS: Our analysis showed that 61% out of the 23 ESBL K. pneumoniae isolates were resistant to ciprofloxacin and 56% to levofloxacin. The PMQR was demonstrated by transforming the plasmids from two isolates P12 and P13 into E. coli JM109. The PMQR gene qnrA was found in 16 isolates and qnrB in 11 isolates. The plasmid pKNMGR13 which conferred an minimum inhibitory concentration (MIC) of more than 240 µg/ml in sensitive E. coli was found to harbour the qnrA1 and qnrB1 allele. Furthermore, the gene aac(6')-1b-cr encoding a variant aminoglycoside 6'-N Acetyl transferase which confers resistance to fluoroquinolones was found in the same plasmid. CONCLUSIONS: Our report shows the prevalence of PMQR mediated by qnrA and qnrB in multidrug-resistant K. pneumoniae isolates from Chennai. A multidrug-resistant plasmid conferring high resistance to ciprofloxacin was found to harbour another PMQR gene, aac(6')-1b-cr mutant gene. This is the first report screening for PMQR in K. pneumoniae isolates from India.